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..aaf9d6421c05ce7fd6bb0877810c7642b2de70ca 100644
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -2286,7 +2286,11 @@ void FullCodeGenerator::EmitInlineSmiBinaryOp(BinaryOperation* expr,
       __ SmiShiftArithmeticRight(rax, rdx, rcx);
       break;
     case Token::SHL:
+#if !V8_USE_31_BITS_SMI_VALUE
       __ SmiShiftLeft(rax, rdx, rcx);
+#else
+      __ SmiShiftLeft(rax, rdx, rcx, &stub_call);
+#endif
       break;
     case Token::SHR:
       __ SmiShiftLogicalRight(rax, rdx, rcx, &stub_call);
@@ -4454,10 +4458,20 @@ void FullCodeGenerator::VisitCountOperation(CountOperation* expr) {
   if (ShouldInlineSmiCase(expr->op())) {
     if (expr->op() == Token::INC) {
       __ SmiAddConstant(rax, rax, Smi::FromInt(1));
+#if V8_USE_31_BITS_SMI_VALUE
+      __ testl(rax, Immediate(0x80000000));
+      __ j(not_zero, &stub_call, Label::kNear);
+#endif
     } else {
       __ SmiSubConstant(rax, rax, Smi::FromInt(1));
+#if V8_USE_31_BITS_SMI_VALUE
+      __ testl(rax, Immediate(0x80000000));
+      __ j(zero, &stub_call, Label::kNear);
+#endif
     }
+#if !V8_USE_31_BITS_SMI_VALUE
     __ j(overflow, &stub_call, Label::kNear);
+#endif
     // 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);