[dev.typeparams] all: merge master (912f075) into dev.typeparams

Conflicts:

- src/cmd/compile/internal/escape/escape.go

  On master, CL 332230 changed the ">=" in HeapAllocReason to ">"; but
  on dev.typeparams, CL 329989 moved HeapAllocReason into utils.go.

Merge List:

+ 2021-07-02 912f075047 net/http: mention socks5 support in proxy
+ 2021-07-02 287c5e8066 cmd/compile: fix stack growing algorithm
+ 2021-07-02 743f03eeb0 spec, unsafe: clarify unsafe.Slice docs
+ 2021-07-02 6125d0c426 cmd/dist: correct comment: SysProcAttri -> SysProcAttr
+ 2021-07-01 03761ede02 net: don't reject null mx records
+ 2021-07-01 877688c838 testing: add TB.Setenv
+ 2021-07-01 ef8ae82b37 cmd/compile: fix bug in dwarf-gen var location generation
+ 2021-07-01 770899f7e1 cmd/go: add a regression test for 'go mod vendor' path traversal
+ 2021-07-01 835d86a17e cmd/go: use path.Dir instead of filepath.Dir for package paths in 'go mod vendor'
+ 2021-07-01 eb437ba92c cmd/compile: make stack value size threshold comparisons consistent
+ 2021-07-01 9d65578b83 cmd/compile: fix typos in document

Change-Id: I08aa852441af0f070aa32dd2f99b6fa4e9d79cfa

4 files changed, 19 insertions, 12 deletions

diff --git a/src/cmd/compile/abi-internal.md b/src/cmd/compile/abi-internal.md
index 7aed7efe97..3619aea4aa 100644
--- a/src/cmd/compile/abi-internal.md
+++ b/src/cmd/compile/abi-internal.md
@@ -233,7 +233,7 @@ stack frame is laid out in the following sequence:
     r1.x    uintptr
     r1.y    [2]uintptr
     a1Spill uint8
-    a2Spill uint8
+    a3Spill uint8
     _       [6]uint8  // alignment padding
 
 In the stack frame, only the `a2` field is initialized on entry; the
diff --git a/src/cmd/compile/internal/escape/utils.go b/src/cmd/compile/internal/escape/utils.go
index 1ac4cc6029..6e2f9c424a 100644
--- a/src/cmd/compile/internal/escape/utils.go
+++ b/src/cmd/compile/internal/escape/utils.go
@@ -186,14 +186,14 @@ func HeapAllocReason(n ir.Node) string {
 		return "too large for stack"
 	}
 
-	if (n.Op() == ir.ONEW || n.Op() == ir.OPTRLIT) && n.Type().Elem().Width >= ir.MaxImplicitStackVarSize {
+	if (n.Op() == ir.ONEW || n.Op() == ir.OPTRLIT) && n.Type().Elem().Width > ir.MaxImplicitStackVarSize {
 		return "too large for stack"
 	}
 
-	if n.Op() == ir.OCLOSURE && typecheck.ClosureType(n.(*ir.ClosureExpr)).Size() >= ir.MaxImplicitStackVarSize {
+	if n.Op() == ir.OCLOSURE && typecheck.ClosureType(n.(*ir.ClosureExpr)).Size() > ir.MaxImplicitStackVarSize {
 		return "too large for stack"
 	}
-	if n.Op() == ir.OMETHVALUE && typecheck.PartialCallType(n.(*ir.SelectorExpr)).Size() >= ir.MaxImplicitStackVarSize {
+	if n.Op() == ir.OMETHVALUE && typecheck.PartialCallType(n.(*ir.SelectorExpr)).Size() > ir.MaxImplicitStackVarSize {
 		return "too large for stack"
 	}
 
