[llvm] [InstCombine] Add support for GEPs in `simplifyNonNullOperand` (PR #128365)

[Nikita Popov via llvm-commits]

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@@ -3996,8 +3996,12 @@ Instruction *InstCombinerImpl::visitCallBase(CallBase &Call) {
     if (V->getType()->isPointerTy()) {
       // Simplify the nonnull operand if the parameter is known to be nonnull.
       // Otherwise, try to infer nonnull for it.
-      if (Call.paramHasNonNullAttr(ArgNo, /*AllowUndefOrPoison=*/true)) {
-        if (Value *Res = simplifyNonNullOperand(V)) {
+      bool HasDereferenceable = Call.getParamDereferenceableBytes(ArgNo) > 0;
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nikic wrote:

Alternatively, could add a HasDereferenceable out parameter to paramHasNonNullAttr.

https://github.com/llvm/llvm-project/pull/128365