[dev.simd] all: merge master (9b2d39b) into dev.simd

Conflicts:

- src/internal/buildcfg/exp.go

Merge List:

+ 2025-09-22 9b2d39b75b cmd/compile/internal/ssa: match style and formatting
+ 2025-09-22 e23edf5e55 runtime: don't re-read metrics before check in TestReadMetricsSched
+ 2025-09-22 177cd8d763 log/slog: use a pooled json encoder
+ 2025-09-22 2353c15785 cmd/cgo/internal/test: skip TestMultipleAssign when using UCRT on Windows
+ 2025-09-22 32dfd69282 cmd/dist: disable FIPS 140-3 mode when testing maphash with purego
+ 2025-09-19 7f6ff5ec3e cmd/compile: fix doc word
+ 2025-09-19 9693b94be0 runtime: include stderr when objdump fails
+ 2025-09-19 8616981ce6 log/slog: optimize slog Level.String() to avoid fmt.Sprintf
+ 2025-09-19 b8af744360 testing: fix example for unexported identifier
+ 2025-09-19 51dc5bfe6c Revert "cmd/go: disable cgo by default if CC unset and  DefaultCC doesn't exist"
+ 2025-09-19 ee7bf06cb3 time: improve ParseDuration performance for invalid input
+ 2025-09-19 f9e61a9a32 cmd/compile: duplicate nil check to two branches of write barrier
+ 2025-09-18 3cf1aaf8b9 runtime: use futexes with 64-bit time on Linux
+ 2025-09-18 0ab038af62 cmd/compile/internal/abi: use clear built-in
+ 2025-09-18 00bf24fdca bytes: use clear in test
+ 2025-09-18 f9701d21d2 crypto: use clear built-in
+ 2025-09-18 a58afe44fa net: fix testHookCanceledDial race
+ 2025-09-18 3203a5da29 net/http: avoid connCount underflow race
+ 2025-09-18 8ca209ec39 context: don't return a non-nil from Err before Done is closed
+ 2025-09-18 3032894e04 runtime: make explicit nil check in heapSetTypeSmallHeader
+ 2025-09-17 ef05b66d61 cmd/internal/obj/riscv: add support for Zicond instructions
+ 2025-09-17 78ef487a6f cmd/compile: fix the issue of shift amount exceeding the valid range
+ 2025-09-17 77aac7bb75 runtime: don't enable heap randomization if MSAN or ASAN is enabled
+ 2025-09-17 465b85eb76 runtime: fix CheckScavengedBitsCleared with randomized heap base
+ 2025-09-17 909704b85e encoding/json/v2: fix typo in comment
+ 2025-09-17 3db5979e8c testing: use reflect.TypeAssert and reflect.TypeFor
+ 2025-09-17 6a8dbbecbf path/filepath: fix EvalSymlinks to return ENOTDIR on plan9
+ 2025-09-17 bffe7ad9f1 go/parser: Add TestBothLineAndLeadComment
+ 2025-09-17 02a888e820 go/ast: document that (*ast.File).Comments is sorted by position
+ 2025-09-16 594deca981 cmd/link: simplify PE relocations mapping
+ 2025-09-16 9df1a289ac go/parser: simplify expectSemi
+ 2025-09-16 72ba117bda internal/buildcfg: enable randomizedHeapBase64 by default
+ 2025-09-16 796ea3bc2e os/user: align test file name and build tags
+ 2025-09-16 a69395eab2 runtime/_mkmalloc: add a copy of cloneNode
+ 2025-09-16 cbdad4fc3c cmd/go: check pattern for utf8 validity before call regexp.MustCompile
+ 2025-09-16 c2d85eb999 cmd/go: disable cgo by default if CC unset and  DefaultCC doesn't exist
+ 2025-09-16 ac82fe68aa bytes,strings: remove reference to non-existent SplitFunc
+ 2025-09-16 0b26678db2 cmd/compile: fix mips zerorange implementation
+ 2025-09-16 e2cfc1eb3a cmd/internal/obj/riscv: improve handling of float point moves
+ 2025-09-16 281c632e6e crypto/x509/internal/macos: standardize package name
+ 2025-09-16 61dc7fe30d iter: document that calling yield after terminated range loop causes runtime panic

Change-Id: Ic06019efc855913632003f41eb10c746b3410b0a

82 files changed, 905 insertions, 276 deletions

diff --git a/src/bytes/bytes.go b/src/bytes/bytes.go
index 9a7f4ee3c9..87183c0195 100644
--- a/src/bytes/bytes.go
+++ b/src/bytes/bytes.go
@@ -508,7 +508,7 @@ func Fields(s []byte) [][]byte {
 // It splits the slice s at each run of code points c satisfying f(c) and
 // returns a slice of subslices of s. If all code points in s satisfy f(c), or
 // len(s) == 0, an empty slice is returned. Every element of the returned slice is
-// non-empty. Unlike [SplitFunc], leading and trailing runs of code points
+// non-empty. Unlike [Split], leading and trailing runs of code points
 // satisfying f(c) are discarded.
 //
 // FieldsFunc makes no guarantees about the order in which it calls f(c)
diff --git a/src/bytes/bytes_test.go b/src/bytes/bytes_test.go
index 03f01582c5..f18915c879 100644
--- a/src/bytes/bytes_test.go
+++ b/src/bytes/bytes_test.go
@@ -891,9 +891,7 @@ func BenchmarkCountSingle(b *testing.B) {
 				b.Fatal("bad count", j, expect)
 			}
 		}
-		for i := 0; i < len(buf); i++ {
-			buf[i] = 0
-		}
+		clear(buf)
 	})
 }
 
diff --git a/src/cmd/asm/internal/asm/testdata/riscv64.s b/src/cmd/asm/internal/asm/testdata/riscv64.s
index 4f7e7acd77..07a898465f 100644
--- a/src/cmd/asm/internal/asm/testdata/riscv64.s
+++ b/src/cmd/asm/internal/asm/testdata/riscv64.s
@@ -195,6 +195,12 @@ start:
 	RDTIME		X5				// f32210c0
 	RDINSTRET	X5				// f32220c0
 
+	// 12.3: Integer Conditional Operations (Zicond)
+	CZEROEQZ	X5, X6, X7			// b353530e
+	CZEROEQZ	X5, X7				// b3d3530e
+	CZERONEZ	X5, X6, X7			// b373530e
+	CZERONEZ	X5, X7				// b3f3530e
+
 	// 13.1: Multiplication Operations
 	MUL	X5, X6, X7				// b3035302
 	MULH	X5, X6, X7				// b3135302
@@ -1952,12 +1958,23 @@ start:
 	MOVF	4(X5), F0				// 07a04200
 	MOVF	F0, 4(X5)				// 27a20200
 	MOVF	F0, F1					// d3000020
+	MOVF	X1, F3					// d38100f0
+	MOVF	F3, X1					// d38001e0
+	MOVF	X0, F3					// d30100f0
+	MOVF	$(0.0), F3				// d30100f0
+
+	// Converted to load of symbol (AUIPC + FLW)
+	MOVF	$(709.78271289338397), F3		// 970f000087a10f00
 
 	MOVD	4(X5), F0				// 07b04200
 	MOVD	F0, 4(X5)				// 27b20200
 	MOVD	F0, F1					// d3000022
+	MOVD	F3, X1					// d38001e2
+	MOVD	X1, F3					// d38100f2
+	MOVD	X0, F3					// d30100f2
+	MOVD	$(0.0), F3				// d30100f2
 
-	// Convert to load of symbol (AUIPC + FLD)
+	// Converted to load of symbol (AUIPC + FLD)
 	MOVD	$(709.78271289338397), F3		// 970f000087b10f00
 
 	// TLS load with local-exec (LUI + ADDIW + ADD of TP + load)
diff --git a/src/cmd/cgo/internal/test/test.go b/src/cmd/cgo/internal/test/test.go
index fb4a8250a2..9626407d88 100644
--- a/src/cmd/cgo/internal/test/test.go
+++ b/src/cmd/cgo/internal/test/test.go
@@ -1096,6 +1096,12 @@ func testErrno(t *testing.T) {
 }
 
 func testMultipleAssign(t *testing.T) {
+	if runtime.GOOS == "windows" && usesUCRT(t) {
+		// UCRT's strtol throws an unrecoverable crash when
+		// using an invalid base (that is, not 0 or 2..36).
+		// See go.dev/issue/62887.
+		t.Skip("skipping test on Windows when linking with UCRT")
+	}
 	p := C.CString("234")
 	n, m := C.strtol(p, nil, 345), C.strtol(p, nil, 10)
 	defer C.free(unsafe.Pointer(p))
diff --git a/src/cmd/cgo/internal/test/test_unix.go b/src/cmd/cgo/internal/test/test_unix.go
index 664c4850d3..9f35583125 100644
--- a/src/cmd/cgo/internal/test/test_unix.go
+++ b/src/cmd/cgo/internal/test/test_unix.go
@@ -6,6 +6,13 @@
 
 package cgotest
 
-import "syscall"
+import (
+	"syscall"
+	"testing"
+)
 
 var syscall_dot_SIGCHLD = syscall.SIGCHLD
+
+func usesUCRT(t *testing.T) bool {
+	return false
+}
diff --git a/src/cmd/cgo/internal/test/test_windows.go b/src/cmd/cgo/internal/test/test_windows.go
index 7bfb33a83c..c6f31430cf 100644
--- a/src/cmd/cgo/internal/test/test_windows.go
+++ b/src/cmd/cgo/internal/test/test_windows.go
@@ -4,6 +4,20 @@
 
 package cgotest
 
-import "syscall"
+import (
+	"internal/syscall/windows"
+	"syscall"
+	"testing"
+)
 
 var syscall_dot_SIGCHLD syscall.Signal
+
+// usesUCRT reports whether the test is using the Windows UCRT (Universal C Runtime).
+func usesUCRT(t *testing.T) bool {
+	name, err := syscall.UTF16PtrFromString("ucrtbase.dll")
+	if err != nil {
+		t.Fatal(err)
+	}
+	h, err := windows.GetModuleHandle(name)
+	return err == nil && h != 0
+}
diff --git a/src/cmd/compile/README.md b/src/cmd/compile/README.md
index 79d2336154..1089348030 100644
--- a/src/cmd/compile/README.md
+++ b/src/cmd/compile/README.md
@@ -57,7 +57,7 @@ terms of these, so the next step after type checking is to convert the syntax
 and types2 representations to ir and types. This process is referred to as
 "noding."
 
-Noding using a process called Unified IR, which builds a node representation
+Noding uses a process called Unified IR, which builds a node representation
 using a serialized version of the typechecked code from step 2.
 Unified IR is also involved in import/export of packages and inlining.
 
diff --git a/src/cmd/compile/internal/abi/abiutils.go b/src/cmd/compile/internal/abi/abiutils.go
index cef7885815..7acab36e8d 100644
--- a/src/cmd/compile/internal/abi/abiutils.go
+++ b/src/cmd/compile/internal/abi/abiutils.go
@@ -664,9 +664,7 @@ func (state *assignState) tryAllocRegs(typ *types.Type) []RegIndex {
 func (pa *ABIParamAssignment) ComputePadding(storage []uint64) []uint64 {
 	nr := len(pa.Registers)
 	padding := storage[:nr]
-	for i := 0; i < nr; i++ {
-		padding[i] = 0
-	}
+	clear(padding)
 	if pa.Type.Kind() != types.TSTRUCT || nr == 0 {
 		return padding
 	}
diff --git a/src/cmd/compile/internal/mips/ggen.go b/src/cmd/compile/internal/mips/ggen.go
index 023f4d958e..394f015589 100644
--- a/src/cmd/compile/internal/mips/ggen.go
+++ b/src/cmd/compile/internal/mips/ggen.go
@@ -5,6 +5,7 @@
 package mips
 
 import (
+	"cmd/compile/internal/base"
 	"cmd/compile/internal/objw"
 	"cmd/compile/internal/types"
 	"cmd/internal/obj"
@@ -17,7 +18,7 @@ func zerorange(pp *objw.Progs, p *obj.Prog, off, cnt int64, _ *uint32) *obj.Prog
 	}
 
 	for cnt != 0 {
-		p = pp.Append(p, mips.AMOVW, obj.TYPE_REG, mips.REGZERO, 0, obj.TYPE_MEM, mips.REGSP, off)
+		p = pp.Append(p, mips.AMOVW, obj.TYPE_REG, mips.REGZERO, 0, obj.TYPE_MEM, mips.REGSP, base.Ctxt.Arch.FixedFrameSize+off)
 		cnt -= int64(types.PtrSize)
 		off += int64(types.PtrSize)
 	}
diff --git a/src/cmd/compile/internal/mips64/ggen.go b/src/cmd/compile/internal/mips64/ggen.go
index 0740d9abe8..740d68e335 100644
--- a/src/cmd/compile/internal/mips64/ggen.go
+++ b/src/cmd/compile/internal/mips64/ggen.go
@@ -17,7 +17,7 @@ func zerorange(pp *objw.Progs, p *obj.Prog, off, cnt int64, _ *uint32) *obj.Prog
 	}
 
 	for cnt != 0 {
-		p = pp.Append(p, mips.AMOVV, obj.TYPE_REG, mips.REGZERO, 0, obj.TYPE_MEM, mips.REGSP, off)
+		p = pp.Append(p, mips.AMOVV, obj.TYPE_REG, mips.REGZERO, 0, obj.TYPE_MEM, mips.REGSP, off+8)
 		cnt -= int64(types.PtrSize)
 		off += int64(types.PtrSize)
 	}
diff --git a/src/cmd/compile/internal/ssa/README.md b/src/cmd/compile/internal/ssa/README.md
index 8184f9c002..3626f5bb7b 100644
--- a/src/cmd/compile/internal/ssa/README.md
+++ b/src/cmd/compile/internal/ssa/README.md
@@ -48,8 +48,7 @@ However, certain types don't come from Go and are special; below we will cover
 
 Some operators contain an auxiliary field. The aux fields are usually printed as
 enclosed in `[]` or `{}`, and could be the constant op argument, argument type,
-etc.
-for example:
+etc. For example:
 
 	v13 (?) = Const64 <int> [1]
 
diff --git a/src/cmd/compile/internal/ssa/_gen/LOONG64.rules b/src/cmd/compile/internal/ssa/_gen/LOONG64.rules
index d0a64364d6..0d2384143c 100644
--- a/src/cmd/compile/internal/ssa/_gen/LOONG64.rules
+++ b/src/cmd/compile/internal/ssa/_gen/LOONG64.rules
@@ -717,7 +717,8 @@
 (SRLVconst [rc] (MOVBUreg x)) && rc >= 8 => (MOVVconst [0])
 
