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| author | David Majnemer <david.majnemer@gmail.com> | 2013-05-18 19:30:37 +0000 |
|---|---|---|
| committer | David Majnemer <david.majnemer@gmail.com> | 2013-05-18 19:30:37 +0000 |
| commit | beab5678a33a333e617079ca851215312446f7b0 (patch) | |
| tree | 4b464da8dc2a5f2076a42717153be3cdab7ce8cb /llvm/test/Transforms | |
| parent | 693a1ca6284f5145d261b390156507f12046d4c6 (diff) | |
| download | bcm5719-llvm-beab5678a33a333e617079ca851215312446f7b0.tar.gz bcm5719-llvm-beab5678a33a333e617079ca851215312446f7b0.zip | |
isKnownToBeAPowerOfTwo: (X & Y) + Y is a power of 2 or zero if y is also.
This is useful if something that looks like (x & (1 << y)) ? 64 : 32 is
the divisor in a modulo operation.
llvm-svn: 182200
Diffstat (limited to 'llvm/test/Transforms')
| -rw-r--r-- | llvm/test/Transforms/InstCombine/rem.ll | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/llvm/test/Transforms/InstCombine/rem.ll b/llvm/test/Transforms/InstCombine/rem.ll index 450a62ae6de..808d51eba1d 100644 --- a/llvm/test/Transforms/InstCombine/rem.ll +++ b/llvm/test/Transforms/InstCombine/rem.ll @@ -149,3 +149,17 @@ define i64 @test15(i32 %x, i32 %y) { %urem = urem i64 %zext1, %zext0 ret i64 %urem } + +define i32 @test16(i32 %x, i32 %y) { +; CHECK: @test16 +; CHECK-NEXT: [[SHR:%.*]] = lshr i32 %y, 11 +; CHECK-NEXT: [[AND:%.*]] = and i32 [[SHR]], 4 +; CHECK-NEXT: [[OR:%.*]] = or i32 [[AND]], 3 +; CHECK-NEXT: [[REM:%.*]] = and i32 [[OR]], %x +; CHECK-NEXT: ret i32 [[REM]] + %shr = lshr i32 %y, 11 + %and = and i32 %shr, 4 + %add = add i32 %and, 4 + %rem = urem i32 %x, %add + ret i32 %rem +} |
