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deps: cherry-pick fc0ddf5 from upstream V8
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Original commit message:

    [snapshot] Always align embedded blob code pointer and size

    Other platforms besides ARM64 Windows may also have alignment
    requirements, e.g. PPC and s390. These requirements may affect
    both the code pointer field and the size field, and so they
    each need alignment directives because they are stored in
    different sections.

    Since aligning wastes a handful of bytes at most, not making
    alignment conditional on the platform type seems like a good idea.

    Refs: #24875
    Change-Id: I1f58606af294be65e74a1f107cd05fc21e032704
    Reviewed-on: https://chromium-review.googlesource.com/c/1433778
    Commit-Queue: Jakob Gruber <jgruber@chromium.org>
    Reviewed-by: Jakob Gruber <jgruber@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#59058}

Refs: v8/v8@fc0ddf5
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addaleax committed Jan 24, 2019
1 parent 061446d commit f9142b8
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Showing 3 changed files with 6 additions and 7 deletions.
2 changes: 1 addition & 1 deletion common.gypi
Original file line number Diff line number Diff line change
Expand Up @@ -38,7 +38,7 @@

# Reset this number to 0 on major V8 upgrades.
# Increment by one for each non-official patch applied to deps/v8.
'v8_embedder_string': '-node.0',
'v8_embedder_string': '-node.1',

##### V8 defaults for Node.js #####

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10 changes: 4 additions & 6 deletions deps/v8/src/snapshot/embedded-file-writer.cc
Original file line number Diff line number Diff line change
Expand Up @@ -364,13 +364,11 @@ void PlatformDependentEmbeddedFileWriter::AlignToCodeAlignment() {
}

void PlatformDependentEmbeddedFileWriter::AlignToDataAlignment() {
#if defined(V8_OS_WIN) && defined(V8_TARGET_ARCH_ARM64)
// On Windows ARM64, instruction "ldr xt,[xn,v8_Default_embedded_blob_]" is
// generated by clang-cl to load elements in v8_Default_embedded_blob_.
// The generated instruction has scale 3 which requires the load target to be
// aligned at 8 bytes (2^3).
// On Windows ARM64, s390, PPC and possibly more platforms, aligned load
// instructions are used to retrieve v8_Default_embedded_blob_ and/or
// v8_Default_embedded_blob_size_. The generated instructions require the
// load target to be aligned at 8 bytes (2^3).
fprintf(fp_, ".balign 8\n");
#endif
}

void PlatformDependentEmbeddedFileWriter::Comment(const char* string) {
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1 change: 1 addition & 0 deletions deps/v8/src/snapshot/embedded-file-writer.h
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Expand Up @@ -196,6 +196,7 @@ class EmbeddedFileWriter {

w->Comment("The size of the embedded blob in bytes.");
w->SectionRoData();
w->AlignToDataAlignment();
w->DeclareUint32(embedded_blob_size_symbol, blob->size());
w->Newline();
}
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