Optionally use 31-bits SMI value for 64-bit system

src/x64/full-codegen-x64.cc

Index: src/x64/full-codegen-x64.cc
diff --git a/src/x64/full-codegen-x64.cc b/src/x64/full-codegen-x64.cc
index bac4e793b279bf4a86353db7024aa92352219e79..9ef38923a9418135a273e6708792be1666819d93 100644
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -2286,7 +2286,7 @@ void FullCodeGenerator::EmitInlineSmiBinaryOp(BinaryOperation* expr,
       __ SmiShiftArithmeticRight(rax, rdx, rcx);
       break;
     case Token::SHL:
-      __ SmiShiftLeft(rax, rdx, rcx);
+      __ SmiShiftLeft(rax, rdx, rcx, &stub_call);
       break;
     case Token::SHR:
       __ SmiShiftLogicalRight(rax, rdx, rcx, &stub_call);
@@ -4454,10 +4454,22 @@ void FullCodeGenerator::VisitCountOperation(CountOperation* expr) {
   if (ShouldInlineSmiCase(expr->op())) {
     if (expr->op() == Token::INC) {
       __ SmiAddConstant(rax, rax, Smi::FromInt(1));

[danno, 2013/08/01 16:45:41]

Handle the overflow case inside the macro assembler, passing the stub-call label
always

[haitao.feng, 2013/08/02 09:35:51]

I am OK to change this but this might affect performance. For the SmiAddConstant
with overflow checking, we will movq(kScratchRegister, rax);
add(kScratchRegister, LoadSmiRegister(1)); j(overflow, fail, near_jump);
movq(rax, kScratchRegister). We need 4 instructions in the normal case than 2
(add, check overflow) inside a loop.

+      if (kSmiValueSize == 31) {
+        // positive overflow
+        __ testl(rax, Immediate(0x80000000));
+        __ j(not_zero, &stub_call, Label::kNear);
+      }
     } else {
       __ SmiSubConstant(rax, rax, Smi::FromInt(1));
+      if (kSmiValueSize == 31) {
+        // negative overflow
+        __ testl(rax, Immediate(0x80000000));
+        __ j(zero, &stub_call, Label::kNear);
+      }
+    }
+    if (kSmiValueSize == 32) {
+      __ j(overflow, &stub_call, Label::kNear);
     }
-    __ j(overflow, &stub_call, Label::kNear);
     // We could eliminate this smi check if we split the code at
     // the first smi check before calling ToNumber.
     patch_site.EmitJumpIfSmi(rax, &done, Label::kNear);