[SubZero] lower float and double constants for MIPS

src/IceTargetLoweringMIPS32.h

 //===- subzero/src/IceTargetLoweringMIPS32.h - MIPS32 lowering ---*- C++-*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 17 matching lines @@
 class TargetMIPS32 : public TargetLowering {
   TargetMIPS32() = delete;
   TargetMIPS32(const TargetMIPS32 &) = delete;
   TargetMIPS32 &operator=(const TargetMIPS32 &) = delete;
 
 public:
   ~TargetMIPS32() override = default;
 
   static void staticInit(GlobalContext *Ctx);
   static bool shouldBePooled(const Constant *C) {
-    if (auto *ConstDouble = llvm::dyn_cast<ConstantDouble>(C)) {
-      return !Utils::isPositiveZero(ConstDouble->getValue());

[Jim Stichnoth, 2016/09/19 20:50:14]

Question about this change.

Both ARM and x86 have idioms for loading a +0.0 pattern into a floating-point
register without requiring a memory load, usually something involving an xor
instruction.

Does MIPS32 have something similar?

If not, then this change is fine.

[jaydeep.patil, 2016/09/20 07:28:27]

Yes, for float/double constant 0 we can use mtc1 $zero.

-    }
+    if (llvm::isa<ConstantDouble>(C))
+      return true;
     if (llvm::isa<ConstantFloat>(C))
       return true;
     return false;
   }
   static std::unique_ptr<::Ice::TargetLowering> create(Cfg *Func) {
     return makeUnique<TargetMIPS32>(Func);
   }
 
   std::unique_ptr<::Ice::Assembler> createAssembler() const override {
     return makeUnique<MIPS32::AssemblerMIPS32>();
@@ skipping 766 matching lines @@
   void lowerGlobals(const VariableDeclarationList &Vars,
                     const std::string &SectionSuffix) override;
   void lowerConstants() override;
   void lowerJumpTables() override;
 
 protected:
   explicit TargetDataMIPS32(GlobalContext *Ctx);
 
 private:
   ~TargetDataMIPS32() override = default;
-  template <typename T> static void emitConstantPool(GlobalContext *Ctx);
 };
 
 class TargetHeaderMIPS32 final : public TargetHeaderLowering {
   TargetHeaderMIPS32() = delete;
   TargetHeaderMIPS32(const TargetHeaderMIPS32 &) = delete;
   TargetHeaderMIPS32 &operator=(const TargetHeaderMIPS32 &) = delete;
 
 public:
   static std::unique_ptr<TargetHeaderLowering> create(GlobalContext *Ctx) {
     return std::unique_ptr<TargetHeaderLowering>(new TargetHeaderMIPS32(Ctx));
   }
 
   void lower() override;
 
 protected:
   explicit TargetHeaderMIPS32(GlobalContext *Ctx);
 
 private:
   ~TargetHeaderMIPS32() = default;
 };
 
 } // end of namespace MIPS32
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGMIPS32_H