diff options
| author | Louis Gerbarg <lgg@apple.com> | 2014-05-28 17:38:31 +0000 |
|---|---|---|
| committer | Louis Gerbarg <lgg@apple.com> | 2014-05-28 17:38:31 +0000 |
| commit | a5423f2598c8579fd5438f71048467db9d13abcd (patch) | |
| tree | 3e7fbcdb1bca62fa6a73a2aee2302c7c021cfa8b /docs | |
| parent | 9b7716192728fbdd8ae2ba9a13dcd65d7fe6509f (diff) | |
| download | llvm-a5423f2598c8579fd5438f71048467db9d13abcd.tar.gz llvm-a5423f2598c8579fd5438f71048467db9d13abcd.tar.bz2 llvm-a5423f2598c8579fd5438f71048467db9d13abcd.tar.xz | |
Add support for combining GEPs across PHI nodes
Currently LLVM will generally merge GEPs. This allows backends to use more
complex addressing modes. In some cases this is not happening because there
is PHI inbetween the two GEPs:
GEP1--\
|-->PHI1-->GEP3
GEP2--/
This patch checks to see if GEP1 and GEP2 are similiar enough that they can be
cloned (GEP12) in GEP3's BB, allowing GEP->GEP merging (GEP123):
GEP1--\ --\ --\
|-->PHI1-->GEP3 ==> |-->PHI2->GEP12->GEP3 == > |-->PHI2->GEP123
GEP2--/ --/ --/
This also breaks certain use chains that are preventing GEP->GEP merges that the
the existing instcombine would merge otherwise.
Tests included.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209755 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'docs')
0 files changed, 0 insertions, 0 deletions