Refactor current VisaRegalloc and corresponding CisaBuilder-calls

* VisaRegalloc::getSigned must be constant
* VisaRegalloc::getRegForValue method not really needed

Author: igorban-intel

IGC/VectorCompiler/lib/GenXCodeGen/GenXCisaBuilder.cpp

@@ -4248,8 +4248,8 @@ GenXKernelBuilder::getRegForValueOrNullAndSaveAlias(Args &&... args) {
  */
 template <typename... Args>
 GenXKernelBuilder::Register *
-GenXKernelBuilder::getRegForValueAndSaveAlias(Args &&... args) {
-  Register *R = RegAlloc->getRegForValue(std::forward<Args>(args)...);
+GenXKernelBuilder::getRegForValueAndSaveAlias(Args &&...args) {
+  Register *R = RegAlloc->getOrCreateRegForValue(std::forward<Args>(args)...);
   SimpleValue SV = std::get<0>(std::make_tuple(args...));
   IGC_ASSERT_MESSAGE(R, "getRegForValue must return non-nullptr register");
   LastUsedAliasMap[SV.getValue()] = R;

IGC/VectorCompiler/lib/GenXCodeGen/GenXVisaRegAlloc.cpp

@@ -792,8 +792,7 @@ GenXVisaRegAlloc::getOrCreateRegForValue(SimpleValue V, Signedness Signed,
  * different signedness between source and destination can make the jitter
  * generate less efficient code.
  */
-genx::Signedness GenXVisaRegAlloc::getSigned(Reg* R)
-{
+genx::Signedness GenXVisaRegAlloc::getSigned(const Reg *R) const {
   return (R && R->Category == vc::RegCategory::General) ? R->Signed
                                                         : DONTCARESIGNED;
 }

IGC/VectorCompiler/lib/GenXCodeGen/GenXVisaRegAlloc.h

@@ -186,14 +186,6 @@ namespace llvm {
     std::list<Reg>& getRegStorage() {
       return RegStorage;
     }
-    // Get the vISA virtual register for a value (assertion failure if none).
-    Reg *getRegForValue(genx::SimpleValue V,
-                        genx::Signedness Signed = genx::DONTCARESIGNED,
-                        Type *OverrideType = nullptr, bool IsBF = false) {
-      Reg *R = getOrCreateRegForValue(V, Signed, OverrideType, IsBF);
-      IGC_ASSERT_MESSAGE(R, "no register allocated for this value");
-      return R;
-    }
     // Get the vISA virtual register for a value or nullptr if there is no
     // register associated with given value.
     Reg *getRegForValueOrNull(genx::SimpleValue V,
@@ -213,7 +205,7 @@ namespace llvm {
     Reg *getRegForValueUntyped(genx::SimpleValue V) const;
 
     // Get the signedness of a register.
-    genx::Signedness getSigned(Reg* R);
+    genx::Signedness getSigned(const Reg *R) const;
 
     // Set callback that will be called each time new register is created.
     // It is used in CisaBuilder when new aliases are created.