Remove some dead optimization pass (NFC).

Change-Id: Ifbd62011610bb8b99a1fccb395647b4e714fcb9b

Author: weiyu-chen

visa/Optimizer.cpp

@@ -10770,174 +10770,7 @@ struct DclMapInfo {
 }  // namespace
 
 //
-// mov (M1, 8) V45(0,0)<1>:q V42(0,0)<8;8,1>:d                                      /// $7
-// mov (M3, 8) V45(2,0)<1>:q V42(1,0)<8;8,1>:d                                      /// $8
-// shl (M1, 8) V46(0,0)<1>:q V45(0,0)<8;8,1>:q 0x2:q                                /// $9
-// shl (M3, 8) V46(2,0)<1>:q V45(2,0)<8;8,1>:q 0x2:q                                /// $10
-//
-// into
-//
-// mov (M1, 8) V45L(0,0)<1>:q V42(0,0)<8;8,1>:d                                      /// $7
-// mov (M3, 8) V45H(0,0)<1>:q V42(1,0)<8;8,1>:d                                      /// $8
-// shl (M1, 8) V46(0,0)<1>:q V45L(0,0)<8;8,1>:q 0x2:q                                /// $9
-// shl (M3, 8) V46(2,0)<1>:q V45H(0,0)<8;8,1>:q 0x2:q                                /// $10
-//
-void Optimizer::splitVariables()
-{
-    if (kernel.getIntKernelAttribute(Attributes::ATTR_Target) != VISA_3D)
-    {
-        return;
-    }
-
-    if (builder.getOption(vISA_Debug))
-    {
-        return;
-    }
-
-    // Only for simd16 and simd32.
-    if (kernel.getSimdSize() == 8)
-    {
-        return;
-    }
-
-    // All declarations in this map are candidates for variable splitting.
-    std::map<const G4_Declare *, DclMapInfo *> DclMap;
-
-    // All instructions to be updated, and the flag indicates if this
-    // instruction defines low part or ont.
-    std::vector<std::pair<G4_INST *, bool>> InstsToUpdate;
-
-    for (G4_BB *bb : fg)
-    {
-        for (G4_INST *inst : *bb)
-        {
-            // Only for variables defined by non-send instructions.
-            if (inst->opcode() == G4_label || inst->isSend())
-                continue;
-
-            // TODO: Allow global variables.
-            auto Dst = inst->getDst();
-            if (!Dst || Dst->getHorzStride() != 1 ||
-                fg.globalOpndHT.isOpndGlobal(Dst))
-                continue;
-            auto Dcl = Dst->getTopDcl();
-            if (!Dcl || !isCandidateDecl(Dcl, builder))
-                continue;
-
-            unsigned LBound = Dst->getLeftBound();
-            unsigned RBound = Dst->getRightBound();
-            if ((LBound == LoLBound && RBound == LoRBound) ||
-                (LBound == HiLBound && RBound == HiRBound))
-            {
-                // OK, only defines low or high part.
-                // Bound constraints imply that def and uses are in two grfs.
-            }
-            else
-            {
-                continue;
-            }
-
-            if (inst->useEmpty())
-            {
-                continue;
-            }
-
-            // Check all uses.
-            bool DoSplitting = true;
-            for (auto UI = inst->use_begin(), UE = inst->use_end(); UI != UE; ++UI)
-            {
-                G4_Operand *Op = UI->first->getOperand(UI->second);
-                if (Op && Op->compareOperand(Dst) != Rel_eq)
-                {
-                    DoSplitting = false;
-                    break;
-                }
-
-                // The def-use chain is broken in the following code:
-                //
-                // mov (8, M1_NM) V33(0,0):df 0  <- not def
-                // mov (8, M3_NM) V33(2,0):df 0  <- not def
-                // mov (8, M1) V33(0,0):df 1     <- def
-                // mov (8, M3_NM) V33(2,0):df 1  <- def
-                //
-                // use of V33(0,0) and V33(2,0)
-                //
-                // FIXME: remove this if def-use chain is accurate.
-                if (UI->first->isWriteEnableInst() && !inst->isWriteEnableInst())
-                {
-                    DoSplitting = false;
-                    break;
-                }
-
-                // Only allow single definition:
-                // mov (8, M1_NM) V33:q 0
-                // mov (8, M1)    V33:q 1
-                // add (8, M1_NM  V34:q V33:q V32:q
-                //
-                if (UI->first->getSingleDef(UI->second) != inst)
-                {
-                    DoSplitting = false;
-                    break;
-                }
-            }
-
-            if (!DoSplitting)
-                continue;
-
-            G4_Type Ty = Dcl->getElemType();
-            auto Iter = DclMap.find(Dcl);
-            if (Iter == DclMap.end())
-            {
-                unsigned NElts = Dcl->getTotalElems();
-                auto DclLow = builder.createTempVar(NElts / 2, Ty, GRFALIGN, "Lo");
-                auto DclHi = builder.createTempVar(NElts / 2, Ty, GRFALIGN, "Hi");
-                DclMap[Dcl] = new DclMapInfo(DclLow, DclHi);
-            }
-            bool IsLow = LBound == LoLBound;
-            InstsToUpdate.push_back(std::make_pair(inst, IsLow));
-        }
-    }
-
-    // Iterate instructions that define hi or low parts. Update their defs and uses.
-    for (auto IPair : InstsToUpdate)
-    {
-        G4_INST *Inst = IPair.first;
-        bool IsLow = IPair.second;
-
-        // Update Inst's Dst.
-        {
-            G4_DstRegRegion *Dst = Inst->getDst();
-            G4_Type Ty = Dst->getType();
-            auto NewDcl = DclMap[Dst->getTopDcl()]->getDcl(builder, Ty, IsLow);
-            auto NewDst = builder.createDst(NewDcl->getRegVar(), 0, 0, 1, Ty);
-            Inst->setDest(NewDst);
-        }
-
-        // Update Inst's uses.
-        for (auto UI = Inst->use_begin(), UE = Inst->use_end(); UI != UE; ++UI)
-        {
-            G4_INST *UseInst = UI->first;
-            G4_SrcRegRegion *UseOpnd = UseInst->getOperand(UI->second)->asSrcRegRegion();
-            G4_Type UseTy = UseOpnd->getType();
-            auto NewUseDcl = DclMap[UseOpnd->getTopDcl()]->getDcl(builder, UseTy, IsLow);
-            auto NewUseOpnd = builder.createSrcRegRegion(
-                UseOpnd->getModifier(), UseOpnd->getRegAccess(),
-                NewUseDcl->getRegVar(), 0, 0, UseOpnd->getRegion(), UseTy);
-            UseInst->setSrc(NewUseOpnd, G4_INST::getSrcNum(UI->second));
-        }
-    }
-
-    // Cleanup.
-    for (auto DI : DclMap)
-    {
-        delete DI.second;
-    }
-}
-
-//
-// replacement of the above that can handle global variables
-// basically we split any 4GRF variables (they typically result from
-// simd16 64-bit vars) into two half if
+// We split any 4GRF variables (they typically result from simd16 64-bit vars) into two half if
 // -- they are not address taken or used in send
 // -- none of the operands cross from the 2nd to the 3rd GRF
 // This is intended to give RA more freedom as the split variables do

visa/Optimizer.h

@@ -223,7 +223,6 @@ class Optimizer
     void cleanupBindless();
     G4_Operand* updateSendsHeaderReuse(std::vector<std::vector<G4_INST*>> &, std::vector<G4_INST*> &, INST_LIST_ITER);
     void countGRFUsage();
-    void splitVariables();
     void changeMoveType();
     void split4GRFVars();