[llvm] [ValueTracking] Support GEPs in matchSimpleRecurrence. (PR #123518)

[Florian Hahn via llvm-commits]

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@@ -1660,6 +1661,11 @@ static void computeKnownBitsFromOperator(const Operator *I,
 
         // We need to take the minimum number of known bits
         KnownBits Known3(BitWidth);
+        if (BitWidth != getBitWidth(L->getType(), Q.DL)) {
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fhahn wrote:

Yep, but unfortunately computeKnowNbits has some assertions that the bitwdith of the operation matches the bassed in KnowBits.

We could operate on a suitable KnownBits object for the getelementptr, and extend as needed as follow-up, if there are any cases this would help.

https://github.com/llvm/llvm-project/pull/123518