MIPS: Implement sqrt in inline assembly.

src/mips/codegen-mips.cc

 // Copyright 2012 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 507 matching lines @@
   masm.GetCode(&desc);
   ASSERT(!RelocInfo::RequiresRelocation(desc));
 
   CPU::FlushICache(buffer, actual_size);
   OS::ProtectCode(buffer, actual_size);
   return FUNCTION_CAST<OS::MemCopyUint8Function>(buffer);
 #endif
 }
 #endif
 
+UnaryMathFunction CreateSqrtFunction() {
+#if defined(USE_SIMULATOR)
+  return &std::sqrt;
+#else
+  size_t actual_size;
+  byte* buffer = static_cast<byte*>(OS::Allocate(1 * KB, &actual_size, true));
+  if (buffer == NULL) return &std::sqrt;
+
+  MacroAssembler masm(NULL, buffer, static_cast<int>(actual_size));
+
+  __ SetCallCDoubleArguments(f12);

[Paul Lind, 2014/01/09 17:46:45]

This is incorrect. For the hard float case it works, since the ABI will pass the
param in f12. But for the SoftFloatABI case, we need to move from a0, a1 (GPR
pair) to f12. 

This function does the opposite since it is meant to prepare for Calling a C
function, and this code is being called FROM a C function with the soft-float
ABI. The ARM code just swapped Result and Arguments calls, since they are
symmetric. But on MIPS, they are not symmetric, so we either need to just code
this inline here, or generate a couple new helper functions. A possible name
might be GetFromCDoubleArguments(). 

[kilvadyb, 2014/01/09 18:46:09]

Done.

+  __ sqrt_d(f0, f12);
+  __ GetCFunctionDoubleResult(f0);

[Paul Lind, 2014/01/09 17:46:45]

As above, in SoftFloatABI mode this also does the wrong move for C code calling
this routine, we need to move from f0 to v0,v1 GPR pair. Maybe
SetForCDoubleResult() for the new helper routine? Better names are welcome!

[kilvadyb, 2014/01/09 18:46:09]

Done.

+  __ Ret();
+
+  CodeDesc desc;
+  masm.GetCode(&desc);
+  ASSERT(!RelocInfo::RequiresRelocation(desc));
+
+  CPU::FlushICache(buffer, actual_size);
+  OS::ProtectCode(buffer, actual_size);
+  return FUNCTION_CAST<UnaryMathFunction>(buffer);
+#endif
+}
+
 #undef __
 
 
-UnaryMathFunction CreateSqrtFunction() {
-  return &sqrt;
-}
-
-
 // -------------------------------------------------------------------------
 // Platform-specific RuntimeCallHelper functions.
 
 void StubRuntimeCallHelper::BeforeCall(MacroAssembler* masm) const {
   masm->EnterFrame(StackFrame::INTERNAL);
   ASSERT(!masm->has_frame());
   masm->set_has_frame(true);
 }
 
 
@@ skipping 543 matching lines @@
     patcher.masm()->nop();  // Pad the empty space.
   }
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_MIPS