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| author | David Majnemer <david.majnemer@gmail.com> | 2014-10-11 10:20:04 +0000 |
|---|---|---|
| committer | David Majnemer <david.majnemer@gmail.com> | 2014-10-11 10:20:04 +0000 |
| commit | fe7fccff11dd78a126199a35b428537385d316a2 (patch) | |
| tree | b2d6bf98c4aa5b24d0f32caad91a7f777ea5b2ac /llvm/test/Transforms | |
| parent | cb9d59665531cb2a894ac8af7e7cf476fba40600 (diff) | |
| download | bcm5719-llvm-fe7fccff11dd78a126199a35b428537385d316a2.tar.gz bcm5719-llvm-fe7fccff11dd78a126199a35b428537385d316a2.zip | |
InstCombine: Don't fold (X <<s log(INT_MIN)) /s INT_MIN to X
Consider the case where X is 2. (2 <<s 31)/s-2147483648 is zero but we
would fold to X. Note that this is valid when we are in the unsigned
domain because we require NUW: 2 <<u 31 results in poison.
This fixes PR21245.
llvm-svn: 219568
Diffstat (limited to 'llvm/test/Transforms')
| -rw-r--r-- | llvm/test/Transforms/InstCombine/div.ll | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/llvm/test/Transforms/InstCombine/div.ll b/llvm/test/Transforms/InstCombine/div.ll index 26e9e336823..5a884ac671d 100644 --- a/llvm/test/Transforms/InstCombine/div.ll +++ b/llvm/test/Transforms/InstCombine/div.ll @@ -247,3 +247,20 @@ define i32 @test28(i32 %a) { ; CHECK-NEXT: %div = mul nuw i32 %a, 12 ; CHECK-NEXT: ret i32 %div } + +define i32 @test29(i32 %a) { + %mul = shl nsw i32 %a, 31 + %div = sdiv i32 %mul, -2147483648 + ret i32 %div +; CHECK-LABEL: @test29( +; CHECK-NEXT: %[[and:.*]] = and i32 %a, 1 +; CHECK-NEXT: ret i32 %[[and]] +} + +define i32 @test30(i32 %a) { + %mul = shl nuw i32 %a, 31 + %div = udiv i32 %mul, -2147483648 + ret i32 %div +; CHECK-LABEL: @test30( +; CHECK-NEXT: ret i32 %a +} |
