Minor fixes and refactors

This commit aims to make minor refactors throughout the codebase to help
with code maintenance.

Author: smilczek

visa/SpillManagerGMRF.h

@@ -601,7 +601,7 @@ class SpillManagerGRF {
   unsigned latestImplicitVarIdCount_;
   const LivenessAnalysis *lvInfo_;
   const LiveRangeVec *lrInfo_;
-  const LR_LIST *spilledLRs_;
+  const LR_LIST *spilledLRs_ = nullptr;
   LSLR_LIST *spilledLSLRs_;
   unsigned spillRangeCount_ = 0;
   unsigned fillRangeCount_ = 0;
@@ -615,21 +615,20 @@ class SpillManagerGRF {
   bool doSpillSpaceCompression;
 
   bool failSafeSpill_;
-  unsigned spillRegStart_;
-  unsigned indrSpillRegStart_;
-  unsigned spillRegOffset_;
+  unsigned spillRegStart_ = 0;
+  unsigned indrSpillRegStart_ = 0;
+  unsigned spillRegOffset_ = 0;
   LSLR_LIST activeLR_;
   std::unordered_set<G4_DstRegRegion *> noRMWNeeded;
 
-  const Interference *spillIntf_;
+  const Interference *spillIntf_ = nullptr;
 
   // CISA instruction id of current instruction
   G4_INST *curInst;
 
   int globalScratchOffset;
 
   const bool useScratchMsg_;
-  bool avoidDstSrcOverlap_;
   // spilled declares that represent a scalar immediate (created due to encoding
   // restrictions) We rematerialize the immediate value instead of spill/fill
   // them. Map stores type used on dst that defined the immediate.

visa/iga/IGALibrary/Backend/Messages/MessageDecoder.hpp

@@ -229,11 +229,11 @@ struct MessageDecoder {
   ///////////////////////////////////////////////////////////////////////////
   // the most generic setter
   void
-  setScatterGatherOpX(std::string msgSym, std::string msgImpl, SendOp op,
-                      AddrType addrType, SendDesc surfaceId, CacheOpt l1,
-                      CacheOpt l3, int addrSize, int bitsPerElemReg,
+  setScatterGatherOpX(const std::string& msgSym, const std::string& msgImpl, const SendOp& op,
+                      const AddrType& addrType, const SendDesc& surfaceId, const CacheOpt& l1,
+                      const CacheOpt& l3, int addrSize, int bitsPerElemReg,
                       int bitsPerElemMem, int elemsPerAddr, int simd,
-                      MessageInfo::Attr extraAttrs = MessageInfo::Attr::NONE) {
+                      const MessageInfo::Attr& extraAttrs = MessageInfo::Attr::NONE) {
     MessageInfo &mi = result.info;
     mi.symbol = msgSym;
     mi.description = msgImpl;

visa/iga/IGALibrary/Backend/Native/Field.hpp

@@ -278,7 +278,7 @@ static inline bool IsDst(OpIx IX) {
 }
 static inline int ToSrcIndex(OpIx IX) {
   IGA_ASSERT(!IsDst(IX), "ToSrcIndex(OpIx) on dst index");
-  return ((IX & 0xF0) >> 4) - 1;
+  return ((IX & 0x30) >> 4) - 1;
 }
 static inline int ToFieldOperandArrayIndex(OpIx IX) {
   return (IX & OpIx::OP_IX_MASK);