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| author | Arnold Schwaighofer <aschwaighofer@apple.com> | 2013-04-12 15:15:19 +0000 |
|---|---|---|
| committer | Arnold Schwaighofer <aschwaighofer@apple.com> | 2013-04-12 15:15:19 +0000 |
| commit | 08a0e8f8dbae6314dade60e1ef92e73e89c5ff23 (patch) | |
| tree | c92a7deba86db295ab34ac2acbcd84ed94d77325 /lib/MC/MCParser/AsmParser.cpp | |
| parent | b6ad2bd51195f7675db0f71c5826a12a2b7090fc (diff) | |
| download | llvm-08a0e8f8dbae6314dade60e1ef92e73e89c5ff23.tar.gz llvm-08a0e8f8dbae6314dade60e1ef92e73e89c5ff23.tar.bz2 llvm-08a0e8f8dbae6314dade60e1ef92e73e89c5ff23.tar.xz | |
LoopVectorizer: integer division is not a reduction operation
Don't classify idiv/udiv as a reduction operation. Integer division is lossy.
For example : (1 / 2) * 4 != 4/2.
Example:
int a[] = { 2, 5, 2, 2}
int x = 80;
for()
x /= a[i];
Scalar:
x /= 2 // = 40
x /= 5 // = 8
x /= 2 // = 4
x /= 2 // = 2
Vectorized:
<80, 1> / <2,5> //= <40,0>
<40, 0> / <2,2> //= <20,0>
20*0 = 0
radar://13640654
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179381 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/MC/MCParser/AsmParser.cpp')
0 files changed, 0 insertions, 0 deletions