[CostModel] Use operands argument in getInstructionCost in more places

[luke]

Summary

The current instruction's pointer operand may be different from the one
specified in the Operands argument. We should use the pointer operand
from here instead in case the user has transformed it.

This manifested itself somewhere down the line in
https://reviews.llvm.org/D149889, but I haven't been able to create a
test case on its own yet unfortunately.

[nikic]

llvm/include/llvm/Analysis/TargetTransformInfoImpl.h

1155

There are more places in here that directly access operands, such as this one. Maybe clean up all of them at once?

[luke]

Update all other uses of getOperand to use Operands argument

[luke]

llvm/include/llvm/Analysis/TargetTransformInfoImpl.h

1258

Note: the logic here still uses the instructions operands, and not the operands argument. But it still seems worthwhile using the argument where we can since the TTI hooks that are ultimately called are passed it. And presumably, that's what they use too.

[nikic]

LGTM

llvm/include/llvm/Analysis/TargetTransformInfoImpl.h

case Instruction::Freeze:
       return TTI::TCC_Free;
     case Instruction::Alloca:
       if (cast<AllocaInst>(U)->isStaticAlloca())
         return TTI::TCC_Free;
       break;
     case Instruction::GetElementPtr: {
       const auto *GEP = cast<GEPOperator>(U);
       return TargetTTI->getGEPCost(GEP->getSourceElementType(),
-                                   GEP->getPointerOperand(),
-                                   Operands.drop_front(), CostKind);
+                                   Operands.front(), Operands.drop_front(),
+                                   CostKind);
     }
     case Instruction::Add:
     case Instruction::FAdd:
     case Instruction::Sub:
     case Instruction::FSub:
     case Instruction::Mul:
     case Instruction::FMul:
     case Instruction::UDiv:
     case Instruction::SDiv:
     case Instruction::FDiv:
     case Instruction::URem:
     case Instruction::SRem:
     case Instruction::FRem:
     case Instruction::Shl:
     case Instruction::LShr:
     case Instruction::AShr:
     case Instruction::And:
     case Instruction::Or:
     case Instruction::Xor:
     case Instruction::FNeg: {
-      const TTI::OperandValueInfo Op1Info = TTI::getOperandInfo(U->getOperand(0));
+      const TTI::OperandValueInfo Op1Info = TTI::getOperandInfo(Operands[0]);
       TTI::OperandValueInfo Op2Info;
       if (Opcode != Instruction::FNeg)
-        Op2Info = TTI::getOperandInfo(U->getOperand(1));
-      SmallVector<const Value *, 2> Operands(U->operand_values());
+        Op2Info = TTI::getOperandInfo(Operands[1]);
       return TargetTTI->getArithmeticInstrCost(Opcode, Ty, CostKind, Op1Info,
                                                Op2Info, Operands, I);
     }
     case Instruction::IntToPtr:
     case Instruction::PtrToInt:
     case Instruction::SIToFP:
     case Instruction::UIToFP:
     case Instruction::FPToUI:
     case Instruction::FPToSI:
     case Instruction::Trunc:
     case Instruction::FPTrunc:
     case Instruction::BitCast:
     case Instruction::FPExt:
     case Instruction::SExt:
     case Instruction::ZExt:
     case Instruction::AddrSpaceCast: {
-      Type *OpTy = U->getOperand(0)->getType();
+      Type *OpTy = Operands[0]->getType();
       return TargetTTI->getCastInstrCost(
           Opcode, Ty, OpTy, TTI::getCastContextHint(I), CostKind, I);
     }
     case Instruction::Store: {
       auto *SI = cast<StoreInst>(U);
-      Type *ValTy = U->getOperand(0)->getType();
-      TTI::OperandValueInfo OpInfo = TTI::getOperandInfo(U->getOperand(0));
+      Type *ValTy = Operands[0]->getType();
+      TTI::OperandValueInfo OpInfo = TTI::getOperandInfo(Operands[0]);
       return TargetTTI->getMemoryOpCost(Opcode, ValTy, SI->getAlign(),
                                         SI->getPointerAddressSpace(), CostKind,
                                         OpInfo, I);
     }
     case Instruction::Load: {
       // FIXME: Arbitary cost which could come from the backend.
       if (CostKind == TTI::TCK_Latency)
         return 4;
case Instruction::Select: {
         assert(Op0->getType()->getScalarSizeInBits() == 1 &&
                Op1->getType()->getScalarSizeInBits() == 1);
 
