cmd/compile: call ginsnop, not ginsnop2 on ppc64le for mid-stack inlining tracebacks

A recent change to fix stacktraces for inlined functions
introduced a regression on ppc64le when compiling position
independent code. That happened because ginsnop2 was called for
the purpose of inserting a NOP to identify the location of
the inlined function, when ginsnop should have been used.
ginsnop2 is intended to be used before deferreturn to ensure
r2 is properly restored when compiling position independent code.
In some cases the location where r2 is loaded from might not be
initialized. If that happens and r2 is used to generate an address,
the result is likely a SEGV.

This fixes that problem.

Fixes #30283

Change-Id: If70ef27fc65ef31969712422306ac3a57adbd5b6
Reviewed-on: https://go-review.googlesource.com/c/163337
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Carlos Eduardo Seo <cseo@linux.vnet.ibm.com>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Andrew Bonventre <andybons@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/compile/internal/amd64/galign.go

@@ -24,6 +24,7 @@ func Init(arch *gc.Arch) {
 	arch.ZeroRange = zerorange
 	arch.ZeroAuto = zeroAuto
 	arch.Ginsnop = ginsnop
+	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = ssaMarkMoves
 	arch.SSAGenValue = ssaGenValue

src/cmd/compile/internal/arm/galign.go

@@ -19,6 +19,7 @@ func Init(arch *gc.Arch) {
 	arch.ZeroRange = zerorange
 	arch.ZeroAuto = zeroAuto
 	arch.Ginsnop = ginsnop
+	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = func(s *gc.SSAGenState, b *ssa.Block) {}
 	arch.SSAGenValue = ssaGenValue

src/cmd/compile/internal/arm64/galign.go

@@ -19,6 +19,7 @@ func Init(arch *gc.Arch) {
 	arch.ZeroRange = zerorange
 	arch.ZeroAuto = zeroAuto
 	arch.Ginsnop = ginsnop
+	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = func(s *gc.SSAGenState, b *ssa.Block) {}
 	arch.SSAGenValue = ssaGenValue

src/cmd/compile/internal/gc/go.go

@@ -255,9 +255,10 @@ type Arch struct {
 	Use387    bool // should 386 backend use 387 FP instructions instead of sse2.
 	SoftFloat bool
 
-	PadFrame  func(int64) int64
-	ZeroRange func(*Progs, *obj.Prog, int64, int64, *uint32) *obj.Prog
-	Ginsnop   func(*Progs) *obj.Prog
+	PadFrame     func(int64) int64
+	ZeroRange    func(*Progs, *obj.Prog, int64, int64, *uint32) *obj.Prog
+	Ginsnop      func(*Progs) *obj.Prog
+	Ginsnopdefer func(*Progs) *obj.Prog // special ginsnop for deferreturn
 
 	// SSAMarkMoves marks any MOVXconst ops that need to avoid clobbering flags.
 	SSAMarkMoves func(*SSAGenState, *ssa.Block)

src/cmd/compile/internal/gc/ssa.go

@@ -5604,7 +5604,7 @@ func (s *SSAGenState) PrepareCall(v *ssa.Value) {
 		// 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.
-		thearch.Ginsnop(s.pp)
+		thearch.Ginsnopdefer(s.pp)
 	}
 
 	if sym, ok := v.Aux.(*obj.LSym); ok {

src/cmd/compile/internal/mips/galign.go

@@ -22,6 +22,7 @@ func Init(arch *gc.Arch) {
 	arch.ZeroRange = zerorange
 	arch.ZeroAuto = zeroAuto
 	arch.Ginsnop = ginsnop
+	arch.Ginsnopdefer = ginsnop
 	arch.SSAMarkMoves = func(s *gc.SSAGenState, b *ssa.Block) {}
 	arch.SSAGenValue = ssaGenValue
 	arch.SSAGenBlock = ssaGenBlock

src/cmd/compile/internal/mips64/galign.go

@@ -22,6 +22,7 @@ func Init(arch *gc.Arch) {
 	arch.ZeroRange = zerorange
 	arch.ZeroAuto = zeroAuto
 	arch.Ginsnop = ginsnop
+	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = func(s *gc.SSAGenState, b *ssa.Block) {}
 	arch.SSAGenValue = ssaGenValue

src/cmd/compile/internal/ppc64/galign.go

@@ -20,7 +20,8 @@ func Init(arch *gc.Arch) {
 
 	arch.ZeroRange = zerorange
 	arch.ZeroAuto = zeroAuto
-	arch.Ginsnop = ginsnop2
+	arch.Ginsnop = ginsnop
+	arch.Ginsnopdefer = ginsnop2
 
 	arch.SSAMarkMoves = ssaMarkMoves
 	arch.SSAGenValue = ssaGenValue

src/cmd/compile/internal/s390x/galign.go

@@ -17,6 +17,7 @@ func Init(arch *gc.Arch) {
 	arch.ZeroRange = zerorange
 	arch.ZeroAuto = zeroAuto
 	arch.Ginsnop = ginsnop
+	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = ssaMarkMoves
 	arch.SSAGenValue = ssaGenValue

src/cmd/compile/internal/wasm/ssa.go

@@ -20,6 +20,7 @@ func Init(arch *gc.Arch) {
 	arch.ZeroRange = zeroRange
 	arch.ZeroAuto = zeroAuto
 	arch.Ginsnop = ginsnop
+	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = ssaMarkMoves
 	arch.SSAGenValue = ssaGenValue

src/cmd/compile/internal/x86/galign.go

@@ -32,6 +32,7 @@ func Init(arch *gc.Arch) {
 	arch.ZeroRange = zerorange
 	arch.ZeroAuto = zeroAuto
 	arch.Ginsnop = ginsnop
+	arch.Ginsnopdefer = ginsnop
 
 	arch.SSAMarkMoves = ssaMarkMoves
 }