Commit Graph

7 Commits

Author SHA1 Message Date
Eric Christopher cee313d288 Revert "Temporarily Revert "Add basic loop fusion pass.""
The reversion apparently deleted the test/Transforms directory.

Will be re-reverting again.

llvm-svn: 358552
2019-04-17 04:52:47 +00:00
Eric Christopher a863435128 Temporarily Revert "Add basic loop fusion pass."
As it's causing some bot failures (and per request from kbarton).

This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda.

llvm-svn: 358546
2019-04-17 02:12:23 +00:00
Nikita Popov af2b0bef43 [ValueTracking] More accurate unsigned sub overflow detection
Second part of D58593.

Compute precise overflow conditions based on all known bits, rather
than just the sign bits. Unsigned a - b overflows iff a < b, and we
can determine whether this always/never happens based on the minimal
and maximal values achievable for a and b subject to the known bits
constraint.

llvm-svn: 355109
2019-02-28 18:04:20 +00:00
Sanjay Patel 63cf26cf01 [InstCombine] fix xor-or-xor fold to check uses and handle commutes
I'm probably missing some way to use m_Deferred to remove the code
duplication, but that can be a follow-up.

The improvement in demand_shrink_nsw.ll is an example of missing
the fold because the pattern matching was deficient. I didn't try
to follow the bits in that test, but Alive says it's correct:
https://rise4fun.com/Alive/ugc

llvm-svn: 341426
2018-09-04 23:22:13 +00:00
Sanjay Patel 018ce562a9 [InstCombine] update tests checks; NFC
llvm-svn: 341424
2018-09-04 23:08:23 +00:00
Craig Topper cff357c322 [InstCombine][KnownBits] Use KnownBits better to detect nsw adds
Change checkRippleForAdd from a heuristic to a full check -
if it is provable that the add does not overflow return true, otherwise false.

Patch by Yoav Ben-Shalom

Differential Revision: https://reviews.llvm.org/D32686

llvm-svn: 302093
2017-05-03 23:22:46 +00:00
Matthias Braun e48484c64f InstCombineSimplifyDemanded: Remove nsw/nuw flags when optimizing demanded bits
When optimizing demanded bits of the operands of an Add we have to
remove the nsw/nuw flags as we have no guarantee anymore that we don't
wrap.  This is legal here because the top bit is not demanded.  In fact
this operaion was already performed but missed in the case of an Add
with a constant on the right side.  To fix this this patch refactors the
code to unify the code paths in SimplifyDemandedUseBits() handling of
Add/Sub:

- The transformation of Add->Or is removed from the simplify demand
  code because the equivalent transformation exists in
  InstCombiner::visitAdd()
- KnownOnes/KnownZero are not adjusted for Add x, C anymore as
  computeKnownBits() already performs these computations.
- The simplification of the operands is unified. In this new version
  constant on the right side of a Sub are shrunk now as I could not find
  a reason why not to do so.
- The special case for clearing nsw/nuw in ShrinkDemandedConstant() is
  not necessary anymore as the caller does that already.

Differential Revision: http://reviews.llvm.org/D9415

llvm-svn: 236269
2015-04-30 22:05:30 +00:00