[llvm] bb12ded - [InstCombine] Refactor and/or of icmp with constant (NFCI)
Nikita Popov via llvm-commits
llvm-commits at lists.llvm.org
Tue Nov 9 12:05:56 PST 2021
Author: Nikita Popov
Date: 2021-11-09T21:05:46+01:00
New Revision: bb12dededeb6558ddd352b40268692041e0fa02c
URL: https://github.com/llvm/llvm-project/commit/bb12dededeb6558ddd352b40268692041e0fa02c
DIFF: https://github.com/llvm/llvm-project/commit/bb12dededeb6558ddd352b40268692041e0fa02c.diff
LOG: [InstCombine] Refactor and/or of icmp with constant (NFCI)
Rather than testing for many specific combinations of predicates
and values, compute the exact icmp regions for both comparisons
and check whether they union/intersect exactly. If they do,
construct the equivalent icmp for the new range. Assuming that the
existing code handled all possible cases, this should be NFC.
Differential Revision: https://reviews.llvm.org/D113367
Added:
Modified:
llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 240b28d62487..fbda801e73e7 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -1322,107 +1322,23 @@ Value *InstCombinerImpl::foldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS,
if (LHS0 != RHS0)
return nullptr;
- // ICMP_[US][GL]E X, C is folded to ICMP_[US][GL]T elsewhere.
- if (PredL == ICmpInst::ICMP_UGE || PredL == ICmpInst::ICMP_ULE ||
- PredR == ICmpInst::ICMP_UGE || PredR == ICmpInst::ICMP_ULE ||
- PredL == ICmpInst::ICMP_SGE || PredL == ICmpInst::ICMP_SLE ||
- PredR == ICmpInst::ICMP_SGE || PredR == ICmpInst::ICMP_SLE)
+ ConstantRange CR1 =
+ ConstantRange::makeExactICmpRegion(PredL, LHSC->getValue());
+ ConstantRange CR2 =
+ ConstantRange::makeExactICmpRegion(PredR, RHSC->getValue());
+ Optional<ConstantRange> CR = CR1.exactIntersectWith(CR2);
+ if (!CR)
return nullptr;
- // We can't fold (ugt x, C) & (sgt x, C2).
- if (!predicatesFoldable(PredL, PredR))
- return nullptr;
-
- // Ensure that the larger constant is on the RHS.
- bool ShouldSwap;
- if (CmpInst::isSigned(PredL) ||
- (ICmpInst::isEquality(PredL) && CmpInst::isSigned(PredR)))
- ShouldSwap = LHSC->getValue().sgt(RHSC->getValue());
- else
- ShouldSwap = LHSC->getValue().ugt(RHSC->getValue());
-
- if (ShouldSwap) {
- std::swap(LHS, RHS);
- std::swap(LHSC, RHSC);
- std::swap(PredL, PredR);
- }
-
- // At this point, we know we have two icmp instructions
- // comparing a value against two constants and and'ing the result
- // together. Because of the above check, we know that we only have
- // icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know
- // (from the icmp folding check above), that the two constants
- // are not equal and that the larger constant is on the RHS
- assert(LHSC != RHSC && "Compares not folded above?");
-
- switch (PredL) {
- default:
- llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_NE:
- switch (PredR) {
- default:
- llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_ULT:
- // (X != 13 & X u< 14) -> X < 13
- if (LHSC->getValue() == (RHSC->getValue() - 1))
- return Builder.CreateICmpULT(LHS0, LHSC);
- if (LHSC->isZero()) // (X != 0 & X u< C) -> X-1 u< C-1
- return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
- false, true);
- break; // (X != 13 & X u< 15) -> no change
- case ICmpInst::ICMP_SLT:
- // (X != 13 & X s< 14) -> X < 13
- if (LHSC->getValue() == (RHSC->getValue() - 1))
- return Builder.CreateICmpSLT(LHS0, LHSC);
- // (X != INT_MIN & X s< C) -> X-(INT_MIN+1) u< (C-(INT_MIN+1))
- if (LHSC->isMinValue(true))
- return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
- true, true);
- break; // (X != 13 & X s< 15) -> no change
- case ICmpInst::ICMP_NE:
- // Potential folds for this case should already be handled.
