From 39983cf491aef22579d993b59a4dffedb190666a Mon Sep 17 00:00:00 2001 From: Matthew Dempsky Date: Mon, 18 Sep 2017 23:29:46 -0700 Subject: [PATCH] cmd/compile: refactor onebitwalktype1 The existing logic tried to advance the offset for each variable's width, but then tried to undo this logic with the array and struct handling code. It can all be much simpler by only worrying about computing offsets within the array and struct code. While here, include a short-circuit for zero-width arrays to fix a pedantic compiler failure case. Passes toolstash-check. Fixes #20739. Change-Id: I98af9bb512a33e3efe82b8bf1803199edb480640 Reviewed-on: https://go-review.googlesource.com/64471 Run-TryBot: Matthew Dempsky TryBot-Result: Gobot Gobot Reviewed-by: Robert Griesemer --- src/cmd/compile/internal/gc/pgen.go | 14 ++--- src/cmd/compile/internal/gc/plive.go | 80 +++++++++----------------- src/cmd/compile/internal/gc/reflect.go | 3 +- test/fixedbugs/issue20739.go | 16 ++++++ 4 files changed, 49 insertions(+), 64 deletions(-) create mode 100644 test/fixedbugs/issue20739.go diff --git a/src/cmd/compile/internal/gc/pgen.go b/src/cmd/compile/internal/gc/pgen.go index 54fdb30d10..417f1ba716 100644 --- a/src/cmd/compile/internal/gc/pgen.go +++ b/src/cmd/compile/internal/gc/pgen.go @@ -42,21 +42,17 @@ func emitptrargsmap() { } off := duint32(lsym, 0, uint32(nbitmap)) off = duint32(lsym, off, uint32(bv.n)) - var xoffset int64 + if Curfn.IsMethod() { - xoffset = 0 - onebitwalktype1(Curfn.Type.Recvs(), &xoffset, bv) + onebitwalktype1(Curfn.Type.Recvs(), 0, bv) } - if Curfn.Type.NumParams() > 0 { - xoffset = 0 - onebitwalktype1(Curfn.Type.Params(), &xoffset, bv) + onebitwalktype1(Curfn.Type.Params(), 0, bv) } - off = dbvec(lsym, off, bv) + if Curfn.Type.NumResults() > 0 { - xoffset = 0 - onebitwalktype1(Curfn.Type.Results(), &xoffset, bv) + onebitwalktype1(Curfn.Type.Results(), 0, bv) off = dbvec(lsym, off, bv) } diff --git a/src/cmd/compile/internal/gc/plive.go b/src/cmd/compile/internal/gc/plive.go index c3bc753d07..57295a7277 100644 --- a/src/cmd/compile/internal/gc/plive.go +++ b/src/cmd/compile/internal/gc/plive.go @@ -355,85 +355,63 @@ func (lv *Liveness) blockEffects(b *ssa.Block) *BlockEffects { // and then simply copied into bv at the correct offset on future calls with // the same type t. On https://rsc.googlecode.com/hg/testdata/slow.go, onebitwalktype1 // accounts for 40% of the 6g execution time. -func onebitwalktype1(t *types.Type, xoffset *int64, bv bvec) { - if t.Align > 0 && *xoffset&int64(t.Align-1) != 0 { +func onebitwalktype1(t *types.Type, off int64, bv bvec) { + if t.Align > 0 && off&int64(t.Align-1) != 0 { Fatalf("onebitwalktype1: invalid initial alignment, %v", t) } switch t.Etype { - case TINT8, - TUINT8, - TINT16, - TUINT16, - TINT32, - TUINT32, - TINT64, - TUINT64, - TINT, - TUINT, - TUINTPTR, - TBOOL, - TFLOAT32, - TFLOAT64, - TCOMPLEX64, - TCOMPLEX128: - *xoffset += t.Width + case TINT8, TUINT8, TINT16, TUINT16, + TINT32, TUINT32, TINT64, TUINT64, + TINT, TUINT, TUINTPTR, TBOOL, + TFLOAT32, TFLOAT64, TCOMPLEX64, TCOMPLEX128: - case TPTR32, - TPTR64, - TUNSAFEPTR, - TFUNC, - TCHAN, - TMAP: - if *xoffset&int64(Widthptr-1) != 0 { + case TPTR32, TPTR64, TUNSAFEPTR, TFUNC, TCHAN, TMAP: + if off&int64(Widthptr-1) != 0 { Fatalf("onebitwalktype1: invalid alignment, %v", t) } - bv.Set(int32(*xoffset / int64(Widthptr))) // pointer - *xoffset += t.Width + bv.Set(int32(off / int64(Widthptr))) // pointer case TSTRING: // struct { byte *str; intgo