[llvm] [LoopVectorize] Add support for vectorisation of simple early exit loops (PR #88385)

[Graham Hunter via llvm-commits]

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@@ -8592,6 +8595,66 @@ ScalarEvolution::BackedgeTakenInfo::getExact(const Loop *L, ScalarEvolution *SE,
   return SE->getUMinFromMismatchedTypes(Ops, /* Sequential */ true);
 }
 
+void ScalarEvolution::BackedgeTakenInfo::getExactExitingBlocks(
+    const Loop *L, ScalarEvolution *SE,
+    SmallVector<BasicBlock *, 4> *Blocks) const {
+  // All exiting blocks we have collected must dominate the only backedge.
+  const BasicBlock *Latch = L->getLoopLatch();
+  if (!Latch || !hasAnyInfo())
+    return;
+
+  for (const auto &ENT : ExitNotTaken) {
+    const SCEV *BECount = ENT.ExactNotTaken;
+    if (BECount == SE->getCouldNotCompute())
+      continue;
+    Blocks->push_back(ENT.ExitingBlock);
+  }
+
+  return;
+}
+
+const SCEV *ScalarEvolution::BackedgeTakenInfo::getSpeculative(
+    const Loop *L, ScalarEvolution *SE,
+    SmallVector<const SCEVPredicate *, 4> *Preds) const {
+  // All exiting blocks we have collected must dominate the only backedge.
+  const BasicBlock *Latch = L->getLoopLatch();
+  if (!Latch)
+    return SE->getCouldNotCompute();
+
+  if (!hasAnyInfo())
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huntergr-arm wrote:

You can combine this with the above '!Latch' check.

https://github.com/llvm/llvm-project/pull/88385