[llvm] [LoopVectorize] Enable more early exit vectorisation tests (PR #117008)

[David Sherwood via llvm-commits]

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@@ -10177,13 +10201,32 @@ bool LoopVectorizePass::processLoop(Loop *L) {
     return false;
   }
 
-  if (LVL.hasUncountableEarlyExit() && !EnableEarlyExitVectorization) {
-    reportVectorizationFailure("Auto-vectorization of loops with uncountable "
-                               "early exit is not enabled",
-                               "Auto-vectorization of loops with uncountable "
-                               "early exit is not enabled",
-                               "UncountableEarlyExitLoopsDisabled", ORE, L);
-    return false;
+  if (LVL.hasUncountableEarlyExit()) {
+    if (!EnableEarlyExitVectorization) {
+      reportVectorizationFailure("Auto-vectorization of loops with uncountable "
+                                 "early exit is not enabled",
+                                 "UncountableEarlyExitLoopsDisabled", ORE, L);
+      return false;
+    }
+
+    // In addUsersInExitBlocks we already bail out if there is an outside use
+    // of a loop-defined variable, but it ignores induction variables which are
+    // handled by InnerLoopVectorizer::fixupIVUsers. We need to bail out if we
+    // encounter induction variables too otherwise fixupIVUsers will crash.
+    for (BasicBlock *BB : L->blocks()) {
+      for (Instruction &I : *BB) {
+        for (User *U : I.users()) {
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david-arm wrote:

This is an issue I believe I described in a previous vectoriser call and at the time I mentioned I had a fix for this already. I just haven't had chance to land the fix because it depended upon this patch landing first. In the spirit of landing small, incremental patches I decided it was best to run all the vectoriser tests with the new flag to get the code defended, then follow on with incremental fixes and additional functionality. This patch holds up several other patches and I would prefer not to make this patch dependent on #120260.

https://github.com/llvm/llvm-project/pull/117008