From 998fe70b683ed64d0bc67d9e0a35f8a7bcbe161d Mon Sep 17 00:00:00 2001 From: David Chase Date: Fri, 26 Feb 2021 17:37:26 -0500 Subject: [PATCH] cmd/compile: fixed which-result confusion in presence of 0-width types A function returning multiple results, some of them zero-width, will have more than one result present at an offset. Be sure that offset AND type match. Includes test. Change-Id: I3eb1f56116d989b4e73f533fefabb1bf554c901b Reviewed-on: https://go-review.googlesource.com/c/go/+/297169 Trust: David Chase Run-TryBot: David Chase TryBot-Result: Go Bot Reviewed-by: Jeremy Faller --- src/cmd/compile/internal/ssa/op.go | 9 ++++--- src/cmd/compile/internal/ssagen/ssa.go | 4 ++-- test/abi/f_ret_z_not.go | 33 ++++++++++++++++++++++++++ test/abi/f_ret_z_not.out | 1 + 4 files changed, 42 insertions(+), 5 deletions(-) create mode 100644 test/abi/f_ret_z_not.go create mode 100644 test/abi/f_ret_z_not.out diff --git a/src/cmd/compile/internal/ssa/op.go b/src/cmd/compile/internal/ssa/op.go index 6949bdca31..ece274b083 100644 --- a/src/cmd/compile/internal/ssa/op.go +++ b/src/cmd/compile/internal/ssa/op.go @@ -86,12 +86,15 @@ type AuxCall struct { abiInfo *abi.ABIParamResultInfo // TODO remove fields above redundant with this information. } -// ResultForOffset returns the index of the result at a particular offset among the results +// ResultForOffsetAndType returns the index of a t-typed result at *A* particular offset among the results. +// An arbitrary number of zero-width-typed results may reside at the same offset with a single not-zero-width +// typed result, but the ones with the same type are all indistinguishable so it doesn't matter "which one" +// is obtained. // This does not include the mem result for the call opcode. -func (a *AuxCall) ResultForOffset(offset int64) int64 { +func (a *AuxCall) ResultForOffsetAndType(offset int64, t *types.Type) int64 { which := int64(-1) for i := int64(0); i < a.NResults(); i++ { // note aux NResults does not include mem result. - if a.OffsetOfResult(i) == offset { + if a.OffsetOfResult(i) == offset && a.TypeOfResult(i) == t { which = i break } diff --git a/src/cmd/compile/internal/ssagen/ssa.go b/src/cmd/compile/internal/ssagen/ssa.go index ba00b9c7f6..865630dd3e 100644 --- a/src/cmd/compile/internal/ssagen/ssa.go +++ b/src/cmd/compile/internal/ssagen/ssa.go @@ -2909,7 +2909,7 @@ func (s *state) expr(n ir.Node) *ssa.Value { addr := s.constOffPtrSP(types.NewPtr(n.Type()), n.Offset) return s.rawLoad(n.Type(), addr) } - which := s.prevCall.Aux.(*ssa.AuxCall).ResultForOffset(n.Offset) + which := s.prevCall.Aux.(*ssa.AuxCall).ResultForOffsetAndType(n.Offset, n.Type()) if which == -1 { // Do the old thing // TODO: Panic instead. addr := s.constOffPtrSP(types.NewPtr(n.Type()), n.Offset) @@ -5119,7 +5119,7 @@ func (s *state) addr(n ir.Node) *ssa.Value { if s.prevCall == nil || s.prevCall.Op != ssa.OpStaticLECall && s.prevCall.Op != ssa.OpInterLECall && s.prevCall.Op != ssa.OpClosureLECall { return s.constOffPtrSP(t, n.Offset) } - which := s.prevCall.Aux.(*ssa.AuxCall).ResultForOffset(n.Offset) + which := s.prevCall.Aux.(*ssa.AuxCall).ResultForOffsetAndType(n.Offset, n.Type()) if which == -1 { // Do the old thing // TODO: Panic instead. return s.constOffPtrSP(t, n.Offset) diff --git a/test/abi/f_ret_z_not.go b/test/abi/f_ret_z_not.go new file mode 100644 index 0000000000..b072aea75e --- /dev/null +++ b/test/abi/f_ret_z_not.go @@ -0,0 +1,33 @@ +// run + +// Copyright 2021 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package main + +import "fmt" + +type Z struct { +} + +type NZ struct { + x, y int +} + +//go:noinline +func f(x,y int) (Z,NZ,Z) { + var z Z + return z,NZ{x,y},z +} + +//go:noinline +func g() (Z,NZ,Z) { + a,b,c := f(3,4) + return c,b,a +} + +func main() { + _,b,_ := g() + fmt.Println(b.x+b.y) +} diff --git a/test/abi/f_ret_z_not.out b/test/abi/f_ret_z_not.out new file mode 100644 index 0000000000..7f8f011eb7 --- /dev/null +++ b/test/abi/f_ret_z_not.out @@ -0,0 +1 @@ +7