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| author | Roman Lebedev <lebedev.ri@gmail.com> | 2019-10-04 22:16:22 +0000 |
|---|---|---|
| committer | Roman Lebedev <lebedev.ri@gmail.com> | 2019-10-04 22:16:22 +0000 |
| commit | fb5af8b9b93cb270fda7832e24cab9cb62dec16f (patch) | |
| tree | a339bff1c5a427fddaf3ac2f873607087f7e61a6 /llvm/test/Transforms/InstCombine/shift.ll | |
| parent | f304d4d185d24eec9f0ca84d566da0d51b2344ef (diff) | |
| download | bcm5719-llvm-fb5af8b9b93cb270fda7832e24cab9cb62dec16f.tar.gz bcm5719-llvm-fb5af8b9b93cb270fda7832e24cab9cb62dec16f.zip | |
[InstCombine] Fold 'icmp eq/ne (?trunc (lshr/ashr %x, bitwidth(x)-1)), 0' -> 'icmp sge/slt %x, 0'
We do indeed already get it right in some cases, but only transitively,
with one-use restrictions. Since we only need to produce a single
comparison, it makes sense to match the pattern directly:
https://rise4fun.com/Alive/kPg
llvm-svn: 373802
Diffstat (limited to 'llvm/test/Transforms/InstCombine/shift.ll')
| -rw-r--r-- | llvm/test/Transforms/InstCombine/shift.ll | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/llvm/test/Transforms/InstCombine/shift.ll b/llvm/test/Transforms/InstCombine/shift.ll index 501f015ed73..9ded69ad7b9 100644 --- a/llvm/test/Transforms/InstCombine/shift.ll +++ b/llvm/test/Transforms/InstCombine/shift.ll @@ -428,8 +428,8 @@ define i8 @test28a(i8 %x, i8 %y) { ; CHECK-LABEL: @test28a( ; CHECK-NEXT: entry: ; CHECK-NEXT: [[TMP1:%.*]] = lshr i8 [[X:%.*]], 7 -; CHECK-NEXT: [[COND1:%.*]] = icmp eq i8 [[TMP1]], 0 -; CHECK-NEXT: br i1 [[COND1]], label [[BB2:%.*]], label [[BB1:%.*]] +; CHECK-NEXT: [[COND1:%.*]] = icmp slt i8 [[X]], 0 +; CHECK-NEXT: br i1 [[COND1]], label [[BB1:%.*]], label [[BB2:%.*]] ; CHECK: bb1: ; CHECK-NEXT: ret i8 [[TMP1]] ; CHECK: bb2: |
