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| author | Keith Randall <khr@golang.org> | 2016-08-16 09:19:05 -0700 |
|---|---|---|
| committer | Keith Randall <khr@golang.org> | 2016-08-16 16:46:48 +0000 |
| commit | d251030fa6feac46e5686a78b9681625447a5871 (patch) | |
| tree | 93cb08803ae2a3125cc6ff07df8d3d2c0cf9bb7a | |
| parent | 562d06fc23261b21d12fbcbd407aadee9cb428cb (diff) | |
| download | go-d251030fa6feac46e5686a78b9681625447a5871.tar.gz go-d251030fa6feac46e5686a78b9681625447a5871.zip | |
cmd/compile: don't fold >32bit constants into a MULQ
Don't fold constant factors into a multiply
beyond the capacity of a MULQ instruction (32 bits).
Fixes #16733
Change-Id: Idc213c6cb06f7c94008a8cf9e60a9e77d085fd89
Reviewed-on: https://go-review.googlesource.com/27160
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
| -rw-r--r-- | src/cmd/compile/internal/ssa/gen/AMD64.rules | 2 | ||||
| -rw-r--r-- | src/cmd/compile/internal/ssa/rewriteAMD64.go | 5 | ||||
| -rw-r--r-- | test/fixedbugs/issue16733.go | 16 |
3 files changed, 21 insertions, 2 deletions
diff --git a/src/cmd/compile/internal/ssa/gen/AMD64.rules b/src/cmd/compile/internal/ssa/gen/AMD64.rules index aa81ca7aa8..f676608c27 100644 --- a/src/cmd/compile/internal/ssa/gen/AMD64.rules +++ b/src/cmd/compile/internal/ssa/gen/AMD64.rules @@ -522,7 +522,7 @@ (XORQconst [c] (XORQconst [d] x)) -> (XORQconst [c ^ d] x) (MULLconst [c] (MULLconst [d] x)) -> (MULLconst [int64(int32(c * d))] x) -(MULQconst [c] (MULQconst [d] x)) -> (MULQconst [c * d] x) +(MULQconst [c] (MULQconst [d] x)) && is32Bit(c*d) -> (MULQconst [c * d] x) (ORQ x (MOVQconst [c])) && is32Bit(c) -> (ORQconst [c] x) (ORQ (MOVQconst [c]) x) && is32Bit(c) -> (ORQconst [c] x) diff --git a/src/cmd/compile/internal/ssa/rewriteAMD64.go b/src/cmd/compile/internal/ssa/rewriteAMD64.go index d09e706fdd..7d07c66ec0 100644 --- a/src/cmd/compile/internal/ssa/rewriteAMD64.go +++ b/src/cmd/compile/internal/ssa/rewriteAMD64.go @@ -9753,7 +9753,7 @@ func rewriteValueAMD64_OpAMD64MULQconst(v *Value, config *Config) bool { b := v.Block _ = b // match: (MULQconst [c] (MULQconst [d] x)) - // cond: + // cond: is32Bit(c*d) // result: (MULQconst [c * d] x) for { c := v.AuxInt @@ -9763,6 +9763,9 @@ func rewriteValueAMD64_OpAMD64MULQconst(v *Value, config *Config) bool { } d := v_0.AuxInt x := v_0.Args[0] + if !(is32Bit(c * d)) { + break + } v.reset(OpAMD64MULQconst) v.AuxInt = c * d v.AddArg(x) diff --git a/test/fixedbugs/issue16733.go b/test/fixedbugs/issue16733.go new file mode 100644 index 0000000000..850b042b62 --- /dev/null +++ b/test/fixedbugs/issue16733.go @@ -0,0 +1,16 @@ +// 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. + +// Issue 16733: don't fold constant factors into a multiply +// beyond the capacity of a MULQ instruction (32 bits). + +package p + +func f(n int64) int64 { + n *= 1000000 + n *= 1000000 + return n +} |