X64: Abstract indexing by a smi to the macro assembler.

src/x64/stub-cache-x64.cc

 // Copyright 2009 the V8 project authors. All rights reserved.
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@@ skipping 33 matching lines @@
 
 static void ProbeTable(MacroAssembler* masm,
                        Code::Flags flags,
                        StubCache::Table table,
                        Register name,
                        Register offset) {
   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, offset, times_4, 0));
+  __ cmpl(name, Operand(kScratchRegister, index.reg, index.scale, 0));

[William Hesse, 2009/09/15 10:12:09]

Document that offset must be zero-extended in the calling context of ProbeTable,
or fix it here.

[Lasse Reichstein, 2009/09/15 10:39:08]

Fixed in SmiToIndex instead. 
I'll document that offset must be a positive smi.

   __ j(not_equal, &miss);
   // Get the code entry from the cache.
   // Use key_offset + kPointerSize, rather than loading value_offset.
   __ movq(kScratchRegister,
-          Operand(kScratchRegister, offset, times_4, kPointerSize));
+          Operand(kScratchRegister, index.reg, index.scale, 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 1777 matching lines @@
   __ Jump(generic_construct_stub, RelocInfo::CODE_TARGET);
 
   // Return the generated code.
   return GetCode();
 }
 
 
 #undef __
 
 } }  // namespace v8::internal