[llvm] [LoopVectorize] Perform loop versioning for some early exit loops (PR #120603)

[David Sherwood via llvm-commits]

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@@ -1735,15 +1772,18 @@ bool LoopVectorizationLegality::isVectorizableEarlyExitLoop() {
   assert(LatchBB->getUniquePredecessor() == SingleUncountableEdge->first &&
          "Expected latch predecessor to be the early exiting block");
 
-  // TODO: Handle loops that may fault.
   Predicates.clear();
-  if (!isDereferenceableReadOnlyLoop(TheLoop, PSE.getSE(), DT, AC,
-                                     &Predicates)) {
-    reportVectorizationFailure(
-        "Loop may fault",
-        "Cannot vectorize potentially faulting early exit loop",
-        "PotentiallyFaultingEarlyExitLoop", ORE, TheLoop);
-    return false;
+  SmallVector<LoadInst *, 4> Loads;
+  if (!isDereferenceableReadOnlyLoop(TheLoop, PSE.getSE(), DT, AC, &Predicates,
+                                     &Loads)) {
+    if (!TTI->getMinPageSize() || !analyzePotentiallyFaultingLoads(&Loads)) {
+      reportVectorizationFailure(
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david-arm wrote:

I've just removed `isDereferenceableReadOnlyLoop` now and inlined some of the logic into the loop above.

https://github.com/llvm/llvm-project/pull/120603