len; } - if *xoffset&int64(Widthptr-1) != 0 { + if off&int64(Widthptr-1) != 0 { Fatalf("onebitwalktype1: invalid alignment, %v", t) } - bv.Set(int32(*xoffset / int64(Widthptr))) //pointer in first slot - *xoffset += t.Width + bv.Set(int32(off / int64(Widthptr))) //pointer in first slot case TINTER: // struct { Itab *tab; void *data; } // or, when isnilinter(t)==true: // struct { Type *type; void *data; } - if *xoffset&int64(Widthptr-1) != 0 { + if off&int64(Widthptr-1) != 0 { Fatalf("onebitwalktype1: invalid alignment, %v", t) } - bv.Set(int32(*xoffset / int64(Widthptr))) // pointer in first slot - bv.Set(int32(*xoffset/int64(Widthptr) + 1)) // pointer in second slot - *xoffset += t.Width + bv.Set(int32(off / int64(Widthptr))) // pointer in first slot + bv.Set(int32(off/int64(Widthptr) + 1)) // pointer in second slot case TSLICE: // struct { byte *array; uintgo len; uintgo cap; } - if *xoffset&int64(Widthptr-1) != 0 { + if off&int64(Widthptr-1) != 0 { Fatalf("onebitwalktype1: invalid TARRAY alignment, %v", t) } - bv.Set(int32(*xoffset / int64(Widthptr))) // pointer in first slot (BitsPointer) - *xoffset += t.Width + bv.Set(int32(off / int64(Widthptr))) // pointer in first slot (BitsPointer) case TARRAY: + elt := t.Elem() + if elt.Width == 0 { + // Short-circuit for #20739. + break + } for i := int64(0); i < t.NumElem(); i++ { - onebitwalktype1(t.Elem(), xoffset, bv) + onebitwalktype1(elt, off, bv) + off += elt.Width } case TSTRUCT: - var o int64 - for _, t1 := range t.Fields().Slice() { - fieldoffset := t1.Offset - *xoffset += fieldoffset - o - onebitwalktype1(t1.Type, xoffset, bv) - o = fieldoffset + t1.Type.Width + for _, f := range t.Fields().Slice() { + onebitwalktype1(f.Type, off+f.Offset, bv) } - *xoffset += t.Width - o - default: Fatalf("onebitwalktype1: unexpected type, %v", t) } @@ -453,8 +431,6 @@ func argswords(lv *Liveness) int32 { // this argument and the in arguments are always assumed live. The vars // argument is a slice of *Nodes. func onebitlivepointermap(lv *Liveness, liveout bvec, vars []*Node, args bvec, locals bvec) { - var xoffset int64 - for i := int32(0); ; i++ { i = liveout.Next(i) if i < 0 { @@ -463,12 +439,10 @@ func onebitlivepointermap(lv *Liveness, liveout bvec, vars []*Node, args bvec, l node := vars[i] switch node.Class() { case PAUTO: - xoffset = node.Xoffset + lv.stkptrsize - onebitwalktype1(node.Type, &xoffset, locals) + onebitwalktype1(node.Type, node.Xoffset+lv.stkptrsize, locals) case PPARAM, PPARAMOUT: - xoffset = node.Xoffset - onebitwalktype1(node.Type, &xoffset, args) + onebitwalktype1(node.Type, node.Xoffset, args) } } } diff --git a/src/cmd/compile/internal/gc/reflect.go b/src/cmd/compile/internal/gc/reflect.go index 0bc0c53631..d268c89e69 100644 --- a/src/cmd/compile/internal/gc/reflect.go +++ b/src/cmd/compile/internal/gc/reflect.go @@ -1774,8 +1774,7 @@ func fillptrmask(t *types.Type, ptrmask []byte) { } vec := bvalloc(8 * int32(len(ptrmask))) - xoffset := int64(0) - onebitwalktype1(t, &xoffset, vec) + onebitwalktype1(t, 0, vec) nptr := typeptrdata(t) / int64(Widthptr) for i := int64(0); i < nptr; i++ { diff --git a/test/fixedbugs/issue20739.go b/test/fixedbugs/issue20739.go new file mode 100644 index 0000000000..b71a25dc42 --- /dev/null +++ b/test/fixedbugs/issue20739.go @@ -0,0 +1,16 @@ +// compile + +// Copyright 2017 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 p + +func F() { + var x struct { + x *int + w [1e9][1e9][1e9][0]*int + y *int + } + println(&x) +} -- 2.48.1