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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/test/Transforms/InstCombine/add.ll | |
| 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/test/Transforms/InstCombine/add.ll')
| -rw-r--r-- | llvm/test/Transforms/InstCombine/add.ll | 10 |
1 files changed, 3 insertions, 7 deletions
diff --git a/llvm/test/Transforms/InstCombine/add.ll b/llvm/test/Transforms/InstCombine/add.ll index a2f35cc4359..c31c74020fa 100644 --- a/llvm/test/Transforms/InstCombine/add.ll +++ b/llvm/test/Transforms/InstCombine/add.ll @@ -951,9 +951,7 @@ define i32 @add_not_increment_commuted(i32 %A, i32 %B) { define i32 @add_to_sub(i32 %M, i32 %B) { ; CHECK-LABEL: @add_to_sub( ; CHECK-NEXT: [[A:%.*]] = mul i32 [[M:%.*]], 42 -; CHECK-NEXT: [[C:%.*]] = xor i32 [[B:%.*]], -1 -; CHECK-NEXT: [[D:%.*]] = add i32 [[A]], [[C]] -; CHECK-NEXT: [[E:%.*]] = add i32 [[D]], 1 +; CHECK-NEXT: [[E:%.*]] = sub i32 [[A]], [[B:%.*]] ; CHECK-NEXT: ret i32 [[E]] ; %A = mul i32 %M, 42 ; thwart complexity-based ordering @@ -966,10 +964,8 @@ define i32 @add_to_sub(i32 %M, i32 %B) { ; E = (~B + A) + 1 = A - B define i32 @add_to_sub2(i32 %A, i32 %M) { ; CHECK-LABEL: @add_to_sub2( -; CHECK-NEXT: [[B:%.*]] = mul i32 [[M:%.*]], 42 -; CHECK-NEXT: [[C:%.*]] = xor i32 [[B]], -1 -; CHECK-NEXT: [[D:%.*]] = add i32 [[C]], [[A:%.*]] -; CHECK-NEXT: [[E:%.*]] = add i32 [[D]], 1 +; CHECK-NEXT: [[TMP1:%.*]] = mul i32 [[M:%.*]], -42 +; CHECK-NEXT: [[E:%.*]] = add i32 [[TMP1]], [[A:%.*]] ; CHECK-NEXT: ret i32 [[E]] ; %B = mul i32 %M, 42 ; thwart complexity-based ordering |
