| Issue |
89414
|
| Summary |
[DAG] SelectionDAG.computeKnownBits - add NSW/NUW flags support to ISD::SHL handling
|
| Labels |
good first issue,
llvm:SelectionDAG
|
| Assignees |
|
| Reporter |
RKSimon
|
The call to KnownBits::shl is currently not handling nodes that have the NSW/NUW flags (or a known non zero shift amount).
https://github.com/llvm/llvm-project/blob/e553ac4d8148291914526f4f66f09e362ce0a63f/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp#L3497-L3506
This task will mainly involve adding test coverage - my advice would be to disable the equivalent handling in ValueTracking, run `check-llvm-transforms` to see what tests start failing and see what equivalent tests can be created for CodeGen/X86
https://github.com/llvm/llvm-project/blob/e553ac4d8148291914526f4f66f09e362ce0a63f/llvm/lib/Analysis/ValueTracking.cpp#L1168-L1182
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