| Issue |
143000
|
| Summary |
[X86] Remove LowerToHorizontalOp and update test coverage
|
| Labels |
backend:X86
|
| Assignees |
|
| Reporter |
RKSimon
|
LowerToHorizontalOp is a x86 DAG lowering that tries to vectorize horizontal add/sub code into SSE HADD/SUB vector instructions.
Its also a lot of X86ISelLowering code that is almost certainly unnecessary now.
SLP + VectorCombine between them should be handling all of this, so the backend is very unlikely to encounter real-world scalar patterns a anymore.
So, this task involves:
- Disable LowerToHorizontalOp
- Review all CodeGen/X86 test changes
- Convert the changed CodeGen/X86 tests into similar PhaseOrdering/X86 tests to track the vectorized IR (for the various slow/fast SSE/AVX targets)
- Replace the CodeGen/X86 test coverage with the real vectorized IR
- Remove LowerToHorizontalOp and all its support methods
- Handle any CodeGen regressions (maybe a cost model, transform or backend fix)
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