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| author | Roman Lebedev <lebedev.ri@gmail.com> | 2019-07-01 15:55:24 +0000 |
|---|---|---|
| committer | Roman Lebedev <lebedev.ri@gmail.com> | 2019-07-01 15:55:24 +0000 |
| commit | 04d3d3bbff55ec3d605c5262551e64e967547599 (patch) | |
| tree | 9edd971f778bd78a55fab1b33fcc5ca0ce4f8730 /llvm/lib/Transforms | |
| parent | 72b8d41ce811fa1a20711e0619d4a5307a754e57 (diff) | |
| download | bcm5719-llvm-04d3d3bbff55ec3d605c5262551e64e967547599.tar.gz bcm5719-llvm-04d3d3bbff55ec3d605c5262551e64e967547599.zip | |
[InstCombine] (Y + ~X) + 1 --> Y - X fold (PR42459)
Summary:
To be noted, this pattern is not unhandled by instcombine per-se,
it is somehow does end up being folded when one runs opt -O3,
but not if it's just -instcombine. Regardless, that fold is
indirect, depends on some other folds, and is thus blind
when there are extra uses.
This does address the regression being exposed in D63992.
https://godbolt.org/z/7DGltU
https://rise4fun.com/Alive/EPO0
Fixes [[ https://bugs.llvm.org/show_bug.cgi?id=42459 | PR42459 ]]
Reviewers: spatel, nikic, huihuiz
Reviewed By: spatel
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63993
llvm-svn: 364792
Diffstat (limited to 'llvm/lib/Transforms')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp index f71d23974ba..0b0cc4bc6e7 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp @@ -1202,7 +1202,10 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) { // (A + 1) + ~B --> A - B // ~B + (A + 1) --> A - B - if (match(&I, m_c_BinOp(m_Add(m_Value(A), m_One()), m_Not(m_Value(B))))) + // (~B + A) + 1 --> A - B + // (A + ~B) + 1 --> A - B + if (match(&I, m_c_BinOp(m_Add(m_Value(A), m_One()), m_Not(m_Value(B)))) || + match(&I, m_BinOp(m_c_Add(m_Not(m_Value(B)), m_Value(A)), m_One()))) return BinaryOperator::CreateSub(A, B); // X % C0 + (( X / C0 ) % C1) * C0 => X % (C0 * C1) |
