Delay the pushing of arguments until just before calling runtime in CompareSt...

src/x64/codegen-x64.cc

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 10270 matching lines @@
 
       // Check for oddballs: true, false, null, undefined.
       __ CmpInstanceType(rcx, ODDBALL_TYPE);
       __ j(equal, &return_not_equal);
 
       // Fall through to the general case.
     }
     __ bind(&slow);
   }
 
-  // Push arguments below the return address to prepare jump to builtin.
-  __ pop(rcx);
-  __ push(rax);
-  __ push(rdx);
-  __ push(rcx);
-
   // Generate the number comparison code.
   if (include_number_compare_) {
     Label non_number_comparison;
     Label unordered;
     FloatingPointHelper::LoadSSE2UnknownOperands(masm, &non_number_comparison);
     __ xorl(rax, rax);
     __ xorl(rcx, rcx);
     __ ucomisd(xmm0, xmm1);
 
     // Don't base result on EFLAGS when a NaN is involved.
     __ j(parity_even, &unordered);
     // Return a result of -1, 0, or 1, based on EFLAGS.
     __ setcc(above, rax);
     __ setcc(below, rcx);
     __ subq(rax, rcx);
-    __ ret(2 * kPointerSize);  // rax, rdx were pushed
+    __ ret(0);
 
     // If one of the numbers was NaN, then the result is always false.
     // The cc is never not-equal.
     __ bind(&unordered);
     ASSERT(cc_ != not_equal);
     if (cc_ == less || cc_ == less_equal) {
       __ Set(rax, 1);
     } else {
       __ Set(rax, -1);
     }
-    __ ret(2 * kPointerSize);  // rax, rdx were pushed
+    __ ret(0);
 
     // The number comparison code did not provide a valid result.
     __ bind(&non_number_comparison);
   }
 
   // Fast negative check for symbol-to-symbol equality.
   Label check_for_strings;
   if (cc_ == equal) {
     BranchIfNonSymbol(masm, &check_for_strings, rax, kScratchRegister);
     BranchIfNonSymbol(masm, &check_for_strings, rdx, kScratchRegister);
 
     // We've already checked for object identity, so if both operands
     // are symbols they aren't equal. Register eax (not rax) already holds a
     // non-zero value, which indicates not equal, so just return.
-    __ ret(2 * kPointerSize);
+    __ ret(0);
   }
 
   __ bind(&check_for_strings);
 
   __ JumpIfNotBothSequentialAsciiStrings(
       rdx, rax, rcx, rbx, &check_unequal_objects);
 
   // Inline comparison of ascii strings.
   StringCompareStub::GenerateCompareFlatAsciiStrings(masm,
                                                      rdx,
@@ skipping 30 matching lines @@
     __ j(zero, &return_unequal);
     __ testb(FieldOperand(rcx, Map::kBitFieldOffset),
              Immediate(1 << Map::kIsUndetectable));
     __ j(zero, &return_unequal);
     // The objects are both undetectable, so they both compare as the value
     // undefined, and are equal.
     __ Set(rax, EQUAL);
     __ bind(&return_unequal);
     // Return non-equal by returning the non-zero object pointer in eax,
     // or return equal if we fell through to here.
-    __ ret(2 * kPointerSize);  // rax, rdx were pushed
+    __ ret(0);
     __ bind(&not_both_objects);
   }
 
-  // must swap argument order
+  // Push arguments below the return address to prepare jump to builtin.
   __ pop(rcx);
-  __ pop(rdx);
-  __ pop(rax);
   __ push(rdx);
   __ push(rax);
 
   // Figure out which native to call and setup the arguments.
   Builtins::JavaScript builtin;
   if (cc_ == equal) {
     builtin = strict_ ? Builtins::STRICT_EQUALS : Builtins::EQUALS;
   } else {
     builtin = Builtins::COMPARE;
     __ Push(Smi::FromInt(NegativeComparisonResult(cc_)));
@@ skipping 1556 matching lines @@
     __ j(not_equal, &loop);
   }
   // Completed loop without finding different characters.
   // Compare lengths (precomputed).
   __ bind(&compare_lengths);
   __ SmiTest(length_difference);
   __ j(not_zero, &result_not_equal);
 
   // Result is EQUAL.
   __ Move(rax, Smi::FromInt(EQUAL));
-  __ ret(2 * kPointerSize);
+  __ ret(0);
 
   Label result_greater;
   __ bind(&result_not_equal);
   // Unequal comparison of left to right, either character or length.
   __ j(greater, &result_greater);
 
   // Result is LESS.
   __ Move(rax, Smi::FromInt(LESS));
-  __ ret(2 * kPointerSize);
+  __ ret(0);
 
   // Result is GREATER.
   __ bind(&result_greater);
   __ Move(rax, Smi::FromInt(GREATER));
-  __ ret(2 * kPointerSize);
+  __ ret(0);
 }
 
 
 void StringCompareStub::Generate(MacroAssembler* masm) {
   Label runtime;
 
   // Stack frame on entry.
   //  rsp[0]: return address
   //  rsp[8]: right string
   //  rsp[16]: left string
 
   __ movq(rdx, Operand(rsp, 2 * kPointerSize));  // left
   __ movq(rax, Operand(rsp, 1 * kPointerSize));  // right
 
   // Check for identity.
   Label not_same;
   __ cmpq(rdx, rax);
   __ j(not_equal, &not_same);
   __ Move(rax, Smi::FromInt(EQUAL));
   __ IncrementCounter(&Counters::string_compare_native, 1);
   __ ret(2 * kPointerSize);
 
   __ bind(&not_same);
 
   // Check that both are sequential ASCII strings.
   __ JumpIfNotBothSequentialAsciiStrings(rdx, rax, rcx, rbx, &runtime);
 
   // Inline comparison of ascii strings.
   __ IncrementCounter(&Counters::string_compare_native, 1);
+  // Drop arguments from the stack
+  __ pop(rcx);
+  __ addq(rsp, Immediate(2 * kPointerSize));
+  __ push(rcx);
   GenerateCompareFlatAsciiStrings(masm, rdx, rax, rcx, rbx, rdi, r8);
 
   // Call the runtime; it returns -1 (less), 0 (equal), or 1 (greater)
   // tagged as a small integer.
   __ bind(&runtime);
   __ TailCallRuntime(Runtime::kStringCompare, 2, 1);
 }
 
 #undef __
 
@@ skipping 92 matching lines @@
 #undef __
 
 void RecordWriteStub::Generate(MacroAssembler* masm) {
   masm->RecordWriteHelper(object_, addr_, scratch_);
   masm->ret(0);
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64