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

[via llvm-commits]

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@@ -5187,6 +5187,59 @@ struct AADereferenceableCallSiteReturned final
 // ------------------------ Align Argument Attribute ------------------------
 
 namespace {
+
+Align getKnownAlignForIntrinsic(Attributor &A, AAAlign &QueryingAA,
+                                const IntrinsicInst &II) {
+  switch (II.getIntrinsicID()) {
+  case Intrinsic::ptrmask: {
+    const auto *ConstVals = A.getAAFor<AAPotentialConstantValues>(
+        QueryingAA, IRPosition::value(*(II.getOperand(1))), DepClassTy::NONE);
+    const auto *AlignAA = A.getAAFor<AAAlign>(QueryingAA, IRPosition::value(II),
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Shoreshen wrote:

Hi @arsenm , this is trying to get the `AAAlign` for the return value of ptrmask, and by doing that we can get the known alignment of that. 

For example if we have:
1. `%p = llvm.ptrmask(%x, %mask)` 
2. We are calculating the known alignment of `%x`
3. There is a load using %p with known alignment of 8

Then we know that `%p`'s known alignment is at least 8, and if `%mask` can not cover, this should be passed to `%x`'s known alignment

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