 // (x + x) << c -> x << c+1
-((SLLV|SLL)const [c] (ADDV x x)) => ((SLLV|SLL)const [c+1] x)
+((SLLV|SLL)const <t> [c] (ADDV x x)) && c < t.Size() * 8 - 1  => ((SLLV|SLL)const [c+1] x)
+((SLLV|SLL)const <t> [c] (ADDV x x)) && c >= t.Size() * 8 - 1 => (MOVVconst [0])
 
 // mul by constant
 (MULV _ (MOVVconst [0])) => (MOVVconst [0])
diff --git a/src/cmd/compile/internal/ssa/_gen/LOONG64Ops.go b/src/cmd/compile/internal/ssa/_gen/LOONG64Ops.go
index 0d5e0eb76f..a3db4def56 100644
--- a/src/cmd/compile/internal/ssa/_gen/LOONG64Ops.go
+++ b/src/cmd/compile/internal/ssa/_gen/LOONG64Ops.go
@@ -247,7 +247,7 @@ func init() {
 		{name: "SLL", argLength: 2, reg: gp21, asm: "SLL"},                        // arg0 << arg1, shift amount is mod 32
 		{name: "SLLV", argLength: 2, reg: gp21, asm: "SLLV"},                      // arg0 << arg1, shift amount is mod 64
 		{name: "SLLconst", argLength: 1, reg: gp11, asm: "SLL", aux: "Int64"},     // arg0 << auxInt, auxInt should be in the range 0 to 31.
-		{name: "SLLVconst", argLength: 1, reg: gp11, asm: "SLLV", aux: "Int64"},   // arg0 << auxInt
+		{name: "SLLVconst", argLength: 1, reg: gp11, asm: "SLLV", aux: "Int64"},   // arg0 << auxInt, auxInt should be in the range 0 to 63.
 		{name: "SRL", argLength: 2, reg: gp21, asm: "SRL"},                        // arg0 >> arg1, shift amount is mod 32
 		{name: "SRLV", argLength: 2, reg: gp21, asm: "SRLV"},                      // arg0 >> arg1, unsigned, shift amount is mod 64
 		{name: "SRLconst", argLength: 1, reg: gp11, asm: "SRL", aux: "Int64"},     // arg0 >> auxInt, auxInt should be in the range 0 to 31.
diff --git a/src/cmd/compile/internal/ssa/rewriteLOONG64.go b/src/cmd/compile/internal/ssa/rewriteLOONG64.go
index 6a9b723c8c..3990b2833b 100644
--- a/src/cmd/compile/internal/ssa/rewriteLOONG64.go
+++ b/src/cmd/compile/internal/ssa/rewriteLOONG64.go
@@ -6561,15 +6561,17 @@ func rewriteValueLOONG64_OpLOONG64SLLV(v *Value) bool {
 }
 func rewriteValueLOONG64_OpLOONG64SLLVconst(v *Value) bool {
 	v_0 := v.Args[0]
-	// match: (SLLVconst [c] (ADDV x x))
+	// match: (SLLVconst <t> [c] (ADDV x x))
+	// cond: c < t.Size() * 8 - 1
 	// result: (SLLVconst [c+1] x)
 	for {
+		t := v.Type
 		c := auxIntToInt64(v.AuxInt)
 		if v_0.Op != OpLOONG64ADDV {
 			break
 		}
 		x := v_0.Args[1]
-		if x != v_0.Args[0] {
+		if x != v_0.Args[0] || !(c < t.Size()*8-1) {
 			break
 		}
 		v.reset(OpLOONG64SLLVconst)
@@ -6577,6 +6579,23 @@ func rewriteValueLOONG64_OpLOONG64SLLVconst(v *Value) bool {
 		v.AddArg(x)
 		return true
 	}
+	// match: (SLLVconst <t> [c] (ADDV x x))
+	// cond: c >= t.Size() * 8 - 1
+	// result: (MOVVconst [0])
+	for {
+		t := v.Type
+		c := auxIntToInt64(v.AuxInt)
+		if v_0.Op != OpLOONG64ADDV {
+			break
+		}
+		x := v_0.Args[1]
+		if x != v_0.Args[0] || !(c >= t.Size()*8-1) {
+			break
+		}
+		v.reset(OpLOONG64MOVVconst)
+		v.AuxInt = int64ToAuxInt(0)
+		return true
+	}
 	// match: (SLLVconst [c] (MOVVconst [d]))
 	// result: (MOVVconst [d<<uint64(c)])
 	for {
@@ -6593,15 +6612,17 @@ func rewriteValueLOONG64_OpLOONG64SLLVconst(v *Value) bool {
 }
 func rewriteValueLOONG64_OpLOONG64SLLconst(v *Value) bool {
 	v_0 := v.Args[0]
-	// match: (SLLconst [c] (ADDV x x))
+	// match: (SLLconst <t> [c] (ADDV x x))
+	// cond: c < t.Size() * 8 - 1
 	// result: (SLLconst [c+1] x)
 	for {
+		t := v.Type
 		c := auxIntToInt64(v.AuxInt)
 		if v_0.Op != OpLOONG64ADDV {
 			break
 		}
 		x := v_0.Args[1]
-		if x != v_0.Args[0] {
+		if x != v_0.Args[0] || !(c < t.Size()*8-1) {
 			break
 		}
 		v.reset(OpLOONG64SLLconst)
@@ -6609,6 +6630,23 @@ func rewriteValueLOONG64_OpLOONG64SLLconst(v *Value) bool {
 		v.AddArg(x)
 		return true
 	}
+	// match: (SLLconst <t> [c] (ADDV x x))
+	// cond: c >= t.Size() * 8 - 1
+	// result: (MOVVconst [0])
+	for {
+		t := v.Type
+		c := auxIntToInt64(v.AuxInt)
+		if v_0.Op != OpLOONG64ADDV {
+			break
+		}
+		x := v_0.Args[1]
+		if x != v_0.Args[0] || !(c >= t.Size()*8-1) {
+			break
+		}
+		v.reset(OpLOONG64MOVVconst)
+		v.AuxInt = int64ToAuxInt(0)
+		return true
+	}
 	return false
 }
 func rewriteValueLOONG64_OpLOONG64SRA(v *Value) bool {
diff --git a/src/cmd/compile/internal/ssa/writebarrier.go b/src/cmd/compile/internal/ssa/writebarrier.go
index 9ef3667d51..ec6901f13e 100644
--- a/src/cmd/compile/internal/ssa/writebarrier.go
+++ b/src/cmd/compile/internal/ssa/writebarrier.go
@@ -303,6 +303,15 @@ func writebarrier(f *Func) {
 		mem := stores[0].MemoryArg()
 		pos := stores[0].Pos
 
+		// If there is a nil check before the WB store, duplicate it to
+		// the two branches, where the store and the WB load occur. So
+		// they are more likely be removed by late nilcheck removal (which
+		// is block-local).
+		var nilcheck, nilcheckThen, nilcheckEnd *Value
+		if a := stores[0].Args[0]; a.Op == OpNilCheck && a.Args[1] == mem {
+			nilcheck = a
+		}
+
 		// If the source of a MoveWB is volatile (will be clobbered by a
 		// function call), we need to copy it to a temporary location, as
 		// marshaling the args of wbMove might clobber the value we're
@@ -377,6 +386,10 @@ func writebarrier(f *Func) {
 		// For each write barrier store, append write barrier code to bThen.
 		memThen := mem
 
+		if nilcheck != nil {
+			nilcheckThen = bThen.NewValue2(nilcheck.Pos, OpNilCheck, nilcheck.Type, nilcheck.Args[0], memThen)
+		}
+
 		// Note: we can issue the write barrier code in any order. In particular,
 		// it doesn't matter if they are in a different order *even if* they end
 		// up referring to overlapping memory regions. For instance if an OpStore
@@ -447,6 +460,9 @@ func writebarrier(f *Func) {
 				// take care of the vast majority of these. We could
 				// patch this up in the signal handler, or use XCHG to
 				// combine the read and the write.
+				if ptr == nilcheck {
+					ptr = nilcheckThen
+				}
 				oldVal := bThen.NewValue2(pos, OpLoad, types.Types[types.TUINTPTR], ptr, memThen)
 				// Save old value to write buffer.
 				addEntry(pos, oldVal)
@@ -459,9 +475,12 @@ func writebarrier(f *Func) {
 		// Now do the rare cases, Zeros and Moves.
 		for _, w := range stores {
 			pos := w.Pos
+			dst := w.Args[0]
+			if dst == nilcheck {
+				dst = nilcheckThen
+			}
 			switch w.Op {
 			case OpZeroWB:
-				dst := w.Args[0]
 				typ := reflectdata.TypeLinksym(w.Aux.(*types.Type))
 				// zeroWB(&typ, dst)
 				taddr := b.NewValue1A(pos, OpAddr, b.Func.Config.Types.Uintptr, typ, sb)
@@ -469,7 +488,6 @@ func writebarrier(f *Func) {
 				f.fe.Func().SetWBPos(pos)
 				nWBops--
 			case OpMoveWB:
-				dst := w.Args[0]
 				src := w.Args[1]
 				if isVolatile(src) {
 					for _, c := range volatiles {
@@ -491,24 +509,29 @@ func writebarrier(f *Func) {
 		// merge memory
 		mem = bEnd.NewValue2(pos, OpPhi, types.TypeMem, mem, memThen)
 
+		if nilcheck != nil {
+			nilcheckEnd = bEnd.NewValue2(nilcheck.Pos, OpNilCheck, nilcheck.Type, nilcheck.Args[0], mem)
+		}
+
 		// Do raw stores after merge point.
 		for _, w := range stores {
 			pos := w.Pos
+			dst := w.Args[0]
+			if dst == nilcheck {
+				dst = nilcheckEnd
+			}
 			switch w.Op {
 			case OpStoreWB:
-				ptr := w.Args[0]
 				val := w.Args[1]
 				if buildcfg.Experiment.CgoCheck2 {
 					// Issue cgo checking code.
-					mem = wbcall(pos, bEnd, cgoCheckPtrWrite, sp, mem, ptr, val)
+					mem = wbcall(pos, bEnd, cgoCheckPtrWrite, sp, mem, dst, val)
 				}
-				mem = bEnd.NewValue3A(pos, OpStore, types.TypeMem, w.Aux, ptr, val, mem)
+				mem = bEnd.NewValue3A(pos, OpStore, types.TypeMem, w.Aux, dst, val, mem)
 			case OpZeroWB:
-				dst := w.Args[0]
 				mem = bEnd.NewValue2I(pos, OpZero, types.TypeMem, w.AuxInt, dst, mem)
 				mem.Aux = w.Aux
 			case OpMoveWB:
-				dst := w.Args[0]
 				src := w.Args[1]
 				if isVolatile(src) {
 					for _, c := range volatiles {
@@ -529,9 +552,8 @@ func writebarrier(f *Func) {
 			case OpVarDef, OpVarLive:
 				mem = bEnd.NewValue1A(pos, w.Op, types.TypeMem, w.Aux, mem)
 			case OpStore:
-				ptr := w.Args[0]
 				val := w.Args[1]
-				mem = bEnd.NewValue3A(pos, OpStore, types.TypeMem, w.Aux, ptr, val, mem)
+				mem = bEnd.NewValue3A(pos, OpStore, types.TypeMem, w.Aux, dst, val, mem)
 			}
 		}
 
@@ -557,6 +579,9 @@ func writebarrier(f *Func) {
 				f.freeValue(w)
 			}
 		}
+		if nilcheck != nil && nilcheck.Uses == 0 {
+			nilcheck.reset(OpInvalid)
+		}
 
 		// put values after the store sequence into the end block
 		bEnd.Values = append(bEnd.Values, after...)
diff --git a/src/cmd/dist/test.go b/src/cmd/dist/test.go
index 1200303334..b9673564ec 100644
--- a/src/cmd/dist/test.go
+++ b/src/cmd/dist/test.go
@@ -705,6 +705,7 @@ func (t *tester) registerTests() {
 				timeout: 300 * time.Second,
 				tags:    []string{"purego"},
 				pkg:     "hash/maphash",
+				env:     []string{"GODEBUG=fips140=off"}, // FIPS 140-3 mode is incompatible with purego
 			})
 	}
 
diff --git a/src/cmd/go/internal/modget/query.go b/src/cmd/go/internal/modget/query.go
index f95b503d8f..05872d52ec 100644
--- a/src/cmd/go/internal/modget/query.go
+++ b/src/cmd/go/internal/modget/query.go
@@ -10,6 +10,7 @@ import (
 	"regexp"
 	"strings"
 	"sync"
+	"unicode/utf8"
 
 	"cmd/go/internal/base"
 	"cmd/go/internal/gover"
@@ -285,6 +286,11 @@ func reportError(q *query, err error) {
 	// TODO(bcmills): Use errors.As to unpack these errors instead of parsing
 	// strings with regular expressions.
 
