[maglev] Fix alias issue in GeneratorRestoreRegister

Temporary fix, ideally we should tell the register allocator to not
alias the input with the output.

Bug: v8:7700, v8:13109
Change-Id: I822e8e957689213499ea34620fcdeb5f532f2f5e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3876382
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Auto-Submit: Victor Gomes <victorgomes@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83001}

src/maglev/maglev-ir.cc

@@ -965,19 +965,31 @@ void GeneratorRestoreRegister::AllocateVreg(
     MaglevVregAllocationState* vreg_state) {
   UseRegister(array_input());
   DefineAsRegister(vreg_state, this);
+  set_temporaries_needed(1);
 }
 void GeneratorRestoreRegister::GenerateCode(MaglevCodeGenState* code_gen_state,
                                             const ProcessingState& state) {
   Register array = ToRegister(array_input());
+  Register result_reg = ToRegister(result());
+  Register temp = temporaries().PopFirst();
+
+  // The input and the output can alias, if that happen we use a temporary
+  // register and a move at the end.
+  Register value = (array == result_reg ? temp : result_reg);
+
   // Loads the current value in the generator register file.
   __ DecompressAnyTagged(
-      ToRegister(result()),
-      FieldOperand(array, FixedArray::OffsetOfElementAt(index())));
+      value, FieldOperand(array, FixedArray::OffsetOfElementAt(index())));
+
   // And trashs it with StaleRegisterConstant.
   __ LoadRoot(kScratchRegister, RootIndex::kStaleRegister);
   __ StoreTaggedField(
       FieldOperand(array, FixedArray::OffsetOfElementAt(index())),
       kScratchRegister);
+
+  if (value != result_reg) {
+    __ Move(result_reg, value);
+  }
 }
 
 void ForInPrepare::AllocateVreg(MaglevVregAllocationState* vreg_state) {