diff options
| -rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 12 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/2008-07-08-ShiftOneAndOne.ll | 10 |
2 files changed, 22 insertions, 0 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 675f7ec571..27af3c397a 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -3473,6 +3473,18 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) { } break; + + case Instruction::Shl: + case Instruction::LShr: + // (1 << x) & 1 --> zext(x == 0) + // (1 >> x) & 1 --> zext(x == 0) + if (AndRHSMask.getLimitedValue() == 1 && Op0LHS == AndRHS) { + Instruction *NewICmp = new ICmpInst(ICmpInst::ICMP_EQ, Op0RHS, + Constant::getNullValue(I.getType())); + InsertNewInstBefore(NewICmp, I); + return new ZExtInst(NewICmp, I.getType()); + } + break; } if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) diff --git a/test/Transforms/InstCombine/2008-07-08-ShiftOneAndOne.ll b/test/Transforms/InstCombine/2008-07-08-ShiftOneAndOne.ll new file mode 100644 index 0000000000..956b9a6ae2 --- /dev/null +++ b/test/Transforms/InstCombine/2008-07-08-ShiftOneAndOne.ll @@ -0,0 +1,10 @@ +; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {icmp ne i32 \%a} +; PR2330 + +define i1 @foo(i32 %a) nounwind { +entry: + %tmp15 = shl i32 1, %a ; <i32> [#uses=1] + %tmp237 = and i32 %tmp15, 1 ; <i32> [#uses=1] + %toBool = icmp eq i32 %tmp237, 0 ; <i1> [#uses=1] + ret i1 %toBool +} |