[llvm] LoopVectorize: run verifyFunction once (PR #91470)

[David Sherwood via llvm-commits]

================
@@ -10359,6 +10357,8 @@ LoopVectorizeResult LoopVectorizePass::runImpl(
     }
   }
 
+  assert(!Changed || !verifyFunction(F, &dbgs()));
----------------
david-arm wrote:

Ah sorry @fhahn, I hadn't appreciated that we might end up verifying even when not vectorising. That's potentially a compile-time regression in some cases then.

https://github.com/llvm/llvm-project/pull/91470