[llvm] [Attributor] Propagate alignment through ptrmask (PR #150158)

[Matt Arsenault via llvm-commits]

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@@ -5502,6 +5528,42 @@ struct AAAlignCallSiteReturned final
   AAAlignCallSiteReturned(const IRPosition &IRP, Attributor &A)
       : Base(IRP, A) {}
 
+  ChangeStatus updateImpl(Attributor &A) override {
+    Instruction *I = getIRPosition().getCtxI();
+    if (auto *II = dyn_cast<IntrinsicInst>(I)) {
+      if (II->getIntrinsicID() == Intrinsic::ptrmask) {
+        const AAPotentialConstantValues *ConstVals =
+            A.getAAFor<AAPotentialConstantValues>(
+                *this, IRPosition::value(*(II->getOperand(1))),
+                DepClassTy::REQUIRED);
+        const AAAlign *AlignAA =
+            A.getAAFor<AAAlign>(*this, IRPosition::value(*(II->getOperand(0))),
+                                DepClassTy::REQUIRED);
+        uint64_t Alignment = 0;
+        if (ConstVals && ConstVals->isValidState()) {
+          unsigned TrailingZeros = 64;
+          for (const auto &It : ConstVals->getAssumedSet())
+            if (It.countTrailingZeros() < TrailingZeros)
+              TrailingZeros = It.countTrailingZeros();
+          if (TrailingZeros < 64)
+            Alignment = 1 << TrailingZeros;
+        }
+        if (AlignAA && AlignAA->isValidState() &&
+            Alignment < AlignAA->getAssumedAlign().value())
+          Alignment = AlignAA->getAssumedAlign().value();
+
+        if (Alignment != 0) {
+          uint64_t OldAssumed = getAssumed();
+          takeAssumedMinimum(Alignment);
+          return OldAssumed == getAssumed() ? ChangeStatus::UNCHANGED
+                                            : ChangeStatus::CHANGED;
+        } else {
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arsenm wrote:

No else after return 

https://github.com/llvm/llvm-project/pull/150158