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| author | Sanjay Patel <spatel@rotateright.com> | 2017-01-30 16:53:03 +0000 |
|---|---|---|
| committer | Sanjay Patel <spatel@rotateright.com> | 2017-01-30 16:53:03 +0000 |
| commit | 8e644c08ee6e921430e1a1f3e9a8b9dab6c0f8f9 (patch) | |
| tree | c1f9cd5f048efeda94fb0389463cf09da54712eb /llvm/test | |
| parent | 5d6687da99d945f4b0b1e020b6583515dca530cc (diff) | |
| download | bcm5719-llvm-8e644c08ee6e921430e1a1f3e9a8b9dab6c0f8f9.tar.gz bcm5719-llvm-8e644c08ee6e921430e1a1f3e9a8b9dab6c0f8f9.zip | |
[InstCombine] fixed to propagate 'exact' on lshr
The original shift is bigger, so this may qualify as 'obvious',
but here's an attempt at an Alive-based proof:
Name: exact
Pre: (C1 u< C2)
%a = shl i8 %x, C1
%b = lshr exact i8 %a, C2
=>
%c = lshr exact i8 %x, C2 - C1
%b = and i8 %c, ((1 << width(C1)) - 1) u>> C2
Optimization is correct!
llvm-svn: 293498
Diffstat (limited to 'llvm/test')
| -rw-r--r-- | llvm/test/Transforms/InstCombine/shift.ll | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/llvm/test/Transforms/InstCombine/shift.ll b/llvm/test/Transforms/InstCombine/shift.ll index ac9b7e1c37f..5e8b4cb3250 100644 --- a/llvm/test/Transforms/InstCombine/shift.ll +++ b/llvm/test/Transforms/InstCombine/shift.ll @@ -937,7 +937,7 @@ define <2 x i32> @test51_splat_vec(<2 x i32> %x) { define i32 @test51_no_nuw(i32 %x) { ; CHECK-LABEL: @test51_no_nuw( -; CHECK-NEXT: [[TMP1:%.*]] = lshr i32 %x, 2 +; CHECK-NEXT: [[TMP1:%.*]] = lshr exact i32 %x, 2 ; CHECK-NEXT: [[B:%.*]] = and i32 [[TMP1]], 536870911 ; CHECK-NEXT: ret i32 [[B]] ; |
