maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity
187,358 Commits 23 Branches 0 Tags 2.2 GiB
Commit Graph

5 Commits

Author SHA1 Message Date
Louis Gerbarg c6b506a0ae 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.

llvm-svn: 209843
 2014-05-29 20:29:47 +00:00
Rafael Espindola 910528a3eb Revert "Add support for combining GEPs across PHI nodes" 
This reverts commit r209755.

it was the real cause of the libc++ build failure.

llvm-svn: 209775
 2014-05-28 21:41:21 +00:00
Louis Gerbarg 727f1cbb17 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.

llvm-svn: 209755
 2014-05-28 17:38:31 +00:00
NAKAMURA Takumi 7ef81a4f98 Revert r209049 and r209065, "Add support for combining GEPs across PHI nodes" 
It broke clang selfhosting even after r209065.

llvm-svn: 209067
 2014-05-17 14:39:21 +00:00
Louis Gerbarg 8d2a43e9be 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.

rdar://15547484

llvm-svn: 209049
 2014-05-16 23:47:24 +00:00