X64 tweaks.

src/x64/macro-assembler-x64.cc

 // Copyright 2011 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 1230 matching lines @@
     }
   }
 }
 
 
 void MacroAssembler::SmiAdd(Register dst,
                             Register src1,
                             Register src2) {
   // No overflow checking. Use only when it's known that
   // overflowing is impossible.
-  ASSERT(!dst.is(src2));
   if (!dst.is(src1)) {
-    movq(dst, src1);
+    if (emit_debug_code()) {
+      movq(kScratchRegister, src1);
+      addq(kScratchRegister, src2);
+      Check(no_overflow, "Smi addition overflow");
+    }
+    lea(dst, Operand(src1, src2, times_1, 0));
+  } else {
+    addq(dst, src2);
+    Assert(no_overflow, "Smi addition overflow");
   }
-  addq(dst, src2);
-  Assert(no_overflow, "Smi addition overflow");
 }
 
 
 void MacroAssembler::SmiSub(Register dst, Register src1, Register src2) {
   // No overflow checking. Use only when it's known that
   // overflowing is impossible (e.g., subtracting two positive smis).
   ASSERT(!dst.is(src2));
   if (!dst.is(src1)) {
     movq(dst, src1);
   }
@@ skipping 1638 matching lines @@
   CPU::FlushICache(address_, size_);
 
   // Check that the code was patched as expected.
   ASSERT(masm_.pc_ == address_ + size_);
   ASSERT(masm_.reloc_info_writer.pos() == address_ + size_ + Assembler::kGap);
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64