[PATCH] D87890: [SCEV] Handle `less` predicates for FoundPred = NE

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev created this revision.
mkazantsev added reviewers: fhahn, asbirlea, lebedev.ri.
Herald added subscribers: llvm-commits, hiraditya.
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mkazantsev requested review of this revision.

Currently these predicates are ignored, yet their handling is
pretty simple. I could not find a single test where it would
 actually change something, but it's only because isImpliedCondOperands
is not smart enough to prove it further on. Yet the situation when
we come there with `less` predicate is pretty common.


https://reviews.llvm.org/D87890

Files:
  llvm/lib/Analysis/ScalarEvolution.cpp


Index: llvm/lib/Analysis/ScalarEvolution.cpp
===================================================================
--- llvm/lib/Analysis/ScalarEvolution.cpp
+++ llvm/lib/Analysis/ScalarEvolution.cpp
@@ -9720,8 +9720,23 @@
 
           if (isImpliedCondOperands(Pred, LHS, RHS, V, getConstant(Min)))
             return true;
+          break;
+
+        // `LHS < RHS` is handled in the same way as `RHS > LHS`.
+        case ICmpInst::ICMP_SLE:
+        case ICmpInst::ICMP_ULE:
+          if (isImpliedCondOperands(CmpInst::getSwappedPredicate(Pred), RHS,
+                                    LHS, V, getConstant(SharperMin)))
+            return true;
           LLVM_FALLTHROUGH;
 
+        case ICmpInst::ICMP_SLT:
+        case ICmpInst::ICMP_ULT:
+          if (isImpliedCondOperands(CmpInst::getSwappedPredicate(Pred), RHS,
+                                    LHS, V, getConstant(Min)))
+            return true;
+          break;
+
         default:
           // No change
           break;


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