cmd/compile: add traceback argument info to ABI0 assembly functions

For ABI0 assembly functions that have Go declarations, generate
traceback argument info and attach it to the assembly functions.
So we can print argument in tracebacks if e.g. assembly function
panics.

Only do this for ABI0 functions, as for ABIInternal assembly
functions it is likely that they never spill arguments to memory.

Change-Id: I7e601ccd9aded5e6af2f02be975bf81ff9948f4d
Reviewed-on: https://go-review.googlesource.com/c/go/+/315870
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>

1 files changed, 21 insertions, 17 deletions

diff --git a/src/cmd/compile/internal/ssagen/ssa.go b/src/cmd/compile/internal/ssagen/ssa.go
index 0d4e3264ba..b8f84f5712 100644
--- a/src/cmd/compile/internal/ssagen/ssa.go
+++ b/src/cmd/compile/internal/ssagen/ssa.go
@@ -6563,15 +6563,27 @@ func (s *State) DebugFriendlySetPosFrom(v *ssa.Value) {
 }
 
 // emit argument info (locations on stack) for traceback.
-func emitArgInfo(e *ssafn, pp *objw.Progs) {
+func emitArgInfo(e *ssafn, f *ssa.Func, pp *objw.Progs) {
 	ft := e.curfn.Type()
 	if ft.NumRecvs() == 0 && ft.NumParams() == 0 {
 		return
 	}
 
-	x := base.Ctxt.Lookup(fmt.Sprintf("%s.arginfo%d", e.curfn.LSym.Name, e.curfn.LSym.ABI()))
+	x := EmitArgInfo(e.curfn, f.OwnAux.ABIInfo())
 	e.curfn.LSym.Func().ArgInfo = x
 
+	// Emit a funcdata pointing at the arg info data.
+	p := pp.Prog(obj.AFUNCDATA)
+	p.From.SetConst(objabi.FUNCDATA_ArgInfo)
+	p.To.Type = obj.TYPE_MEM
+	p.To.Name = obj.NAME_EXTERN
+	p.To.Sym = x
+}
+
+// emit argument info (locations on stack) of f for traceback.
+func EmitArgInfo(f *ir.Func, abiInfo *abi.ABIParamResultInfo) *obj.LSym {
+	x := base.Ctxt.Lookup(fmt.Sprintf("%s.arginfo%d", f.LSym.Name, f.ABI))
+
 	PtrSize := int64(types.PtrSize)
 
 	isAggregate := func(t *types.Type) bool {
@@ -6696,27 +6708,19 @@ func emitArgInfo(e *ssafn, pp *objw.Progs) {
 	}
 
 	c := true
-outer:
-	for _, fs := range &types.RecvsParams {
-		for _, a := range fs(ft).Fields().Slice() {
-			if !c {
-				writebyte(_dotdotdot)
-				break outer
-			}
-			c = visitType(a.Offset, a.Type, 0)
+	for _, a := range abiInfo.InParams() {
+		if !c {
+			writebyte(_dotdotdot)
+			break
 		}
+		c = visitType(a.FrameOffset(abiInfo), a.Type, 0)
 	}
 	writebyte(_endSeq)
 	if wOff > maxLen {
 		base.Fatalf("ArgInfo too large")
 	}
 
-	// Emit a funcdata pointing at the arg info data.
-	p := pp.Prog(obj.AFUNCDATA)
-	p.From.SetConst(objabi.FUNCDATA_ArgInfo)
-	p.To.Type = obj.TYPE_MEM
-	p.To.Name = obj.NAME_EXTERN
-	p.To.Sym = x
+	return x
 }
 
 // genssa appends entries to pp for each instruction in f.
@@ -6727,7 +6731,7 @@ func genssa(f *ssa.Func, pp *objw.Progs) {
 	e := f.Frontend().(*ssafn)
 
 	s.livenessMap, s.partLiveArgs = liveness.Compute(e.curfn, f, e.stkptrsize, pp)
-	emitArgInfo(e, pp)
+	emitArgInfo(e, f, pp)
 
 	openDeferInfo := e.curfn.LSym.Func().OpenCodedDeferInfo
 	if openDeferInfo != nil {