         SmallVector<const Value *, 2> Operands{Op0, Op1};
         return TargetTTI->getArithmeticInstrCost(
             match(U, m_LogicalOr()) ? Instruction::Or : Instruction::And, Ty,
             CostKind, Op1Info, Op2Info, Operands, I);
       }
-      Type *CondTy = U->getOperand(0)->getType();
+      Type *CondTy = Operands[0]->getType();
       return TargetTTI->getCmpSelInstrCost(Opcode, U->getType(), CondTy,
                                            CmpInst::BAD_ICMP_PREDICATE,
                                            CostKind, I);
     }
     case Instruction::ICmp:
     case Instruction::FCmp: {
-      Type *ValTy = U->getOperand(0)->getType();
+      Type *ValTy = Operands[0]->getType();
       // TODO: Also handle ICmp/FCmp constant expressions.
       return TargetTTI->getCmpSelInstrCost(Opcode, ValTy, U->getType(),
                                            I ? cast<CmpInst>(I)->getPredicate()
                                              : CmpInst::BAD_ICMP_PREDICATE,
                                            CostKind, I);
     }
     case Instruction::InsertElement: {
       auto *IE = dyn_cast<InsertElementInst>(U);
       if (!IE)
         return TTI::TCC_Basic; // FIXME
       unsigned Idx = -1;
-      if (auto *CI = dyn_cast<ConstantInt>(IE->getOperand(2)))
+      if (auto *CI = dyn_cast<ConstantInt>(Operands[2]))
         if (CI->getValue().getActiveBits() <= 32)
           Idx = CI->getZExtValue();
       return TargetTTI->getVectorInstrCost(*IE, Ty, CostKind, Idx);
     }
     case Instruction::ShuffleVector: {
       auto *Shuffle = dyn_cast<ShuffleVectorInst>(U);
       if (!Shuffle)
         return TTI::TCC_Basic; // FIXME
 
       auto *VecTy = cast<VectorType>(U->getType());
-      auto *VecSrcTy = cast<VectorType>(U->getOperand(0)->getType());
+      auto *VecSrcTy = cast<VectorType>(Operands[0]->getType());
       int NumSubElts, SubIndex;
 
       if (Shuffle->changesLength()) {
         // Treat a 'subvector widening' as a free shuffle.
         if (Shuffle->increasesLength() && Shuffle->isIdentityWithPadding())
           return 0;
 
         if (Shuffle->isExtractSubvectorMask(SubIndex))
           return TargetTTI->getShuffleCost(TTI::SK_ExtractSubvector, VecSrcTy,
                                            Shuffle->getShuffleMask(), CostKind,
                                            SubIndex, VecTy, Operands);
case Instruction::ShuffleVector: {
                                        Shuffle->getShuffleMask(), CostKind, 0,
                                        nullptr, Operands);
     }
     case Instruction::ExtractElement: {
       auto *EEI = dyn_cast<ExtractElementInst>(U);
       if (!EEI)
         return TTI::TCC_Basic; // FIXME
       unsigned Idx = -1;
-      if (auto *CI = dyn_cast<ConstantInt>(EEI->getOperand(1)))
+      if (auto *CI = dyn_cast<ConstantInt>(Operands[1]))
         if (CI->getValue().getActiveBits() <= 32)
           Idx = CI->getZExtValue();
-      Type *DstTy = U->getOperand(0)->getType();
+      Type *DstTy = Operands[0]->getType();
       return TargetTTI->getVectorInstrCost(*EEI, DstTy, CostKind, Idx);
     }
     }
 
     // By default, just classify everything as 'basic' or -1 to represent that
     // don't know the throughput cost.
     return CostKind == TTI::TCK_RecipThroughput ? -1 : TTI::TCC_Basic;
   }