[llvm] 0af42d3 - [PatternMatch][LVI] Handle select-form and/or in LVI
Nikita Popov via llvm-commits
llvm-commits at lists.llvm.org
Sun Dec 27 08:41:14 PST 2020
Author: Nikita Popov
Date: 2020-12-27T17:39:02+01:00
New Revision: 0af42d3dc73e8f08e37811131c31358ecb9adf20
URL: https://github.com/llvm/llvm-project/commit/0af42d3dc73e8f08e37811131c31358ecb9adf20
DIFF: https://github.com/llvm/llvm-project/commit/0af42d3dc73e8f08e37811131c31358ecb9adf20.diff
LOG: [PatternMatch][LVI] Handle select-form and/or in LVI
Following the discussion in D93065, this adds m_LogicalAnd() and
m_LogicalOr() matchers, that match A && B and A || B logical
operations, either as bitwise operations or select expressions.
As an example usage, LVI is adapted to use these matchers for its
condition reasoning.
The plan here is to switch other parts of LLVM that reason about
and/or of conditions to also support the select forms, and then
merge D93065 (or a variant thereof) to disable the poison-unsafe
select to and/or transform.
Differential Revision: https://reviews.llvm.org/D93827
Added:
Modified:
llvm/include/llvm/IR/PatternMatch.h
llvm/lib/Analysis/LazyValueInfo.cpp
llvm/test/Transforms/CorrelatedValuePropagation/basic.ll
Removed:
################################################################################
diff --git a/llvm/include/llvm/IR/PatternMatch.h b/llvm/include/llvm/IR/PatternMatch.h
index c40f5d1d15d1..166ad23de969 100644
--- a/llvm/include/llvm/IR/PatternMatch.h
+++ b/llvm/include/llvm/IR/PatternMatch.h
@@ -2387,6 +2387,58 @@ inline VScaleVal_match m_VScale(const DataLayout &DL) {
return VScaleVal_match(DL);
}
+template <typename LHS, typename RHS, unsigned Opcode>
+struct LogicalOp_match {
+ LHS L;
+ RHS R;
+
+ LogicalOp_match(const LHS &L, const RHS &R) : L(L), R(R) {}
+
+ template <typename T> bool match(T *V) {
+ if (auto *I = dyn_cast<Instruction>(V)) {
+ if (!I->getType()->isIntOrIntVectorTy(1))
+ return false;
+
+ if (I->getOpcode() == Opcode && L.match(I->getOperand(0)) &&
+ R.match(I->getOperand(1)))
+ return true;
+
+ if (auto *SI = dyn_cast<SelectInst>(I)) {
+ if (Opcode == Instruction::And) {
+ if (const auto *C = dyn_cast<Constant>(SI->getFalseValue()))
+ if (C->isNullValue() && L.match(SI->getCondition()) &&
+ R.match(SI->getTrueValue()))
+ return true;
+ } else {
+ assert(Opcode == Instruction::Or);
+ if (const auto *C = dyn_cast<Constant>(SI->getTrueValue()))
+ if (C->isOneValue() && L.match(SI->getCondition()) &&
+ R.match(SI->getFalseValue()))
+ return true;
+ }
+ }
+ }
+
+ return false;
+ }
+};
+
+/// Matches L && R either in the form of L & R or L ? R : false.
+/// Note that the latter form is poison-blocking.
+template <typename LHS, typename RHS>
+inline LogicalOp_match<LHS, RHS, Instruction::And>
+m_LogicalAnd(const LHS &L, const RHS &R) {
+ return LogicalOp_match<LHS, RHS, Instruction::And>(L, R);
+}
+
+/// Matches L || R either in the form of L | R or L ? true : R.
+/// Note that the latter form is poison-blocking.
