diff options
| -rw-r--r-- | lib/Transforms/InstCombine/InstCombineShifts.cpp | 3 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/shift.ll | 19 |
2 files changed, 21 insertions, 1 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineShifts.cpp b/lib/Transforms/InstCombine/InstCombineShifts.cpp index e3232a491b..a0c5ef5338 100644 --- a/lib/Transforms/InstCombine/InstCombineShifts.cpp +++ b/lib/Transforms/InstCombine/InstCombineShifts.cpp @@ -168,8 +168,9 @@ static bool CanEvaluateShifted(Value *V, unsigned NumBits, bool isLeftShift, // We can always turn lshr(c1)+shl(c2) -> lshr(c3)+and(c4), but it isn't // profitable unless we know the and'd out bits are already zero. if (CI->getZExtValue() > NumBits) { + unsigned LowBits = CI->getZExtValue() - NumBits; if (MaskedValueIsZero(I->getOperand(0), - APInt::getLowBitsSet(TypeWidth, NumBits))) + APInt::getLowBitsSet(TypeWidth, NumBits) << LowBits)) return true; } diff --git a/test/Transforms/InstCombine/shift.ll b/test/Transforms/InstCombine/shift.ll index 8d1c82991f..4f6939d632 100644 --- a/test/Transforms/InstCombine/shift.ll +++ b/test/Transforms/InstCombine/shift.ll @@ -452,3 +452,22 @@ define i32 @test38(i32 %x) nounwind readnone { ; CHECK-NEXT: ret i32 } +; <rdar://problem/8756731> +; CHECK: @test39 +define i8 @test39(i32 %a0) { +entry: + %tmp4 = trunc i32 %a0 to i8 +; CHECK: and i8 %tmp49, 64 + %tmp5 = shl i8 %tmp4, 5 + %tmp48 = and i8 %tmp5, 32 + %tmp49 = lshr i8 %tmp48, 5 + %tmp50 = mul i8 %tmp49, 64 + %tmp51 = xor i8 %tmp50, %tmp5 +; CHECK: and i8 %0, 16 + %tmp52 = and i8 %tmp51, -128 + %tmp53 = lshr i8 %tmp52, 7 + %tmp54 = mul i8 %tmp53, 16 + %tmp55 = xor i8 %tmp54, %tmp51 +; CHECK: ret i8 %tmp551 + ret i8 %tmp55 +} |