Some assembler-level optimizations on ARM.

src/arm/macro-assembler-arm.cc

 // Copyright 2012 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 2947 matching lines @@
 void MacroAssembler::JumpIfNotBothSmi(Register reg1,
                                       Register reg2,
                                       Label* on_not_both_smi) {
   STATIC_ASSERT(kSmiTag == 0);
   tst(reg1, Operand(kSmiTagMask));
   tst(reg2, Operand(kSmiTagMask), eq);
   b(ne, on_not_both_smi);
 }
 
 
+void MacroAssembler::UntagAndJumpIfSmi(
+    Register dst, Register src, Label* smi_case) {
+  STATIC_ASSERT(kSmiTag == 0);
+  mov(dst, Operand(src, ASR, kSmiTagSize), SetCC);
+  b(cc, smi_case);  // Shifter carry is not set for a smi.
+}
+
+
+void MacroAssembler::UntagAndJumpIfNotSmi(
+    Register dst, Register src, Label* smi_case) {

[ulan, 2012/01/27 15:24:35]

smi_case should be non_smi_case

+  STATIC_ASSERT(kSmiTag == 0);
+  mov(dst, Operand(src, ASR, kSmiTagSize), SetCC);
+  b(cs, smi_case);  // Shifter carry is set for a non-smi.
+}
+
+
 void MacroAssembler::JumpIfEitherSmi(Register reg1,
                                      Register reg2,
                                      Label* on_either_smi) {
   STATIC_ASSERT(kSmiTag == 0);
   tst(reg1, Operand(kSmiTagMask));
   tst(reg2, Operand(kSmiTagMask), ne);
   b(eq, on_either_smi);
 }
 
 
@@ skipping 726 matching lines @@
 void CodePatcher::EmitCondition(Condition cond) {
   Instr instr = Assembler::instr_at(masm_.pc_);
   instr = (instr & ~kCondMask) | cond;
   masm_.emit(instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM