[PATCH] D96929: [ValueTracking] Improve impliesPoison
Juneyoung Lee via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Thu Feb 18 18:50:07 PST 2021
aqjune updated this revision to Diff 324838.
aqjune added a comment.
Herald added a subscriber: dexonsmith.
Use m_WithOverflowInst
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D96929/new/
https://reviews.llvm.org/D96929
Files:
llvm/include/llvm/Analysis/ValueTracking.h
llvm/include/llvm/IR/PatternMatch.h
llvm/lib/Analysis/ValueTracking.cpp
llvm/test/Transforms/InstCombine/umul-sign-check.ll
Index: llvm/test/Transforms/InstCombine/umul-sign-check.ll
===================================================================
--- llvm/test/Transforms/InstCombine/umul-sign-check.ll
+++ llvm/test/Transforms/InstCombine/umul-sign-check.ll
@@ -1,5 +1,6 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -instcombine -S %s | FileCheck %s
+; RUN: opt -instcombine -instcombine-unsafe-select-transform=0 -S %s | FileCheck %s
; Check that we simplify llvm.umul.with.overflow, if the overflow check is
; weakened by or (icmp ne %res, 0) %overflow. This is generated by code using
Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -4852,11 +4852,19 @@
if (Depth >= MaxDepth)
return false;
- const auto *I = dyn_cast<Instruction>(V);
- if (I && propagatesPoison(cast<Operator>(I))) {
- return any_of(I->operands(), [=](const Value *Op) {
- return directlyImpliesPoison(ValAssumedPoison, Op, Depth + 1);
- });
+ if (const auto *I = dyn_cast<Instruction>(V)) {
+ if (propagatesPoison(cast<Operator>(I)))
+ return any_of(I->operands(), [=](const Value *Op) {
+ return directlyImpliesPoison(ValAssumedPoison, Op, Depth + 1);
+ });
+
+ // V = extractvalue V0, idx
+ // V2 = extractvalue V0, idx2
+ // V0's elements are all poison or not. (e.g., add_with_overflow)
+ const WithOverflowInst *II;
+ if (match(I, m_ExtractValue(m_WithOverflowInst(II))) &&
+ match(ValAssumedPoison, m_ExtractValue(m_Specific(II))))
+ return true;
}
return false;
}
Index: llvm/include/llvm/IR/PatternMatch.h
===================================================================
--- llvm/include/llvm/IR/PatternMatch.h
+++ llvm/include/llvm/IR/PatternMatch.h
@@ -708,6 +708,10 @@
inline bind_ty<BinaryOperator> m_BinOp(BinaryOperator *&I) { return I; }
/// Match a with overflow intrinsic, capturing it if we match.
inline bind_ty<WithOverflowInst> m_WithOverflowInst(WithOverflowInst *&I) { return I; }
+inline bind_ty<const WithOverflowInst>
+m_WithOverflowInst(const WithOverflowInst *&I) {
+ return I;
+}
/// Match a Constant, capturing the value if we match.
inline bind_ty<Constant> m_Constant(Constant *&C) { return C; }
@@ -2314,9 +2318,13 @@
ExtractValue_match(const Opnd_t &V) : Val(V) {}
template <typename OpTy> bool match(OpTy *V) {
- if (auto *I = dyn_cast<ExtractValueInst>(V))
- return I->getNumIndices() == 1 && I->getIndices()[0] == Ind &&
- Val.match(I->getAggregateOperand());
+ if (auto *I = dyn_cast<ExtractValueInst>(V)) {
+ // If Ind is -1, don't inspect indices
+ if (Ind != -1 &&
+ !(I->getNumIndices() == 1 && I->getIndices()[0] == (unsigned)Ind))
+ return false;
+ return Val.match(I->getAggregateOperand());
+ }
return false;
}
};
@@ -2328,6 +2336,13 @@
return ExtractValue_match<Ind, Val_t>(V);
}
+/// Match an ExtractValue instruction with any index.
+/// For example m_ExtractValue(...)
+template <typename Val_t>
+inline ExtractValue_match<-1, Val_t> m_ExtractValue(const Val_t &V) {
+ return ExtractValue_match<-1, Val_t>(V);
+}
+
/// Matcher for a single index InsertValue instruction.
template <int Ind, typename T0, typename T1> struct InsertValue_match {
T0 Op0;
Index: llvm/include/llvm/Analysis/ValueTracking.h
===================================================================
--- llvm/include/llvm/Analysis/ValueTracking.h
+++ llvm/include/llvm/Analysis/ValueTracking.h
@@ -582,6 +582,8 @@
/// poison.
/// Formally, given I = `r = op v1 v2 .. vN`, propagatesPoison returns true
/// if, for all i, r is evaluated to poison or op raises UB if vi = poison.
+ /// If vi is a vector or an aggregate and r is a single value, any poison
+ /// element in vi should make r poison or raise UB.
/// To filter out operands that raise UB on poison, you can use
/// getGuaranteedNonPoisonOp.
bool propagatesPoison(const Operator *I);
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