From be7a1070700e591732b254e29f2dd703325fb52a Mon Sep 17 00:00:00 2001 From: David Green Date: Sun, 8 Dec 2019 15:33:24 +0000 Subject: [ARM] Teach the Arm cost model that a Shift can be folded into other instructions This attempts to teach the cost model in Arm that code such as: %s = shl i32 %a, 3 %a = and i32 %s, %b Can under Arm or Thumb2 become: and r0, r1, r2, lsl #3 So the cost of the shift can essentially be free. To do this without trying to artificially adjust the cost of the "and" instruction, it needs to get the users of the shl and check if they are a type of instruction that the shift can be folded into. And so it needs to have access to the actual instruction in getArithmeticInstrCost, which if available is added as an extra parameter much like getCastInstrCost. We otherwise limit it to shifts with a single user, which should hopefully handle most of the cases. The list of instruction that the shift can be folded into include ADC, ADD, AND, BIC, CMP, EOR, MVN, ORR, ORN, RSB, SBC and SUB. This translates to Add, Sub, And, Or, Xor and ICmp. Differential Revision: https://reviews.llvm.org/D70966 --- llvm/lib/Analysis/TargetTransformInfo.cpp | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'llvm/lib/Analysis') diff --git a/llvm/lib/Analysis/TargetTransformInfo.cpp b/llvm/lib/Analysis/TargetTransformInfo.cpp index d36efc973a4..2e92855d858 100644 --- a/llvm/lib/Analysis/TargetTransformInfo.cpp +++ b/llvm/lib/Analysis/TargetTransformInfo.cpp @@ -592,10 +592,10 @@ TargetTransformInfo::getOperandInfo(Value *V, OperandValueProperties &OpProps) { int TargetTransformInfo::getArithmeticInstrCost( unsigned Opcode, Type *Ty, OperandValueKind Opd1Info, OperandValueKind Opd2Info, OperandValueProperties Opd1PropInfo, - OperandValueProperties Opd2PropInfo, - ArrayRef Args) const { - int Cost = TTIImpl->getArithmeticInstrCost(Opcode, Ty, Opd1Info, Opd2Info, - Opd1PropInfo, Opd2PropInfo, Args); + OperandValueProperties Opd2PropInfo, ArrayRef Args, + const Instruction *CxtI) const { + int Cost = TTIImpl->getArithmeticInstrCost( + Opcode, Ty, Opd1Info, Opd2Info, Opd1PropInfo, Opd2PropInfo, Args, CxtI); assert(Cost >= 0 && "TTI should not produce negative costs!"); return Cost; } @@ -1183,7 +1183,7 @@ int TargetTransformInfo::getInstructionThroughput(const Instruction *I) const { Op2VK = getOperandInfo(I->getOperand(1), Op2VP); SmallVector Operands(I->operand_values()); return getArithmeticInstrCost(I->getOpcode(), I->getType(), Op1VK, Op2VK, - Op1VP, Op2VP, Operands); + Op1VP, Op2VP, Operands, I); } case Instruction::FNeg: { TargetTransformInfo::OperandValueKind Op1VK, Op2VK; @@ -1193,7 +1193,7 @@ int TargetTransformInfo::getInstructionThroughput(const Instruction *I) const { Op2VP = OP_None; SmallVector Operands(I->operand_values()); return getArithmeticInstrCost(I->getOpcode(), I->getType(), Op1VK, Op2VK, - Op1VP, Op2VP, Operands); + Op1VP, Op2VP, Operands, I); } case Instruction::Select: { const SelectInst *SI = cast(I); -- cgit v1.2.3