[clang] [llvm] Add support for flag output operand "=@cc" for SystemZ. (PR #125970)

[Ulrich Weigand via cfe-commits]

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@@ -8804,6 +8804,7 @@ SmallVector<SDValue, 4> static simplifyAssumingCCVal(SDValue &Val, SDValue &CC,
   default:
     return {};
   case ISD::Constant:
+  case ISD::CopyFromReg:
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uweigand wrote:

This is not correct.  It will lead to complex subtrees potentially being built up with binary operations that cannot be simplified.  This whole routine is set up to only handle constant values.

https://github.com/llvm/llvm-project/pull/125970