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[maglev] Add character to set of saved registers in StringAt

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... otherwise AllocateRaw can call the allocation builtin,
that can trigger a GC and read the character as a pointer.

Bug: v8:7700, v8:13397
Change-Id: If4e15fc8bfe0f94c53fe77022b18d5d4a6168702
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3964754
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Auto-Submit: Victor Gomes <victorgomes@chromium.org>
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83826}
This commit is contained in:
Victor Gomes 2022-10-20 17:14:23 +02:00 committed by V8 LUCI CQ
parent d1dcdd9a21
commit fb84e6c437
1 changed files with 11 additions and 5 deletions
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16
src/maglev/maglev-ir.cc
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@ -2000,10 +2000,17 @@ void StringAt::GenerateCode(MaglevAssembler* masm,
__ JumpToDeferredIf(
greater,
[](MaglevAssembler* masm, ZoneLabelRef done, Register character,
StringAt* node) {
Register scratch1, StringAt* node) {
Register result_string = ToRegister(node->result());
RegisterSnapshot save_registers = node->register_snapshot();
__ Push(character); // Spill character before inlined allocation.
// If {character} alias with {result_string}, use the second scratch
// register.
if (character == result_string) {
DCHECK_NE(scratch1, character);
__ Move(scratch1, character);
character = scratch1;
}
save_registers.live_registers.set(character);
AllocateRaw(masm, save_registers, result_string,
SeqTwoByteString::SizeFor(1));
__ LoadRoot(kScratchRegister, RootIndex::kStringMap);
@ -2014,12 +2021,11 @@ void StringAt::GenerateCode(MaglevAssembler* masm,
Immediate(Name::kEmptyHashField));
__ StoreTaggedField(FieldOperand(result_string, String::kLengthOffset),
Immediate(1));
__ Pop(kScratchRegister); // Restore character.
__ movw(FieldOperand(result_string, SeqTwoByteString::kHeaderSize),
kScratchRegister);
character);
__ jmp(*done);
},
done, character, this);
done, character, scratch1, this);
// Load one byte string from a predefined/cached table.
__ bind(&cached_one_byte_string);