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author | Chris Lattner <sabre@nondot.org> | 2010-08-27 22:53:44 +0000 |
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committer | Chris Lattner <sabre@nondot.org> | 2010-08-27 22:53:44 +0000 |
commit | 4ece577019705e0a4d7f80f8e8fc1f3cfde276ee (patch) | |
tree | 409b539215f3192ae9c1676a89f5ffd5cbcfb8a1 /test/Transforms | |
parent | 0991dfbbe048a88c0f85618f8c9a21d11b34d69c (diff) | |
download | external_llvm-4ece577019705e0a4d7f80f8e8fc1f3cfde276ee.zip external_llvm-4ece577019705e0a4d7f80f8e8fc1f3cfde276ee.tar.gz external_llvm-4ece577019705e0a4d7f80f8e8fc1f3cfde276ee.tar.bz2 |
Enhance the shift propagator to handle the case when you have:
A = shl x, 42
...
B = lshr ..., 38
which can be transformed into:
A = shl x, 4
...
iff we can prove that the would-be-shifted-in bits
are already zero. This eliminates two shifts in the testcase
and allows eliminate of the whole i128 chain in the real example.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112314 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'test/Transforms')
-rw-r--r-- | test/Transforms/InstCombine/shift.ll | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/test/Transforms/InstCombine/shift.ll b/test/Transforms/InstCombine/shift.ll index 91a8ed7..34e1835 100644 --- a/test/Transforms/InstCombine/shift.ll +++ b/test/Transforms/InstCombine/shift.ll @@ -425,3 +425,18 @@ entry: ; CHECK: ret i128 %ins } +define i64 @test37(i128 %A, i32 %B) { +entry: + %tmp27 = shl i128 %A, 64 + %tmp22 = zext i32 %B to i128 + %tmp23 = shl i128 %tmp22, 96 + %ins = or i128 %tmp23, %tmp27 + %tmp45 = lshr i128 %ins, 64 + %tmp46 = trunc i128 %tmp45 to i64 + ret i64 %tmp46 + +; CHECK: %tmp23 = shl i128 %tmp22, 32 +; CHECK: %ins = or i128 %tmp23, %A +; CHECK: %tmp46 = trunc i128 %ins to i64 +} + |