[llvm] r266987 - Refactor implied condition logic from ValueTracking directly into CmpInst. NFC.
Philip Reames via llvm-commits
llvm-commits at lists.llvm.org
Thu Apr 21 07:47:35 PDT 2016
The naming of isTrueWhenOperandsMatch and isFalseWhenOperandsMatch
aren't exactly clear. Reading through code, I'd have no idea what they
do. Possibly: isImpliedByMatchingCompare(Pred)? I don't really like
that either, but its better than what we have.
Philip
On 04/21/2016 07:04 AM, Chad Rosier via llvm-commits wrote:
> Author: mcrosier
> Date: Thu Apr 21 09:04:54 2016
> New Revision: 266987
>
> URL: http://llvm.org/viewvc/llvm-project?rev=266987&view=rev
> Log:
> Refactor implied condition logic from ValueTracking directly into CmpInst. NFC.
>
> Differential Revision: http://reviews.llvm.org/D19330
>
> Modified:
> llvm/trunk/include/llvm/IR/InstrTypes.h
> llvm/trunk/lib/Analysis/ValueTracking.cpp
> llvm/trunk/lib/IR/Instructions.cpp
>
> Modified: llvm/trunk/include/llvm/IR/InstrTypes.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/InstrTypes.h?rev=266987&r1=266986&r2=266987&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/IR/InstrTypes.h (original)
> +++ llvm/trunk/include/llvm/IR/InstrTypes.h Thu Apr 21 09:04:54 2016
> @@ -1067,6 +1067,18 @@ public:
> return isFalseWhenEqual(getPredicate());
> }
>
> + /// @brief Determine if Pred1 implies Pred2 is true when two compares have
> + /// matching operands.
> + bool isTrueWhenOperandsMatch(Predicate Pred2) {
> + return isTrueWhenOperandsMatch(getPredicate(), Pred2);
> + }
> +
> + /// @brief Determine if Pred1 implies Pred2 is false when two compares have
> + /// matching operands.
> + bool isFalseWhenOperandsMatch(Predicate Pred2) {
> + return isFalseWhenOperandsMatch(getPredicate(), Pred2);
> + }
> +
> /// @returns true if the predicate is unsigned, false otherwise.
> /// @brief Determine if the predicate is an unsigned operation.
> static bool isUnsigned(Predicate predicate);
> @@ -1087,6 +1099,14 @@ public:
> /// Determine if the predicate is false when comparing a value with itself.
> static bool isFalseWhenEqual(Predicate predicate);
>
> + /// Determine if Pred1 implies Pred2 is true when two compares have matching
> + /// operands.
> + static bool isTrueWhenOperandsMatch(Predicate Pred1, Predicate Pred2);
> +
> + /// Determine if Pred1 implies Pred2 is false when two compares have matching
> + /// operands.
> + static bool isFalseWhenOperandsMatch(Predicate Pred1, Predicate Pred2);
> +
> /// @brief Methods for support type inquiry through isa, cast, and dyn_cast:
> static inline bool classof(const Instruction *I) {
> return I->getOpcode() == Instruction::ICmp ||
>
> Modified: llvm/trunk/lib/Analysis/ValueTracking.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ValueTracking.cpp?rev=266987&r1=266986&r2=266987&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Analysis/ValueTracking.cpp (original)
> +++ llvm/trunk/lib/Analysis/ValueTracking.cpp Thu Apr 21 09:04:54 2016
> @@ -3935,61 +3935,11 @@ static Optional<bool> isImpliedCondMatch
> std::swap(BLHS, BRHS);
> BPred = ICmpInst::getSwappedPredicate(BPred);
> }
> -
> - // If the predicates match, then we know the first condition implies the
> - // second is true.
> - if (APred == BPred)
> + if (CmpInst::isTrueWhenOperandsMatch(APred, BPred))
> return true;
> -
> - // If an inverted APred matches BPred, we can infer the second condition is
> - // false.
> - if (CmpInst::getInversePredicate(APred) == BPred)
> + if (CmpInst::isFalseWhenOperandsMatch(APred, BPred))
> return false;
>
> - // If a swapped APred matches BPred, we can infer the second condition is
> - // false in many cases.