+	if !utf8.ValidString(q.pattern) || !utf8.ValidString(q.version) {
+		base.Errorf("go: %s", errStr)
+		return
+	}
+
 	patternRE := regexp.MustCompile("(?m)(?:[ \t(\"`]|^)" + regexp.QuoteMeta(q.pattern) + "(?:[ @:;)\"`]|$)")
 	if patternRE.MatchString(errStr) {
 		if q.rawVersion == "" {
diff --git a/src/cmd/go/testdata/script/get_panic_issue75251.txt b/src/cmd/go/testdata/script/get_panic_issue75251.txt
new file mode 100644
index 0000000000..2cc3f3a9c4
--- /dev/null
+++ b/src/cmd/go/testdata/script/get_panic_issue75251.txt
@@ -0,0 +1,16 @@
+# Issue #75251: Don't panic if the package path or the package version
+# contains invalid UTF-8 characters.
+
+go mod init m
+
+! go get golang.org/x/net/http/httpguts�v0.43.0 # contains 0xff byte
+! stderr panic
+stderr 'malformed module path'
+
+! go get golang.org/x/net/http/httpguts�@v0.43.0 # contains 0xff byte
+! stderr panic
+stderr 'malformed module path'
+
+! go get golang.org/x/net/http/httpguts@�v0.43.0 # contains 0xff byte
+! stderr panic
+stderr 'disallowed version string'
diff --git a/src/cmd/internal/obj/riscv/anames.go b/src/cmd/internal/obj/riscv/anames.go
index 88ac746573..a8807fc7a8 100644
--- a/src/cmd/internal/obj/riscv/anames.go
+++ b/src/cmd/internal/obj/riscv/anames.go
@@ -61,6 +61,8 @@ var Anames = []string{
 	"CSRRWI",
 	"CSRRSI",
 	"CSRRCI",
+	"CZEROEQZ",
+	"CZERONEZ",
 	"MUL",
 	"MULH",
 	"MULHU",
diff --git a/src/cmd/internal/obj/riscv/cpu.go b/src/cmd/internal/obj/riscv/cpu.go
index e265e04482..305ef061e3 100644
--- a/src/cmd/internal/obj/riscv/cpu.go
+++ b/src/cmd/internal/obj/riscv/cpu.go
@@ -409,6 +409,10 @@ const (
 	ACSRRSI
 	ACSRRCI
 
+	// 12.3: Integer Conditional Operations (Zicond)
+	ACZEROEQZ
+	ACZERONEZ
+
 	// 13.1: Multiplication Operations
 	AMUL
 	AMULH
diff --git a/src/cmd/internal/obj/riscv/inst.go b/src/cmd/internal/obj/riscv/inst.go
index a6a03dc565..a5b3acdb18 100644
--- a/src/cmd/internal/obj/riscv/inst.go
+++ b/src/cmd/internal/obj/riscv/inst.go
@@ -1,4 +1,4 @@
-// Code generated by ./parse.py -go rv64_a rv64_c rv64_d rv64_f rv64_i rv64_m rv64_q rv64_zba rv64_zbb rv64_zbs rv_a rv_c rv_c_d rv_d rv_f rv_i rv_m rv_q rv_s rv_system rv_v rv_zba rv_zbb rv_zbs rv_zicsr; DO NOT EDIT.
+// Code generated by ./parse.py -go rv64_a rv64_c rv64_d rv64_f rv64_i rv64_m rv64_q rv64_zba rv64_zbb rv64_zbs rv_a rv_c rv_c_d rv_d rv_f rv_i rv_m rv_q rv_s rv_system rv_v rv_zba rv_zbb rv_zbs rv_zicond rv_zicsr; DO NOT EDIT.
 package riscv
 
 import "cmd/internal/obj"
@@ -194,6 +194,10 @@ func encode(a obj.As) *inst {
 		return &inst{0x13, 0x1, 0x0, 0x1, 1537, 0x30}
 	case ACTZW:
 		return &inst{0x1b, 0x1, 0x0, 0x1, 1537, 0x30}
+	case ACZEROEQZ:
+		return &inst{0x33, 0x5, 0x0, 0x0, 224, 0x7}
+	case ACZERONEZ:
+		return &inst{0x33, 0x7, 0x0, 0x0, 224, 0x7}
 	case ADIV:
 		return &inst{0x33, 0x4, 0x0, 0x0, 32, 0x1}
 	case ADIVU:
diff --git a/src/cmd/internal/obj/riscv/obj.go b/src/cmd/internal/obj/riscv/obj.go
index 1538d03179..9d595f301c 100644
--- a/src/cmd/internal/obj/riscv/obj.go
+++ b/src/cmd/internal/obj/riscv/obj.go
@@ -29,6 +29,7 @@ import (
 	"internal/abi"
 	"internal/buildcfg"
 	"log"
+	"math"
 	"math/bits"
 	"strings"
 )
@@ -145,9 +146,29 @@ func progedit(ctxt *obj.Link, p *obj.Prog, newprog obj.ProgAlloc) {
 			p.From.Offset = 0
 		}
 
+	case AMOVF:
+		if p.From.Type == obj.TYPE_FCONST && p.From.Name == obj.NAME_NONE && p.From.Reg == obj.REG_NONE {
+			f64 := p.From.Val.(float64)
+			f32 := float32(f64)
+			if math.Float32bits(f32) == 0 {
+				p.From.Type = obj.TYPE_REG
+				p.From.Reg = REG_ZERO
+				break
+			}
+			p.From.Type = obj.TYPE_MEM
+			p.From.Sym = ctxt.Float32Sym(f32)
+			p.From.Name = obj.NAME_EXTERN
+			p.From.Offset = 0
+		}
+
 	case AMOVD:
 		if p.From.Type == obj.TYPE_FCONST && p.From.Name == obj.NAME_NONE && p.From.Reg == obj.REG_NONE {
 			f64 := p.From.Val.(float64)
+			if math.Float64bits(f64) == 0 {
+				p.From.Type = obj.TYPE_REG
+				p.From.Reg = REG_ZERO
+				break
+			}
 			p.From.Type = obj.TYPE_MEM
 			p.From.Sym = ctxt.Float64Sym(f64)
 			p.From.Name = obj.NAME_EXTERN
@@ -1927,6 +1948,10 @@ var instructions = [ALAST & obj.AMask]instructionData{
 	ACSRRW & obj.AMask:  {enc: iIIEncoding, immForm: ACSRRWI},
 	ACSRRWI & obj.AMask: {enc: iIIEncoding},
 
+	// 12.3: "Zicond" Extension for Integer Conditional Operations
+	ACZERONEZ & obj.AMask: {enc: rIIIEncoding, ternary: true},
+	ACZEROEQZ & obj.AMask: {enc: rIIIEncoding, ternary: true},
+
 	// 13.1: Multiplication Operations
 	AMUL & obj.AMask:    {enc: rIIIEncoding, ternary: true},
 	AMULH & obj.AMask:   {enc: rIIIEncoding, ternary: true},
@@ -3254,16 +3279,37 @@ func instructionsForMOV(p *obj.Prog) []*instruction {
 	case p.From.Type == obj.TYPE_REG && p.To.Type == obj.TYPE_REG:
 		// Handle register to register moves.
 		switch p.As {
-		case AMOV: // MOV Ra, Rb -> ADDI $0, Ra, Rb
+		case AMOV:
+			// MOV Ra, Rb -> ADDI $0, Ra, Rb
 			ins.as, ins.rs1, ins.rs2, ins.imm = AADDI, uint32(p.From.Reg), obj.REG_NONE, 0
-		case AMOVW: // MOVW Ra, Rb -> ADDIW $0, Ra, Rb
+		case AMOVW:
+			// MOVW Ra, Rb -> ADDIW $0, Ra, Rb
 			ins.as, ins.rs1, ins.rs2, ins.imm = AADDIW, uint32(p.From.Reg), obj.REG_NONE, 0
-		case AMOVBU: // MOVBU Ra, Rb -> ANDI $255, Ra, Rb
+		case AMOVBU:
+			// MOVBU Ra, Rb -> ANDI $255, Ra, Rb
 			ins.as, ins.rs1, ins.rs2, ins.imm = AANDI, uint32(p.From.Reg), obj.REG_NONE, 255
-		case AMOVF: // MOVF Ra, Rb -> FSGNJS Ra, Ra, Rb
-			ins.as, ins.rs1 = AFSGNJS, uint32(p.From.Reg)
-		case AMOVD: // MOVD Ra, Rb -> FSGNJD Ra, Ra, Rb
-			ins.as, ins.rs1 = AFSGNJD, uint32(p.From.Reg)
+		case AMOVF:
+			// MOVF Ra, Rb -> FSGNJS Ra, Ra, Rb
+			//          or -> FMVWX  Ra, Rb
+			//          or -> FMVXW  Ra, Rb
+			if ins.rs2 >= REG_X0 && ins.rs2 <= REG_X31 && ins.rd >= REG_F0 && ins.rd <= REG_F31 {
+				ins.as = AFMVWX
+			} else if ins.rs2 >= REG_F0 && ins.rs2 <= REG_F31 && ins.rd >= REG_X0 && ins.rd <= REG_X31 {
+				ins.as = AFMVXW
+			} else {
+				ins.as, ins.rs1 = AFSGNJS, uint32(p.From.Reg)
+			}
+		case AMOVD:
+			// MOVD Ra, Rb -> FSGNJD Ra, Ra, Rb
+			//          or -> FMVDX  Ra, Rb
+			//          or -> FMVXD  Ra, Rb
+			if ins.rs2 >= REG_X0 && ins.rs2 <= REG_X31 && ins.rd >= REG_F0 && ins.rd <= REG_F31 {
+				ins.as = AFMVDX
+			} else if ins.rs2 >= REG_F0 && ins.rs2 <= REG_F31 && ins.rd >= REG_X0 && ins.rd <= REG_X31 {
+				ins.as = AFMVXD
+			} else {
+				ins.as, ins.rs1 = AFSGNJD, uint32(p.From.Reg)
+			}
 		case AMOVB, AMOVH:
 			if buildcfg.GORISCV64 >= 22 {
 				// Use SEXTB or SEXTH to extend.
diff --git a/src/cmd/internal/pkgpattern/pkgpattern.go b/src/cmd/internal/pkgpattern/pkgpattern.go
index 1496eebb3e..5bbe8a52fb 100644
--- a/src/cmd/internal/pkgpattern/pkgpattern.go
+++ b/src/cmd/internal/pkgpattern/pkgpattern.go
@@ -7,6 +7,7 @@ package pkgpattern
 import (
 	"regexp"
 	"strings"
+	"unicode/utf8"
 )
 
 // Note: most of this code was originally part of the cmd/go/internal/search
@@ -71,7 +72,7 @@ func matchPatternInternal(pattern string, vendorExclude bool) func(name string)
 
 	const vendorChar = "\x00"
 
-	if vendorExclude && strings.Contains(pattern, vendorChar) {
+	if vendorExclude && strings.Contains(pattern, vendorChar) || !utf8.ValidString(pattern) {
 		return func(name string) bool { return false }
 	}
 
diff --git a/src/cmd/link/internal/loadpe/ldpe.go b/src/cmd/link/internal/loadpe/ldpe.go
index b895ac4149..d3a050135c 100644
--- a/src/cmd/link/internal/loadpe/ldpe.go
+++ b/src/cmd/link/internal/loadpe/ldpe.go
@@ -17,6 +17,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"strconv"
 	"strings"
 )
 
@@ -348,11 +349,11 @@ func Load(l *loader.Loader, arch *sys.Arch, localSymVersion int, input *bio.Read
 				return nil, fmt.Errorf("relocation number %d symbol index idx=%d cannot be large then number of symbols %d", j, r.SymbolTableIndex, len(f.COFFSymbols))
 			}
 			pesym := &f.COFFSymbols[r.SymbolTableIndex]
-			_, gosym, err := state.readpesym(pesym)
+			_, rSym, err := state.readpesym(pesym)
 			if err != nil {
 				return nil, err
 			}
-			if gosym == 0 {
+			if rSym == 0 {
 				name, err := pesym.FullName(f.StringTable)
 				if err != nil {
 					name = string(pesym.Name[:])
@@ -360,90 +361,53 @@ func Load(l *loader.Loader, arch *sys.Arch, localSymVersion int, input *bio.Read
 				return nil, fmt.Errorf("reloc of invalid sym %s idx=%d type=%d", name, r.SymbolTableIndex, pesym.Type)
 			}
 
