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

src/ia32/codegen-ia32.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 11821 matching lines @@
     __ j(above_equal, &return_not_equal);
 
     // Check for oddballs: true, false, null, undefined.
     __ CmpInstanceType(ecx, ODDBALL_TYPE);
     __ j(equal, &return_not_equal);
 
     // Fall through to the general case.
     __ bind(&slow);
   }
 
-  // Push arguments below the return address.
-  __ pop(ecx);
-  __ push(eax);
-  __ push(edx);
-  __ push(ecx);
-
   // Generate the number comparison code.
   if (include_number_compare_) {
     Label non_number_comparison;
     Label unordered;
     if (CpuFeatures::IsSupported(SSE2)) {
       CpuFeatures::Scope use_sse2(SSE2);
       CpuFeatures::Scope use_cmov(CMOV);
 
       FloatingPointHelper::LoadSSE2Operands(masm, &non_number_comparison);
       __ ucomisd(xmm0, xmm1);
 
       // Don't base result on EFLAGS when a NaN is involved.
       __ j(parity_even, &unordered, not_taken);
       // Return a result of -1, 0, or 1, based on EFLAGS.
       __ mov(eax, 0);  // equal
       __ mov(ecx, Immediate(Smi::FromInt(1)));
       __ cmov(above, eax, Operand(ecx));
       __ mov(ecx, Immediate(Smi::FromInt(-1)));
       __ cmov(below, eax, Operand(ecx));
-      __ ret(2 * kPointerSize);
+      __ ret(0);
     } else {
       FloatingPointHelper::CheckFloatOperands(
           masm, &non_number_comparison, ebx);
       FloatingPointHelper::LoadFloatOperands(masm, ecx);
       __ FCmp();
 
       // Don't base result on EFLAGS when a NaN is involved.
       __ j(parity_even, &unordered, not_taken);
 
       Label below_label, above_label;
-      // Return a result of -1, 0, or 1, based on EFLAGS. In all cases remove
-      // two arguments from the stack as they have been pushed in preparation
-      // of a possible runtime call.
+      // Return a result of -1, 0, or 1, based on EFLAGS.
       __ j(below, &below_label, not_taken);
       __ j(above, &above_label, not_taken);
 
       __ xor_(eax, Operand(eax));
-      __ ret(2 * kPointerSize);
+      __ ret(0);
 
       __ bind(&below_label);
       __ mov(eax, Immediate(Smi::FromInt(-1)));
-      __ ret(2 * kPointerSize);
+      __ ret(0);
 
       __ bind(&above_label);
       __ mov(eax, Immediate(Smi::FromInt(1)));
-      __ ret(2 * kPointerSize);
+      __ 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) {
       __ mov(eax, Immediate(Smi::FromInt(1)));
     } else {
       __ mov(eax, Immediate(Smi::FromInt(-1)));
     }
-    __ ret(2 * kPointerSize);  // eax, edx 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, eax, ecx);
     BranchIfNonSymbol(masm, &check_for_strings, edx, ecx);
 
     // We've already checked for object identity, so if both operands
     // are symbols they aren't equal. Register eax already holds a
     // non-zero value, which indicates not equal, so just return.
-    __ ret(2 * kPointerSize);
+    __ ret(0);
   }
 
   __ bind(&check_for_strings);
 
   __ JumpIfNotBothSequentialAsciiStrings(edx, eax, ecx, ebx,
                                          &check_unequal_objects);
 
   // Inline comparison of ascii strings.
   StringCompareStub::GenerateCompareFlatAsciiStrings(masm,
                                                      edx,
@@ skipping 32 matching lines @@
     __ j(zero, &return_unequal);
     __ test_b(FieldOperand(ebx, Map::kBitFieldOffset),
               1 << Map::kIsUndetectable);
     __ j(zero, &return_unequal);
     // The objects are both undetectable, so they both compare as the value
     // undefined, and are equal.
     __ Set(eax, Immediate(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);  // rax, rdx were pushed
     __ bind(&not_both_objects);
   }
 
-  // must swap argument order
+  // Push arguments below the return address.
   __ pop(ecx);
-  __ pop(edx);
-  __ pop(eax);
   __ push(edx);
   __ push(eax);
 
   // 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(Immediate(Smi::FromInt(NegativeComparisonResult(cc_))));
@@ skipping 1556 matching lines @@
 
   // Compare lengths -  strings up to min-length are equal.
   __ bind(&compare_lengths);
   __ test(length_delta, Operand(length_delta));
   __ j(not_zero, &result_not_equal);
 
   // Result is EQUAL.
   ASSERT_EQ(0, EQUAL);
   ASSERT_EQ(0, kSmiTag);
   __ Set(eax, Immediate(Smi::FromInt(EQUAL)));
-  __ ret(2 * kPointerSize);
+  __ ret(0);
 
   __ bind(&result_not_equal);
   __ j(greater, &result_greater);
 
   // Result is LESS.
   __ Set(eax, Immediate(Smi::FromInt(LESS)));
-  __ ret(2 * kPointerSize);
+  __ ret(0);
 
   // Result is GREATER.
   __ bind(&result_greater);
   __ Set(eax, Immediate(Smi::FromInt(GREATER)));
-  __ ret(2 * kPointerSize);
+  __ ret(0);
 }
 
 
 void StringCompareStub::Generate(MacroAssembler* masm) {
   Label runtime;
 
   // Stack frame on entry.
   //  esp[0]: return address
   //  esp[4]: right string
   //  esp[8]: left string
 
   __ mov(edx, Operand(esp, 2 * kPointerSize));  // left
   __ mov(eax, Operand(esp, 1 * kPointerSize));  // right
 
   Label not_same;
   __ cmp(edx, Operand(eax));
   __ j(not_equal, &not_same);
   ASSERT_EQ(0, EQUAL);
   ASSERT_EQ(0, kSmiTag);
   __ Set(eax, Immediate(Smi::FromInt(EQUAL)));
   __ IncrementCounter(&Counters::string_compare_native, 1);
   __ ret(2 * kPointerSize);
 
   __ bind(&not_same);
 
   // Check that both objects are sequential ascii strings.
   __ JumpIfNotBothSequentialAsciiStrings(edx, eax, ecx, ebx, &runtime);
 
   // Compare flat ascii strings.
+  // Drop arguments from the stack.
+  __ pop(ecx);
+  __ add(Operand(esp), Immediate(2 * kPointerSize));
+  __ push(ecx);
   GenerateCompareFlatAsciiStrings(masm, edx, eax, ecx, ebx, edi);
 
   // 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 198 matching lines @@
   masm.GetCode(&desc);
   // Call the function from C++.
   return FUNCTION_CAST<MemCopyFunction>(buffer);
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32