18 files changed, 14 insertions, 103 deletions
diff --git a/src/cmd/compile/internal/amd64/galign.go b/src/cmd/compile/internal/amd64/galign.go
index 3b13e123a7..ca44263afc 100644
--- a/src/cmd/compile/internal/amd64/galign.go
+++ b/src/cmd/compile/internal/amd64/galign.go
@@ -18,7 +18,6 @@ func Init(arch *ssagen.ArchInfo) {
 
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = ssaMarkMoves
 	arch.SSAGenValue = ssaGenValue
diff --git a/src/cmd/compile/internal/arm/galign.go b/src/cmd/compile/internal/arm/galign.go
index d68500280d..23e52bacbf 100644
--- a/src/cmd/compile/internal/arm/galign.go
+++ b/src/cmd/compile/internal/arm/galign.go
@@ -18,7 +18,6 @@ func Init(arch *ssagen.ArchInfo) {
 	arch.SoftFloat = buildcfg.GOARM == 5
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = func(s *ssagen.State, b *ssa.Block) {}
 	arch.SSAGenValue = ssaGenValue
diff --git a/src/cmd/compile/internal/arm64/galign.go b/src/cmd/compile/internal/arm64/galign.go
index 2a61b9dd99..3ebd860de8 100644
--- a/src/cmd/compile/internal/arm64/galign.go
+++ b/src/cmd/compile/internal/arm64/galign.go
@@ -18,7 +18,6 @@ func Init(arch *ssagen.ArchInfo) {
 	arch.PadFrame = padframe
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = func(s *ssagen.State, b *ssa.Block) {}
 	arch.SSAGenValue = ssaGenValue
diff --git a/src/cmd/compile/internal/mips/galign.go b/src/cmd/compile/internal/mips/galign.go
index f892923ba0..4e6897042e 100644
--- a/src/cmd/compile/internal/mips/galign.go
+++ b/src/cmd/compile/internal/mips/galign.go
@@ -21,7 +21,6 @@ func Init(arch *ssagen.ArchInfo) {
 	arch.SoftFloat = (buildcfg.GOMIPS == "softfloat")
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 	arch.SSAMarkMoves = func(s *ssagen.State, b *ssa.Block) {}
 	arch.SSAGenValue = ssaGenValue
 	arch.SSAGenBlock = ssaGenBlock
diff --git a/src/cmd/compile/internal/mips64/galign.go b/src/cmd/compile/internal/mips64/galign.go
index af81366e51..412bc71aab 100644
--- a/src/cmd/compile/internal/mips64/galign.go
+++ b/src/cmd/compile/internal/mips64/galign.go
@@ -21,7 +21,6 @@ func Init(arch *ssagen.ArchInfo) {
 	arch.SoftFloat = buildcfg.GOMIPS64 == "softfloat"
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = func(s *ssagen.State, b *ssa.Block) {}
 	arch.SSAGenValue = ssaGenValue
diff --git a/src/cmd/compile/internal/ppc64/galign.go b/src/cmd/compile/internal/ppc64/galign.go
index 590290fa37..bff3e38f42 100644
--- a/src/cmd/compile/internal/ppc64/galign.go
+++ b/src/cmd/compile/internal/ppc64/galign.go
@@ -20,7 +20,6 @@ func Init(arch *ssagen.ArchInfo) {
 
