Several changes to Mips backend, experimental fp support being the most

important.
- Cleanup in the Subtarget info with addition of new features, not all support
  yet, but they allow the future inclusion of features easier. Among new features,
  we have : Arch family info (mips1, mips2, ...), ABI info (o32, eabi), 64-bit
  integer
  and float registers, allegrex vector FPU (VFPU), single float only support.
- TargetMachine now detects allegrex core.
- Added allegrex (Mips32r2) sext_inreg instructions.
- *Added Float Point Instructions*, handling single float only, and
  aliased accesses for 32-bit FPUs.
- Some cleanup in FP instruction formats and FP register classes.
- Calling conventions improved to support mips 32-bit EABI.
- Added Asm Printer support for fp cond codes.
- Added support for sret copy to a return register.
- EABI support added into LowerCALL and FORMAL_ARGS.
- MipsFunctionInfo now keeps a virtual register per function to track the
  sret on function entry until function ret.
- MipsInstrInfo FP support into methods (isMoveInstr, isLoadFromStackSlot, ...),
  FP cond codes mapping and initial FP Branch Analysis.
- Two new Mips SDNode to handle fp branch and compare instructions : FPBrcond,
  FPCmp
- MipsTargetLowering : handling different FP classes, Allegrex support, sret
  return copy, no homing location within EABI, non 32-bit stack objects
  arguments, and asm constraint for float.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53146 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/Mips/MipsSubtarget.cpp

@@ -14,15 +14,29 @@
 #include "MipsSubtarget.h"
 #include "Mips.h"
 #include "MipsGenSubtarget.inc"
+#include "llvm/Module.h"
 using namespace llvm;
 
 MipsSubtarget::MipsSubtarget(const TargetMachine &TM, const Module &M, 
                              const std::string &FS, bool little) : 
-  IsMipsIII(false),
-  IsLittle(little)
+  MipsArchVersion(Mips1), MipsABI(O32), IsLittle(little), IsSingleFloat(false),
+  IsFP64bit(false), IsGP64bit(false), HasAllegrexVFPU(false), IsAllegrex(false)
 {
   std::string CPU = "mips1";
 
   // Parse features string.
   ParseSubtargetFeatures(FS, CPU);
+
+  // When only the target triple is specified and is 
+  // a allegrex target, set the features. We also match
+  // big and little endian allegrex cores (dont really
+  // know if a big one exists)
+  const std::string& TT = M.getTargetTriple();
+  if (TT.find("mipsallegrex") != std::string::npos) {
+    MipsABI = EABI;
+    IsSingleFloat = true;
+    MipsArchVersion = Mips2;
+    HasAllegrexVFPU = true; // Enables Allegrex Vector FPU (not supported yet)
+    IsAllegrex = true;
+  }
 }