[PATCH] D92152: [SCEV] Use isKnownPredicateAt in isLoopBackedgeGuardedByCond

[Max Kazantsev via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG14f2ad0e3cc5: [SCEV] Use isKnownPredicateAt in isLoopBackedgeGuardedByCond (authored by mkazantsev).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D92152/new/

https://reviews.llvm.org/D92152

Files:
  llvm/lib/Analysis/ScalarEvolution.cpp
  llvm/test/Transforms/LoopStrengthReduce/post-inc-icmpzero.ll


Index: llvm/test/Transforms/LoopStrengthReduce/post-inc-icmpzero.ll
===================================================================
--- llvm/test/Transforms/LoopStrengthReduce/post-inc-icmpzero.ll
+++ llvm/test/Transforms/LoopStrengthReduce/post-inc-icmpzero.ll
@@ -69,7 +69,7 @@
 ; CHECK-NEXT:    [[UGLYGEP2:%.*]] = bitcast i8* [[UGLYGEP]] to i16*
 ; CHECK-NEXT:    [[TMP29:%.*]] = load i16, i16* [[LSR_IV810]], align 2
 ; CHECK-NEXT:    store i16 [[TMP29]], i16* [[UGLYGEP2]], align 2
-; CHECK-NEXT:    [[LSR_IV_NEXT]] = add i64 [[LSR_IV]], 2
+; CHECK-NEXT:    [[LSR_IV_NEXT]] = add nuw nsw i64 [[LSR_IV]], 2
 ; CHECK-NEXT:    [[LSR_IV_NEXT3:%.*]] = inttoptr i64 [[LSR_IV_NEXT]] to i16*
 ; CHECK-NEXT:    [[SCEVGEP9:%.*]] = getelementptr [33 x i16], [33 x i16]* [[LSR_IV8]], i64 0, i64 1
 ; CHECK-NEXT:    [[TMP3]] = bitcast i16* [[SCEVGEP9]] to [33 x i16]*
Index: llvm/lib/Analysis/ScalarEvolution.cpp
===================================================================
--- llvm/lib/Analysis/ScalarEvolution.cpp
+++ llvm/lib/Analysis/ScalarEvolution.cpp
@@ -9911,42 +9911,7 @@
   if (isImpliedViaGuard(Latch, Pred, LHS, RHS))
     return true;
 
-  for (DomTreeNode *DTN = DT[Latch], *HeaderDTN = DT[L->getHeader()];
-       DTN != HeaderDTN; DTN = DTN->getIDom()) {
-    assert(DTN && "should reach the loop header before reaching the root!");
-
-    BasicBlock *BB = DTN->getBlock();
-    if (isImpliedViaGuard(BB, Pred, LHS, RHS))
-      return true;
-
-    BasicBlock *PBB = BB->getSinglePredecessor();
-    if (!PBB)
-      continue;
-
-    BranchInst *ContinuePredicate = dyn_cast<BranchInst>(PBB->getTerminator());
-    if (!ContinuePredicate || !ContinuePredicate->isConditional())
-      continue;
-
-    Value *Condition = ContinuePredicate->getCondition();
-
-    // If we have an edge `E` within the loop body that dominates the only
-    // latch, the condition guarding `E` also guards the backedge.  This
-    // reasoning works only for loops with a single latch.
-
-    BasicBlockEdge DominatingEdge(PBB, BB);
-    if (DominatingEdge.isSingleEdge()) {
-      // We're constructively (and conservatively) enumerating edges within the
-      // loop body that dominate the latch.  The dominator tree better agree
-      // with us on this:
-      assert(DT.dominates(DominatingEdge, Latch) && "should be!");
-
-      if (isImpliedCond(Pred, LHS, RHS, Condition,
-                        BB != ContinuePredicate->getSuccessor(0)))
-        return true;
-    }
-  }
-
-  return false;
+  return isKnownPredicateAt(Pred, LHS, RHS, Latch->getTerminator());
 }
 
 bool ScalarEvolution::isBasicBlockEntryGuardedByCond(const BasicBlock *BB,


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