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnopdefer
 
 	arch.SSAMarkMoves = ssaMarkMoves
 	arch.SSAGenValue = ssaGenValue
diff --git a/src/cmd/compile/internal/ppc64/ggen.go b/src/cmd/compile/internal/ppc64/ggen.go
index c76962cfb8..3ae6422bf9 100644
--- a/src/cmd/compile/internal/ppc64/ggen.go
+++ b/src/cmd/compile/internal/ppc64/ggen.go
@@ -53,30 +53,3 @@ func ginsnop(pp *objw.Progs) *obj.Prog {
 	p.To.Reg = ppc64.REG_R0
 	return p
 }
-
-func ginsnopdefer(pp *objw.Progs) *obj.Prog {
-	// On PPC64 two nops are required in the defer case.
-	//
-	// (see gc/cgen.go, gc/plive.go -- copy of comment below)
-	//
-	// On ppc64, when compiling Go into position
-	// independent code on ppc64le we insert an
-	// instruction to reload the TOC pointer from the
-	// stack as well. See the long comment near
-	// jmpdefer in runtime/asm_ppc64.s for why.
-	// If the MOVD is not needed, insert a hardware NOP
-	// so that the same number of instructions are used
-	// on ppc64 in both shared and non-shared modes.
-
-	ginsnop(pp)
-	if base.Ctxt.Flag_shared {
-		p := pp.Prog(ppc64.AMOVD)
-		p.From.Type = obj.TYPE_MEM
-		p.From.Offset = 24
-		p.From.Reg = ppc64.REGSP
-		p.To.Type = obj.TYPE_REG
-		p.To.Reg = ppc64.REG_R2
-		return p
-	}
-	return ginsnop(pp)
-}
diff --git a/src/cmd/compile/internal/riscv64/galign.go b/src/cmd/compile/internal/riscv64/galign.go
index 338248a7cf..846ed8fb38 100644
--- a/src/cmd/compile/internal/riscv64/galign.go
+++ b/src/cmd/compile/internal/riscv64/galign.go
@@ -16,7 +16,6 @@ func Init(arch *ssagen.ArchInfo) {
 	arch.MAXWIDTH = 1 << 50
 
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 	arch.ZeroRange = zeroRange
 
 	arch.SSAMarkMoves = ssaMarkMoves
diff --git a/src/cmd/compile/internal/s390x/galign.go b/src/cmd/compile/internal/s390x/galign.go
index b004a2db0a..d880834c22 100644
--- a/src/cmd/compile/internal/s390x/galign.go
+++ b/src/cmd/compile/internal/s390x/galign.go
@@ -16,7 +16,6 @@ func Init(arch *ssagen.ArchInfo) {
 
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = ssaMarkMoves
 	arch.SSAGenValue = ssaGenValue
diff --git a/src/cmd/compile/internal/ssagen/arch.go b/src/cmd/compile/internal/ssagen/arch.go
index 957fb3e84a..483e45cad4 100644
--- a/src/cmd/compile/internal/ssagen/arch.go
+++ b/src/cmd/compile/internal/ssagen/arch.go
@@ -29,8 +29,7 @@ type ArchInfo struct {
 	// at function entry, and it is ok to clobber registers.
 	ZeroRange func(*objw.Progs, *obj.Prog, int64, int64, *uint32) *obj.Prog
 
-	Ginsnop      func(*objw.Progs) *obj.Prog
-	Ginsnopdefer func(*objw.Progs) *obj.Prog // special ginsnop for deferreturn
+	Ginsnop func(*objw.Progs) *obj.Prog
 
 	// SSAMarkMoves marks any MOVXconst ops that need to avoid clobbering flags.
 	SSAMarkMoves func(*State, *ssa.Block)
diff --git a/src/cmd/compile/internal/ssagen/ssa.go b/src/cmd/compile/internal/ssagen/ssa.go
index 7e2f6a7471..161469ea67 100644
--- a/src/cmd/compile/internal/ssagen/ssa.go
+++ b/src/cmd/compile/internal/ssagen/ssa.go
@@ -7335,18 +7335,6 @@ func (s *State) PrepareCall(v *ssa.Value) {
 
 	call, ok := v.Aux.(*ssa.AuxCall)
 
-	if ok && call.Fn == ir.Syms.Deferreturn {
-		// Deferred calls will appear to be returning to
-		// the CALL deferreturn(SB) that we are about to emit.
-		// However, the stack trace code will show the line
-		// of the instruction byte before the return PC.
-		// To avoid that being an unrelated instruction,
-		// insert an actual hardware NOP that will have the right line number.
-		// This is different from obj.ANOP, which is a virtual no-op
-		// that doesn't make it into the instruction stream.
-		Arch.Ginsnopdefer(s.pp)
-	}
-
 	if ok {
 		// Record call graph information for nowritebarrierrec
 		// analysis.
diff --git a/src/cmd/compile/internal/wasm/ssa.go b/src/cmd/compile/internal/wasm/ssa.go
index 31b09016eb..0b2ca3fdbb 100644
--- a/src/cmd/compile/internal/wasm/ssa.go
+++ b/src/cmd/compile/internal/wasm/ssa.go
@@ -24,7 +24,6 @@ func Init(arch *ssagen.ArchInfo) {
 