-			rSym := gosym
 			rSize := uint8(4)
 			rOff := int32(r.VirtualAddress)
-			var rAdd int64
 			var rType objabi.RelocType
 			switch arch.Family {
 			default:
 				return nil, fmt.Errorf("%s: unsupported arch %v", pn, arch.Family)
-			case sys.I386, sys.AMD64:
+			case sys.I386:
 				switch r.Type {
-				default:
-					return nil, fmt.Errorf("%s: %v: unknown relocation type %v", pn, state.sectsyms[rsect], r.Type)
-
-				case IMAGE_REL_I386_REL32, IMAGE_REL_AMD64_REL32,
-					IMAGE_REL_AMD64_ADDR32, // R_X86_64_PC32
-					IMAGE_REL_AMD64_ADDR32NB:
-					if r.Type == IMAGE_REL_AMD64_ADDR32NB {
-						rType = objabi.R_PEIMAGEOFF
-					} else {
-						rType = objabi.R_PCREL
-					}
-
-					rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
-
-				case IMAGE_REL_I386_DIR32NB, IMAGE_REL_I386_DIR32:
-					if r.Type == IMAGE_REL_I386_DIR32NB {
-						rType = objabi.R_PEIMAGEOFF
-					} else {
-						rType = objabi.R_ADDR
-					}
-
-					// load addend from image
-					rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
-
-				case IMAGE_REL_AMD64_ADDR64: // R_X86_64_64
-					rSize = 8
-
+				case IMAGE_REL_I386_REL32:
+					rType = objabi.R_PCREL
+				case IMAGE_REL_I386_DIR32:
 					rType = objabi.R_ADDR
-
-					// load addend from image
-					rAdd = int64(binary.LittleEndian.Uint64(state.sectdata[rsect][rOff:]))
+				case IMAGE_REL_I386_DIR32NB:
+					rType = objabi.R_PEIMAGEOFF
 				}
-
-			case sys.ARM:
+			case sys.AMD64:
 				switch r.Type {
-				default:
-					return nil, fmt.Errorf("%s: %v: unknown ARM relocation type %v", pn, state.sectsyms[rsect], r.Type)
-
-				case IMAGE_REL_ARM_SECREL:
+				case IMAGE_REL_AMD64_REL32:
 					rType = objabi.R_PCREL
-
-					rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
-
-				case IMAGE_REL_ARM_ADDR32, IMAGE_REL_ARM_ADDR32NB:
-					if r.Type == IMAGE_REL_ARM_ADDR32NB {
-						rType = objabi.R_PEIMAGEOFF
-					} else {
-						rType = objabi.R_ADDR
-					}
-
-					rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
-
-				case IMAGE_REL_ARM_BRANCH24:
-					rType = objabi.R_CALLARM
-
-					rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
+				case IMAGE_REL_AMD64_ADDR32:
+					rType = objabi.R_ADDR
+				case IMAGE_REL_AMD64_ADDR64:
+					rType = objabi.R_ADDR
+					rSize = 8
+				case IMAGE_REL_AMD64_ADDR32NB:
+					rType = objabi.R_PEIMAGEOFF
 				}
-
 			case sys.ARM64:
 				switch r.Type {
-				default:
-					return nil, fmt.Errorf("%s: %v: unknown ARM64 relocation type %v", pn, state.sectsyms[rsect], r.Type)
-
-				case IMAGE_REL_ARM64_ADDR32, IMAGE_REL_ARM64_ADDR32NB:
-					if r.Type == IMAGE_REL_ARM64_ADDR32NB {
-						rType = objabi.R_PEIMAGEOFF
-					} else {
-						rType = objabi.R_ADDR
-					}
-
-					rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
+				case IMAGE_REL_ARM64_ADDR32:
+					rType = objabi.R_ADDR
+				case IMAGE_REL_ARM64_ADDR32NB:
+					rType = objabi.R_PEIMAGEOFF
 				}
 			}
-
+			if rType == 0 {
+				return nil, fmt.Errorf("%s: %v: unknown relocation type %v", pn, state.sectsyms[rsect], r.Type)
+			}
+			var rAdd int64
+			switch rSize {
+			default:
+				panic("unexpected relocation size " + strconv.Itoa(int(rSize)))
+			case 4:
+				rAdd = int64(int32(binary.LittleEndian.Uint32(state.sectdata[rsect][rOff:])))
+			case 8:
+				rAdd = int64(binary.LittleEndian.Uint64(state.sectdata[rsect][rOff:]))
+			}
 			// ld -r could generate multiple section symbols for the
 			// same section but with different values, we have to take
 			// that into account, or in the case of split resources,
diff --git a/src/context/context.go b/src/context/context.go
index 4fb537e233..232fc55d87 100644
--- a/src/context/context.go
+++ b/src/context/context.go
@@ -463,6 +463,8 @@ func (c *cancelCtx) Done() <-chan struct{} {
 func (c *cancelCtx) Err() error {
 	// An atomic load is ~5x faster than a mutex, which can matter in tight loops.
 	if err := c.err.Load(); err != nil {
+		// Ensure the done channel has been closed before returning a non-nil error.
+		<-c.Done()
 		return err.(error)
 	}
 	return nil
diff --git a/src/context/x_test.go b/src/context/x_test.go
index 937cab1445..0cf19688c3 100644
--- a/src/context/x_test.go
+++ b/src/context/x_test.go
@@ -1177,3 +1177,23 @@ func (c *customContext) Err() error {
 func (c *customContext) Value(key any) any {
 	return c.parent.Value(key)
 }
+
+// Issue #75533.
+func TestContextErrDoneRace(t *testing.T) {
+	// 4 iterations reliably reproduced #75533.
+	for range 10 {
+		ctx, cancel := WithCancel(Background())
+		donec := ctx.Done()
+		go cancel()
+		for ctx.Err() == nil {
+			if runtime.GOARCH == "wasm" {
+				runtime.Gosched() // need to explicitly yield
+			}
+		}
+		select {
+		case <-donec:
+		default:
+			t.Fatalf("ctx.Err is non-nil, but ctx.Done is not closed")
+		}
+	}
+}
diff --git a/src/crypto/internal/fips140/mlkem/field.go b/src/crypto/internal/fips140/mlkem/field.go
index 1a42818247..577062526c 100644
--- a/src/crypto/internal/fips140/mlkem/field.go
+++ b/src/crypto/internal/fips140/mlkem/field.go
@@ -203,9 +203,7 @@ func sliceForAppend(in []byte, n int) (head, tail []byte) {
 // followed by ByteEncode₁, according to FIPS 203, Algorithm 5.
 func ringCompressAndEncode1(s []byte, f ringElement) []byte {
 	s, b := sliceForAppend(s, encodingSize1)
-	for i := range b {
-		b[i] = 0
-	}
+	clear(b)
 	for i := range f {
 		b[i/8] |= uint8(compress(f[i], 1) << (i % 8))
 	}
diff --git a/src/crypto/internal/fips140/sha3/sha3.go b/src/crypto/internal/fips140/sha3/sha3.go
index 7513f8ef5d..5c77fae4e7 100644
--- a/src/crypto/internal/fips140/sha3/sha3.go
+++ b/src/crypto/internal/fips140/sha3/sha3.go
@@ -61,9 +61,7 @@ func (d *Digest) Size() int { return d.outputLen }
 // Reset resets the Digest to its initial state.
 func (d *Digest) Reset() {
 	// Zero the permutation's state.
-	for i := range d.a {
-		d.a[i] = 0
-	}
+	clear(d.a[:])
 	d.state = spongeAbsorbing
 	d.n = 0
 }
diff --git a/src/crypto/rc4/rc4.go b/src/crypto/rc4/rc4.go
index 90943a0935..eebc1c04cb 100644
--- a/src/crypto/rc4/rc4.go
+++ b/src/crypto/rc4/rc4.go
@@ -55,9 +55,7 @@ func NewCipher(key []byte) (*Cipher, error) {
 // Deprecated: Reset can't guarantee that the key will be entirely removed from
 // the process's memory.
 func (c *Cipher) Reset() {
-	for i := range c.s {
-		c.s[i] = 0
-	}
+	clear(c.s[:])
 	c.i, c.j = 0, 0
 }
 
diff --git a/src/crypto/tls/conn.go b/src/crypto/tls/conn.go
index d4d68c0744..09dc9ea94c 100644
--- a/src/crypto/tls/conn.go
+++ b/src/crypto/tls/conn.go
@@ -220,9 +220,7 @@ func (hc *halfConn) changeCipherSpec() error {
 	hc.mac = hc.nextMac
 	hc.nextCipher = nil
 	hc.nextMac = nil
-	for i := range hc.seq {
-		hc.seq[i] = 0
-	}
+	clear(hc.seq[:])
 	return nil
 }
 
@@ -231,9 +229,7 @@ func (hc *halfConn) setTrafficSecret(suite *cipherSuiteTLS13, level QUICEncrypti
 	hc.level = level
 	key, iv := suite.trafficKey(secret)
 	hc.cipher = suite.aead(key, iv)
-	for i := range hc.seq {
-		hc.seq[i] = 0
-	}
+	clear(hc.seq[:])
 }
 
 // incSeq increments the sequence number.
diff --git a/src/crypto/tls/handshake_server_test.go b/src/crypto/tls/handshake_server_test.go
index 4df3f5a737..941f2a3373 100644
--- a/src/crypto/tls/handshake_server_test.go
+++ b/src/crypto/tls/handshake_server_test.go
@@ -1590,9 +1590,7 @@ var getConfigForClientTests = []struct {
 		},
 		func(clientHello *ClientHelloInfo) (*Config, error) {
 			config := testConfig.Clone()
-			for i := range config.SessionTicketKey {
-				config.SessionTicketKey[i] = 0
-			}
+			clear(config.SessionTicketKey[:])
 			config.sessionTicketKeys = nil
 			return config, nil
 		},
diff --git a/src/crypto/x509/internal/macos/corefoundation.go b/src/crypto/x509/internal/macos/corefoundation.go
index b4032a5d91..23fbe35c24 100644
--- a/src/crypto/x509/internal/macos/corefoundation.go
+++ b/src/crypto/x509/internal/macos/corefoundation.go
@@ -4,10 +4,10 @@
 
 //go:build darwin
 
-// Package macOS provides cgo-less wrappers for Core Foundation and
+// Package macos provides cgo-less wrappers for Core Foundation and
 // Security.framework, similarly to how package syscall provides access to
 // libSystem.dylib.
-package macOS
+package macos
 
 import (
 	"bytes"
diff --git a/src/crypto/x509/internal/macos/security.go b/src/crypto/x509/internal/macos/security.go
index f9f37b1666..6af19bafe5 100644
--- a/src/crypto/x509/internal/macos/security.go
+++ b/src/crypto/x509/internal/macos/security.go
@@ -4,7 +4,7 @@
 
 //go:build darwin
 
-package macOS
+package macos
 
 import (
 	"errors"
diff --git a/src/crypto/x509/root_darwin.go b/src/crypto/x509/root_darwin.go
index b5d7b6350b..3e9aa1ba09 100644
--- a/src/crypto/x509/root_darwin.go
+++ b/src/crypto/x509/root_darwin.go
@@ -5,51 +5,51 @@
 package x509
 
 import (
-	macOS "crypto/x509/internal/macos"
+	"crypto/x509/internal/macos"
 	"errors"
 	"fmt"
 )
 
 func (c *Certificate) systemVerify(opts *VerifyOptions) (chains [][]*Certificate, err error) {
-	certs := macOS.CFArrayCreateMutable()
-	defer macOS.ReleaseCFArray(certs)
-	leaf, err := macOS.SecCertificateCreateWithData(c.Raw)
+	certs := macos.CFArrayCreateMutable()
+	defer macos.ReleaseCFArray(certs)
+	leaf, err := macos.SecCertificateCreateWithData(c.Raw)
 	if err != nil {
 		return nil, errors.New("invalid leaf certificate")
 	}
-	macOS.CFArrayAppendValue(certs, leaf)
+	macos.CFArrayAppendValue(certs, leaf)
 	if opts.Intermediates != nil {
 		for _, lc := range opts.Intermediates.lazyCerts {
 			c, err := lc.getCert()
 			if err != nil {
 				return nil, err
 			}
-			sc, err := macOS.SecCertificateCreateWithData(c.Raw)
+			sc, err := macos.SecCertificateCreateWithData(c.Raw)
 			if err != nil {
 				return nil, err
 			}
-			macOS.CFArrayAppendValue(certs, sc)
+			macos.CFArrayAppendValue(certs, sc)
 		}
 	}
 
-	policies := macOS.CFArrayCreateMutable()
-	defer macOS.ReleaseCFArray(policies)
-	sslPolicy, err := macOS.SecPolicyCreateSSL(opts.DNSName)
+	policies := macos.CFArrayCreateMutable()
+	defer macos.ReleaseCFArray(policies)
+	sslPolicy, err := macos.SecPolicyCreateSSL(opts.DNSName)
 	if err != nil {
 		return nil, err
 	}
-	macOS.CFArrayAppendValue(policies, sslPolicy)
+	macos.CFArrayAppendValue(policies, sslPolicy)
 
-	trustObj, err := macOS.SecTrustCreateWithCertificates(certs, policies)
+	trustObj, err := macos.SecTrustCreateWithCertificates(certs, policies)
 	if err != nil {
 		return nil, err
 	}
-	defer macOS.CFRelease(trustObj)
+	defer macos.CFRelease(trustObj)
 
 	if !opts.CurrentTime.IsZero() {
-		dateRef := macOS.TimeToCFDateRef(opts.CurrentTime)
-		defer macOS.CFRelease(dateRef)
-		if err := macOS.SecTrustSetVerifyDate(trustObj, dateRef); err != nil {
+		dateRef := macos.TimeToCFDateRef(opts.CurrentTime)
+		defer macos.CFRelease(dateRef)
+		if err := macos.SecTrustSetVerifyDate(trustObj, dateRef); err != nil {
 			return nil, err
 		}
 	}
@@ -59,13 +59,13 @@ func (c *Certificate) systemVerify(opts *VerifyOptions) (chains [][]*Certificate
 	// always enforce its SCT requirements, and there are still _some_ people
 	// using TLS or OCSP for that.
 
-	if ret, err := macOS.SecTrustEvaluateWithError(trustObj); err != nil {
+	if ret, err := macos.SecTrustEvaluateWithError(trustObj); err != nil {
 		switch ret {
-		case macOS.ErrSecCertificateExpired:
+		case macos.ErrSecCertificateExpired:
 			return nil, CertificateInvalidError{c, Expired, err.Error()}
-		case macOS.ErrSecHostNameMismatch:
+		case macos.ErrSecHostNameMismatch:
 			return nil, HostnameError{c, opts.DNSName}
-		case macOS.ErrSecNotTrusted:
+		case macos.ErrSecNotTrusted:
 			return nil, UnknownAuthorityError{Cert: c}
 		default:
 			return nil, fmt.Errorf("x509: %s", err)
@@ -73,13 +73,13 @@ func (c *Certificate) systemVerify(opts *VerifyOptions) (chains [][]*Certificate
 	}
 
 	chain := [][]*Certificate{{}}
-	chainRef, err := macOS.SecTrustCopyCertificateChain(trustObj)
+	chainRef, err := macos.SecTrustCopyCertificateChain(trustObj)
 	if err != nil {
 		return nil, err
 	}
-	defer macOS.CFRelease(chainRef)
-	for i := 0; i < macOS.CFArrayGetCount(chainRef); i++ {
-		certRef := macOS.CFArrayGetValueAtIndex(chainRef, i)
+	defer macos.CFRelease(chainRef)
+	for i := 0; i < macos.CFArrayGetCount(chainRef); i++ {
+		certRef := macos.CFArrayGetValueAtIndex(chainRef, i)
 		cert, err := exportCertificate(certRef)
 		if err != nil {
 			return nil, err
@@ -88,7 +88,7 @@ func (c *Certificate) systemVerify(opts *VerifyOptions) (chains [][]*Certificate
 	}
 	if len(chain[0]) == 0 {
 		// This should _never_ happen, but to be safe
-		return nil, errors.New("x509: macOS certificate verification internal error")
+		return nil, errors.New("x509: macos certificate verification internal error")
 	}
 
 	if opts.DNSName != "" {
@@ -118,8 +118,8 @@ func (c *Certificate) systemVerify(opts *VerifyOptions) (chains [][]*Certificate
 }
 
 // exportCertificate returns a *Certificate for a SecCertificateRef.
-func exportCertificate(cert macOS.CFRef) (*Certificate, error) {
-	data, err := macOS.SecCertificateCopyData(cert)
+func exportCertificate(cert macos.CFRef) (*Certificate, error) {
+	data, err := macos.SecCertificateCopyData(cert)
 	if err != nil {
 		return nil, err
 	}
diff --git a/src/encoding/json/v2/arshal_time.go b/src/encoding/json/v2/arshal_time.go
index 70dca8a294..027503734e 100644
--- a/src/encoding/json/v2/arshal_time.go
+++ b/src/encoding/json/v2/arshal_time.go
@@ -465,7 +465,7 @@ func appendDurationISO8601(b []byte, d time.Duration) []byte {
 }
 
 // daysPerYear is the exact average number of days in a year according to
-// the Gregorian calender, which has an extra day each year that is
+// the Gregorian calendar, which has an extra day each year that is
 // a multiple of 4, unless it is evenly divisible by 100 but not by 400.
 // This does not take into account leap seconds, which are not deterministic.
 const daysPerYear = 365.2425
diff --git a/src/go/ast/ast.go b/src/go/ast/ast.go
index 2a0d9e6860..9aca39e868 100644
--- a/src/go/ast/ast.go
+++ b/src/go/ast/ast.go
@@ -1064,7 +1064,7 @@ type File struct {
 	Scope              *Scope          // package scope (this file only). Deprecated: see Object
 	Imports            []*ImportSpec   // imports in this file
 	Unresolved         []*Ident        // unresolved identifiers in this file. Deprecated: see Object
-	Comments           []*CommentGroup // list of all comments in the source file
+	Comments           []*CommentGroup // comments in the file, in lexical order
 	GoVersion          string          // minimum Go version required by //go:build or // +build directives
 }
 
diff --git a/src/go/parser/parser.go b/src/go/parser/parser.go
index 9ee1576a99..e725371e76 100644
--- a/src/go/parser/parser.go
+++ b/src/go/parser/parser.go
@@ -345,30 +345,29 @@ func (p *parser) expectClosing(tok token.Token, context string) token.Pos {
 
