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[liftoff][arm64] Remove frame size padding to 4k

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Before https://crrev.com/c/3054114 we needed to pad the frame size to 4k
so that it fits into a 'sub' instruction as an immediate.
Since frame sizes larger than 4k use special OOL code now, this is not
required any more.
We thus remove the padding to save stack space.

R=ahaas@chromium.org

Bug: chromium:1379364
Change-Id: I155628141d2c0438415ccff36a4de8f7d1ad4fd3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3991050
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83999}
This commit is contained in:
Clemens Backes 2022-10-31 16:28:34 +01:00 committed by V8 LUCI CQ
parent 01a368bb49
commit 2f5fbb1381
2 changed files with 19 additions and 17 deletions
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25
src/wasm/baseline/arm64/liftoff-assembler-arm64.h
View File

@ -298,27 +298,18 @@ void LiftoffAssembler::AlignFrameSize() {
// The frame_size includes the frame marker. The frame marker has already been
// pushed on the stack though, so we don't need to allocate memory for it
// anymore.
int initial_frame_size = GetTotalFrameSize() - 2 * kSystemPointerSize;
int frame_size = initial_frame_size;
int frame_size = GetTotalFrameSize() - 2 * kSystemPointerSize;
static_assert(kStackSlotSize == kXRegSize,
"kStackSlotSize must equal kXRegSize");
// The stack pointer is required to be quadword aligned.
// Misalignment will cause a stack alignment fault.
frame_size = RoundUp(frame_size, kQuadWordSizeInBytes);
if (!IsImmAddSub(frame_size)) {
// Round the stack to a page to try to fit a add/sub immediate.
frame_size = RoundUp(frame_size, 0x1000);
if (!IsImmAddSub(frame_size)) {
// Stack greater than 4M! Because this is a quite improbable case, we
// just fallback to TurboFan.
bailout(kOtherReason, "Stack too big");
return;
}
}
if (frame_size > initial_frame_size) {
// Record the padding, as it is needed for GC offsets later.
max_used_spill_offset_ += (frame_size - initial_frame_size);
int misalignment = frame_size % kQuadWordSizeInBytes;
if (misalignment) {
int padding = kQuadWordSizeInBytes - misalignment;
frame_size += padding;
max_used_spill_offset_ += padding;
}
}
@ -337,7 +328,6 @@ void LiftoffAssembler::PatchPrepareStackFrame(
// The stack pointer is required to be quadword aligned.
// Misalignment will cause a stack alignment fault.
DCHECK_EQ(frame_size, RoundUp(frame_size, kQuadWordSizeInBytes));
DCHECK(IsImmAddSub(frame_size));
PatchingAssembler patching_assembler(AssemblerOptions{},
buffer_start_ + offset, 1);
@ -345,6 +335,7 @@ void LiftoffAssembler::PatchPrepareStackFrame(
if (V8_LIKELY(frame_size < 4 * KB)) {
// This is the standard case for small frames: just subtract from SP and be
// done with it.
DCHECK(IsImmAddSub(frame_size));
patching_assembler.PatchSubSp(frame_size);
return;
}

11
test/mjsunit/regress/wasm/regress-1379364.js Normal file
View File

@ -0,0 +1,11 @@
// Copyright 2022 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.
d8.file.execute("test/mjsunit/wasm/wasm-module-builder.js");
const builder = new WasmModuleBuilder();
builder.addFunction(undefined, kSig_d_v)
.addLocals(kWasmExternRef, 16000)
.addBody([kExprUnreachable]);
builder.toModule();