X64: Convert smis to holding 32 bits of payload.

src/x64/stub-cache-x64.cc

 // Copyright 2009 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 29 matching lines @@
 // StubCompiler static helper functions
 
 #define __ ACCESS_MASM(masm)
 
 
 static void ProbeTable(MacroAssembler* masm,
                        Code::Flags flags,
                        StubCache::Table table,
                        Register name,
                        Register offset) {
-  // The offset register must hold a *positive* smi.
+  ASSERT_EQ(8, kPointerSize);
+  ASSERT_EQ(16, sizeof(StubCache::Entry));
+  // The offset register holds the entry offset times four (due to masking
+  // and shifting optimizations).
   ExternalReference key_offset(SCTableReference::keyReference(table));
   Label miss;
 
   __ movq(kScratchRegister, key_offset);
-  SmiIndex index = masm->SmiToIndex(offset, offset, kPointerSizeLog2);
   // Check that the key in the entry matches the name.
-  __ cmpl(name, Operand(kScratchRegister, index.reg, index.scale, 0));
+  // Multiply entry offset by 16 to get the entry address. Since the
+  // offset register already holds the entry offset times four, multiply
+  // by a further four.
+  __ cmpl(name, Operand(kScratchRegister, offset, times_4, 0));
   __ j(not_equal, &miss);
   // Get the code entry from the cache.
   // Use key_offset + kPointerSize, rather than loading value_offset.
   __ movq(kScratchRegister,
-          Operand(kScratchRegister, index.reg, index.scale, kPointerSize));
+          Operand(kScratchRegister, offset, times_4, kPointerSize));
   // Check that the flags match what we're looking for.
   __ movl(offset, FieldOperand(kScratchRegister, Code::kFlagsOffset));
   __ and_(offset, Immediate(~Code::kFlagsNotUsedInLookup));
   __ cmpl(offset, Immediate(flags));
   __ j(not_equal, &miss);
 
   // Jump to the first instruction in the code stub.
   __ addq(kScratchRegister, Immediate(Code::kHeaderSize - kHeapObjectTag));
   __ jmp(kScratchRegister);
 
@@ skipping 1778 matching lines @@
   __ Jump(generic_construct_stub, RelocInfo::CODE_TARGET);
 
   // Return the generated code.
   return GetCode();
 }
 
 
 #undef __
 
 } }  // namespace v8::internal