[maglev][arm] Implement BuiltinStringPrototypeCharCodeOrCodePointAt

Bug: v8:7700
Change-Id: I1424987e6170f47aec947c992d8123c9de91e619
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4642191
Commit-Queue: Leszek Swirski <[email protected]>
Auto-Submit: Victor Gomes <[email protected]>
Commit-Queue: Victor Gomes <[email protected]>
Reviewed-by: Leszek Swirski <[email protected]>
Cr-Commit-Position: refs/heads/main@{#88488}

src/maglev/arm/maglev-ir-arm.cc

@@ -91,7 +91,33 @@ void BuiltinStringFromCharCode::SetValueLocationConstraints() {
 }
 void BuiltinStringFromCharCode::GenerateCode(MaglevAssembler* masm,
  const ProcessingState& state) {
- MAGLEV_NODE_NOT_IMPLEMENTED(BuiltinStringFromCharCode);
+ MaglevAssembler::ScratchRegisterScope temps(masm);
+ Register scratch = temps.Acquire();
+ Register result_string = ToRegister(result());
+ if (Int32Constant* constant = code_input().node()->TryCast<Int32Constant>()) {
+ int32_t char_code = constant->value();
+ if (0 <= char_code && char_code < String::kMaxOneByteCharCode) {
+ __ LoadSingleCharacterString(result_string, char_code);
+ } else {
+ // Ensure that {result_string} never aliases {scratch}, otherwise the
+ // store will fail.
+ bool reallocate_result = (scratch == result_string);
+ if (reallocate_result) {
+ result_string = temps.Acquire();
+ }
+ DCHECK(scratch != result_string);
+ __ AllocateTwoByteString(register_snapshot(), result_string, 1);
+ __ Move(scratch, char_code & 0xFFFF);
+ __ strh(scratch,
+ FieldMemOperand(result_string, SeqTwoByteString::kHeaderSize));
+ if (reallocate_result) {
+ __ Move(ToRegister(result()), result_string);
+ }
+ }
+ } else {
+ __ StringFromCharCode(register_snapshot(), nullptr, result_string,
+ ToRegister(code_input()), scratch);
+ }
 }
 
 int BuiltinStringPrototypeCharCodeOrCodePointAt::MaxCallStackArgs() const {