[llvm] [LoopIdiom] Fix a DL-related crash in optimizeCRCLoop (PR #161509)

[Ramkumar Ramachandra via llvm-commits]

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@@ -1545,6 +1545,12 @@ bool LoopIdiomRecognize::optimizeCRCLoop(const PolynomialInfo &Info) {
   if (TT.getArch() == Triple::hexagon)
     return false;
 
+  // Check that the DataLayout allows us to index into the new 256-entry CRC
+  // table.
+  Type *IdxTy = SE->getDataLayout().getIndexType(M.getContext(), 0);
+  if (IdxTy->getIntegerBitWidth() < 8)
+    return false;
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artagnon wrote:

Hm, pending on @nikic's expertise, I don't think anything in LLVM would work in the exotic scenario.

https://github.com/llvm/llvm-project/pull/161509