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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 | 51a0280d296405cb1fdb268e5387867e0db2e46e (patch) | |
| tree | a353cfd76a552d24b9873dc5b7d2e560a11678f7 /tools | |
| parent | af9e3557552c341615052a05d4eeb36d7fd5c33f (diff) | |
| download | external_llvm-51a0280d296405cb1fdb268e5387867e0db2e46e.zip external_llvm-51a0280d296405cb1fdb268e5387867e0db2e46e.tar.gz external_llvm-51a0280d296405cb1fdb268e5387867e0db2e46e.tar.bz2 | |
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
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188315 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'tools')
0 files changed, 0 insertions, 0 deletions