[PATCH] D97360: [TTI] Consider select form of and/or i1 as having arithmetic cost

[Juneyoung Lee via Phabricator via llvm-commits]

aqjune created this revision.
aqjune added reviewers: fhahn, nikic, spatel, dmgreen.
aqjune requested review of this revision.
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This is a patch that updates the cost of `select i1 a, b, false` to be equivalent to that of `and i1 a, b`
as well as the cost of `select i1 a, true, b` equivalent to `or i1 a, b`.

Until now, these selects were folded into and/or i1 by InstCombine, but the transformation is poison-unsafe.
This is a step towards removing the unsafe transformation. D93065 <https://reviews.llvm.org/D93065> has relevant transformations linked.
These selects should be translated into the assemblies as and/or i1 do in the same manner. The cost should be equivalent.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D97360

Files:
  llvm/include/llvm/Analysis/TargetTransformInfoImpl.h


Index: llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
===================================================================
--- llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
+++ llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
@@ -22,8 +22,11 @@
 #include "llvm/IR/GetElementPtrTypeIterator.h"
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/Operator.h"
+#include "llvm/IR/PatternMatch.h"
 #include "llvm/IR/Type.h"
 
+using namespace llvm::PatternMatch;
+
 namespace llvm {
 
 /// Base class for use as a mix-in that aids implementing
@@ -990,6 +993,18 @@
                                         CostKind, I);
     }
     case Instruction::Select: {
+      const Value *Op0, *Op1;
+      if (match(U, m_LogicalAnd(m_Value(Op0), m_Value(Op1))) ||
+          match(U, m_LogicalOr(m_Value(Op0), m_Value(Op1)))) {
+        TTI::OperandValueProperties Op1VP = TTI::OP_None;
+        TTI::OperandValueProperties Op2VP = TTI::OP_None;
+        TTI::OperandValueKind Op1VK = TTI::getOperandInfo(Op0, Op1VP);
+        TTI::OperandValueKind Op2VK = TTI::getOperandInfo(Op1, Op2VP);
+        SmallVector<const Value *, 2> Operands{Op0, Op1};
+        return TargetTTI->getArithmeticInstrCost(
+            match(U, m_LogicalOr()) ? Instruction::Or : Instruction::And,
+            Ty, CostKind, Op1VK, Op2VK, Op1VP, Op2VP, Operands, I);
+      }
       Type *CondTy = U->getOperand(0)->getType();
       return TargetTTI->getCmpSelInstrCost(Opcode, U->getType(), CondTy,
                                            CmpInst::BAD_ICMP_PREDICATE,


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