[llvm] [IR] Require that ptrmask mask matches pointer index size (PR #69343)

[Alexander Richardson via llvm-commits]

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@@ -7420,11 +7420,12 @@ void SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I,
   }
   case Intrinsic::ptrmask: {
     SDValue Ptr = getValue(I.getOperand(0));
-    SDValue Const = getValue(I.getOperand(1));
+    SDValue Mask = getValue(I.getOperand(1));
 
     EVT PtrVT = Ptr.getValueType();
-    setValue(&I, DAG.getNode(ISD::AND, sdl, PtrVT, Ptr,
-                             DAG.getZExtOrTrunc(Const, sdl, PtrVT)));
+    assert(PtrVT == Mask.getValueType() &&
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arichardson wrote:

I had a quick [look at CHERI LLVM](https://github.com/CTSRD-CHERI/llvm-project/blob/20ce0d45e296b441250cd30df1a93f607107f189/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp#L7225) and it appears this code has not been adapted (yet), so it seems like it hasn't compiled any code where ptrmask reaches SDAG. Having an assertion with a sensible error message rather than failures later on is definitely an improvement :) 

https://github.com/llvm/llvm-project/pull/69343