[Subzero][MIPS32] Implements lowering of alloca instruction

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 71 matching lines @@
   RegNumT getStackReg() const override { return RegMIPS32::Reg_SP; }
   RegNumT getFrameReg() const override { return RegMIPS32::Reg_FP; }
   RegNumT getFrameOrStackReg() const override {
     return UsesFramePointer ? getFrameReg() : getStackReg();
   }
   size_t typeWidthInBytesOnStack(Type Ty) const override {
     // Round up to the next multiple of 4 bytes. In particular, i1, i8, and i16
     // are rounded up to 4 bytes.
     return (typeWidthInBytes(Ty) + 3) & ~3;
   }
-  uint32_t getStackAlignment() const override {
-    // TODO(sehr): what is the stack alignment?
-    return 1;
-  }
+  uint32_t getStackAlignment() const override;
   void reserveFixedAllocaArea(size_t Size, size_t Align) override {
-    // TODO(sehr): Implement fixed stack layout.
-    (void)Size;
-    (void)Align;
-    llvm::report_fatal_error("Not yet implemented");
+    FixedAllocaSizeBytes = Size;
+    assert(llvm::isPowerOf2_32(Align));
+    FixedAllocaAlignBytes = Align;
+    PrologEmitsFixedAllocas = true;
   }
   int32_t getFrameFixedAllocaOffset() const override {
     // TODO(sehr): Implement fixed stack layout.
     llvm::report_fatal_error("Not yet implemented");
     return 0;
   }
 
+  uint32_t maxOutArgsSizeBytes() const override { return MaxOutArgsSizeBytes; }
+
   bool shouldSplitToVariable64On32(Type Ty) const override {
     return Ty == IceType_i64;
   }
 
   // TODO(ascull): what is the best size of MIPS?
   SizeT getMinJumpTableSize() const override { return 3; }
   void emitJumpTable(const Cfg *Func,
                      const InstJumpTable *JumpTable) const override;
 
   void emitVariable(const Variable *Var) const override;
@@ skipping 322 matching lines @@
     return getPhysicalRegister(RegMIPS32::Reg_ZERO, IceType_i32);
   }
 
   Variable *I32Reg(RegNumT RegNum = RegNumT()) {
     return makeReg(IceType_i32, RegNum);
   }
 
   static Type stackSlotType();
   Variable *copyToReg(Operand *Src, RegNumT RegNum = RegNumT());
 
+  void unsetIfNonLeafFunc();
+
   // Iterates over the CFG and determines the maximum outgoing stack arguments
   // bytes. This information is later used during addProlog() to pre-allocate
   // the outargs area
   void findMaxStackOutArgsSize();
 
   void addProlog(CfgNode *Node) override;
   void addEpilog(CfgNode *Node) override;
 
   // Ensure that a 64-bit Variable has been split into 2 32-bit
   // Variables, creating them if necessary.  This is needed for all
@@ skipping 96 matching lines @@
   uint32_t MaxOutArgsSizeBytes = 0;
   static SmallBitVector TypeToRegisterSet[RCMIPS32_NUM];
   static SmallBitVector TypeToRegisterSetUnfiltered[RCMIPS32_NUM];
   static SmallBitVector RegisterAliases[RegMIPS32::Reg_NUM];
   SmallBitVector RegsUsed;
   VarList PhysicalRegisters[IceType_NUM];
   VarList PreservedGPRs;
   static constexpr uint32_t CHAR_BITS = 8;
   static constexpr uint32_t INT32_BITS = 32;
   size_t SpillAreaSizeBytes = 0;
+  size_t FixedAllocaSizeBytes = 0;
+  size_t FixedAllocaAlignBytes = 0;
 
 private:
   ENABLE_MAKE_UNIQUE;
 
   class ComputationTracker {
   public:
     ComputationTracker() = default;
     ~ComputationTracker() = default;
 
     void forgetProducers() { KnownComputations.clear(); }
@@ skipping 91 matching lines @@
   explicit TargetHeaderMIPS32(GlobalContext *Ctx);
 
 private:
   ~TargetHeaderMIPS32() = default;
 };
 
 } // end of namespace MIPS32
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGMIPS32_H