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

[Matt Arsenault via llvm-commits]

================
@@ -5188,6 +5188,83 @@ struct AADereferenceableCallSiteReturned final
 // ------------------------ Align Argument Attribute ------------------------
 
 namespace {
+
+static std::optional<uint64_t>
+getKnownAlignForIntrinsic(Attributor &A, AAAlign &QueryingAA,
+                          const IntrinsicInst *II) {
+  switch (II->getIntrinsicID()) {
+  case Intrinsic::ptrmask: {
+    auto *ConstVals = A.getAAFor<AAPotentialConstantValues>(
+        QueryingAA, IRPosition::value(*(II->getOperand(1))), DepClassTy::NONE);
+    const AAAlign *AlignAA = A.getAAFor<AAAlign>(
+        QueryingAA, IRPosition::value(*(II)), DepClassTy::NONE);
+    if (ConstVals && ConstVals->isValidState()) {
+      if (ConstVals->isAtFixpoint()) {
+        const DataLayout &DL = A.getDataLayout();
+        unsigned Size =
+            DL.getPointerTypeSizeInBits(II->getOperand(0)->getType());
+        uint64_t TrailingZeros = Size;
+        for (const auto &It : ConstVals->getAssumedSet())
+          if (It.countTrailingZeros() < TrailingZeros)
+            TrailingZeros = It.countTrailingZeros();
+        if (TrailingZeros < Size) {
+          uint64_t Mask = 1 << TrailingZeros;
+          if (Mask >= AlignAA->getKnownAlign().value()) {
+            return 0;
+          }
+        }
+        return AlignAA->getKnownAlign().value();
+      }
+    } else if (AlignAA) {
+      return AlignAA->getKnownAlign().value();
+    }
+    break;
+  }
+  default:
+    break;
+  }
+  return std::nullopt;
+}
+
+static std::optional<uint64_t>
+getAssumedAlignForIntrinsic(Attributor &A, AAAlign &QueryingAA,
+                            const IntrinsicInst *II) {
+  switch (II->getIntrinsicID()) {
+  case Intrinsic::ptrmask: {
+    const AAPotentialConstantValues *ConstVals =
+        A.getAAFor<AAPotentialConstantValues>(
+            QueryingAA, IRPosition::value(*(II->getOperand(1))),
+            DepClassTy::REQUIRED);
+    const AAAlign *AlignAA =
+        A.getAAFor<AAAlign>(QueryingAA, IRPosition::value(*(II->getOperand(0))),
+                            DepClassTy::REQUIRED);
+    uint64_t Alignment = 0;
+    if (ConstVals && ConstVals->isValidState()) {
+      const DataLayout &DL = A.getDataLayout();
+      unsigned Size = DL.getPointerTypeSizeInBits(II->getOperand(0)->getType());
+      unsigned TrailingZeros = Size;
+      for (const auto &It : ConstVals->getAssumedSet())
+        if (It.countTrailingZeros() < TrailingZeros)
+          TrailingZeros = It.countTrailingZeros();
+      if (TrailingZeros < Size)
+        Alignment = 1 << TrailingZeros;
+    }
+    if (AlignAA && AlignAA->isValidState() &&
+        Alignment < AlignAA->getAssumedAlign().value())
+      Alignment = AlignAA->getAssumedAlign().value();
+
+    if (Alignment != 0) {
+      return Alignment;
+    }
+    return QueryingAA.getAssumedAlign().value();
+    break;
----------------
arsenm wrote:

Dead break 

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