 	arch.ZeroRange = zeroRange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = ssaMarkMoves
 	arch.SSAGenValue = ssaGenValue
@@ -126,7 +125,11 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 	case ssa.OpWasmLoweredStaticCall, ssa.OpWasmLoweredClosureCall, ssa.OpWasmLoweredInterCall:
 		s.PrepareCall(v)
 		if call, ok := v.Aux.(*ssa.AuxCall); ok && call.Fn == ir.Syms.Deferreturn {
-			// add a resume point before call to deferreturn so it can be called again via jmpdefer
+			// The runtime needs to inject jumps to
+			// deferreturn calls using the address in
+			// _func.deferreturn. Hence, the call to
+			// deferreturn must itself be a resumption
+			// point so it gets a target PC.
 			s.Prog(wasm.ARESUMEPOINT)
 		}
 		if v.Op == ssa.OpWasmLoweredClosureCall {
diff --git a/src/cmd/compile/internal/x86/galign.go b/src/cmd/compile/internal/x86/galign.go
index 00a20e429f..5565bd32c7 100644
--- a/src/cmd/compile/internal/x86/galign.go
+++ b/src/cmd/compile/internal/x86/galign.go
@@ -34,7 +34,6 @@ func Init(arch *ssagen.ArchInfo) {
 
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
-	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = ssaMarkMoves
 }
diff --git a/src/cmd/internal/obj/arm/asm5.go b/src/cmd/internal/obj/arm/asm5.go
index ccf5f9e7f8..7b1682776e 100644
--- a/src/cmd/internal/obj/arm/asm5.go
+++ b/src/cmd/internal/obj/arm/asm5.go
@@ -355,11 +355,10 @@ var oprange [ALAST & obj.AMask][]Optab
 var xcmp [C_GOK + 1][C_GOK + 1]bool
 
 var (
-	deferreturn *obj.LSym
-	symdiv      *obj.LSym
-	symdivu     *obj.LSym
-	symmod      *obj.LSym
-	symmodu     *obj.LSym
+	symdiv  *obj.LSym
+	symdivu *obj.LSym
+	symmod  *obj.LSym
+	symmodu *obj.LSym
 )
 
 // Note about encoding: Prog.scond holds the condition encoding,
@@ -1219,8 +1218,6 @@ func buildop(ctxt *obj.Link) {
 		return
 	}
 
-	deferreturn = ctxt.LookupABI("runtime.deferreturn", obj.ABIInternal)
-
 	symdiv = ctxt.Lookup("runtime._div")
 	symdivu = ctxt.Lookup("runtime._divu")
 	symmod = ctxt.Lookup("runtime._mod")
diff --git a/src/cmd/internal/obj/wasm/wasmobj.go b/src/cmd/internal/obj/wasm/wasmobj.go
index ceeae7a257..4d276db678 100644
--- a/src/cmd/internal/obj/wasm/wasmobj.go
+++ b/src/cmd/internal/obj/wasm/wasmobj.go
@@ -129,8 +129,6 @@ var (
 	morestackNoCtxt *obj.LSym
 	gcWriteBarrier  *obj.LSym
 	sigpanic        *obj.LSym
-	deferreturn     *obj.LSym
-	jmpdefer        *obj.LSym
 )
 
 const (
@@ -143,10 +141,6 @@ func instinit(ctxt *obj.Link) {
 	morestackNoCtxt = ctxt.Lookup("runtime.morestack_noctxt")
 	gcWriteBarrier = ctxt.LookupABI("runtime.gcWriteBarrier", obj.ABIInternal)
 	sigpanic = ctxt.LookupABI("runtime.sigpanic", obj.ABIInternal)
-	deferreturn = ctxt.LookupABI("runtime.deferreturn", obj.ABIInternal)
-	// jmpdefer is defined in assembly as ABI0. The compiler will
-	// generate a direct ABI0 call from Go, so look for that.
-	jmpdefer = ctxt.LookupABI(`"".jmpdefer`, obj.ABI0)
 }
 
 func preprocess(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
@@ -423,12 +417,6 @@ func preprocess(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
 				pcAfterCall-- // sigpanic expects to be called without advancing the pc
 			}
 
-			// jmpdefer manipulates the return address on the stack so deferreturn gets called repeatedly.
-			// Model this in WebAssembly with a loop.
-			if call.To.Sym == deferreturn {
-				p = appendp(p, ALoop)
-			}
-
 			// SP -= 8
 			p = appendp(p, AGet, regAddr(REG_SP))
 			p = appendp(p, AI32Const, constAddr(8))
@@ -479,15 +467,6 @@ func preprocess(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
 				break
 			}
 
