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

[David Sherwood via llvm-commits]

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@@ -10542,8 +10611,19 @@ bool LoopVectorizePass::processLoop(Loop *L) {
     unsigned SelectedIC = std::max(IC, UserIC);
     //  Optimistically generate runtime checks if they are needed. Drop them if
     //  they turn out to not be profitable.
-    if (VF.Width.isVector() || SelectedIC > 1)
+    if (VF.Width.isVector() || SelectedIC > 1) {
+      if (LVL.getNumPotentiallyFaultingLoads()) {
+        assert(SelectedIC == 1 &&
+               "Interleaving not supported for early exit loops and "
+               "potentially faulting loads");
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david-arm wrote:

Yeah potentially, although currently we won't vectorise with UF>1 anyway because it's explicitly disabled in `selectInterleaveCount`. That's because we don't yet handle or'ing together the multiple early exit conditions for all the parts in vplan. So I didn't try adding support for runtime checks when UF>1 because there isn't any way to test it.

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