Florian Hahn f8734a5e10
[SCEV] Introduce SCEVUse, use it instead of const SCEV * (NFCI). (#91961)
This patch introduces SCEVUse, which is a tagged pointer containing the
used const SCEV *, plus extra bits to store NUW/NSW flags that are only
valid at the specific use.

This was suggested by @nikic as an alternative
to https://github.com/llvm/llvm-project/pull/90742.

This patch just updates most SCEV infrastructure to operate on SCEVUse
instead of const SCEV *. It does not introduce any code that makes use
of the use-specific flags yet which I'll share as follow-ups.

Compile-time impact: https://llvm-compile-time-tracker.com/compare.php?from=ee34eb6edccdebc2a752ffecdde5faae6b0d5593&to=5a7727d7819414d2acbc5b6ab740f0fc2363e842&stat=instructions%3Au
2026-03-13 16:23:06 +00:00
..

Polly - Polyhedral optimizations for LLVM
-----------------------------------------
http://polly.llvm.org/

Polly uses a mathematical representation, the polyhedral model, to represent and
transform loops and other control flow structures. Using an abstract
representation it is possible to reason about transformations in a more general
way and to use highly optimized linear programming libraries to figure out the
optimal loop structure. These transformations can be used to do constant
propagation through arrays, remove dead loop iterations, optimize loops for
cache locality, optimize arrays, apply advanced automatic parallelization, drive
vectorization, or they can be used to do software pipelining.