-			// jmpdefer removes the frame of deferreturn from the Go stack.
-			// However, its WebAssembly function still returns normally,
-			// so we need to return from deferreturn without removing its
-			// stack frame (no RET), because the frame is already gone.
-			if call.To.Sym == jmpdefer {
-				p = appendp(p, AReturn)
-				break
-			}
-
 			// return value of call is on the top of the stack, indicating whether to unwind the WebAssembly stack
 			if call.As == ACALLNORESUME && call.To.Sym != sigpanic { // sigpanic unwinds the stack, but it never resumes
 				// trying to unwind WebAssembly stack but call has no resume point, terminate with error
@@ -500,21 +479,6 @@ func preprocess(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
 				unwindExitBranches = append(unwindExitBranches, p)
 			}
 
-			// jump to before the call if jmpdefer has reset the return address to the call's PC
-			if call.To.Sym == deferreturn {
-				// get PC_B from -8(SP)
-				p = appendp(p, AGet, regAddr(REG_SP))
-				p = appendp(p, AI32Const, constAddr(8))
-				p = appendp(p, AI32Sub)
-				p = appendp(p, AI32Load16U, constAddr(0))
-				p = appendp(p, ATee, regAddr(REG_PC_B))
-
-				p = appendp(p, AI32Const, constAddr(call.Pc))
-				p = appendp(p, AI32Eq)
-				p = appendp(p, ABrIf, constAddr(0))
-				p = appendp(p, AEnd) // end of Loop
-			}
-
 		case obj.ARET, ARETUNWIND:
 			ret := *p
 			p.As = obj.ANOP
diff --git a/src/cmd/internal/obj/x86/asm6.go b/src/cmd/internal/obj/x86/asm6.go
index 17fa76727e..331a98dfef 100644
--- a/src/cmd/internal/obj/x86/asm6.go
+++ b/src/cmd/internal/obj/x86/asm6.go
@@ -43,7 +43,6 @@ import (
 
 var (
 	plan9privates *obj.LSym
-	deferreturn   *obj.LSym
 )
 
 // Instruction layout.
diff --git a/src/cmd/internal/objabi/funcid.go b/src/cmd/internal/objabi/funcid.go
index d881cdd061..68f6a26a76 100644
--- a/src/cmd/internal/objabi/funcid.go
+++ b/src/cmd/internal/objabi/funcid.go
@@ -34,7 +34,6 @@ const (
 	FuncID_gogo
 	FuncID_gopanic
 	FuncID_handleAsyncEvent
-	FuncID_jmpdefer
 	FuncID_mcall
 	FuncID_morestack
 	FuncID_mstart
@@ -60,7 +59,6 @@ var funcIDs = map[string]FuncID{
 	"gogo":             FuncID_gogo,
 	"gopanic":          FuncID_gopanic,
 	"handleAsyncEvent": FuncID_handleAsyncEvent,
-	"jmpdefer":         FuncID_jmpdefer,
 	"main":             FuncID_runtime_main,
 	"mcall":            FuncID_mcall,
 	"morestack":        FuncID_morestack,
diff --git a/src/cmd/link/internal/ld/pcln.go b/src/cmd/link/internal/ld/pcln.go
index 05fd302369..70e3e1284b 100644
--- a/src/cmd/link/internal/ld/pcln.go
+++ b/src/cmd/link/internal/ld/pcln.go
@@ -129,11 +129,10 @@ func computeDeferReturn(ctxt *Link, deferReturnSym, s loader.Sym) uint32 {
 	for ri := 0; ri < relocs.Count(); ri++ {
 		r := relocs.At(ri)
 		if target.IsWasm() && r.Type() == objabi.R_ADDR {
-			// Wasm does not have a live variable set at the deferreturn
-			// call itself. Instead it has one identified by the
-			// resumption point immediately preceding the deferreturn.
-			// The wasm code has a R_ADDR relocation which is used to
-			// set the resumption point to PC_B.
+			// wasm/ssa.go generates an ARESUMEPOINT just
+			// before the deferreturn call. The "PC" of
+			// the deferreturn call is stored in the
+			// R_ADDR relocation on the ARESUMEPOINT.
 			lastWasmAddr = uint32(r.Add())
 		}
 		if r.Type().IsDirectCall() && (r.Sym() == deferReturnSym || ldr.IsDeferReturnTramp(r.Sym())) {