Revert "[AMDGPU][CodeGenPrepare] Narrow 64 bit math to 32 bit if profitable" (#133880)

Reverts llvm/llvm-project#130577

1 files changed, 0 insertions, 84 deletions

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUCodeGenPrepare.cpp b/llvm/lib/Target/AMDGPU/AMDGPUCodeGenPrepare.cpp
index eb5c160..9c482ae 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUCodeGenPrepare.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUCodeGenPrepare.cpp
@@ -1561,87 +1561,6 @@ void AMDGPUCodeGenPrepareImpl::expandDivRem64(BinaryOperator &I) const {
   llvm_unreachable("not a division");
 }
 
-Type *findSmallestLegalBits(Instruction *I, int OrigBit, int MaxBitsNeeded,
-                            const TargetLowering *TLI, const DataLayout &DL) {
-  if (MaxBitsNeeded >= OrigBit)
-    return nullptr;
-
-  Type *NewType = I->getType()->getWithNewBitWidth(MaxBitsNeeded);
-  while (OrigBit > MaxBitsNeeded) {
-    if (TLI->isOperationLegalOrCustom(
-            TLI->InstructionOpcodeToISD(I->getOpcode()),
-            TLI->getValueType(DL, NewType, true)))
-      return NewType;
-
-    MaxBitsNeeded *= 2;
-    NewType = I->getType()->getWithNewBitWidth(MaxBitsNeeded);
-  }
-  return nullptr;
-}
-
-static bool tryNarrowMathIfNoOverflow(Instruction *I, const TargetLowering *TLI,
-                                      const TargetTransformInfo &TTI,
-                                      const DataLayout &DL) {
-  unsigned Opc = I->getOpcode();
-  Type *OldType = I->getType();
-
-  if (Opc != Instruction::Add && Opc != Instruction::Mul)
-    return false;
-
-  unsigned OrigBit = OldType->getScalarSizeInBits();
-  unsigned MaxBitsNeeded = OrigBit;
-
-  switch (Opc) {
-  case Instruction::Add:
-    MaxBitsNeeded = KnownBits::add(computeKnownBits(I->getOperand(0), DL),
-                                   computeKnownBits(I->getOperand(1), DL))
-                        .countMaxActiveBits();
-    break;
-  case Instruction::Mul:
-    MaxBitsNeeded = KnownBits::mul(computeKnownBits(I->getOperand(0), DL),
-                                   computeKnownBits(I->getOperand(1), DL))
-                        .countMaxActiveBits();
-    break;
-  default:
-    llvm_unreachable("Unexpected opcode, only valid for Instruction::Add and "
-                     "Instruction::Mul.");
-  }
-
-  MaxBitsNeeded = std::max<unsigned>(bit_ceil(MaxBitsNeeded), 8);
-  Type *NewType = findSmallestLegalBits(I, OrigBit, MaxBitsNeeded, TLI, DL);
-
-  if (!NewType)
-    return false;
-
-  // Old cost
-  InstructionCost OldCost =
-      TTI.getArithmeticInstrCost(Opc, OldType, TTI::TCK_RecipThroughput);
-  // New cost of new op
-  InstructionCost NewCost =
-      TTI.getArithmeticInstrCost(Opc, NewType, TTI::TCK_RecipThroughput);
-  // New cost of narrowing 2 operands (use trunc)
-  NewCost += 2 * TTI.getCastInstrCost(Instruction::Trunc, NewType, OldType,
-                                      TTI.getCastContextHint(I),
-                                      TTI::TCK_RecipThroughput);
-  // New cost of zext narrowed result to original type
-  NewCost +=
-      TTI.getCastInstrCost(Instruction::ZExt, OldType, NewType,
-                           TTI.getCastContextHint(I), TTI::TCK_RecipThroughput);
-  if (NewCost >= OldCost)
-    return false;
-
-  IRBuilder<> Builder(I);
-  Value *Trunc0 = Builder.CreateTrunc(I->getOperand(0), NewType);
-  Value *Trunc1 = Builder.CreateTrunc(I->getOperand(1), NewType);
-  Value *Arith =
-      Builder.CreateBinOp((Instruction::BinaryOps)Opc, Trunc0, Trunc1);
-
-  Value *Zext = Builder.CreateZExt(Arith, OldType);
-  I->replaceAllUsesWith(Zext);
-  I->eraseFromParent();
-  return true;
-}
-
 bool AMDGPUCodeGenPrepareImpl::visitBinaryOperator(BinaryOperator &I) {
   if (foldBinOpIntoSelect(I))
     return true;
@@ -1726,9 +1645,6 @@ bool AMDGPUCodeGenPrepareImpl::visitBinaryOperator(BinaryOperator &I) {
     }
   }
 
-  Changed = tryNarrowMathIfNoOverflow(&I, ST.getTargetLowering(),
-                                      TM.getTargetTransformInfo(F), DL);
-
   return Changed;
 }