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Revert "[codegen] Align the code start at 64 byte in x64"

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This reverts commit 40af03b8c3.

Reason for revert: Breaks on win https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Win64%20-%20debug/39151/overview

Original change's description:
> [codegen] Align the code start at 64 byte in x64
>
> In order to make loop header aligned at 64 byte (relative to memory address), code start should also be aligned at 64 byte.
>
> Bug: chromium:1231471
> Change-Id: I95390babd9cc78492e0beb0f1b03901eb481d5d5
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3094167
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Commit-Queue: Hao A Xu <hao.a.xu@intel.com>
> Cr-Commit-Position: refs/heads/main@{#76484}

Bug: chromium:1231471
Change-Id: I93ad896d40e8bb906a05eab8e03980ce2061b9c0
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3118005
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Owners-Override: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#76488}
This commit is contained in:
Leszek Swirski 2021-08-25 12:25:17 +00:00 committed by V8 LUCI CQ
parent d7d5b448ee
commit 1acb1cd9ba
5 changed files with 4 additions and 27 deletions
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9
src/common/globals.h
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@ -590,14 +590,9 @@ constexpr intptr_t kPointerAlignmentMask = kPointerAlignment - 1;
constexpr intptr_t kDoubleAlignment = 8;
constexpr intptr_t kDoubleAlignmentMask = kDoubleAlignment - 1;
// Desired alignment for generated code is 64 bytes on x64 (to allow 64-bytes
// loop header alignment) and 32 bytes (to improve cache line utilization) on
// other architectures.
#if V8_TARGET_ARCH_X64
constexpr int kCodeAlignmentBits = 6;
#else
// Desired alignment for generated code is 32 bytes (to improve cache line
// utilization).
constexpr int kCodeAlignmentBits = 5;
#endif
constexpr intptr_t kCodeAlignment = 1 << kCodeAlignmentBits;
constexpr intptr_t kCodeAlignmentMask = kCodeAlignment - 1;

2
src/objects/code.h
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@ -547,7 +547,7 @@ class Code : public HeapObject {
#elif V8_TARGET_ARCH_LOONG64
static constexpr int kHeaderPaddingSize = 24;
#elif V8_TARGET_ARCH_X64
static constexpr int kHeaderPaddingSize = COMPRESS_POINTERS_BOOL ? 12 : 56;
static constexpr int kHeaderPaddingSize = COMPRESS_POINTERS_BOOL ? 12 : 24;
#elif V8_TARGET_ARCH_ARM
static constexpr int kHeaderPaddingSize = 12;
#elif V8_TARGET_ARCH_IA32

6
src/snapshot/embedded/platform-embedded-file-writer-aix.cc
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@ -65,14 +65,8 @@ void PlatformEmbeddedFileWriterAIX::DeclareSymbolGlobal(const char* name) {
}
void PlatformEmbeddedFileWriterAIX::AlignToCodeAlignment() {
#if V8_TARGET_ARCH_X64
// On x64 use 64-bytes code alignment to allow 64-bytes loop header alignment.
STATIC_ASSERT((1 << 6) >= kCodeAlignment);
fprintf(fp_, ".align 6\n");
#else
STATIC_ASSERT((1 << 5) >= kCodeAlignment);
fprintf(fp_, ".align 5\n");
#endif
}
void PlatformEmbeddedFileWriterAIX::AlignToDataAlignment() {

6
src/snapshot/embedded/platform-embedded-file-writer-generic.cc
View File

@ -74,14 +74,8 @@ void PlatformEmbeddedFileWriterGeneric::DeclareSymbolGlobal(const char* name) {
}
void PlatformEmbeddedFileWriterGeneric::AlignToCodeAlignment() {
#if V8_TARGET_ARCH_X64
// On x64 use 64-bytes code alignment to allow 64-bytes loop header alignment.
STATIC_ASSERT(64 >= kCodeAlignment);
fprintf(fp_, ".balign 64\n");
#else
STATIC_ASSERT(32 >= kCodeAlignment);
fprintf(fp_, ".balign 32\n");
#endif
}
void PlatformEmbeddedFileWriterGeneric::AlignToDataAlignment() {

8
src/snapshot/embedded/platform-embedded-file-writer-mac.cc
View File

@ -56,18 +56,12 @@ void PlatformEmbeddedFileWriterMac::DeclareSymbolGlobal(const char* name) {
// prevents something along the compilation chain from messing with the
// embedded blob. Using .global here causes embedded blob hash verification
// failures at runtime.
STATIC_ASSERT(32 >= kCodeAlignment);
fprintf(fp_, ".private_extern _%s\n", name);
}
void PlatformEmbeddedFileWriterMac::AlignToCodeAlignment() {
#if V8_TARGET_ARCH_X64
// On x64 use 64-bytes code alignment to allow 64-bytes loop header alignment.
STATIC_ASSERT(64 >= kCodeAlignment);
fprintf(fp_, ".balign 64\n");
#else
STATIC_ASSERT(32 >= kCodeAlignment);
fprintf(fp_, ".balign 32\n");
#endif
}
void PlatformEmbeddedFileWriterMac::AlignToDataAlignment() {