[x64] Smi zero can be used as an immediate.

src/compiler/x64/code-generator-x64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/code-generator.h"
 
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
 #include "src/scopes.h"
@@ skipping 20 matching lines @@
     return ToImmediate(instr_->InputAt(index));
   }
 
   Operand InputOperand(size_t index, int extra = 0) {
     return ToOperand(instr_->InputAt(index), extra);
   }
 
   Operand OutputOperand() { return ToOperand(instr_->Output()); }
 
   Immediate ToImmediate(InstructionOperand* operand) {
-    return Immediate(ToConstant(operand).ToInt32());
+    Constant constant = ToConstant(operand);
+    if (constant.type() == Constant::kFloat64) {
+      DCHECK_EQ(0, bit_cast<int64_t>(constant.ToFloat64()));
+      return Immediate(0);
+    }
+    return Immediate(constant.ToInt32());
   }
 
   Operand ToOperand(InstructionOperand* op, int extra = 0) {
     DCHECK(op->IsStackSlot() || op->IsDoubleStackSlot());
     // The linkage computes where all spill slots are located.
     FrameOffset offset = linkage()->GetFrameOffset(
         AllocatedOperand::cast(op)->index(), frame(), extra);
     return Operand(offset.from_stack_pointer() ? rsp : rbp, offset.offset());
   }
 
@@ skipping 1653 matching lines @@
     }
   }
   MarkLazyDeoptSite();
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace compiler
 }  // namespace v8