@@ -206,7 +206,7 @@ func HeapAllocReason(n ir.Node) string {
 		if !ir.IsSmallIntConst(r) {
 			return "non-constant size"
 		}
-		if t := n.Type(); t.Elem().Width != 0 && ir.Int64Val(r) >= ir.MaxImplicitStackVarSize/t.Elem().Width {
+		if t := n.Type(); t.Elem().Width != 0 && ir.Int64Val(r) > ir.MaxImplicitStackVarSize/t.Elem().Width {
 			return "too large for stack"
 		}
 	}
diff --git a/src/cmd/compile/internal/ssa/debug.go b/src/cmd/compile/internal/ssa/debug.go
index eaa94975ec..8e2872363b 100644
--- a/src/cmd/compile/internal/ssa/debug.go
+++ b/src/cmd/compile/internal/ssa/debug.go
@@ -1115,8 +1115,14 @@ func (state *debugState) buildLocationLists(blockLocs []*BlockDebug) {
 			continue
 		}
 
+		mustBeFirst := func(v *Value) bool {
+			return v.Op == OpPhi || v.Op.isLoweredGetClosurePtr() ||
+				v.Op == OpArgIntReg || v.Op == OpArgFloatReg
+		}
+
 		zeroWidthPending := false
-		apcChangedSize := 0 // size of changedVars for leading Args, Phi, ClosurePtr
+		blockPrologComplete := false // set to true at first non-zero-width op
+		apcChangedSize := 0          // size of changedVars for leading Args, Phi, ClosurePtr
 		// expect to see values in pattern (apc)* (zerowidth|real)*
 		for _, v := range b.Values {
 			slots := state.valueNames[v.ID]
@@ -1125,16 +1131,16 @@ func (state *debugState) buildLocationLists(blockLocs []*BlockDebug) {
 
 			if opcodeTable[v.Op].zeroWidth {
 				if changed {
-					if hasAnyArgOp(v) || v.Op == OpPhi || v.Op.isLoweredGetClosurePtr() {
+					if mustBeFirst(v) || v.Op == OpArg {
 						// These ranges begin at true beginning of block, not after first instruction
-						if zeroWidthPending {
-							panic(fmt.Errorf("Unexpected op '%s' mixed with OpArg/OpPhi/OpLoweredGetClosurePtr at beginning of block %s in %s\n%s", v.LongString(), b, b.Func.Name, b.Func))
+						if blockPrologComplete && mustBeFirst(v) {
+							panic(fmt.Errorf("Unexpected placement of op '%s' appearing after non-pseudo-op at beginning of block %s in %s\n%s", v.LongString(), b, b.Func.Name, b.Func))
 						}
 						apcChangedSize = len(state.changedVars.contents())
+						// Other zero-width ops must wait on a "real" op.
+						zeroWidthPending = true
 						continue
 					}
-					// Other zero-width ops must wait on a "real" op.
-					zeroWidthPending = true
 				}
 				continue
 			}
@@ -1145,6 +1151,7 @@ func (state *debugState) buildLocationLists(blockLocs []*BlockDebug) {
 			// Not zero-width; i.e., a "real" instruction.
 
 			zeroWidthPending = false
+			blockPrologComplete = true
 			for i, varID := range state.changedVars.contents() {
 				if i < apcChangedSize { // buffered true start-of-block changes
 					state.updateVar(VarID(varID), v.Block, BlockStart)
diff --git a/src/cmd/compile/internal/walk/builtin.go b/src/cmd/compile/internal/walk/builtin.go
index e1a2319e14..af4f8f4822 100644
--- a/src/cmd/compile/internal/walk/builtin.go
+++ b/src/cmd/compile/internal/walk/builtin.go
@@ -489,7 +489,7 @@ func walkNew(n *ir.UnaryExpr, init *ir.Nodes) ir.Node {
 		base.Errorf("%v can't be allocated in Go; it is incomplete (or unallocatable)", n.Type().Elem())
 	}
 	if n.Esc() == ir.EscNone {
-		if t.Size() >= ir.MaxImplicitStackVarSize {
+		if t.Size() > ir.MaxImplicitStackVarSize {
 			base.Fatalf("large ONEW with EscNone: %v", n)
 		}
 		return stackTempAddr(init, t)