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[Liftoff][arm] Leave scratch register to the assembler

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In {Assembler::and_} we might need to use the scratch register. Thus use
a free LiftoffRegister instead to emit i32 popcnt.

R=ahaas@chromium.org
CC=george.wort@arm.com

Bug: chromium:918284
Change-Id: Ia814899bf6e33dd4989fd09329542b4bc09b48df
Reviewed-on: https://chromium-review.googlesource.com/c/1405036
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58723}
This commit is contained in:
Clemens Hammacher 2019-01-10 16:18:35 +01:00 committed by Commit Bot
parent 1efa000b54
commit f59d6d96e1
2 changed files with 24 additions and 4 deletions
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7
src/wasm/baseline/arm/liftoff-assembler-arm.h
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@ -682,10 +682,9 @@ bool LiftoffAssembler::emit_i32_ctz(Register dst, Register src) {
bool LiftoffAssembler::emit_i32_popcnt(Register dst, Register src) {
{
UseScratchRegisterScope temps(this);
LiftoffRegList pinned;
pinned.set(dst);
Register scratch = GetUnusedRegister(kGpReg, pinned).gp();
Register scratch_2 = temps.Acquire();
LiftoffRegList pinned = LiftoffRegList::ForRegs(dst);
Register scratch = pinned.set(GetUnusedRegister(kGpReg, pinned)).gp();
Register scratch_2 = GetUnusedRegister(kGpReg, pinned).gp();
// x = x - ((x & (0x55555555 << 1)) >> 1)
and_(scratch, src, Operand(0xaaaaaaaa));
sub(dst, src, Operand(scratch, LSR, 1));

21
test/mjsunit/regress/wasm/regress-918284.js Normal file
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@ -0,0 +1,21 @@
// Copyright 2019 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
load('test/mjsunit/wasm/wasm-constants.js');
load('test/mjsunit/wasm/wasm-module-builder.js');
const builder = new WasmModuleBuilder();
builder.addFunction(undefined, kSig_i_i)
.addLocals({i32_count: 7})
.addBody([
kExprI32Const, 0,
kExprIf, kWasmI32, // @11 i32
kExprI32Const, 0,
kExprElse, // @15
kExprI32Const, 1,
kExprEnd, // @18
kExprTeeLocal, 0,
kExprI32Popcnt
]);
builder.instantiate();