 // expectSemi consumes a semicolon and returns the applicable line comment.
 func (p *parser) expectSemi() (comment *ast.CommentGroup) {
-	// semicolon is optional before a closing ')' or '}'
-	if p.tok != token.RPAREN && p.tok != token.RBRACE {
-		switch p.tok {
-		case token.COMMA:
-			// permit a ',' instead of a ';' but complain
-			p.errorExpected(p.pos, "';'")
-			fallthrough
-		case token.SEMICOLON:
-			if p.lit == ";" {
-				// explicit semicolon
-				p.next()
-				comment = p.lineComment // use following comments
-			} else {
-				// artificial semicolon
-				comment = p.lineComment // use preceding comments
-				p.next()
-			}
-			return comment
-		default:
-			p.errorExpected(p.pos, "';'")
-			p.advance(stmtStart)
+	switch p.tok {
+	case token.RPAREN, token.RBRACE:
+		return nil // semicolon is optional before a closing ')' or '}'
+	case token.COMMA:
+		// permit a ',' instead of a ';' but complain
+		p.errorExpected(p.pos, "';'")
+		fallthrough
+	case token.SEMICOLON:
+		if p.lit == ";" {
+			// explicit semicolon
+			p.next()
+			comment = p.lineComment // use following comments
+		} else {
+			// artificial semicolon
+			comment = p.lineComment // use preceding comments
+			p.next()
 		}
+		return comment
+	default:
+		p.errorExpected(p.pos, "';'")
+		p.advance(stmtStart)
+		return nil
 	}
-	return nil
 }
 
 func (p *parser) atComma(context string, follow token.Token) bool {
diff --git a/src/go/parser/parser_test.go b/src/go/parser/parser_test.go
index 2516cedc88..87b7d7bbab 100644
--- a/src/go/parser/parser_test.go
+++ b/src/go/parser/parser_test.go
@@ -896,3 +896,53 @@ func test() {
 		t.Fatalf("unexpected f.Comments got:\n%v\nwant:\n%v", got.String(), want.String())
 	}
 }
+
+// TestBothLineAndLeadComment makes sure that we populate the
+// p.lineComment field even though there is a comment after the
+// line comment.
+func TestBothLineAndLeadComment(t *testing.T) {
+	const src = `package test
+
+var _ int; /* line comment */
+// Doc comment
+func _() {}
+
+var _ int; /* line comment */
+// Some comment
+
+func _() {}
+`
+
+	fset := token.NewFileSet()
+	f, _ := ParseFile(fset, "", src, ParseComments|SkipObjectResolution)
+
+	lineComment := f.Decls[0].(*ast.GenDecl).Specs[0].(*ast.ValueSpec).Comment
+	docComment := f.Decls[1].(*ast.FuncDecl).Doc
+
+	if lineComment == nil {
+		t.Fatal("missing line comment")
+	}
+	if docComment == nil {
+		t.Fatal("missing doc comment")
+	}
+
+	if lineComment.List[0].Text != "/* line comment */" {
+		t.Errorf(`unexpected line comment got = %q; want "/* line comment */"`, lineComment.List[0].Text)
+	}
+	if docComment.List[0].Text != "// Doc comment" {
+		t.Errorf(`unexpected line comment got = %q; want "// Doc comment"`, docComment.List[0].Text)
+	}
+
+	lineComment2 := f.Decls[2].(*ast.GenDecl).Specs[0].(*ast.ValueSpec).Comment
+	if lineComment2 == nil {
+		t.Fatal("missing line comment")
+	}
+	if lineComment.List[0].Text != "/* line comment */" {
+		t.Errorf(`unexpected line comment got = %q; want "/* line comment */"`, lineComment.List[0].Text)
+	}
+
+	docComment2 := f.Decls[3].(*ast.FuncDecl).Doc
+	if docComment2 != nil {
+		t.Errorf("unexpected doc comment %v", docComment2)
+	}
+}
diff --git a/src/internal/buildcfg/exp.go b/src/internal/buildcfg/exp.go
index 734059e6d8..b05150373b 100644
--- a/src/internal/buildcfg/exp.go
+++ b/src/internal/buildcfg/exp.go
@@ -79,10 +79,11 @@ func ParseGOEXPERIMENT(goos, goarch, goexp string) (*ExperimentFlags, error) {
 	dwarf5Supported := (goos != "darwin" && goos != "ios" && goos != "aix")
 
 	baseline := goexperiment.Flags{
-		RegabiWrappers:  regabiSupported,
-		RegabiArgs:      regabiSupported,
-		SIMD:            goarch == "amd64", // TODO remove this (default to false) when dev.simd is merged
-		Dwarf5:          dwarf5Supported,
+		RegabiWrappers:       regabiSupported,
+		RegabiArgs:           regabiSupported,
+		SIMD:                 goarch == "amd64", // TODO remove this (default to false) when dev.simd is merged
+		Dwarf5:               dwarf5Supported,
+		RandomizedHeapBase64: true,
 	}
 
 	// Start with the statically enabled set of experiments.
diff --git a/src/iter/iter.go b/src/iter/iter.go
index 3eaeb9e1fd..3d0caebf1e 100644
--- a/src/iter/iter.go
+++ b/src/iter/iter.go
@@ -28,6 +28,8 @@ or index-value pairs.
 Yield returns true if the iterator should continue with the next
 element in the sequence, false if it should stop.
 
+Yield panics if called after it returns false.
+
 For instance, [maps.Keys] returns an iterator that produces the sequence
 of keys of the map m, implemented as follows:
 
diff --git a/src/log/slog/internal/benchmarks/benchmarks.go b/src/log/slog/internal/benchmarks/benchmarks.go
index 3a28523beb..a94ecfa743 100644
--- a/src/log/slog/internal/benchmarks/benchmarks.go
+++ b/src/log/slog/internal/benchmarks/benchmarks.go
@@ -31,12 +31,19 @@ import (
 
 const testMessage = "Test logging, but use a somewhat realistic message length."
 
+type event struct {
+	ID    string
+	Index int
+	Flag  bool
+}
+
 var (
 	testTime     = time.Date(2022, time.May, 1, 0, 0, 0, 0, time.UTC)
 	testString   = "7e3b3b2aaeff56a7108fe11e154200dd/7819479873059528190"
 	testInt      = 32768
 	testDuration = 23 * time.Second
 	testError    = errors.New("fail")
+	testEvent    = event{"abcdefgh", 65536, true}
 )
 
 var testAttrs = []slog.Attr{
diff --git a/src/log/slog/internal/benchmarks/benchmarks_test.go b/src/log/slog/internal/benchmarks/benchmarks_test.go
index 18643b73e6..3fec261279 100644
--- a/src/log/slog/internal/benchmarks/benchmarks_test.go
+++ b/src/log/slog/internal/benchmarks/benchmarks_test.go
@@ -80,12 +80,12 @@ func BenchmarkAttrs(b *testing.B) {
 							slog.Int("status", testInt),
 							slog.Duration("duration", testDuration),
 							slog.Time("time", testTime),
-							slog.Any("error", testError),
+							slog.Any("event", testEvent),
 							slog.String("string", testString),
 							slog.Int("status", testInt),
 							slog.Duration("duration", testDuration),
 							slog.Time("time", testTime),
-							slog.Any("error", testError),
+							slog.Any("event", testEvent),
 						)
 					},
 				},
@@ -103,37 +103,37 @@ func BenchmarkAttrs(b *testing.B) {
 							slog.Int("status", testInt),
 							slog.Duration("duration", testDuration),
 							slog.Time("time", testTime),
-							slog.Any("error", testError),
+							slog.Any("event", testEvent),
 							slog.String("string", testString),
 							slog.Int("status", testInt),
 							slog.Duration("duration", testDuration),
 							slog.Time("time", testTime),
-							slog.Any("error", testError),
+							slog.Any("event", testEvent),
 							slog.String("string", testString),
 							slog.Int("status", testInt),
 							slog.Duration("duration", testDuration),
 							slog.Time("time", testTime),
-							slog.Any("error", testError),
+							slog.Any("event", testEvent),
 							slog.String("string", testString),
 							slog.Int("status", testInt),
 							slog.Duration("duration", testDuration),
 							slog.Time("time", testTime),
-							slog.Any("error", testError),
+							slog.Any("event", testEvent),
 							slog.String("string", testString),
 							slog.Int("status", testInt),
 							slog.Duration("duration", testDuration),
 							slog.Time("time", testTime),
-							slog.Any("error", testError),
+							slog.Any("event", testEvent),
 							slog.String("string", testString),
 							slog.Int("status", testInt),
 							slog.Duration("duration", testDuration),
 							slog.Time("time", testTime),
-							slog.Any("error", testError),
+							slog.Any("event", testEvent),
 							slog.String("string", testString),
 							slog.Int("status", testInt),
 							slog.Duration("duration", testDuration),
 							slog.Time("time", testTime),
-							slog.Any("error", testError),
+							slog.Any("event", testEvent),
 						)
 					},
 				},
diff --git a/src/log/slog/json_handler.go b/src/log/slog/json_handler.go
index f139c54139..9c7045cda9 100644
--- a/src/log/slog/json_handler.go
+++ b/src/log/slog/json_handler.go
@@ -137,15 +137,40 @@ func appendJSONValue(s *handleState, v Value) error {
 	return nil
 }
 
-func appendJSONMarshal(buf *buffer.Buffer, v any) error {
+type jsonEncoder struct {
+	buf *bytes.Buffer
 	// Use a json.Encoder to avoid escaping HTML.
-	var bb bytes.Buffer
-	enc := json.NewEncoder(&bb)
-	enc.SetEscapeHTML(false)
-	if err := enc.Encode(v); err != nil {
+	json *json.Encoder
+}
+
+var jsonEncoderPool = &sync.Pool{
+	New: func() any {
+		enc := &jsonEncoder{
+			buf: new(bytes.Buffer),
+		}
+		enc.json = json.NewEncoder(enc.buf)
+		enc.json.SetEscapeHTML(false)
+		return enc
+	},
+}
+
+func appendJSONMarshal(buf *buffer.Buffer, v any) error {
+	j := jsonEncoderPool.Get().(*jsonEncoder)
+	defer func() {
+		// To reduce peak allocation, return only smaller buffers to the pool.
+		const maxBufferSize = 16 << 10
+		if j.buf.Cap() > maxBufferSize {
+			return
+		}
+		j.buf.Reset()
+		jsonEncoderPool.Put(j)
+	}()
+
+	if err := j.json.Encode(v); err != nil {
 		return err
 	}
-	bs := bb.Bytes()
+
+	bs := j.buf.Bytes()
 	buf.Write(bs[:len(bs)-1]) // remove final newline
 	return nil
 }
diff --git a/src/log/slog/json_handler_test.go b/src/log/slog/json_handler_test.go
index 65130f2426..fd6b2e39d4 100644
--- a/src/log/slog/json_handler_test.go
+++ b/src/log/slog/json_handler_test.go
@@ -142,6 +142,39 @@ func jsonValueString(v Value) string {
 	return string(buf)
 }
 
+func TestJSONAllocs(t *testing.T) {
+	ctx := t.Context()
+	l := New(NewJSONHandler(io.Discard, &HandlerOptions{}))
+	testErr := errors.New("an error occurred")
+	testEvent := struct {
+		ID      int
+		Scope   string
+		Enabled bool
+	}{
+		123456, "abcdefgh", true,
+	}
+
+	t.Run("message", func(t *testing.T) {
+		wantAllocs(t, 0, func() {
+			l.LogAttrs(ctx, LevelInfo,
+				"hello world",
+			)
+		})
+	})
+	t.Run("attrs", func(t *testing.T) {
+		wantAllocs(t, 1, func() {
+			l.LogAttrs(ctx, LevelInfo,
+				"hello world",
+				String("component", "subtest"),
+				Int("id", 67890),
+				Bool("flag", true),
+				Any("error", testErr),
+				Any("event", testEvent),
+			)
+		})
+	})
+}
+
 func BenchmarkJSONHandler(b *testing.B) {
 	for _, bench := range []struct {
 		name string
diff --git a/src/log/slog/level.go b/src/log/slog/level.go
index 2957585e0e..9e812eb165 100644
--- a/src/log/slog/level.go
+++ b/src/log/slog/level.go
@@ -61,7 +61,11 @@ func (l Level) String() string {
 		if val == 0 {
 			return base
 		}
-		return fmt.Sprintf("%s%+d", base, val)
+		sval := strconv.Itoa(int(val))
+		if val > 0 {
+			sval = "+" + sval
+		}
+		return base + sval
 	}
 
 	switch {
diff --git a/src/log/slog/level_test.go b/src/log/slog/level_test.go
index 73be1126b2..c9a1c16c03 100644
--- a/src/log/slog/level_test.go
+++ b/src/log/slog/level_test.go
@@ -215,3 +215,25 @@ func TestLevelVarString(t *testing.T) {
 		t.Errorf("got %q, want %q", got, want)
 	}
 }
+
+func BenchmarkLevelString(b *testing.B) {
+	levels := []Level{
+		0,
+		LevelError,
+		LevelError + 2,
+		LevelError - 2,
+		LevelWarn,
+		LevelWarn - 1,
+		LevelInfo,
+		LevelInfo + 1,
+		LevelInfo - 3,
+		LevelDebug,
+		LevelDebug - 2,
+	}
+	b.ResetTimer()
+	for b.Loop() {
+		for _, level := range levels {
+			_ = level.String()
+		}
+	}
+}
diff --git a/src/net/fd_unix.go b/src/net/fd_unix.go
index 40ecbef2e8..0d4303e2cc 100644
--- a/src/net/fd_unix.go
+++ b/src/net/fd_unix.go
@@ -82,6 +82,9 @@ func (fd *netFD) connect(ctx context.Context, la, ra syscall.Sockaddr) (rsa sysc
 			defer fd.pfd.SetWriteDeadline(noDeadline)
 		}
 
