X64 Implementation: Implement floating-point compare

src/x64/macro-assembler-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
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 //       disclaimer in the documentation and/or other materials provided
@@ skipping 402 matching lines @@
   // Link this handler.
   movq(Operand(kScratchRegister, 0), rsp);
 }
 
 
 void MacroAssembler::Ret() {
   ret(0);
 }
 
 
+void MacroAssembler::FCmp() {
+  fcompp();
+  push(rax);
+  fnstsw_ax();
+  sahf();

[Lasse Reichstein, 2009/06/26 09:41:04]

Add comment that sahf isn't safe to use. 
We should add something to CpuProbe to test its availability, and find an
alternative if it doesn't exist.

[William Hesse, 2009/06/26 19:45:59]

Done.

+  pop(rax);
+}
+
+
 void MacroAssembler::CmpObjectType(Register heap_object,
                                    InstanceType type,
                                    Register map) {
   movq(map, FieldOperand(heap_object, HeapObject::kMapOffset));
   CmpInstanceType(map, type);
 }
 
 
 void MacroAssembler::CmpInstanceType(Register map, InstanceType type) {
   cmpb(FieldOperand(map, Map::kInstanceTypeOffset),
@@ skipping 397 matching lines @@
   push(rcx);
 
   // Clear the top frame.
   ExternalReference c_entry_fp_address(Top::k_c_entry_fp_address);
   movq(kScratchRegister, c_entry_fp_address);
   movq(Operand(kScratchRegister, 0), Immediate(0));
 }
 
 
 } }  // namespace v8::internal