[Autobackout][FuncReg]Revert of change: 65480d4

 Introduce surface commoning

.

Author: KorovinVlad

IGC/VectorCompiler/lib/GenXCodeGen/GenXCategory.cpp

@@ -201,7 +201,6 @@ namespace {
   private:
     using ConvListT = std::array<llvm::Instruction *, vc::numRegCategories()>;
 
-    bool commonUpSurface(BasicBlock *BB);
     bool processFunction(Function *F);
     bool fixCircularPhis(Function *F);
     bool processValue(Value *V);
@@ -506,50 +505,6 @@ static bool commonUpPredicate(BasicBlock *BB) {
   return Changed;
 }
 
-/***********************************************************************
- * isToSurfaceConversion : returns true if the input instruction is a
- * surface conversion intrinsic.
- */
-static bool isToSurfaceConversion(Instruction *I,
-                                  const GenXLiveness *Liveness) {
-  if (IntrinsicInst *IC = dyn_cast<IntrinsicInst>(I)) {
-    unsigned IntrinsicID = vc::getAnyIntrinsicID(IC);
-    if (IntrinsicID != GenXIntrinsic::genx_convert)
-      return false;
-    if (auto LR = Liveness->getLiveRangeOrNull(I)) {
-      auto Cat = LR->getCategory();
-      if (Cat == vc::RegCategory::Surface)
-        return true;
-    }
-  }
-  return false;
-}
-
-/***********************************************************************
- * commonUpSurface : perform surface commoning to reduce number of
- * instructions to stop the surface conversion falling outside of the
- * register into which it points to avoid going out of spec (256). The
- * logic is applied within a basic block to avoid dramatic live ranges
- * increase.
- */
-bool GenXCategory::commonUpSurface(BasicBlock *BB) {
-  bool Modified = false;
-  // Maps the original value to after-conversion value.
-  SmallDenseMap<Value *, Value *> ConvMap;
-  for (auto bi = BB->begin(), be = BB->end(); bi != be; ++bi) {
-    Instruction *I = &*bi;
-    if (!isToSurfaceConversion(I, Liveness))
-      continue;
-    IGC_ASSERT(I->hasOneUse());
-    if (!ConvMap.insert({I->getOperand(0), I}).second) {
-      Modified = true;
-      I->replaceAllUsesWith(ConvMap[I->getOperand(0)]);
-      ToErase.push_back(I);
-    }
-  }
-  return Modified;
-}
-
 /***********************************************************************
  * processFunction : run the category conversion pass for this Function
  *
@@ -583,8 +538,6 @@ bool GenXCategory::processFunction(Function *F)
 
     // This commons up constpred calls just loaded.
     Modified |= commonUpPredicate(BB);
-    // This commons up to-surface conversion calls.
-    Modified |= commonUpSurface(BB);
 
     // Erase instructions (and their live ranges) as requested by processValue.
     for (unsigned i = 0, e = ToErase.size(); i != e; ++i) {