SCEV: thread samesign in isBasicBlockEntryGuardedByCond (NFC) #125840
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isBasicBlockEntryGuardedByCond inadvertedenly drops samesign information when calling ICmpInst::getNonStrictPredicate. Fix this.
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@llvm/pr-subscribers-llvm-analysis @llvm/pr-subscribers-llvm-ir Author: Ramkumar Ramachandra (artagnon) ChangesisBasicBlockEntryGuardedByCond inadvertedenly drops samesign information when calling ICmpInst::getNonStrictPredicate. Fix this. Full diff: https://github.com/llvm/llvm-project/pull/125840.diff 2 Files Affected:
diff --git a/llvm/include/llvm/IR/Instructions.h b/llvm/include/llvm/IR/Instructions.h
index 9a41971b63373c..a1f964352207f7 100644
--- a/llvm/include/llvm/IR/Instructions.h
+++ b/llvm/include/llvm/IR/Instructions.h
@@ -1231,6 +1231,18 @@ class ICmpInst: public CmpInst {
return getSwappedCmpPredicate(getCmpPredicate());
}
+ /// @returns the non-strict predicate along with samesign information: static
+ /// variant.
+ static CmpPredicate getNonStrictCmpPredicate(CmpPredicate Pred) {
+ return {getNonStrictPredicate(Pred), Pred.hasSameSign()};
+ }
+
+ /// For example, SGT -> SGE, SLT -> SLE, ULT -> ULE, UGT -> UGE.
+ /// @returns the non-strict predicate along with samesign information.
+ Predicate getNonStrictCmpPredicate() const {
+ return getNonStrictCmpPredicate(getCmpPredicate());
+ }
+
/// For example, EQ->EQ, SLE->SLE, UGT->SGT, etc.
/// @returns the predicate that would be the result if the operand were
/// regarded as signed.
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 0d7bbe3f996408..1673dc3acd2a12 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -11632,8 +11632,9 @@ bool ScalarEvolution::isBasicBlockEntryGuardedByCond(const BasicBlock *BB,
// non-strict comparison is known from ranges and non-equality is known from
// dominating predicates. If we are proving strict comparison, we always try
// to prove non-equality and non-strict comparison separately.
- auto NonStrictPredicate = ICmpInst::getNonStrictPredicate(Pred);
- const bool ProvingStrictComparison = (Pred != NonStrictPredicate);
+ CmpPredicate NonStrictPredicate = ICmpInst::getNonStrictCmpPredicate(Pred);
+ const bool ProvingStrictComparison =
+ (Pred != static_cast<CmpInst::Predicate>(NonStrictPredicate));
bool ProvedNonStrictComparison = false;
bool ProvedNonEquality = false;
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nikic
approved these changes
Feb 10, 2025
Collaborator
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/73/builds/12973 Here is the relevant piece of the build log for the reference |
Contributor
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Looks like this broke check-clang on mac: http://45.33.8.238/macm1/100556/step_6.txt (Linux seems happy.) Please take a look and revert for now if it takes a while to fix. |
Contributor
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@nico Pretty sure I see spurious failures of that test on aarch64 all the time. Does it fail persistently after this change? |
Contributor
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You're right, it cycled green on the next build (http://45.33.8.238/macm1/100557/summary.html). If this is a known flake:
|
Contributor
Author
Please mark it as UNSUPPORTED and file an issue. A quick search didn't pull anything up. |
Contributor
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Icohedron
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…25840) isBasicBlockEntryGuardedByCond inadvertedenly drops samesign information when calling ICmpInst::getNonStrictPredicate. Fix this.
Icohedron
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See llvm#126619 and discussion on llvm#125840
joaosaffran
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See llvm#126619 and discussion on llvm#125840
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See llvm#126619 and discussion on llvm#125840
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isBasicBlockEntryGuardedByCond inadvertedenly drops samesign information when calling ICmpInst::getNonStrictPredicate. Fix this.