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>

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

@@ -13,10 +13,12 @@ import (
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
 	"cmd/compile/internal/liveness"
+	"cmd/compile/internal/objw"
 	"cmd/compile/internal/ssagen"
 	"cmd/compile/internal/typecheck"
 	"cmd/compile/internal/types"
 	"cmd/compile/internal/walk"
+	"cmd/internal/obj"
 )
 
 // "Portable" code generation.
@@ -47,6 +49,10 @@ func enqueueFunc(fn *ir.Func) {
 		a := ssagen.AbiForBodylessFuncStackMap(fn)
 		abiInfo := a.ABIAnalyzeFuncType(fn.Type().FuncType()) // abiInfo has spill/home locations for wrapper
 		liveness.WriteFuncMap(fn, abiInfo)
+		if fn.ABI == obj.ABI0 {
+			x := ssagen.EmitArgInfo(fn, abiInfo)
+			objw.Global(x, int32(len(x.P)), obj.RODATA|obj.LOCAL)
+		}
 		return
 	}
 

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 _, a := range abiInfo.InParams() {
-	for _, fs := range &types.RecvsParams {
+		if !c {
-		for _, a := range fs(ft).Fields().Slice() {
+			writebyte(_dotdotdot)
-			if !c {
+			break
-				writebyte(_dotdotdot)
-				break outer
-			}
-			c = visitType(a.Offset, a.Type, 0)
 		}
+		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.
+	return x
-	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
 }
 
 // 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 {

src/cmd/internal/obj/plist.go

@@ -75,38 +75,51 @@ func Flushplist(ctxt *Link, plist *Plist, newprog ProgAlloc, myimportpath string
 		newprog = ctxt.NewProg
 	}
 
-	// Add reference to Go arguments for C or assembly functions without them.
+	// Add reference to Go arguments for assembly functions without them.
-	for _, s := range text {
+	if ctxt.IsAsm {
-		if !strings.HasPrefix(s.Name, "\"\".") {
+		for _, s := range text {
-			continue
+			if !strings.HasPrefix(s.Name, "\"\".") {
-		}
+				continue
-		if s.ABIWrapper() {
+			}
-			// Don't create an args_stackmap symbol reference for an ABI
+			// The current args_stackmap generation in the compiler assumes
-			// wrapper function
+			// that the function in question is ABI0, so avoid introducing
-			continue
+			// an args_stackmap reference if the func is not ABI0 (better to
-		}
+			// have no stackmap than an incorrect/lying stackmap).
-		// The current args_stackmap generation in the compiler assumes
+			if s.ABI() != ABI0 {
-		// that the function in question is ABI0, so avoid introducing
+				continue
-		// an args_stackmap reference if the func is not ABI0 (better to
+			}
-		// have no stackmap than an incorrect/lying stackmap).
+			foundArgMap, foundArgInfo := false, false
-		if s.ABI() != ABI0 {
+			for p := s.Func().Text; p != nil; p = p.Link {
-			continue
+				if p.As == AFUNCDATA && p.From.Type == TYPE_CONST {
-		}
+					if p.From.Offset == objabi.FUNCDATA_ArgsPointerMaps {
-		found := false
+						foundArgMap = true
-		for p := s.Func().Text; p != nil; p = p.Link {
+					}
-			if p.As == AFUNCDATA && p.From.Type == TYPE_CONST && p.From.Offset == objabi.FUNCDATA_ArgsPointerMaps {
+					if p.From.Offset == objabi.FUNCDATA_ArgInfo {
-				found = true
+						foundArgInfo = true
-				break
+					}
+					if foundArgMap && foundArgInfo {
+						break
+					}
+				}
+			}
+			if !foundArgMap {
+				p := Appendp(s.Func().Text, newprog)
+				p.As = AFUNCDATA
+				p.From.Type = TYPE_CONST
+				p.From.Offset = objabi.FUNCDATA_ArgsPointerMaps
+				p.To.Type = TYPE_MEM
+				p.To.Name = NAME_EXTERN
+				p.To.Sym = ctxt.LookupDerived(s, s.Name+".args_stackmap")
+			}
+			if !foundArgInfo {
+				p := Appendp(s.Func().Text, newprog)
+				p.As = AFUNCDATA
+				p.From.Type = TYPE_CONST
+				p.From.Offset = objabi.FUNCDATA_ArgInfo
+				p.To.Type = TYPE_MEM
+				p.To.Name = NAME_EXTERN
+				p.To.Sym = ctxt.LookupDerived(s, fmt.Sprintf("%s.arginfo%d", s.Name, s.ABI()))
 			}
-		}
-		if !found {
-			p := Appendp(s.Func().Text, newprog)
-			p.As = AFUNCDATA
-			p.From.Type = TYPE_CONST
-			p.From.Offset = objabi.FUNCDATA_ArgsPointerMaps
-			p.To.Type = TYPE_MEM
-			p.To.Name = NAME_EXTERN
-			p.To.Sym = ctxt.LookupDerived(s, s.Name+".args_stackmap")
 		}
 	}