From 1747788c5668e76a238221ae4982daa5bdf24939 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Alexandru=20Mo=C8=99oi?= Date: Mon, 4 Apr 2016 23:33:30 +0200 Subject: [PATCH] cmd/compile: add a pass to print bound checks MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Since BCE happens over several passes (opt, loopbce, prove) it's easy to regress especially with rewriting. The pass is only activated with special debug flag. Change-Id: I46205982e7a2751156db8e875d69af6138068f59 Reviewed-on: https://go-review.googlesource.com/21510 Run-TryBot: Alexandru Moșoi TryBot-Result: Gobot Gobot Reviewed-by: David Chase --- src/cmd/compile/internal/ssa/checkbce.go | 23 ++++++ src/cmd/compile/internal/ssa/compile.go | 3 + src/cmd/compile/internal/ssa/phiopt.go | 4 ++ test/checkbce.go | 89 ++++++++++++++++++++++++ 4 files changed, 119 insertions(+) create mode 100644 src/cmd/compile/internal/ssa/checkbce.go create mode 100644 test/checkbce.go diff --git a/src/cmd/compile/internal/ssa/checkbce.go b/src/cmd/compile/internal/ssa/checkbce.go new file mode 100644 index 0000000000..820ea6e809 --- /dev/null +++ b/src/cmd/compile/internal/ssa/checkbce.go @@ -0,0 +1,23 @@ +// 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. + +package ssa + +// checkbce prints all bounds checks that are present in the function. +// Useful to find regressions. checkbce is only activated when with +// corresponsing debug options, so it's off by default. +// See test/checkbce.go +func checkbce(f *Func) { + if f.pass.debug <= 0 { + return + } + + for _, b := range f.Blocks { + for _, v := range b.Values { + if v.Op == OpIsInBounds || v.Op == OpIsSliceInBounds { + f.Config.Warnl(v.Line, "Found %v", v.Op) + } + } + } +} diff --git a/src/cmd/compile/internal/ssa/compile.go b/src/cmd/compile/internal/ssa/compile.go index 4a880f31f3..d52ae9c6da 100644 --- a/src/cmd/compile/internal/ssa/compile.go +++ b/src/cmd/compile/internal/ssa/compile.go @@ -242,6 +242,7 @@ var passes = [...]pass{ {name: "dec", fn: dec, required: true}, {name: "late opt", fn: opt, required: true}, // TODO: split required rules and optimizing rules {name: "generic deadcode", fn: deadcode}, + {name: "check bce", fn: checkbce}, {name: "fuse", fn: fuse}, {name: "dse", fn: dse}, {name: "tighten", fn: tighten}, // move values closer to their uses @@ -290,6 +291,8 @@ var passOrder = [...]constraint{ // tighten will be most effective when as many values have been removed as possible {"generic deadcode", "tighten"}, {"generic cse", "tighten"}, + // checkbce needs the values removed + {"generic deadcode", "check bce"}, // don't run optimization pass until we've decomposed builtin objects {"decompose builtin", "late opt"}, // don't layout blocks until critical edges have been removed diff --git a/src/cmd/compile/internal/ssa/phiopt.go b/src/cmd/compile/internal/ssa/phiopt.go index 132366cfc1..2d0a45733a 100644 --- a/src/cmd/compile/internal/ssa/phiopt.go +++ b/src/cmd/compile/internal/ssa/phiopt.go @@ -1,3 +1,7 @@ +// 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. + package ssa // phiopt eliminates boolean Phis based on the previous if. diff --git a/test/checkbce.go b/test/checkbce.go new file mode 100644 index 0000000000..a3b0100db8 --- /dev/null +++ b/test/checkbce.go @@ -0,0 +1,89 @@ +// +build amd64 +// errorcheck -0 -d=ssa/check_bce/debug=3 + +package main + +func f0(a []int) { + a[0] = 1 // ERROR "Found IsInBounds$" + a[0] = 1 + a[6] = 1 // ERROR "Found IsInBounds$" + a[6] = 1 + a[5] = 1 + a[5] = 1 +} + +func f1(a [256]int, i int) { + useInt(a[i]) // ERROR "Found IsInBounds$" + useInt(a[i%256]) // ERROR "Found IsInBounds$" + useInt(a[i&255]) + useInt(a[i&17]) + + if 4 <= i && i < len(a) { + useInt(a[i]) + useInt(a[i-1]) // ERROR "Found IsInBounds$" + useInt(a[i-4]) // ERROR "Found IsInBounds$" + } +} + +func f2(a [256]int, i uint) { + useInt(a[i]) // ERROR "Found IsInBounds$" + useInt(a[i%256]) + useInt(a[i&255]) + useInt(a[i&17]) +} + +func f3(a [256]int, i uint8) { + useInt(a[i]) + useInt(a[i+10]) + useInt(a[i+14]) +} + +func f4(a [27]int, i uint8) { + useInt(a[i%15]) + useInt(a[i%19]) + useInt(a[i%27]) +} + +func f5(a []int) { + if len(a) > 5 { + useInt(a[5]) + useSlice(a[6:]) + useSlice(a[:6]) // ERROR "Found IsSliceInBounds$" + } +} + +func g1(a []int) { + for i := range a { + a[i] = i + useSlice(a[:i+1]) + useSlice(a[:i]) + } +} + +func g2(a []int) { + useInt(a[3]) // ERROR "Found IsInBounds$" + useInt(a[2]) + useInt(a[1]) + useInt(a[0]) +} + +func g3(a []int) { + for i := range a[:256] { // ERROR "Found IsSliceInBounds$" + useInt(a[i]) // ERROR "Found IsInBounds$" + } + b := a[:256] + for i := range b { + useInt(b[i]) + } +} + +//go:noinline +func useInt(a int) { +} + +//go:noinline +func useSlice(a []int) { +} + +func main() { +} -- 2.48.1