+		// Load the hook function synchronously to prevent a race
+		// with test code that restores the old value.
+		testHookCanceledDial := testHookCanceledDial
 		stop := context.AfterFunc(ctx, func() {
 			// Force the runtime's poller to immediately give up
 			// waiting for writability, unblocking waitWrite
diff --git a/src/net/http/transport.go b/src/net/http/transport.go
index 139ad84af0..5cef9be487 100644
--- a/src/net/http/transport.go
+++ b/src/net/http/transport.go
@@ -1382,7 +1382,10 @@ func (w *wantConn) cancel(t *Transport) {
 	w.done = true
 	w.mu.Unlock()
 
-	if pc != nil {
+	// HTTP/2 connections (pc.alt != nil) aren't removed from the idle pool on use,
+	// and should not be added back here. If the pconn isn't in the idle pool,
+	// it's because we removed it due to an error.
+	if pc != nil && pc.alt == nil {
 		t.putOrCloseIdleConn(pc)
 	}
 }
diff --git a/src/net/http/transport_test.go b/src/net/http/transport_test.go
index 810f21f3a5..75dbd25d22 100644
--- a/src/net/http/transport_test.go
+++ b/src/net/http/transport_test.go
@@ -7625,3 +7625,35 @@ func TestTransportServerProtocols(t *testing.T) {
 		})
 	}
 }
+
+func TestIssue61474(t *testing.T) {
+	run(t, testIssue61474, []testMode{http2Mode})
+}
+func testIssue61474(t *testing.T, mode testMode) {
+	if testing.Short() {
+		return
+	}
+
+	// This test reliably exercises the condition causing #61474,
+	// but requires many iterations to do so.
+	// Keep the test around for now, but don't run it by default.
+	t.Skip("test is too large")
+
+	cst := newClientServerTest(t, mode, HandlerFunc(func(rw ResponseWriter, req *Request) {
+	}), func(tr *Transport) {
+		tr.MaxConnsPerHost = 1
+	})
+	var wg sync.WaitGroup
+	defer wg.Wait()
+	for range 100000 {
+		wg.Go(func() {
+			ctx, cancel := context.WithTimeout(t.Context(), 1*time.Millisecond)
+			defer cancel()
+			req, _ := NewRequestWithContext(ctx, "GET", cst.ts.URL, nil)
+			resp, err := cst.c.Do(req)
+			if err == nil {
+				resp.Body.Close()
+			}
+		})
+	}
+}
diff --git a/src/os/user/cgo_unix_test.go b/src/os/user/cgo_lookup_unix_test.go
index 6d16aa20b3..cd225eb8df 100644
--- a/src/os/user/cgo_unix_test.go
+++ b/src/os/user/cgo_lookup_unix_test.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build (darwin || dragonfly || freebsd || (!android && linux) || netbsd || openbsd || solaris) && cgo && !osusergo
+//go:build (cgo || darwin) && !osusergo && unix && !android
 
 package user
 
diff --git a/src/path/filepath/symlink_plan9.go b/src/path/filepath/symlink_plan9.go
index 820d150d97..b29abe1dfd 100644
--- a/src/path/filepath/symlink_plan9.go
+++ b/src/path/filepath/symlink_plan9.go
@@ -16,8 +16,8 @@ func evalSymlinks(path string) (string, error) {
 		// Check validity of path
 		_, err := os.Lstat(path)
 		if err != nil {
-			// Return the same error value as on other operating systems
-			if strings.HasSuffix(err.Error(), "not a directory") {
+			// Return the same error value as on other operating systems.
+			if strings.Contains(err.Error(), "not a directory") {
 				err = syscall.ENOTDIR
 			}
 			return "", err
diff --git a/src/runtime/_mkmalloc/astutil/clone.go b/src/runtime/_mkmalloc/astutil/clone.go
new file mode 100644
index 0000000000..16ea7163ca
--- /dev/null
+++ b/src/runtime/_mkmalloc/astutil/clone.go
@@ -0,0 +1,73 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file is a copy of golang.org/x/tools/internal/astutil/clone.go
+
+package astutil
+
+import (
+	"go/ast"
+	"reflect"
+)
+
+// CloneNode returns a deep copy of a Node.
+// It omits pointers to ast.{Scope,Object} variables.
+func CloneNode[T ast.Node](n T) T {
+	return cloneNode(n).(T)
+}
+
+func cloneNode(n ast.Node) ast.Node {
+	var clone func(x reflect.Value) reflect.Value
+	set := func(dst, src reflect.Value) {
+		src = clone(src)
+		if src.IsValid() {
+			dst.Set(src)
+		}
+	}
+	clone = func(x reflect.Value) reflect.Value {
+		switch x.Kind() {
+		case reflect.Pointer:
+			if x.IsNil() {
+				return x
+			}
+			// Skip fields of types potentially involved in cycles.
+			switch x.Interface().(type) {
+			case *ast.Object, *ast.Scope:
+				return reflect.Zero(x.Type())
+			}
+			y := reflect.New(x.Type().Elem())
+			set(y.Elem(), x.Elem())
+			return y
+
+		case reflect.Struct:
+			y := reflect.New(x.Type()).Elem()
+			for i := 0; i < x.Type().NumField(); i++ {
+				set(y.Field(i), x.Field(i))
+			}
+			return y
+
+		case reflect.Slice:
+			if x.IsNil() {
+				return x
+			}
+			y := reflect.MakeSlice(x.Type(), x.Len(), x.Cap())
+			for i := 0; i < x.Len(); i++ {
+				set(y.Index(i), x.Index(i))
+			}
+			return y
+
+		case reflect.Interface:
+			y := reflect.New(x.Type()).Elem()
+			set(y, x.Elem())
+			return y
+
+		case reflect.Array, reflect.Chan, reflect.Func, reflect.Map, reflect.UnsafePointer:
+			panic(x) // unreachable in AST
+
+		default:
+			return x // bool, string, number
+		}
+	}
+	return clone(reflect.ValueOf(n)).Interface().(ast.Node)
+}
diff --git a/src/runtime/defs2_linux.go b/src/runtime/defs2_linux.go
index 5d6730a7ad..597073c39d 100644
--- a/src/runtime/defs2_linux.go
+++ b/src/runtime/defs2_linux.go
@@ -48,6 +48,7 @@ const (
 	EINTR  = C.EINTR
 	EAGAIN = C.EAGAIN
 	ENOMEM = C.ENOMEM
+	ENOSYS = C.ENOSYS
 
 	PROT_NONE  = C.PROT_NONE
 	PROT_READ  = C.PROT_READ
diff --git a/src/runtime/defs_linux.go b/src/runtime/defs_linux.go
index 296fcb4bfd..d2b619ecab 100644
--- a/src/runtime/defs_linux.go
+++ b/src/runtime/defs_linux.go
@@ -37,6 +37,7 @@ const (
 	EINTR  = C.EINTR
 	EAGAIN = C.EAGAIN
 	ENOMEM = C.ENOMEM
+	ENOSYS = C.ENOSYS
 
 	PROT_NONE  = C.PROT_NONE
 	PROT_READ  = C.PROT_READ
diff --git a/src/runtime/defs_linux_386.go b/src/runtime/defs_linux_386.go
index 5fef55610f..e902d8175c 100644
--- a/src/runtime/defs_linux_386.go
+++ b/src/runtime/defs_linux_386.go
@@ -9,6 +9,7 @@ const (
 	_EINTR  = 0x4
 	_EAGAIN = 0xb
 	_ENOMEM = 0xc
+	_ENOSYS = 0x26
 
 	_PROT_NONE  = 0x0
 	_PROT_READ  = 0x1
@@ -136,16 +137,30 @@ type fpstate struct {
 	anon0     [48]byte
 }
 
-type timespec struct {
+// The timespec structs and types are defined in Linux in
+// include/uapi/linux/time_types.h and include/uapi/asm-generic/posix_types.h.
+type timespec32 struct {
 	tv_sec  int32
 	tv_nsec int32
 }
 
 //go:nosplit
-func (ts *timespec) setNsec(ns int64) {
+func (ts *timespec32) setNsec(ns int64) {
 	ts.tv_sec = timediv(ns, 1e9, &ts.tv_nsec)
 }
 
+type timespec struct {
+	tv_sec  int64
+	tv_nsec int64
+}
+
+//go:nosplit
+func (ts *timespec) setNsec(ns int64) {
+	var newNS int32
+	ts.tv_sec = int64(timediv(ns, 1e9, &newNS))
+	ts.tv_nsec = int64(newNS)
+}
+
 type timeval struct {
 	tv_sec  int32
 	tv_usec int32
@@ -223,8 +238,8 @@ type ucontext struct {
 }
 
 type itimerspec struct {
-	it_interval timespec
-	it_value    timespec
+	it_interval timespec32
+	it_value    timespec32
 }
 
 type itimerval struct {
diff --git a/src/runtime/defs_linux_amd64.go b/src/runtime/defs_linux_amd64.go
index dce7799b6a..9a908c9400 100644
--- a/src/runtime/defs_linux_amd64.go
+++ b/src/runtime/defs_linux_amd64.go
@@ -9,6 +9,7 @@ const (
 	_EINTR  = 0x4
 	_EAGAIN = 0xb
 	_ENOMEM = 0xc
+	_ENOSYS = 0x26
 
 	_PROT_NONE  = 0x0
 	_PROT_READ  = 0x1
diff --git a/src/runtime/defs_linux_arm.go b/src/runtime/defs_linux_arm.go
index 71cf8c6d50..35c4faf964 100644
--- a/src/runtime/defs_linux_arm.go
+++ b/src/runtime/defs_linux_arm.go
@@ -11,6 +11,7 @@ const (
 	_EINTR  = 0x4
 	_ENOMEM = 0xc
 	_EAGAIN = 0xb
+	_ENOSYS = 0x26
 
 	_PROT_NONE  = 0
 	_PROT_READ  = 0x1
@@ -95,16 +96,30 @@ const (
 	_SOCK_DGRAM = 0x2
 )
 
-type timespec struct {
+// The timespec structs and types are defined in Linux in
+// include/uapi/linux/time_types.h and include/uapi/asm-generic/posix_types.h.
+type timespec32 struct {
 	tv_sec  int32
 	tv_nsec int32
 }
 
 //go:nosplit
-func (ts *timespec) setNsec(ns int64) {
+func (ts *timespec32) setNsec(ns int64) {
 	ts.tv_sec = timediv(ns, 1e9, &ts.tv_nsec)
 }
 
+type timespec struct {
+	tv_sec  int64
+	tv_nsec int64
+}
+
+//go:nosplit
+func (ts *timespec) setNsec(ns int64) {
+	var newNS int32
+	ts.tv_sec = int64(timediv(ns, 1e9, &newNS))
+	ts.tv_nsec = int64(newNS)
+}
+
 type stackt struct {
 	ss_sp    *byte
 	ss_flags int32
@@ -155,8 +170,8 @@ func (tv *timeval) set_usec(x int32) {
 }
 
 type itimerspec struct {
-	it_interval timespec
-	it_value    timespec
+	it_interval timespec32
+	it_value    timespec32
 }
 
 type itimerval struct {
diff --git a/src/runtime/defs_linux_arm64.go b/src/runtime/defs_linux_arm64.go
index 606cd70494..4992e91ea6 100644
--- a/src/runtime/defs_linux_arm64.go
+++ b/src/runtime/defs_linux_arm64.go
@@ -9,6 +9,7 @@ const (
 	_EINTR  = 0x4
 	_EAGAIN = 0xb
 	_ENOMEM = 0xc
+	_ENOSYS = 0x26
 
 	_PROT_NONE  = 0x0
 	_PROT_READ  = 0x1
diff --git a/src/runtime/defs_linux_loong64.go b/src/runtime/defs_linux_loong64.go
index b983725160..670d4c318d 100644
--- a/src/runtime/defs_linux_loong64.go
+++ b/src/runtime/defs_linux_loong64.go
@@ -10,6 +10,7 @@ const (
 	_EINTR  = 0x4
 	_EAGAIN = 0xb
 	_ENOMEM = 0xc
+	_ENOSYS = 0x26
 
 	_PROT_NONE  = 0x0
 	_PROT_READ  = 0x1
diff --git a/src/runtime/defs_linux_mips64x.go b/src/runtime/defs_linux_mips64x.go
index 8a0af41234..7449d2cfac 100644
--- a/src/runtime/defs_linux_mips64x.go
+++ b/src/runtime/defs_linux_mips64x.go
@@ -12,6 +12,7 @@ const (
 	_EINTR  = 0x4
 	_EAGAIN = 0xb
 	_ENOMEM = 0xc
+	_ENOSYS = 0x26
 
 	_PROT_NONE  = 0x0
 	_PROT_READ  = 0x1
diff --git a/src/runtime/defs_linux_mipsx.go b/src/runtime/defs_linux_mipsx.go
index 8322beab2b..cec504c885 100644
--- a/src/runtime/defs_linux_mipsx.go
+++ b/src/runtime/defs_linux_mipsx.go
@@ -12,6 +12,7 @@ const (
 	_EINTR  = 0x4
 	_EAGAIN = 0xb
 	_ENOMEM = 0xc
+	_ENOSYS = 0x26
 
 	_PROT_NONE  = 0x0
 	_PROT_READ  = 0x1
@@ -93,16 +94,30 @@ const (
 	_SIGEV_THREAD_ID = 0x4
 )
 
-type timespec struct {
+// The timespec structs and types are defined in Linux in
+// include/uapi/linux/time_types.h and include/uapi/asm-generic/posix_types.h.
+type timespec32 struct {
 	tv_sec  int32
 	tv_nsec int32
 }
 
 //go:nosplit
-func (ts *timespec) setNsec(ns int64) {
+func (ts *timespec32) setNsec(ns int64) {
 	ts.tv_sec = timediv(ns, 1e9, &ts.tv_nsec)
 }
 
+type timespec struct {
+	tv_sec  int64
+	tv_nsec int64
+}
+
+//go:nosplit
+func (ts *timespec) setNsec(ns int64) {
+	var newNS int32
+	ts.tv_sec = int64(timediv(ns, 1e9, &newNS))
+	ts.tv_nsec = int64(newNS)
+}
+
 type timeval struct {
 	tv_sec  int32
 	tv_usec int32
@@ -138,8 +153,8 @@ type siginfo struct {
 }
 
 type itimerspec struct {
-	it_interval timespec
-	it_value    timespec
+	it_interval timespec32
+	it_value    timespec32
 }
 
 type itimerval struct {
diff --git a/src/runtime/defs_linux_ppc64.go b/src/runtime/defs_linux_ppc64.go
index f87924affe..dc45f37b7c 100644
--- a/src/runtime/defs_linux_ppc64.go
+++ b/src/runtime/defs_linux_ppc64.go
@@ -9,6 +9,7 @@ const (
 	_EINTR  = 0x4
 	_EAGAIN = 0xb
 	_ENOMEM = 0xc
+	_ENOSYS = 0x26
 
