[llvm] [InstCombine] Simplify nonnull pointers (PR #128111)

[Nikita Popov via llvm-commits]

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@@ -3993,10 +3993,20 @@ Instruction *InstCombinerImpl::visitCallBase(CallBase &Call) {
   unsigned ArgNo = 0;
 
   for (Value *V : Call.args()) {
-    if (V->getType()->isPointerTy() &&
-        !Call.paramHasAttr(ArgNo, Attribute::NonNull) &&
-        isKnownNonZero(V, getSimplifyQuery().getWithInstruction(&Call)))
-      ArgNos.push_back(ArgNo);
+    if (V->getType()->isPointerTy()) {
+      // Simplify the nonnull operand before nonnull inference to avoid
+      // unnecessary queries.
+      if (Call.paramHasNonNullAttr(ArgNo, /*AllowUndefOrPoison=*/true)) {
+        if (Value *Res = simplifyNonNullOperand(V)) {
+          replaceOperand(Call, ArgNo, Res);
+          Changed = true;
+        }
+      }
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nikic wrote:

Can else this instead of querying nonnull again? (Will no longer infer nonnull for dereferenceable, but we shouldn't need to ?)

https://github.com/llvm/llvm-project/pull/128111