+template <typename LHS, typename RHS>
+inline LogicalOp_match<LHS, RHS, Instruction::Or>
+m_LogicalOr(const LHS &L, const RHS &R) {
+ return LogicalOp_match<LHS, RHS, Instruction::Or>(L, R);
+}
+
} // end namespace PatternMatch
} // end namespace llvm
diff --git a/llvm/lib/Analysis/LazyValueInfo.cpp b/llvm/lib/Analysis/LazyValueInfo.cpp
index a2f0bd872573..aadb90d372f4 100644
--- a/llvm/lib/Analysis/LazyValueInfo.cpp
+++ b/llvm/lib/Analysis/LazyValueInfo.cpp
@@ -1205,22 +1205,20 @@ getValueFromConditionImpl(Value *Val, Value *Cond, bool isTrueDest,
// true dest path both of the conditions hold. Similarly for conditions of
// the form (cond1 || cond2), we know that on the false dest path neither
// condition holds.
- BinaryOperator *BO = dyn_cast<BinaryOperator>(Cond);
- if (!BO || (isTrueDest && BO->getOpcode() != BinaryOperator::And) ||
- (!isTrueDest && BO->getOpcode() != BinaryOperator::Or))
+ Value *L, *R;
+ if (isTrueDest ? !match(Cond, m_LogicalAnd(m_Value(L), m_Value(R)))
+ : !match(Cond, m_LogicalOr(m_Value(L), m_Value(R))))
return ValueLatticeElement::getOverdefined();
// Prevent infinite recursion if Cond references itself as in this example:
// Cond: "%tmp4 = and i1 %tmp4, undef"
// BL: "%tmp4 = and i1 %tmp4, undef"
// BR: "i1 undef"
- Value *BL = BO->getOperand(0);
- Value *BR = BO->getOperand(1);
- if (BL == Cond || BR == Cond)
+ if (L == Cond || R == Cond)
return ValueLatticeElement::getOverdefined();
- return intersect(getValueFromCondition(Val, BL, isTrueDest, Visited),
- getValueFromCondition(Val, BR, isTrueDest, Visited));
+ return intersect(getValueFromCondition(Val, L, isTrueDest, Visited),
+ getValueFromCondition(Val, R, isTrueDest, Visited));
}
static ValueLatticeElement
diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/basic.ll b/llvm/test/Transforms/CorrelatedValuePropagation/basic.ll
index e4748e71baa5..bec6f9431c9d 100644
--- a/llvm/test/Transforms/CorrelatedValuePropagation/basic.ll
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/basic.ll
@@ -1069,10 +1069,8 @@ define void @select_and(i32 %a, i1* %p) {
; CHECK-NEXT: [[AND:%.*]] = select i1 [[CMP1]], i1 [[CMP2]], i1 false
; CHECK-NEXT: br i1 [[AND]], label [[GUARD:%.*]], label [[EXIT:%.*]]
; CHECK: guard:
-; CHECK-NEXT: [[C1:%.*]] = icmp sgt i32 [[A]], 20
-; CHECK-NEXT: store i1 [[C1]], i1* [[P:%.*]], align 1
-; CHECK-NEXT: [[C2:%.*]] = icmp slt i32 [[A]], -20
-; CHECK-NEXT: store i1 [[C2]], i1* [[P]], align 1
+; CHECK-NEXT: store i1 false, i1* [[P:%.*]], align 1
+; CHECK-NEXT: store i1 false, i1* [[P]], align 1
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: ret void
@@ -1168,10 +1166,8 @@ define void @select_or(i32 %a, i1* %p) {
; CHECK-NEXT: [[OR:%.*]] = select i1 [[CMP1]], i1 true, i1 [[CMP2]]
; CHECK-NEXT: br i1 [[OR]], label [[EXIT:%.*]], label [[GUARD:%.*]]
; CHECK: guard:
-; CHECK-NEXT: [[C1:%.*]] = icmp sgt i32 [[A]], 20
-; CHECK-NEXT: store i1 [[C1]], i1* [[P:%.*]], align 1
-; CHECK-NEXT: [[C2:%.*]] = icmp slt i32 [[A]], -20
-; CHECK-NEXT: store i1 [[C2]], i1* [[P]], align 1
+; CHECK-NEXT: store i1 false, i1* [[P:%.*]], align 1
+; CHECK-NEXT: store i1 false, i1* [[P]], align 1
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: ret void
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