From: Matthew Dempsky <mdempsky@google.com>
Date: Sun, 20 Aug 2023 21:27:27 +0000 (-0700)
Subject: cmd/compile/internal/types: replace BOGUS_FUNARG_OFFSET with BADWIDTH
X-Git-Tag: go1.22rc1~1140
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=b0a17c04890c32dd0527061c132c639a01ee6f6f;p=gostls13.git

cmd/compile/internal/types: replace BOGUS_FUNARG_OFFSET with BADWIDTH

We already have a magic constant to represent fields that haven't had
their offsets calculated. We don't need two.

Change-Id: Ibfa95a3a15a5cd43e1e5ec7d0971d3e61d47fb3c
Reviewed-on: https://go-review.googlesource.com/c/go/+/521317
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
---

diff --git a/src/cmd/compile/internal/abi/abiutils.go b/src/cmd/compile/internal/abi/abiutils.go
index f8e4e8ae0d..78094d4ae9 100644
--- a/src/cmd/compile/internal/abi/abiutils.go
+++ b/src/cmd/compile/internal/abi/abiutils.go
@@ -445,19 +445,18 @@ func (config *ABIConfig) ABIAnalyze(t *types.Type, setNname bool) *ABIParamResul
 }
 
 func (config *ABIConfig) updateOffset(result *ABIParamResultInfo, f *types.Field, a ABIParamAssignment, isReturn, setNname bool) {
+	if f.Offset != types.BADWIDTH {
+		base.Fatalf("field offset for %s at %s has been set to %d", f.Sym.Name, base.FmtPos(f.Pos), f.Offset)
+	}
+
 	// Everything except return values in registers has either a frame home (if not in a register) or a frame spill location.
 	if !isReturn || len(a.Registers) == 0 {
 		// The type frame offset DOES NOT show effects of minimum frame size.
 		// Getting this wrong breaks stackmaps, see liveness/plive.go:WriteFuncMap and typebits/typebits.go:Set
 		off := a.FrameOffset(result)
-		fOffset := f.Offset
-		if fOffset == types.BOGUS_FUNARG_OFFSET {
-			if setNname && f.Nname != nil {
-				f.Nname.(*ir.Name).SetFrameOffset(off)
-				f.Nname.(*ir.Name).SetIsOutputParamInRegisters(false)
-			}
-		} else {
-			base.Fatalf("field offset for %s at %s has been set to %d", f.Sym.Name, base.FmtPos(f.Pos), fOffset)
+		if setNname && f.Nname != nil {
+			f.Nname.(*ir.Name).SetFrameOffset(off)
+			f.Nname.(*ir.Name).SetIsOutputParamInRegisters(false)
 		}
 	} else {
 		if setNname && f.Nname != nil {
diff --git a/src/cmd/compile/internal/ssagen/ssa.go b/src/cmd/compile/internal/ssagen/ssa.go
index 89e14786b0..9b93b599f3 100644
--- a/src/cmd/compile/internal/ssagen/ssa.go
+++ b/src/cmd/compile/internal/ssagen/ssa.go
@@ -306,13 +306,6 @@ func (s *state) emitOpenDeferInfo() {
 	off = dvarint(x, off, -firstOffset)
 }
 
-func okOffset(offset int64) int64 {
-	if offset == types.BOGUS_FUNARG_OFFSET {
-		panic(fmt.Errorf("Bogus offset %d", offset))
-	}
-	return offset
-}
-
 // buildssa builds an SSA function for fn.
 // worker indicates which of the backend workers is doing the processing.
 func buildssa(fn *ir.Func, worker int) *ssa.Func {
diff --git a/src/cmd/compile/internal/types/type.go b/src/cmd/compile/internal/types/type.go
index 343cc69c18..f03aabe430 100644
--- a/src/cmd/compile/internal/types/type.go
+++ b/src/cmd/compile/internal/types/type.go
@@ -409,8 +409,7 @@ type Field struct {
 	Nname Object
 
 	// Offset in bytes of this field or method within its enclosing struct
-	// or interface Type.  Exception: if field is function receiver, arg or
-	// result, then this is BOGUS_FUNARG_OFFSET; types does not know the Abi.
+	// or interface Type. For parameters, this is BADWIDTH.
 	Offset int64
 }
 
@@ -1686,14 +1685,6 @@ func NewInterface(methods []*Field) *Type {
 	return t
 }
 
-const BOGUS_FUNARG_OFFSET = -1000000000
-
-func unzeroFieldOffsets(f []*Field) {
-	for i := range f {
-		f[i].Offset = BOGUS_FUNARG_OFFSET // This will cause an explosion if it is not corrected
-	}
-}
-
 // NewSignature returns a new function type for the given receiver,
 // parameters, and results, any of which may be nil.
 func NewSignature(recv *Field, params, results []*Field) *Type {
@@ -1711,11 +1702,6 @@ func NewSignature(recv *Field, params, results []*Field) *Type {
 		return s
 	}
 
-	if recv != nil {
-		recv.Offset = BOGUS_FUNARG_OFFSET
-	}
-	unzeroFieldOffsets(params)
-	unzeroFieldOffsets(results)
 	ft.Receiver = funargs(recvs)
 	ft.Params = funargs(params)
 	ft.Results = funargs(results)