From 978af9c2dbb4982f62dee6b84c48e06e0d4c085c Mon Sep 17 00:00:00 2001 From: Keith Randall Date: Thu, 11 May 2017 14:46:49 -0700 Subject: [PATCH] cmd/compile: fix store chain in schedule pass 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/43294 Run-TryBot: Keith Randall TryBot-Result: Gobot Gobot Reviewed-by: Cherry Zhang --- 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 e5de48965b..82d7b7687b 100644 --- a/src/cmd/compile/internal/ssa/check.go +++ b/src/cmd/compile/internal/ssa/check.go @@ -309,6 +309,39 @@ 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 356d44787f..2e9464eb0d 100644 --- a/src/cmd/compile/internal/ssa/schedule.go +++ b/src/cmd/compile/internal/ssa/schedule.go @@ -132,19 +132,20 @@ 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 } } } @@ -163,15 +164,15 @@ 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 +} -- 2.50.0