llvm-project

History

Philip Reames 2ca8a3f213 [SCEV] Stop blindly propagating flags from inbound geps to SCEV nodes This fixes a violation of the wrap flag rules introduced in `c4048d8f`. This was also noted in the (very old) PR23527. The issue being fixed is that we assume the inbound flag on any GEP assumes that all users of any gep (or add) which happens to map to that SCEV would also be UB if the (other) gep overflowed. That's simply not true. In terms of the test diffs, I don't see anything seriously problematic. The lost flags are expected (given the semantic restriction on when its legal to tag the SCEV), and there are several cases where the previously inferred flags are unsound per the new semantics. The only common trend I noticed when looking at the deltas is that by not considering branch on poison as immediate UB in ValueTracking, we do miss a few cases we could reclaim. We may be able to claw some of these back with the follow ideas mentioned in PR51817. It's worth noting that most of the changes are analysis result only changes. The two transform changes are pretty minimal. In one case, we miss the opportunity to infer a nuw (correctly). In the other, we fail to fold an exit and produce a loop invariant form instead. This one is probably over-reduced as the program appears to be undefined in practice, and neither before or after exploits that. Differential Revision: https://reviews.llvm.org/D109789		2021-10-01 16:30:44 -07:00
..
cmake	[Windows][Polly] Disable LLVMPolly module for all compilers on Windows	2020-09-15 09:12:38 +03:00
docs	polly: remove the old reference to svn in the doc	2021-08-27 10:46:50 +02:00
include/polly	[Polly] Reject regions entered by an indirectbr/callbr.	2021-09-27 18:49:11 -05:00
lib	[Polly] Check the properties of accesses to operands of a matrix-matrix	2021-09-28 22:58:57 +05:00
test	[SCEV] Stop blindly propagating flags from inbound geps to SCEV nodes	2021-10-01 16:30:44 -07:00
tools	…
unittests	[Polly] Don't redundantly link libPolly into unittests.	2021-08-24 03:07:30 -05:00
utils	Harmonize Python shebang	2020-07-16 21:53:45 +02:00
www	[Branch-Rename] Fix some links	2021-02-01 16:43:21 +05:30
.arclint	…
.gitattributes	…
.gitignore	…
CMakeLists.txt	Remove .svn from exclude list as we moved to git	2020-10-21 16:09:21 +02:00
CREDITS.txt	…
LICENSE.TXT	Rename top-level LICENSE.txt files to LICENSE.TXT	2021-03-10 21:26:24 -08:00
README	…

README

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.