diff options
| -rw-r--r-- | llvm/lib/Analysis/ValueTracking.cpp | 4 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/bitreverse-known-bits.ll | 17 |
2 files changed, 19 insertions, 2 deletions
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp index cd7ce930900..85846bc687b 100644 --- a/llvm/lib/Analysis/ValueTracking.cpp +++ b/llvm/lib/Analysis/ValueTracking.cpp @@ -1414,8 +1414,8 @@ static void computeKnownBitsFromOperator(const Operator *I, APInt &KnownZero, default: break; case Intrinsic::bitreverse: computeKnownBits(I->getOperand(0), KnownZero2, KnownOne2, Depth + 1, Q); - KnownZero = KnownZero2.reverseBits(); - KnownOne = KnownOne2.reverseBits(); + KnownZero |= KnownZero2.reverseBits(); + KnownOne |= KnownOne2.reverseBits(); break; case Intrinsic::bswap: computeKnownBits(I->getOperand(0), KnownZero2, KnownOne2, Depth + 1, Q); diff --git a/llvm/test/Transforms/InstCombine/bitreverse-known-bits.ll b/llvm/test/Transforms/InstCombine/bitreverse-known-bits.ll index b73df77b925..cd1523a3b06 100644 --- a/llvm/test/Transforms/InstCombine/bitreverse-known-bits.ll +++ b/llvm/test/Transforms/InstCombine/bitreverse-known-bits.ll @@ -1,5 +1,6 @@ ; RUN: opt < %s -S -instcombine | FileCheck %s +declare i8 @llvm.bitreverse.i8(i8) declare i32 @llvm.bitreverse.i32(i32) ; CHECK-LABEL: @test1 @@ -32,3 +33,19 @@ define i1 @test3(i32 %arg) { %res = icmp eq i32 %and, 0 ret i1 %res } + +; CHECK-LABEL: @add_bitreverse +; Make sure we process range metadata on bitreverse +define i8 @add_bitreverse(i8 %a) { + %b = and i8 %a, 252 + ; known bits for the bitreverse will say the result is in the range [0, 64) + ; but the metadata says [0, 16). So make sure the range metadata wins. + ; add %reverse, 1111 0000 + ; should become + ; or %reverse, 1111 0000 + %reverse = call i8 @llvm.bitreverse.i8(i8 %b), !range !1 + %c = add i8 %reverse, -16 +; CHECK: or i8 %reverse, -16 + ret i8 %c +} +!1 = !{i8 0, i8 16} |
