[Subzero][MIPS32] Adds prolog instructions for MIPS32

src/IceInstMIPS32.def

@@ -101,7 +101,7 @@
     ALIASES1(Reg_SP))                                                          \
   X(Reg_FP,       30,  "fp",    0, 0, 0, 1, 0, 0, 0, 0, 0,                     \
     ALIASES1(Reg_FP))                                                          \
-  X(Reg_RA,       31,  "ra",    0, 1, 0, 0, 0, 0, 0, 0, 0,                     \
+  X(Reg_RA,       31,  "ra",    0, 0, 0, 0, 0, 0, 0, 0, 0,                     \
     ALIASES1(Reg_RA))                                                          \
   X(Reg_LO,       0,   "lo",    0, 0, 0, 0, 0, 0, 0, 0, 0,                     \
     ALIASES2(Reg_LO, Reg_LOHI))                                                \

src/IceTargetLoweringMIPS32.h

@@ -447,6 +447,11 @@ public:
   static Type stackSlotType();
   Variable *copyToReg(Operand *Src, RegNumT RegNum = RegNumT());
 
+  // 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;
 
@@ -457,6 +462,9 @@ public:
   Operand *loOperand(Operand *Operand);
   Operand *hiOperand(Operand *Operand);
 
+  void finishArgumentLowering(Variable *Arg, Variable *FramePtr,
+                              size_t BasicFrameOffset, size_t *InArgsSizeBytes);
+
   Operand *legalizeUndef(Operand *From, RegNumT RegNum = RegNumT());
 
   /// Helper class that understands the Calling Convention and register
@@ -543,13 +551,18 @@ protected:
 
   bool UsesFramePointer = false;
   bool NeedsStackAlignment = false;
+  bool MaybeLeafFunc = true;
+  bool PrologEmitsFixedAllocas = false;
+  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;
 
 private:
   ENABLE_MAKE_UNIQUE;

tests_lit/llvm2ice_tests/uncond_br.ll

@@ -23,8 +23,8 @@ target:
 }
 
 ; MIPS32-LABEL: uncond1
-; MIPS32:   b  {{[0-9]+}} <.Luncond1$target>
+; MIPS32:   b  {{[0-9a-f]+}} <.Luncond1$target>
 ; MIPS32: <.Luncond1$target>:
 ; MIPS32: li
 ; MIPS32: addu
-; MIPS32: b {{[0-9]+}} <.Luncond1$target>
+; MIPS32: b {{[0-9a-f]+}} <.Luncond1$target>