From 3d5cf72ca9beaedc5dcc8b094945de95fa35a670 Mon Sep 17 00:00:00 2001 From: Cherry Zhang Date: Wed, 17 Aug 2016 13:29:19 -0400 Subject: [PATCH] cmd/compile: CSE copied tuple selectors In CSE if a tuple generator is CSE'd to a different block, its selectors are copied to the same block. In this case, also CES the copied selectors. Test copied from Keith's CL 27202. Fixes #16741. Change-Id: I2fc8b9513d430f10d6104275cfff5fb75d3ef3d9 Reviewed-on: https://go-review.googlesource.com/27236 Run-TryBot: Cherry Zhang TryBot-Result: Gobot Gobot Reviewed-by: David Chase Reviewed-by: Keith Randall --- src/cmd/compile/internal/ssa/cse.go | 11 +++++++++++ test/fixedbugs/issue16741.go | 17 +++++++++++++++++ 2 files changed, 28 insertions(+) create mode 100644 test/fixedbugs/issue16741.go diff --git a/src/cmd/compile/internal/ssa/cse.go b/src/cmd/compile/internal/ssa/cse.go index a000c577d1..c0ddc83681 100644 --- a/src/cmd/compile/internal/ssa/cse.go +++ b/src/cmd/compile/internal/ssa/cse.go @@ -166,7 +166,10 @@ func cse(f *Func) { // if we rewrite a tuple generator to a new one in a different block, // copy its selectors to the new generator's block, so tuple generator // and selectors stay together. + // be careful not to copy same selectors more than once (issue 16741). + copiedSelects := make(map[ID][]*Value) for _, b := range f.Blocks { + out: for _, v := range b.Values { if rewrite[v.ID] != nil { continue @@ -180,8 +183,16 @@ func cse(f *Func) { t := rewrite[v.Args[0].ID] if t != nil && t.Block != b { // v.Args[0] is tuple generator, CSE'd into a different block as t, v is left behind + for _, c := range copiedSelects[t.ID] { + if v.Op == c.Op { + // an equivalent selector is already copied + rewrite[v.ID] = c + continue out + } + } c := v.copyInto(t.Block) rewrite[v.ID] = c + copiedSelects[t.ID] = append(copiedSelects[t.ID], c) } } } diff --git a/test/fixedbugs/issue16741.go b/test/fixedbugs/issue16741.go new file mode 100644 index 0000000000..9946062df7 --- /dev/null +++ b/test/fixedbugs/issue16741.go @@ -0,0 +1,17 @@ +// compile + +// Copyright 2016 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. + +// Make sure CSE of multi-output opcodes works correctly +// with select0/1 operations. + +package main + +func div(d, r int64) int64 { + if m := d % r; m > 0 { + return d/r + 1 + } + return d / r +} -- 2.48.1