[llvm] [DAG] Remove AssertZext if the input is masked (PR #146052)

[Pierre van Houtryve via llvm-commits]

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@@ -15136,21 +15136,31 @@ SDValue DAGCombiner::visitAssertExt(SDNode *N) {
     }
   }
 
-  // If we have (AssertZext (and (AssertSext X, iX), M), iY) and Y is smaller
-  // than X, and the And doesn't change the lower iX bits, we can move the
-  // AssertZext in front of the And and drop the AssertSext.
   if (Opcode == ISD::AssertZext && N0.getOpcode() == ISD::AND &&
-      N0.hasOneUse() && N0.getOperand(0).getOpcode() == ISD::AssertSext &&
-      isa<ConstantSDNode>(N0.getOperand(1))) {
-    SDValue BigA = N0.getOperand(0);
-    EVT BigA_AssertVT = cast<VTSDNode>(BigA.getOperand(1))->getVT();
+      N0.hasOneUse() && isa<ConstantSDNode>(N0.getOperand(1))) {
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Pierre-vh wrote:

It's unnecessary I think, especially if we just return N0

https://github.com/llvm/llvm-project/pull/146052