[builtins] Combine SmiUntag with loading a value

Combining the load with the SmiUntag let's us have better
instruction selection opportunities against not doing it.

Bug: v8:9771
Change-Id: I6b6391398413ee1bc808c71d48474e9336c09f2b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1826734
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64025}

src/builtins/arm64/builtins-arm64.cc

@@ -1313,9 +1313,8 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
   // Get bytecode array and bytecode offset from the stack frame.
   __ Ldr(kInterpreterBytecodeArrayRegister,
          MemOperand(fp, InterpreterFrameConstants::kBytecodeArrayFromFp));
-  __ Ldr(kInterpreterBytecodeOffsetRegister,
-         MemOperand(fp, InterpreterFrameConstants::kBytecodeOffsetFromFp));
-  __ SmiUntag(kInterpreterBytecodeOffsetRegister);
+  __ SmiUntag(kInterpreterBytecodeOffsetRegister,
+              MemOperand(fp, InterpreterFrameConstants::kBytecodeOffsetFromFp));
 
   // Either return, or advance to the next bytecode and dispatch.
   Label do_return;
@@ -1545,9 +1544,8 @@ static void Generate_InterpreterEnterBytecode(MacroAssembler* masm) {
   }
 
   // Get the target bytecode offset from the frame.
-  __ Ldr(kInterpreterBytecodeOffsetRegister,
-         MemOperand(fp, InterpreterFrameConstants::kBytecodeOffsetFromFp));
-  __ SmiUntag(kInterpreterBytecodeOffsetRegister);
+  __ SmiUntag(kInterpreterBytecodeOffsetRegister,
+              MemOperand(fp, InterpreterFrameConstants::kBytecodeOffsetFromFp));
 
   // Dispatch to the target bytecode.
   __ Ldrb(x23, MemOperand(kInterpreterBytecodeArrayRegister,
@@ -1562,9 +1560,8 @@ void Builtins::Generate_InterpreterEnterBytecodeAdvance(MacroAssembler* masm) {
   // Get bytecode array and bytecode offset from the stack frame.
   __ ldr(kInterpreterBytecodeArrayRegister,
          MemOperand(fp, InterpreterFrameConstants::kBytecodeArrayFromFp));
-  __ ldr(kInterpreterBytecodeOffsetRegister,
-         MemOperand(fp, InterpreterFrameConstants::kBytecodeOffsetFromFp));
-  __ SmiUntag(kInterpreterBytecodeOffsetRegister);
+  __ SmiUntag(kInterpreterBytecodeOffsetRegister,
+              MemOperand(fp, InterpreterFrameConstants::kBytecodeOffsetFromFp));
 
   // Load the current bytecode.
   __ Ldrb(x1, MemOperand(kInterpreterBytecodeArrayRegister,

src/builtins/x64/builtins-x64.cc

@@ -1199,9 +1199,8 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
   // Get bytecode array and bytecode offset from the stack frame.
   __ movq(kInterpreterBytecodeArrayRegister,
           Operand(rbp, InterpreterFrameConstants::kBytecodeArrayFromFp));
-  __ movq(kInterpreterBytecodeOffsetRegister,
-          Operand(rbp, InterpreterFrameConstants::kBytecodeOffsetFromFp));
-  __ SmiUntag(kInterpreterBytecodeOffsetRegister);
+  __ SmiUntag(kInterpreterBytecodeOffsetRegister,
+              Operand(rbp, InterpreterFrameConstants::kBytecodeOffsetFromFp));
 
   // Either return, or advance to the next bytecode and dispatch.
   Label do_return;
@@ -1426,9 +1425,8 @@ static void Generate_InterpreterEnterBytecode(MacroAssembler* masm) {
   }
 
   // Get the target bytecode offset from the frame.
-  __ movq(kInterpreterBytecodeOffsetRegister,
-          Operand(rbp, InterpreterFrameConstants::kBytecodeOffsetFromFp));
-  __ SmiUntag(kInterpreterBytecodeOffsetRegister);
+  __ SmiUntag(kInterpreterBytecodeOffsetRegister,
+              Operand(rbp, InterpreterFrameConstants::kBytecodeOffsetFromFp));
 
   // Dispatch to the target bytecode.
   __ movzxbq(r11, Operand(kInterpreterBytecodeArrayRegister,
@@ -1443,9 +1441,8 @@ void Builtins::Generate_InterpreterEnterBytecodeAdvance(MacroAssembler* masm) {
   // Get bytecode array and bytecode offset from the stack frame.
   __ movq(kInterpreterBytecodeArrayRegister,
           Operand(rbp, InterpreterFrameConstants::kBytecodeArrayFromFp));
-  __ movq(kInterpreterBytecodeOffsetRegister,
-          Operand(rbp, InterpreterFrameConstants::kBytecodeOffsetFromFp));
-  __ SmiUntag(kInterpreterBytecodeOffsetRegister);
+  __ SmiUntag(kInterpreterBytecodeOffsetRegister,
+              Operand(rbp, InterpreterFrameConstants::kBytecodeOffsetFromFp));
 
   // Load the current bytecode.
   __ movzxbq(rbx, Operand(kInterpreterBytecodeArrayRegister,