> - if (CmpInst::getSwappedPredicate(APred) == BPred) {
> - switch (APred) {
> - default:
> - break;
> - case CmpInst::ICMP_UGT: // A >u B implies A <u B is false.
> - case CmpInst::ICMP_ULT: // A <u B implies A >u B is false.
> - case CmpInst::ICMP_SGT: // A >s B implies A <s B is false.
> - case CmpInst::ICMP_SLT: // A <s B implies A >s B is false.
> - return false;
> - }
> - }
> -
> - // The predicates must match sign or at least one of them must be an equality
> - // comparison (which is signless).
> - if (ICmpInst::isSigned(APred) != ICmpInst::isSigned(BPred) &&
> - !ICmpInst::isEquality(APred) && !ICmpInst::isEquality(BPred))
> - return None;
> -
> - switch (APred) {
> - default:
> - break;
> - case CmpInst::ICMP_EQ:
> - // A == B implies A > B and A < B are false.
> - if (CmpInst::isFalseWhenEqual(BPred))
> - return false;
> -
> - break;
> - case CmpInst::ICMP_UGT:
> - case CmpInst::ICMP_ULT:
> - case CmpInst::ICMP_SGT:
> - case CmpInst::ICMP_SLT:
> - // A > B implies A == B is false.
> - // A < B implies A == B is false.
> - if (BPred == CmpInst::ICMP_EQ)
> - return false;
> -
> - // A > B implies A != B is true.
> - // A < B implies A != B is true.
> - if (BPred == CmpInst::ICMP_NE)
> - return true;
> - break;
> - }
> return None;
> }
>
>
> Modified: llvm/trunk/lib/IR/Instructions.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/Instructions.cpp?rev=266987&r1=266986&r2=266987&view=diff
> ==============================================================================
> --- llvm/trunk/lib/IR/Instructions.cpp (original)
> +++ llvm/trunk/lib/IR/Instructions.cpp Thu Apr 21 09:04:54 2016
> @@ -3597,6 +3597,58 @@ bool CmpInst::isFalseWhenEqual(Predicate
> }
> }
>
> +bool CmpInst::isTrueWhenOperandsMatch(Predicate Pred1, Predicate Pred2) {
> + // If the predicates match, then we know the first condition implies the
> + // second is true.
> + if (Pred1 == Pred2)
> + return true;
> +
> + switch (Pred1) {
> + default:
> + break;
> + case ICMP_UGT: // A >u B implies A != B is true.
> + case ICMP_ULT: // A <u B implies A != B is true.
> + case ICMP_SGT: // A >s B implies A != B is true.
> + case ICMP_SLT: // A <s B implies A != B is true.
> + return Pred2 == ICMP_NE;
> + }
> + return false;
> +}
> +
> +bool CmpInst::isFalseWhenOperandsMatch(Predicate Pred1, Predicate Pred2) {
> + // If an inverted Pred1 matches Pred2, we can infer the second condition is
> + // false.
> + if (getInversePredicate(Pred1) == Pred2)
> + return true;
> +
> + // If a swapped Pred1 matches Pred2, we can infer the second condition is
> + // false in many cases.
> + if (getSwappedPredicate(Pred1) == Pred2) {
> + switch (Pred1) {
> + default:
> + break;
> + case ICMP_UGT: // A >u B implies A <u B is false.
> + case ICMP_ULT: // A <u B implies A >u B is false.
> + case ICMP_SGT: // A >s B implies A <s B is false.
> + case ICMP_SLT: // A <s B implies A >s B is false.
> + return true;
> + }
> + }
> + // A == B implies A > B and A < B are false.
> + if (Pred1 == ICMP_EQ && isFalseWhenEqual(Pred2))
> + return true;
> +
> + switch (Pred1) {
> + default:
> + break;
> + case ICMP_UGT: // A >u B implies A == B is false.
> + case ICMP_ULT: // A <u B implies A == B is false.
> + case ICMP_SGT: // A >s B implies A == B is false.
> + case ICMP_SLT: // A <s B implies A == B is false.
> + return Pred2 == ICMP_EQ;
> + }
> + return false;
> +}
>
> //===----------------------------------------------------------------------===//
> // SwitchInst Implementation
>
>
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