[all-commits] [llvm/llvm-project] eeb2f7: [SelectionDAG][X86] Fix the assertion failure in R...

[Shengchen Kan via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: eeb2f72a493368d892653203feec03ce484bf17c
      https://github.com/llvm/llvm-project/commit/eeb2f72a493368d892653203feec03ce484bf17c
  Author: Shengchen Kan <shengchen.kan at intel.com>
  Date:   2024-05-27 (Mon, 27 May 2024)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    M llvm/lib/Target/X86/X86ISelLowering.cpp

  Log Message:
  -----------
  [SelectionDAG][X86] Fix the assertion failure in Release build after #91747 (#93434)

In #91747, we changed the SDNode from `X86ISD::SUB` (FROM) to
`X86ISD::CCMP`
(TO) in the DAGCombine. The value type of `X86ISD::SUB` can be `i8, i32`
while the value type of `X86ISD::CCMP` is i32. This breaks the
assumption
that the value type should match after the combine and triggers the
error

```
SelectionDAG.cpp:10942: void
llvm::SelectionDAG::transferDbgValues(llvm::SDValue, llvm::SDValue,
unsigned int, unsigned int, bool): Assertion `FromNode && ToNode &&
"Can't modify dbg values"' failed.
```

when running tests

llvm/test/CodeGen/X86/apx/ccmp.ll
llvm/test/CodeGen/X86/apx/ctest.ll

in Release build when LLVM_ENABLE_ASSERTIONS is on.

In this patch, we fix it by creating a merged value.



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