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| author | Jim Grosbach <grosbach@apple.com> | 2013-08-13 21:30:58 +0000 |
|---|---|---|
| committer | Jim Grosbach <grosbach@apple.com> | 2013-08-13 21:30:58 +0000 |
| commit | 327ccc787eb5dec947a99a99390313a9fa88f907 (patch) | |
| tree | 7f85aab36caaf898ebb10d093fe66f93a6fe37ee /lldb/source/Plugins/ObjectFile | |
| parent | d505fbf40376dd7ace0ef50e794a840f54091586 (diff) | |
| download | bcm5719-llvm-327ccc787eb5dec947a99a99390313a9fa88f907.tar.gz bcm5719-llvm-327ccc787eb5dec947a99a99390313a9fa88f907.zip | |
DAG: Combine (and (setne X, 0), (setne X, -1)) -> (setuge (add X, 1), 2)
A common idiom is to use zero and all-ones as sentinal values and to
check for both in a single conditional ("x != 0 && x != (unsigned)-1").
That generates code, for i32, like:
testl %edi, %edi
setne %al
cmpl $-1, %edi
setne %cl
andb %al, %cl
With this transform, we generate the simpler:
incl %edi
cmpl $1, %edi
seta %al
Similar improvements for other integer sizes and on other platforms. In
general, combining the two setcc instructions into one is better.
rdar://14689217
llvm-svn: 188315
Diffstat (limited to 'lldb/source/Plugins/ObjectFile')
0 files changed, 0 insertions, 0 deletions