 	_PROT_NONE  = 0x0
 	_PROT_READ  = 0x1
diff --git a/src/runtime/defs_linux_ppc64le.go b/src/runtime/defs_linux_ppc64le.go
index f87924affe..dc45f37b7c 100644
--- a/src/runtime/defs_linux_ppc64le.go
+++ b/src/runtime/defs_linux_ppc64le.go
@@ -9,6 +9,7 @@ const (
 	_EINTR  = 0x4
 	_EAGAIN = 0xb
 	_ENOMEM = 0xc
+	_ENOSYS = 0x26
 
 	_PROT_NONE  = 0x0
 	_PROT_READ  = 0x1
diff --git a/src/runtime/defs_linux_riscv64.go b/src/runtime/defs_linux_riscv64.go
index 29b1ef2a50..b73e208ac3 100644
--- a/src/runtime/defs_linux_riscv64.go
+++ b/src/runtime/defs_linux_riscv64.go
@@ -10,6 +10,7 @@ const (
 	_EINTR  = 0x4
 	_EAGAIN = 0xb
 	_ENOMEM = 0xc
+	_ENOSYS = 0x26
 
 	_PROT_NONE  = 0x0
 	_PROT_READ  = 0x1
diff --git a/src/runtime/defs_linux_s390x.go b/src/runtime/defs_linux_s390x.go
index b0280213b3..c03d0f2117 100644
--- a/src/runtime/defs_linux_s390x.go
+++ b/src/runtime/defs_linux_s390x.go
@@ -10,6 +10,7 @@ const (
 	_EINTR  = 0x4
 	_EAGAIN = 0xb
 	_ENOMEM = 0xc
+	_ENOSYS = 0x26
 
 	_PROT_NONE  = 0x0
 	_PROT_READ  = 0x1
diff --git a/src/runtime/export_test.go b/src/runtime/export_test.go
index fc77b535da..a7b51dd6c7 100644
--- a/src/runtime/export_test.go
+++ b/src/runtime/export_test.go
@@ -9,7 +9,6 @@ package runtime
 import (
 	"internal/abi"
 	"internal/goarch"
-	"internal/goexperiment"
 	"internal/goos"
 	"internal/runtime/atomic"
 	"internal/runtime/gc"
@@ -1122,8 +1121,6 @@ func CheckScavengedBitsCleared(mismatches []BitsMismatch) (n int, ok bool) {
 		// Lock so that we can safely access the bitmap.
 		lock(&mheap_.lock)
 
-		heapBase := mheap_.pages.inUse.ranges[0].base.addr()
-		secondArenaBase := arenaBase(arenaIndex(heapBase) + 1)
 	chunkLoop:
 		for i := mheap_.pages.start; i < mheap_.pages.end; i++ {
 			chunk := mheap_.pages.tryChunkOf(i)
@@ -1140,14 +1137,6 @@ func CheckScavengedBitsCleared(mismatches []BitsMismatch) (n int, ok bool) {
 				want := chunk.scavenged[j] &^ chunk.pallocBits[j]
 				got := chunk.scavenged[j]
 				if want != got {
-					// When goexperiment.RandomizedHeapBase64 is set we use a
-					// series of padding pages to generate randomized heap base
-					// address which have both the alloc and scav bits set. If
-					// we see this for a chunk between the address of the heap
-					// base, and the address of the second arena continue.
-					if goexperiment.RandomizedHeapBase64 && (cb >= heapBase && cb < secondArenaBase) {
-						continue
-					}
 					ok = false
 					if n >= len(mismatches) {
 						break chunkLoop
@@ -1165,6 +1154,37 @@ func CheckScavengedBitsCleared(mismatches []BitsMismatch) (n int, ok bool) {
 
 		getg().m.mallocing--
 	})
+
+	if randomizeHeapBase && len(mismatches) > 0 {
+		// When goexperiment.RandomizedHeapBase64 is set we use a series of
+		// padding pages to generate randomized heap base address which have
+		// both the alloc and scav bits set. Because of this we expect exactly
+		// one arena will have mismatches, so check for that explicitly and
+		// remove the mismatches if that property holds. If we see more than one
+		// arena with this property, that is an indication something has
+		// actually gone wrong, so return the mismatches.
+		//
+		// We do this, instead of ignoring the mismatches in the chunkLoop, because
+		// it's not easy to determine which arena we added the padding pages to
+		// programmatically, without explicitly recording the base address somewhere
+		// in a global variable (which we'd rather not do as the address of that variable
+		// is likely to be somewhat predictable, potentially defeating the purpose
+		// of our randomization).
+		affectedArenas := map[arenaIdx]bool{}
+		for _, mismatch := range mismatches {
+			if mismatch.Base > 0 {
+				affectedArenas[arenaIndex(mismatch.Base)] = true
+			}
+		}
+		if len(affectedArenas) == 1 {
+			ok = true
+			// zero the mismatches
+			for i := range n {
+				mismatches[i] = BitsMismatch{}
+			}
+		}
+	}
+
 	return
 }
 
diff --git a/src/runtime/malloc.go b/src/runtime/malloc.go
index ec5f0765ba..5b5a633d9a 100644
--- a/src/runtime/malloc.go
+++ b/src/runtime/malloc.go
@@ -349,7 +349,7 @@ const (
 
 	// randomizeHeapBase indicates if the heap base address should be randomized.
 	// See comment in mallocinit for how the randomization is performed.
-	randomizeHeapBase = goexperiment.RandomizedHeapBase64 && goarch.PtrSize == 8 && !isSbrkPlatform
+	randomizeHeapBase = goexperiment.RandomizedHeapBase64 && goarch.PtrSize == 8 && !isSbrkPlatform && !raceenabled && !msanenabled && !asanenabled
 
 	// randHeapBasePrefixMask is used to extract the top byte of the randomized
 	// heap base address.
diff --git a/src/runtime/mbitmap.go b/src/runtime/mbitmap.go
index 9872e5297f..508de9a115 100644
--- a/src/runtime/mbitmap.go
+++ b/src/runtime/mbitmap.go
@@ -714,6 +714,26 @@ func heapSetTypeNoHeader(x, dataSize uintptr, typ *_type, span *mspan) uintptr {
 }
 
 func heapSetTypeSmallHeader(x, dataSize uintptr, typ *_type, header **_type, span *mspan) uintptr {
+	if header == nil {
+		// This nil check and throw is almost pointless. Normally we would
+		// expect header to never be nil. However, this is called on potentially
+		// freshly-allocated virtual memory. As of 2025, the compiler-inserted
+		// nil check is not a branch but a memory read that we expect to fault
+		// if the pointer really is nil.
+		//
+		// However, this causes a read of the page, and operating systems may
+		// take it as a hint to back the accessed memory with a read-only zero
+		// page. However, we immediately write to this memory, which can then
+		// force operating systems to have to update the page table and flush
+		// the TLB.
+		//
+		// This nil check is thus an explicit branch instead of what the compiler
+		// would insert circa 2025, which is a memory read instruction.
+		//
+		// See go.dev/issue/74375 for details of a similar issue in
+		// spanInlineMarkBits.
+		throw("runtime: pointer to heap type header nil?")
+	}
 	*header = typ
 	if doubleCheckHeapSetType {
 		doubleCheckHeapType(x, dataSize, typ, header, span)
diff --git a/src/runtime/metrics_test.go b/src/runtime/metrics_test.go
index 3989b79293..af042f4445 100644
--- a/src/runtime/metrics_test.go
+++ b/src/runtime/metrics_test.go
@@ -1760,8 +1760,6 @@ func TestReadMetricsSched(t *testing.T) {
 			metrics.Read(s[:])
 			return s[notInGo].Value.Uint64() >= count
 		})
-
-		metrics.Read(s[:])
 		logMetrics(t, s[:])
 		check(t, &s[notInGo], count, count+generalSlack)
 
@@ -1782,8 +1780,6 @@ func TestReadMetricsSched(t *testing.T) {
 			metrics.Read(s[:])
 			return s[waiting].Value.Uint64() >= waitingCount
 		})
-
-		metrics.Read(s[:])
 		logMetrics(t, s[:])
 		check(t, &s[waiting], waitingCount, waitingCount+waitingSlack)
 
diff --git a/src/runtime/os_linux.go b/src/runtime/os_linux.go
index f9fe1b5f33..080dd96532 100644
--- a/src/runtime/os_linux.go
+++ b/src/runtime/os_linux.go
@@ -40,9 +40,6 @@ type mOS struct {
 	waitsema uint32 // semaphore for parking on locks
 }
 
-//go:noescape
-func futex(addr unsafe.Pointer, op int32, val uint32, ts, addr2 unsafe.Pointer, val3 uint32) int32
-
 // Linux futex.
 //
 //	futexsleep(uint32 *addr, uint32 val)
@@ -79,7 +76,7 @@ func futexsleep(addr *uint32, val uint32, ns int64) {
 
 	var ts timespec
 	ts.setNsec(ns)
-	futex(unsafe.Pointer(addr), _FUTEX_WAIT_PRIVATE, val, unsafe.Pointer(&ts), nil, 0)
+	futex(unsafe.Pointer(addr), _FUTEX_WAIT_PRIVATE, val, &ts, nil, 0)
 }
 
 // If any procs are sleeping on addr, wake up at most cnt.
diff --git a/src/runtime/os_linux_futex32.go b/src/runtime/os_linux_futex32.go
new file mode 100644
index 0000000000..fdf99e5669
--- /dev/null
+++ b/src/runtime/os_linux_futex32.go
@@ -0,0 +1,40 @@
+// Copyright 2025 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux && (386 || arm || mips || mipsle || ppc)
+
+package runtime
+
+import (
+	"internal/runtime/atomic"
+	"unsafe"
+)
+
+//go:noescape
+func futex_time32(addr unsafe.Pointer, op int32, val uint32, ts *timespec32, addr2 unsafe.Pointer, val3 uint32) int32
+
+//go:noescape
+func futex_time64(addr unsafe.Pointer, op int32, val uint32, ts *timespec, addr2 unsafe.Pointer, val3 uint32) int32
+
+var is32bitOnly atomic.Bool
+
+//go:nosplit
+func futex(addr unsafe.Pointer, op int32, val uint32, ts *timespec, addr2 unsafe.Pointer, val3 uint32) int32 {
+	if !is32bitOnly.Load() {
+		ret := futex_time64(addr, op, val, ts, addr2, val3)
+		// futex_time64 is only supported on Linux 5.0+
+		if ret != -_ENOSYS {
+			return ret
+		}
+		is32bitOnly.Store(true)
+	}
+	// Downgrade ts.
+	var ts32 timespec32
+	var pts32 *timespec32
+	if ts != nil {
+		ts32.setNsec(ts.tv_sec*1e9 + ts.tv_nsec)
+		pts32 = &ts32
+	}
+	return futex_time32(addr, op, val, pts32, addr2, val3)
+}
diff --git a/src/runtime/os_linux_futex64.go b/src/runtime/os_linux_futex64.go
new file mode 100644
index 0000000000..487d0e0397
--- /dev/null
+++ b/src/runtime/os_linux_futex64.go
@@ -0,0 +1,14 @@
+// Copyright 2025 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux && !(386 || arm || mips || mipsle || ppc || s390)
+
+package runtime
+
+import (
+	"unsafe"
+)
+
+//go:noescape
+func futex(addr unsafe.Pointer, op int32, val uint32, ts *timespec, addr2 unsafe.Pointer, val3 uint32) int32
diff --git a/src/runtime/sys_linux_386.s b/src/runtime/sys_linux_386.s
index 8e832687e0..1c3f1ff3e6 100644
--- a/src/runtime/sys_linux_386.s
+++ b/src/runtime/sys_linux_386.s
@@ -48,6 +48,7 @@
 #define SYS_madvise		219
 #define SYS_gettid		224
 #define SYS_futex		240
+#define SYS_futex_time64	422
 #define SYS_sched_getaffinity	242
 #define SYS_set_thread_area	243
 #define SYS_exit_group		252
@@ -532,9 +533,10 @@ TEXT runtime·madvise(SB),NOSPLIT,$0
 	MOVL	AX, ret+12(FP)
 	RET
 
+// Linux: kernel/futex/syscalls.c, requiring COMPAT_32BIT_TIME
 // int32 futex(int32 *uaddr, int32 op, int32 val,
-//	struct timespec *timeout, int32 *uaddr2, int32 val2);
-TEXT runtime·futex(SB),NOSPLIT,$0
+//	struct old_timespec32 *timeout, int32 *uaddr2, int32 val2);
+TEXT runtime·futex_time32(SB),NOSPLIT,$0
 	MOVL	$SYS_futex, AX
 	MOVL	addr+0(FP), BX
 	MOVL	op+4(FP), CX
@@ -546,6 +548,21 @@ TEXT runtime·futex(SB),NOSPLIT,$0
 	MOVL	AX, ret+24(FP)
 	RET
 
+// Linux: kernel/futex/syscalls.c
+// int32 futex(int32 *uaddr, int32 op, int32 val,
+//	struct timespec *timeout, int32 *uaddr2, int32 val2);
+TEXT runtime·futex_time64(SB),NOSPLIT,$0
+	MOVL	$SYS_futex_time64, AX
+	MOVL	addr+0(FP), BX
+	MOVL	op+4(FP), CX
+	MOVL	val+8(FP), DX
+	MOVL	ts+12(FP), SI
+	MOVL	addr2+16(FP), DI
+	MOVL	val3+20(FP), BP
+	INVOKE_SYSCALL
+	MOVL	AX, ret+24(FP)
+	RET
+
 // int32 clone(int32 flags, void *stack, M *mp, G *gp, void (*fn)(void));
 TEXT runtime·clone(SB),NOSPLIT,$0
 	MOVL	$SYS_clone, AX
diff --git a/src/runtime/sys_linux_arm.s b/src/runtime/sys_linux_arm.s
index 992d32ab6c..44b56ccb9f 100644
--- a/src/runtime/sys_linux_arm.s
+++ b/src/runtime/sys_linux_arm.s
@@ -30,6 +30,7 @@
 #define SYS_sigaltstack (SYS_BASE + 186)
 #define SYS_mmap2 (SYS_BASE + 192)
 #define SYS_futex (SYS_BASE + 240)
+#define SYS_futex_time64 (SYS_BASE + 422)
 #define SYS_exit_group (SYS_BASE + 248)
 #define SYS_munmap (SYS_BASE + 91)
 #define SYS_madvise (SYS_BASE + 220)
@@ -403,9 +404,10 @@ finish:
 
