llvm-6502

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Jingyue Wu dcc9291851 [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

2014-06-17 00:42:07 +00:00

CMakeLists.txt

…

InstCombine.h

[InstCombine] mark ADD with nuw if no unsigned overflow

2014-06-17 00:42:07 +00:00

InstCombineAddSub.cpp

[InstCombine] mark ADD with nuw if no unsigned overflow

2014-06-17 00:42:07 +00:00

InstCombineAndOrXor.cpp

Reorder shuffle and binary operation.

2014-05-11 08:46:12 +00:00