[Subzero][MIPS32] Fix alloca alignment and offset for Om1 and O2 optimization

src/IceTargetLoweringMIPS32.h

Index: src/IceTargetLoweringMIPS32.h
diff --git a/src/IceTargetLoweringMIPS32.h b/src/IceTargetLoweringMIPS32.h
index 842f266e2be730aced312e48437e56d3910393bb..664f6b126096dbe7500873a0149e24018d086c7e 100644
--- a/src/IceTargetLoweringMIPS32.h
+++ b/src/IceTargetLoweringMIPS32.h
@@ -103,7 +103,9 @@ public:
     PrologEmitsFixedAllocas = true;
   }
   int32_t getFrameFixedAllocaOffset() const override {
-    return FixedAllocaSizeBytes - (SpillAreaSizeBytes - MaxOutArgsSizeBytes);
+    int32_t FixedAllocaOffset =
+        Utils::applyAlignment(CurrentAllocaOffset, FixedAllocaAlignBytes);
+    return FixedAllocaOffset - MaxOutArgsSizeBytes;
   }
 
   uint32_t maxOutArgsSizeBytes() const override { return MaxOutArgsSizeBytes; }
@@ -700,10 +702,7 @@ protected:
   void lowerSwitch(const InstSwitch *Instr) override;
   void lowerUnreachable(const InstUnreachable *Instr) override;
   void prelowerPhis() override;
-  uint32_t getCallStackArgumentsSizeBytes(const InstCall *Instr) override {
-    (void)Instr;
-    return 0;
-  }
+  uint32_t getCallStackArgumentsSizeBytes(const InstCall *Instr) override;
   void genTargetHelperCallFor(Inst *Instr) override;
   void doAddressOptLoad() override;
   void doAddressOptStore() override;
@@ -749,6 +748,7 @@ protected:
   bool VariableAllocaUsed = false;
   uint32_t MaxOutArgsSizeBytes = 0;
   uint32_t TotalStackSizeBytes = 0;
+  uint32_t CurrentAllocaOffset = 0;
   static SmallBitVector TypeToRegisterSet[RCMIPS32_NUM];
   static SmallBitVector TypeToRegisterSetUnfiltered[RCMIPS32_NUM];
   static SmallBitVector RegisterAliases[RegMIPS32::Reg_NUM];