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| author | Florian Hahn <flo@fhahn.com> | 2021-06-21 19:11:11 +0100 |
|---|---|---|
| committer | Florian Hahn <flo@fhahn.com> | 2021-06-22 11:27:51 +0100 |
| commit | d17798823ca2213af353e125f6f5233522dda7ce (patch) | |
| tree | fb1dcea5d956ba67f1121e6583780a7b7f50f886 /llvm/lib/Bitcode/Reader/BitcodeReader.cpp | |
| parent | 98e2b1a8dd8ff03b6289a40a16fe749834257494 (diff) | |
[SCEV] Retain AddExpr flags when subtracting a foldable constant.
Currently we drop wrapping flags for expressions like (A + C1)<flags> - C2.
But we can retain flags under certain conditions:
* Adding a smaller constant is NUW if the original AddExpr was NUW.
* Adding a constant with the same sign and small magnitude is NSW, if the
original AddExpr was NSW.
This can improve results after using `SimplifyICmpOperands`, which may
subtract one in order to use stricter predicates, as is the case for
`isKnownPredicate`.
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D104319
Diffstat (limited to 'llvm/lib/Bitcode/Reader/BitcodeReader.cpp')
0 files changed, 0 insertions, 0 deletions