 	RET
 
+// Linux: kernel/futex/syscalls.c, requiring COMPAT_32BIT_TIME
 // int32 futex(int32 *uaddr, int32 op, int32 val,
-//	struct timespec *timeout, int32 *uaddr2, int32 val2);
-TEXT runtime·futex(SB),NOSPLIT,$0
+//	struct old_timespec32 *timeout, int32 *uaddr2, int32 val2);
+TEXT runtime·futex_time32(SB),NOSPLIT,$0
 	MOVW    addr+0(FP), R0
 	MOVW    op+4(FP), R1
 	MOVW    val+8(FP), R2
@@ -417,6 +419,21 @@ TEXT runtime·futex(SB),NOSPLIT,$0
 	MOVW	R0, ret+24(FP)
 	RET
 
+// Linux: kernel/futex/syscalls.c
+// int32 futex(int32 *uaddr, int32 op, int32 val,
+//	struct timespec *timeout, int32 *uaddr2, int32 val2);
+TEXT runtime·futex_time64(SB),NOSPLIT,$0
+	MOVW    addr+0(FP), R0
+	MOVW    op+4(FP), R1
+	MOVW    val+8(FP), R2
+	MOVW    ts+12(FP), R3
+	MOVW    addr2+16(FP), R4
+	MOVW    val3+20(FP), R5
+	MOVW	$SYS_futex_time64, R7
+	SWI	$0
+	MOVW	R0, ret+24(FP)
+	RET
+
 // int32 clone(int32 flags, void *stack, M *mp, G *gp, void (*fn)(void));
 TEXT runtime·clone(SB),NOSPLIT,$0
 	MOVW	flags+0(FP), R0
diff --git a/src/runtime/sys_linux_mipsx.s b/src/runtime/sys_linux_mipsx.s
index 5e6b6c1504..6f11841efc 100644
--- a/src/runtime/sys_linux_mipsx.s
+++ b/src/runtime/sys_linux_mipsx.s
@@ -34,6 +34,7 @@
 #define SYS_mincore		4217
 #define SYS_gettid		4222
 #define SYS_futex		4238
+#define SYS_futex_time64	4422
 #define SYS_sched_getaffinity	4240
 #define SYS_exit_group		4246
 #define SYS_timer_create	4257
@@ -362,8 +363,10 @@ TEXT runtime·madvise(SB),NOSPLIT,$0-16
 	MOVW	R2, ret+12(FP)
 	RET
 
-// int32 futex(int32 *uaddr, int32 op, int32 val, struct timespec *timeout, int32 *uaddr2, int32 val2);
-TEXT runtime·futex(SB),NOSPLIT,$20-28
+// Linux: kernel/futex/syscalls.c, requiring COMPAT_32BIT_TIME
+// int32 futex(int32 *uaddr, int32 op, int32 val,
+//	struct old_timespec32 *timeout, int32 *uaddr2, int32 val2);
+TEXT runtime·futex_time32(SB),NOSPLIT,$20-28
 	MOVW	addr+0(FP), R4
 	MOVW	op+4(FP), R5
 	MOVW	val+8(FP), R6
@@ -382,6 +385,27 @@ TEXT runtime·futex(SB),NOSPLIT,$20-28
 	MOVW	R2, ret+24(FP)
 	RET
 
+// Linux: kernel/futex/syscalls.c
+// int32 futex(int32 *uaddr, int32 op, int32 val,
+//	struct timespec *timeout, int32 *uaddr2, int32 val2);
+TEXT runtime·futex_time64(SB),NOSPLIT,$20-28
+	MOVW	addr+0(FP), R4
+	MOVW	op+4(FP), R5
+	MOVW	val+8(FP), R6
+	MOVW	ts+12(FP), R7
+
+	MOVW	addr2+16(FP), R8
+	MOVW	val3+20(FP), R9
+
+	MOVW	R8, 16(R29)
+	MOVW	R9, 20(R29)
+
+	MOVW	$SYS_futex_time64, R2
+	SYSCALL
+	BEQ	R7, 2(PC)
+	SUBU	R2, R0, R2	// caller expects negative errno
+	MOVW	R2, ret+24(FP)
+	RET
 
 // int32 clone(int32 flags, void *stk, M *mp, G *gp, void (*fn)(void));
 TEXT runtime·clone(SB),NOSPLIT|NOFRAME,$0-24
diff --git a/src/runtime/unsafepoint_test.go b/src/runtime/unsafepoint_test.go
index 2c97adead8..79f0171854 100644
--- a/src/runtime/unsafepoint_test.go
+++ b/src/runtime/unsafepoint_test.go
@@ -43,7 +43,7 @@ func TestUnsafePoint(t *testing.T) {
 	cmd := exec.Command(testenv.GoToolPath(t), "tool", "objdump", "-s", "setGlobalPointer", os.Args[0])
 	out, err := cmd.CombinedOutput()
 	if err != nil {
-		t.Fatalf("can't objdump %v", err)
+		t.Fatalf("can't objdump %v:\n%s", err, out)
 	}
 	lines := strings.Split(string(out), "\n")[1:]
 
diff --git a/src/strings/strings.go b/src/strings/strings.go
index 3cc3e79f98..1efd00d5f0 100644
--- a/src/strings/strings.go
+++ b/src/strings/strings.go
@@ -433,7 +433,7 @@ func Fields(s string) []string {
 // FieldsFunc splits the string s at each run of Unicode code points c satisfying f(c)
 // and returns an array of slices of s. If all code points in s satisfy f(c) or the
 // string is empty, an empty slice is returned. Every element of the returned slice is
-// non-empty. Unlike [SplitFunc], leading and trailing runs of code points satisfying f(c)
+// non-empty. Unlike [Split], leading and trailing runs of code points satisfying f(c)
 // are discarded.
 //
 // FieldsFunc makes no guarantees about the order in which it calls f(c)
diff --git a/src/testing/fuzz.go b/src/testing/fuzz.go
index c07d6a0604..5867935b81 100644
--- a/src/testing/fuzz.go
+++ b/src/testing/fuzz.go
@@ -163,23 +163,23 @@ func (f *F) Add(args ...any) {
 
 // supportedTypes represents all of the supported types which can be fuzzed.
 var supportedTypes = map[reflect.Type]bool{
-	reflect.TypeOf(([]byte)("")):  true,
-	reflect.TypeOf((string)("")):  true,
-	reflect.TypeOf((bool)(false)): true,
-	reflect.TypeOf((byte)(0)):     true,
-	reflect.TypeOf((rune)(0)):     true,
-	reflect.TypeOf((float32)(0)):  true,
-	reflect.TypeOf((float64)(0)):  true,
-	reflect.TypeOf((int)(0)):      true,
-	reflect.TypeOf((int8)(0)):     true,
-	reflect.TypeOf((int16)(0)):    true,
-	reflect.TypeOf((int32)(0)):    true,
-	reflect.TypeOf((int64)(0)):    true,
-	reflect.TypeOf((uint)(0)):     true,
-	reflect.TypeOf((uint8)(0)):    true,
-	reflect.TypeOf((uint16)(0)):   true,
-	reflect.TypeOf((uint32)(0)):   true,
-	reflect.TypeOf((uint64)(0)):   true,
+	reflect.TypeFor[[]byte]():  true,
+	reflect.TypeFor[string]():  true,
+	reflect.TypeFor[bool]():    true,
+	reflect.TypeFor[byte]():    true,
+	reflect.TypeFor[rune]():    true,
+	reflect.TypeFor[float32](): true,
+	reflect.TypeFor[float64](): true,
+	reflect.TypeFor[int]():     true,
+	reflect.TypeFor[int8]():    true,
+	reflect.TypeFor[int16]():   true,
+	reflect.TypeFor[int32]():   true,
+	reflect.TypeFor[int64]():   true,
+	reflect.TypeFor[uint]():    true,
+	reflect.TypeFor[uint8]():   true,
+	reflect.TypeFor[uint16]():  true,
+	reflect.TypeFor[uint32]():  true,
+	reflect.TypeFor[uint64]():  true,
 }
 
 // Fuzz runs the fuzz function, ff, for fuzz testing. If ff fails for a set of
@@ -224,7 +224,7 @@ func (f *F) Fuzz(ff any) {
 	if fnType.Kind() != reflect.Func {
 		panic("testing: F.Fuzz must receive a function")
 	}
-	if fnType.NumIn() < 2 || fnType.In(0) != reflect.TypeOf((*T)(nil)) {
+	if fnType.NumIn() < 2 || fnType.In(0) != reflect.TypeFor[*T]() {
 		panic("testing: fuzz target must receive at least two arguments, where the first argument is a *T")
 	}
 	if fnType.NumOut() != 0 {
diff --git a/src/testing/quick/quick.go b/src/testing/quick/quick.go
index 8ef9cf7dda..6b3089d049 100644
--- a/src/testing/quick/quick.go
+++ b/src/testing/quick/quick.go
@@ -64,7 +64,7 @@ func Value(t reflect.Type, rand *rand.Rand) (value reflect.Value, ok bool) {
 // hint is used for shrinking as a function of indirection level so
 // that recursive data structures will terminate.
 func sizedValue(t reflect.Type, rand *rand.Rand, size int) (value reflect.Value, ok bool) {
-	if m, ok := reflect.Zero(t).Interface().(Generator); ok {
+	if m, ok := reflect.TypeAssert[Generator](reflect.Zero(t)); ok {
 		return m.Generate(rand, size), true
 	}
 
diff --git a/src/testing/testing.go b/src/testing/testing.go
index 2f0206b0a4..3f76446549 100644
--- a/src/testing/testing.go
+++ b/src/testing/testing.go
@@ -30,9 +30,9 @@
 //	import "testing"
 //
 //	func TestAbs(t *testing.T) {
-//	    got := Abs(-1)
+//	    got := abs(-1)
 //	    if got != 1 {
-//	        t.Errorf("Abs(-1) = %d; want 1", got)
+//	        t.Errorf("abs(-1) = %d; want 1", got)
 //	    }
 //	}
 //
diff --git a/src/time/format.go b/src/time/format.go
index 87e990d48a..ad5486f4d2 100644
--- a/src/time/format.go
+++ b/src/time/format.go
@@ -1602,6 +1602,16 @@ func leadingFraction(s string) (x uint64, scale float64, rem string) {
 	return x, scale, s[i:]
 }
 
+// parseDurationError describes a problem parsing a duration string.
+type parseDurationError struct {
+	message string
+	value   string
+}
+
+func (e *parseDurationError) Error() string {
+	return "time: " + e.message + " " + quote(e.value)
+}
+
 var unitMap = map[string]uint64{
 	"ns": uint64(Nanosecond),
 	"us": uint64(Microsecond),
@@ -1637,7 +1647,7 @@ func ParseDuration(s string) (Duration, error) {
 		return 0, nil
 	}
 	if s == "" {
-		return 0, errors.New("time: invalid duration " + quote(orig))
+		return 0, &parseDurationError{"invalid duration", orig}
 	}
 	for s != "" {
 		var (
@@ -1649,13 +1659,13 @@ func ParseDuration(s string) (Duration, error) {
 
 		// The next character must be [0-9.]
 		if !(s[0] == '.' || '0' <= s[0] && s[0] <= '9') {
-			return 0, errors.New("time: invalid duration " + quote(orig))
+			return 0, &parseDurationError{"invalid duration", orig}
 		}
 		// Consume [0-9]*
 		pl := len(s)
 		v, s, err = leadingInt(s)
 		if err != nil {
-			return 0, errors.New("time: invalid duration " + quote(orig))
+			return 0, &parseDurationError{"invalid duration", orig}
 		}
 		pre := pl != len(s) // whether we consumed anything before a period
 
@@ -1669,7 +1679,7 @@ func ParseDuration(s string) (Duration, error) {
 		}
 		if !pre && !post {
 			// no digits (e.g. ".s" or "-.s")
-			return 0, errors.New("time: invalid duration " + quote(orig))
+			return 0, &parseDurationError{"invalid duration", orig}
 		}
 
 		// Consume unit.
@@ -1681,17 +1691,17 @@ func ParseDuration(s string) (Duration, error) {
 			}
 		}
 		if i == 0 {
-			return 0, errors.New("time: missing unit in duration " + quote(orig))
+			return 0, &parseDurationError{"missing unit in duration", orig}
 		}
 		u := s[:i]
 		s = s[i:]
 		unit, ok := unitMap[u]
 		if !ok {
-			return 0, errors.New("time: unknown unit " + quote(u) + " in duration " + quote(orig))
+			return 0, &parseDurationError{"unknown unit " + quote(u) + " in duration", orig}
 		}
 		if v > 1<<63/unit {
 			// overflow
-			return 0, errors.New("time: invalid duration " + quote(orig))
+			return 0, &parseDurationError{"invalid duration", orig}
 		}
 		v *= unit
 		if f > 0 {
@@ -1700,19 +1710,19 @@ func ParseDuration(s string) (Duration, error) {
 			v += uint64(float64(f) * (float64(unit) / scale))
 			if v > 1<<63 {
 				// overflow
-				return 0, errors.New("time: invalid duration " + quote(orig))
+				return 0, &parseDurationError{"invalid duration", orig}
 			}
 		}
 		d += v
 		if d > 1<<63 {
-			return 0, errors.New("time: invalid duration " + quote(orig))
+			return 0, &parseDurationError{"invalid duration", orig}
 		}
 	}
 	if neg {
 		return -Duration(d), nil
 	}
 	if d > 1<<63-1 {
-		return 0, errors.New("time: invalid duration " + quote(orig))
+		return 0, &parseDurationError{"invalid duration", orig}
 	}
 	return Duration(d), nil
 }
diff --git a/src/time/time_test.go b/src/time/time_test.go
index a2d4305c8c..a453ee043c 100644
--- a/src/time/time_test.go
+++ b/src/time/time_test.go
@@ -1620,6 +1620,13 @@ func BenchmarkParseDuration(b *testing.B) {
 	}
 }
 
+func BenchmarkParseDurationError(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		ParseDuration("9223372036854775810ns") // overflow
+		ParseDuration("9007199254.740993")     // missing unit
+	}
+}
+
 func BenchmarkHour(b *testing.B) {
 	t := Now()
 	for i := 0; i < b.N; i++ {