MIPS: Implement sqrt in inline assembly.

src/mips/codegen-mips.cc

Index: src/mips/codegen-mips.cc
diff --git a/src/mips/codegen-mips.cc b/src/mips/codegen-mips.cc
index 7a207120a23d020c958855588ac084532d3b7bee..f28634a310f725999ef4e0c93a600af5ba1d0b8c 100644
--- a/src/mips/codegen-mips.cc
+++ b/src/mips/codegen-mips.cc
@@ -525,13 +525,33 @@ OS::MemCopyUint8Function CreateMemCopyUint8Function(
 }
 #endif
 
-#undef __
+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));
 
-UnaryMathFunction CreateSqrtFunction() {
-  return &sqrt;
+  __ 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 __
+
 
 // -------------------------------------------------------------------------
 // Platform-specific RuntimeCallHelper functions.