- break;
- }
- break;
- case ICmpInst::ICMP_UGT:
- switch (PredR) {
- default:
- llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_NE:
- // (X u> 13 & X != 14) -> X u> 14
- if (RHSC->getValue() == (LHSC->getValue() + 1))
- return Builder.CreateICmp(PredL, LHS0, RHSC);
- // X u> C & X != UINT_MAX -> (X-(C+1)) u< UINT_MAX-(C+1)
- if (RHSC->isMaxValue(false))
- return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
- false, true);
- break; // (X u> 13 & X != 15) -> no change
- case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) -> (X-14) u< 1
- return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
- false, true);
- }
- break;
- case ICmpInst::ICMP_SGT:
- switch (PredR) {
- default:
- llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_NE:
- // (X s> 13 & X != 14) -> X s> 14
- if (RHSC->getValue() == (LHSC->getValue() + 1))
- return Builder.CreateICmp(PredL, LHS0, RHSC);
- // X s> C & X != INT_MAX -> (X-(C+1)) u< INT_MAX-(C+1)
- if (RHSC->isMaxValue(true))
- return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
- true, true);
- break; // (X s> 13 & X != 15) -> no change
- case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) -> (X-14) u< 1
- return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(), true,
- true);
- }
- break;
- }
-
- return nullptr;
+ CmpInst::Predicate Pred;
+ APInt NewRHS, Offset;
+ CR->getEquivalentICmp(Pred, NewRHS, Offset);
+
+ Type *Ty = LHS0->getType();
+ Value *NewLHS = LHS0;
+ if (Offset != 0)
+ NewLHS = Builder.CreateAdd(NewLHS, ConstantInt::get(Ty, Offset));
+ return Builder.CreateICmp(Pred, NewLHS, ConstantInt::get(Ty, NewRHS));
}
Value *InstCombinerImpl::foldLogicOfFCmps(FCmpInst *LHS, FCmpInst *RHS,
@@ -2551,100 +2467,23 @@ Value *InstCombinerImpl::foldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS,
if (LHS0 != RHS0)
return nullptr;
- // ICMP_[US][GL]E X, C is folded to ICMP_[US][GL]T elsewhere.
- if (PredL == ICmpInst::ICMP_UGE || PredL == ICmpInst::ICMP_ULE ||
- PredR == ICmpInst::ICMP_UGE || PredR == ICmpInst::ICMP_ULE ||
- PredL == ICmpInst::ICMP_SGE || PredL == ICmpInst::ICMP_SLE ||
- PredR == ICmpInst::ICMP_SGE || PredR == ICmpInst::ICMP_SLE)
+ ConstantRange CR1 =
+ ConstantRange::makeExactICmpRegion(PredL, LHSC->getValue());
+ ConstantRange CR2 =
+ ConstantRange::makeExactICmpRegion(PredR, RHSC->getValue());
+ Optional<ConstantRange> CR = CR1.exactUnionWith(CR2);
+ if (!CR)
return nullptr;
- // We can't fold (ugt x, C) | (sgt x, C2).
- if (!predicatesFoldable(PredL, PredR))
- return nullptr;
-
- // Ensure that the larger constant is on the RHS.
- bool ShouldSwap;
- if (CmpInst::isSigned(PredL) ||
- (ICmpInst::isEquality(PredL) && CmpInst::isSigned(PredR)))
- ShouldSwap = LHSC->getValue().sgt(RHSC->getValue());
- else
- ShouldSwap = LHSC->getValue().ugt(RHSC->getValue());
-
- if (ShouldSwap) {
- std::swap(LHS, RHS);
- std::swap(LHSC, RHSC);
- std::swap(PredL, PredR);
- }
-
- // At this point, we know we have two icmp instructions
- // comparing a value against two constants and or'ing the result
- // together. Because of the above check, we know that we only have
- // ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the
- // icmp folding check above), that the two constants are not
- // equal.
- assert(LHSC != RHSC && "Compares not folded above?");
-
- switch (PredL) {
- default:
- llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_EQ:
- switch (PredR) {
- default:
- llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_EQ:
- // Potential folds for this case should already be handled.
- break;
- case ICmpInst::ICMP_UGT:
- // (X == 0 || X u> C) -> (X-1) u>= C
- if (LHSC->isMinValue(false))
- return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue() + 1,
- false, false);
- // (X == 13 | X u> 14) -> no change
- break;
- case ICmpInst::ICMP_SGT:
- // (X == INT_MIN || X s> C) -> (X-(INT_MIN+1)) u>= C-INT_MIN
- if (LHSC->isMinValue(true))
- return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue() + 1,
- true, false);
- // (X == 13 | X s> 14) -> no change
- break;
- }
- break;
- case ICmpInst::ICMP_ULT:
- switch (PredR) {
- default:
- llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change
- // (X u< C || X == UINT_MAX) => (X-C) u>= UINT_MAX-C
- if (RHSC->isMaxValue(false))
- return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue(),
- false, false);
- break;
- case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) -> (X-13) u> 2
- assert(!RHSC->isMaxValue(false) && "Missed icmp simplification");
- return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue() + 1,
- false, false);
- }
- break;
- case ICmpInst::ICMP_SLT:
- switch (PredR) {
- default:
- llvm_unreachable("Unknown integer condition code!");
- case ICmpInst::ICMP_EQ:
- // (X s< C || X == INT_MAX) => (X-C) u>= INT_MAX-C
- if (RHSC->isMaxValue(true))
- return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue(),
- true, false);
- // (X s< 13 | X == 14) -> no change
- break;
- case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) -> (X-13) u> 2
- assert(!RHSC->isMaxValue(true) && "Missed icmp simplification");
- return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue() + 1, true,
- false);
- }
- break;
- }
- return nullptr;
+ CmpInst::Predicate Pred;
+ APInt NewRHS, Offset;
+ CR->getEquivalentICmp(Pred, NewRHS, Offset);
+
+ Type *Ty = LHS0->getType();
+ Value *NewLHS = LHS0;
+ if (Offset != 0)
+ NewLHS = Builder.CreateAdd(NewLHS, ConstantInt::get(Ty, Offset));
+ return Builder.CreateICmp(Pred, NewLHS, ConstantInt::get(Ty, NewRHS));
}
// FIXME: We use commutative matchers (m_c_*) for some, but not all, matches
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