forked from OSchip/llvm-project
[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
This commit is contained in:
Nikita Popov
parent
8d499bd5bc
commit
bb12dedede
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@ -1322,107 +1322,23 @@ Value *InstCombinerImpl::foldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS,
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if (LHS0 != RHS0)
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return nullptr;
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// ICMP_[US][GL]E X, C is folded to ICMP_[US][GL]T elsewhere.
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if (PredL == ICmpInst::ICMP_UGE || PredL == ICmpInst::ICMP_ULE ||
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PredR == ICmpInst::ICMP_UGE || PredR == ICmpInst::ICMP_ULE ||
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PredL == ICmpInst::ICMP_SGE || PredL == ICmpInst::ICMP_SLE ||
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PredR == ICmpInst::ICMP_SGE || PredR == ICmpInst::ICMP_SLE)
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ConstantRange CR1 =
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ConstantRange::makeExactICmpRegion(PredL, LHSC->getValue());
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ConstantRange CR2 =
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ConstantRange::makeExactICmpRegion(PredR, RHSC->getValue());
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Optional<ConstantRange> CR = CR1.exactIntersectWith(CR2);
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if (!CR)
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return nullptr;
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// We can't fold (ugt x, C) & (sgt x, C2).
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if (!predicatesFoldable(PredL, PredR))
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return nullptr;
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CmpInst::Predicate Pred;
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APInt NewRHS, Offset;
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CR->getEquivalentICmp(Pred, NewRHS, Offset);
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// Ensure that the larger constant is on the RHS.
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bool ShouldSwap;
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if (CmpInst::isSigned(PredL) ||
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(ICmpInst::isEquality(PredL) && CmpInst::isSigned(PredR)))
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ShouldSwap = LHSC->getValue().sgt(RHSC->getValue());
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else
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ShouldSwap = LHSC->getValue().ugt(RHSC->getValue());
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if (ShouldSwap) {
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std::swap(LHS, RHS);
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std::swap(LHSC, RHSC);
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std::swap(PredL, PredR);
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}
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// At this point, we know we have two icmp instructions
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// comparing a value against two constants and and'ing the result
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// together. Because of the above check, we know that we only have
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// icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know
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// (from the icmp folding check above), that the two constants
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// are not equal and that the larger constant is on the RHS
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assert(LHSC != RHSC && "Compares not folded above?");
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switch (PredL) {
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default:
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llvm_unreachable("Unknown integer condition code!");
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case ICmpInst::ICMP_NE:
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switch (PredR) {
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default:
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llvm_unreachable("Unknown integer condition code!");
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case ICmpInst::ICMP_ULT:
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// (X != 13 & X u< 14) -> X < 13
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if (LHSC->getValue() == (RHSC->getValue() - 1))
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return Builder.CreateICmpULT(LHS0, LHSC);
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if (LHSC->isZero()) // (X != 0 & X u< C) -> X-1 u< C-1
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return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
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false, true);
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break; // (X != 13 & X u< 15) -> no change
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case ICmpInst::ICMP_SLT:
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// (X != 13 & X s< 14) -> X < 13
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if (LHSC->getValue() == (RHSC->getValue() - 1))
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return Builder.CreateICmpSLT(LHS0, LHSC);
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// (X != INT_MIN & X s< C) -> X-(INT_MIN+1) u< (C-(INT_MIN+1))
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if (LHSC->isMinValue(true))
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return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
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true, true);
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break; // (X != 13 & X s< 15) -> no change
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case ICmpInst::ICMP_NE:
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// Potential folds for this case should already be handled.
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break;
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}
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break;
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case ICmpInst::ICMP_UGT:
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switch (PredR) {
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default:
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llvm_unreachable("Unknown integer condition code!");
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case ICmpInst::ICMP_NE:
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// (X u> 13 & X != 14) -> X u> 14
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if (RHSC->getValue() == (LHSC->getValue() + 1))
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return Builder.CreateICmp(PredL, LHS0, RHSC);
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// X u> C & X != UINT_MAX -> (X-(C+1)) u< UINT_MAX-(C+1)
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if (RHSC->isMaxValue(false))
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return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
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false, true);
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break; // (X u> 13 & X != 15) -> no change
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case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) -> (X-14) u< 1
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return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
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false, true);
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}
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break;
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case ICmpInst::ICMP_SGT:
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switch (PredR) {
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default:
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llvm_unreachable("Unknown integer condition code!");
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case ICmpInst::ICMP_NE:
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// (X s> 13 & X != 14) -> X s> 14
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if (RHSC->getValue() == (LHSC->getValue() + 1))
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return Builder.CreateICmp(PredL, LHS0, RHSC);
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// X s> C & X != INT_MAX -> (X-(C+1)) u< INT_MAX-(C+1)
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if (RHSC->isMaxValue(true))
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return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
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true, true);
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break; // (X s> 13 & X != 15) -> no change
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case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) -> (X-14) u< 1
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return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(), true,
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true);
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}
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break;
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}
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return nullptr;
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Type *Ty = LHS0->getType();
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Value *NewLHS = LHS0;
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if (Offset != 0)
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NewLHS = Builder.CreateAdd(NewLHS, ConstantInt::get(Ty, Offset));
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return Builder.CreateICmp(Pred, NewLHS, ConstantInt::get(Ty, NewRHS));
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}
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Value *InstCombinerImpl::foldLogicOfFCmps(FCmpInst *LHS, FCmpInst *RHS,
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@ -2551,100 +2467,23 @@ Value *InstCombinerImpl::foldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS,
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if (LHS0 != RHS0)
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return nullptr;
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// ICMP_[US][GL]E X, C is folded to ICMP_[US][GL]T elsewhere.
