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| author | Jingyue Wu <jingyue@google.com> | 2014-06-17 00:42:07 +0000 |
|---|---|---|
| committer | Jingyue Wu <jingyue@google.com> | 2014-06-17 00:42:07 +0000 |
| commit | dcc92918519125050edd5823567179143b20042a (patch) | |
| tree | 98286f32d174b34f057a2052e1c4bf4c5055c7c8 /lib/Support | |
| parent | 4072aa3649ff90ab4ea2b7c7ff5970ec1be496eb (diff) | |
| download | llvm-dcc92918519125050edd5823567179143b20042a.tar.gz llvm-dcc92918519125050edd5823567179143b20042a.tar.bz2 llvm-dcc92918519125050edd5823567179143b20042a.tar.xz | |
[InstCombine] mark ADD with nuw if no unsigned overflow
Summary:
As a starting step, we only use one simple heuristic: if the sign bits
of both a and b are zero, we can prove "add a, b" do not unsigned
overflow, and thus convert it to "add nuw a, b".
Updated all affected tests and added two new tests (@zero_sign_bit and
@zero_sign_bit2) in AddOverflow.ll
Test Plan: make check-all
Reviewers: eliben, rafael, meheff, chandlerc
Reviewed By: chandlerc
Subscribers: chandlerc, llvm-commits
Differential Revision: http://reviews.llvm.org/D4144
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211084 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Support')
0 files changed, 0 insertions, 0 deletions