From 1054085dcf88ce802e6aa45078f9d7f3abf5b85d Mon Sep 17 00:00:00 2001 From: Keith Randall Date: Thu, 11 May 2017 14:46:49 -0700 Subject: [release-branch.go1.8] cmd/compile: fix store chain in schedule pass Cherry-pick of CL 43294. Tuple ops are weird. They are essentially a pair of ops, one which consumes a mem and one which generates a mem (the Select1). The schedule pass didn't handle these quite right. Fix the scheduler to include both parts of the paired op in the store chain. That makes sure that loads are correctly ordered with respect to the first of the pair. Add a check for the ssacheck builder, that there is only one live store at a time. I thought we already had such a check, but apparently not... Fixes #20335 Change-Id: I59eb3446a329100af38d22820b1ca2190ca46a78 Reviewed-on: https://go-review.googlesource.com/43411 Run-TryBot: Austin Clements TryBot-Result: Gobot Gobot Reviewed-by: Keith Randall --- src/cmd/compile/internal/ssa/check.go | 33 ++++++++++++++++++++++++++++++++ src/cmd/compile/internal/ssa/schedule.go | 31 +++++++++++++++--------------- test/fixedbugs/issue20335.go | 19 ++++++++++++++++++ 3 files changed, 68 insertions(+), 15 deletions(-) create mode 100644 test/fixedbugs/issue20335.go diff --git a/src/cmd/compile/internal/ssa/check.go b/src/cmd/compile/internal/ssa/check.go index d78e915091..d6d39aee76 100644 --- a/src/cmd/compile/internal/ssa/check.go +++ b/src/cmd/compile/internal/ssa/check.go @@ -294,6 +294,39 @@ func checkFunc(f *Func) { } } } + + // Check that if a tuple has a memory type, it is second. + for _, b := range f.Blocks { + for _, v := range b.Values { + if v.Type.IsTuple() && v.Type.FieldType(0).IsMemory() { + f.Fatalf("memory is first in a tuple: %s\n", v.LongString()) + } + } + } + + // Check that only one memory is live at any point. + // TODO: make this check examine interblock. + if f.scheduled { + for _, b := range f.Blocks { + var mem *Value // the live memory + for _, v := range b.Values { + if v.Op != OpPhi { + for _, a := range v.Args { + if a.Type.IsMemory() || a.Type.IsTuple() && a.Type.FieldType(1).IsMemory() { + if mem == nil { + mem = a + } else if mem != a { + f.Fatalf("two live mems @ %s: %s and %s", v, mem, a) + } + } + } + } + if v.Type.IsMemory() || v.Type.IsTuple() && v.Type.FieldType(1).IsMemory() { + mem = v + } + } + } + } } // domCheck reports whether x dominates y (including x==y). diff --git a/src/cmd/compile/internal/ssa/schedule.go b/src/cmd/compile/internal/ssa/schedule.go index a455a9a399..78b61f0959 100644 --- a/src/cmd/compile/internal/ssa/schedule.go +++ b/src/cmd/compile/internal/ssa/schedule.go @@ -148,19 +148,20 @@ func schedule(f *Func) { } } + // TODO: make this logic permanent in types.IsMemory? + isMem := func(v *Value) bool { + return v.Type.IsMemory() || v.Type.IsTuple() && v.Type.FieldType(1).IsMemory() + } + for _, b := range f.Blocks { // Find store chain for block. // Store chains for different blocks overwrite each other, so // the calculated store chain is good only for this block. for _, v := range b.Values { - if v.Op != OpPhi && v.Type.IsMemory() { - mem := v - if v.Op == OpSelect1 { - v = v.Args[0] - } + if v.Op != OpPhi && isMem(v) { for _, w := range v.Args { - if w.Type.IsMemory() { - nextMem[w.ID] = mem + if isMem(w) { + nextMem[w.ID] = v } } } @@ -179,15 +180,15 @@ func schedule(f *Func) { uses[w.ID]++ } // Any load must come before the following store. - if v.Type.IsMemory() || !w.Type.IsMemory() { - continue // not a load - } - s := nextMem[w.ID] - if s == nil || s.Block != b { - continue + if !isMem(v) && isMem(w) { + // v is a load. + s := nextMem[w.ID] + if s == nil || s.Block != b { + continue + } + additionalArgs[s.ID] = append(additionalArgs[s.ID], v) + uses[v.ID]++ } - additionalArgs[s.ID] = append(additionalArgs[s.ID], v) - uses[v.ID]++ } } diff --git a/test/fixedbugs/issue20335.go b/test/fixedbugs/issue20335.go new file mode 100644 index 0000000000..185c2f06ea --- /dev/null +++ b/test/fixedbugs/issue20335.go @@ -0,0 +1,19 @@ +// 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. + +// Issue 20335: don't reorder loads with stores. +// This test should fail on the ssacheck builder +// without the fix in the CL that added this file. +// TODO: check the generated assembly? + +package a + +import "sync/atomic" + +func f(p, q *int32) bool { + x := *q + return atomic.AddInt32(p, 1) == x +} -- cgit v1.2.3-54-g00ecf