[llvm] c93a39d - [SCEV][NFC] Introduce isKnownPredicateAt method

[Max Kazantsev via llvm-commits]

Author: Max Kazantsev
Date: 2020-10-01T12:11:24+07:00
New Revision: c93a39dd1fdd74cb87ef65cfd42d81c62a07ed91

URL: https://github.com/llvm/llvm-project/commit/c93a39dd1fdd74cb87ef65cfd42d81c62a07ed91
DIFF: https://github.com/llvm/llvm-project/commit/c93a39dd1fdd74cb87ef65cfd42d81c62a07ed91.diff

LOG: [SCEV][NFC] Introduce isKnownPredicateAt method

We can query known predicates in different points, respecting
their dominating conditions.

Added: 
    

Modified: 
    llvm/include/llvm/Analysis/ScalarEvolution.h
    llvm/lib/Analysis/ScalarEvolution.cpp

Removed: 
    


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diff  --git a/llvm/include/llvm/Analysis/ScalarEvolution.h b/llvm/include/llvm/Analysis/ScalarEvolution.h
index 4fc1ee08caf7..febca473776a 100644
--- a/llvm/include/llvm/Analysis/ScalarEvolution.h
+++ b/llvm/include/llvm/Analysis/ScalarEvolution.h
@@ -916,6 +916,11 @@ class ScalarEvolution {
   bool isKnownPredicate(ICmpInst::Predicate Pred, const SCEV *LHS,
                         const SCEV *RHS);
 
+  /// Test if the given expression is known to satisfy the condition described
+  /// by Pred, LHS, and RHS in the given Context.
+  bool isKnownPredicateAt(ICmpInst::Predicate Pred, const SCEV *LHS,
+                        const SCEV *RHS, const Instruction *Context);
+
   /// Test if the condition described by Pred, LHS, RHS is known to be true on
   /// every iteration of the loop of the recurrency LHS.
   bool isKnownOnEveryIteration(ICmpInst::Predicate Pred,

diff  --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 8759f86e031d..e51b31673105 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -9100,6 +9100,14 @@ bool ScalarEvolution::isKnownPredicate(ICmpInst::Predicate Pred,
   return isKnownViaNonRecursiveReasoning(Pred, LHS, RHS);
 }
 
+bool ScalarEvolution::isKnownPredicateAt(ICmpInst::Predicate Pred,
+                                         const SCEV *LHS, const SCEV *RHS,
+                                         const Instruction *Context) {
+  // TODO: Analyze guards and assumes from Context's block.
+  return isKnownPredicate(Pred, LHS, RHS) ||
+         isBasicBlockEntryGuardedByCond(Context->getParent(), Pred, LHS, RHS);
+}
+
 bool ScalarEvolution::isKnownOnEveryIteration(ICmpInst::Predicate Pred,
                                               const SCEVAddRecExpr *LHS,
                                               const SCEV *RHS) {