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if (PredL == ICmpInst::ICMP_UGE || PredL == ICmpInst::ICMP_ULE ||
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PredR == ICmpInst::ICMP_UGE || PredR == ICmpInst::ICMP_ULE ||
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PredL == ICmpInst::ICMP_SGE || PredL == ICmpInst::ICMP_SLE ||
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PredR == ICmpInst::ICMP_SGE || PredR == ICmpInst::ICMP_SLE)
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ConstantRange CR1 =
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ConstantRange::makeExactICmpRegion(PredL, LHSC->getValue());
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ConstantRange CR2 =
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ConstantRange::makeExactICmpRegion(PredR, RHSC->getValue());
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Optional<ConstantRange> CR = CR1.exactUnionWith(CR2);
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if (!CR)
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return nullptr;
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// We can't fold (ugt x, C) | (sgt x, C2).
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if (!predicatesFoldable(PredL, PredR))
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return nullptr;
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CmpInst::Predicate Pred;
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APInt NewRHS, Offset;
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CR->getEquivalentICmp(Pred, NewRHS, Offset);
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// Ensure that the larger constant is on the RHS.
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bool ShouldSwap;
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if (CmpInst::isSigned(PredL) ||
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(ICmpInst::isEquality(PredL) && CmpInst::isSigned(PredR)))
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ShouldSwap = LHSC->getValue().sgt(RHSC->getValue());
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else
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ShouldSwap = LHSC->getValue().ugt(RHSC->getValue());
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if (ShouldSwap) {
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std::swap(LHS, RHS);
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std::swap(LHSC, RHSC);
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std::swap(PredL, PredR);
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}
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// At this point, we know we have two icmp instructions
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// comparing a value against two constants and or'ing the result
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// together. Because of the above check, we know that we only have
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// ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the
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// icmp folding check above), that the two constants are not
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// equal.
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assert(LHSC != RHSC && "Compares not folded above?");
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switch (PredL) {
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default:
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llvm_unreachable("Unknown integer condition code!");
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case ICmpInst::ICMP_EQ:
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switch (PredR) {
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default:
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llvm_unreachable("Unknown integer condition code!");
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case ICmpInst::ICMP_EQ:
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// Potential folds for this case should already be handled.
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break;
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case ICmpInst::ICMP_UGT:
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// (X == 0 || X u> C) -> (X-1) u>= C
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if (LHSC->isMinValue(false))
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return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue() + 1,
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false, false);
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// (X == 13 | X u> 14) -> no change
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break;
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case ICmpInst::ICMP_SGT:
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// (X == INT_MIN || X s> C) -> (X-(INT_MIN+1)) u>= C-INT_MIN
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if (LHSC->isMinValue(true))
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return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue() + 1,
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true, false);
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// (X == 13 | X s> 14) -> no change
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break;
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}
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break;
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case ICmpInst::ICMP_ULT:
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switch (PredR) {
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default:
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llvm_unreachable("Unknown integer condition code!");
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case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change
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// (X u< C || X == UINT_MAX) => (X-C) u>= UINT_MAX-C
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if (RHSC->isMaxValue(false))
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return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue(),
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false, false);
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break;
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case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) -> (X-13) u> 2
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assert(!RHSC->isMaxValue(false) && "Missed icmp simplification");
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return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue() + 1,
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false, false);
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}
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break;
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case ICmpInst::ICMP_SLT:
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switch (PredR) {
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default:
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llvm_unreachable("Unknown integer condition code!");
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case ICmpInst::ICMP_EQ:
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// (X s< C || X == INT_MAX) => (X-C) u>= INT_MAX-C
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if (RHSC->isMaxValue(true))
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return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue(),
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true, false);
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// (X s< 13 | X == 14) -> no change
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break;
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case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) -> (X-13) u> 2
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assert(!RHSC->isMaxValue(true) && "Missed icmp simplification");
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return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue() + 1, true,
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false);
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}
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break;
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}
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return nullptr;
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Type *Ty = LHS0->getType();
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Value *NewLHS = LHS0;
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if (Offset != 0)
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NewLHS = Builder.CreateAdd(NewLHS, ConstantInt::get(Ty, Offset));
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return Builder.CreateICmp(Pred, NewLHS, ConstantInt::get(Ty, NewRHS));
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}
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// FIXME: We use commutative matchers (m_c_*) for some, but not all, matches
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