diff options
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp | 10 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/bitreverse-fold.ll | 11 |
2 files changed, 21 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp index c3fa7be3272..cde26cc24c2 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp @@ -788,6 +788,16 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) { break; } + case Intrinsic::bitreverse: { + Value *IIOperand = II->getArgOperand(0); + Value *X = nullptr; + + // bitreverse(bitreverse(x)) -> x + if (match(IIOperand, m_Intrinsic<Intrinsic::bitreverse>(m_Value(X)))) + return ReplaceInstUsesWith(CI, X); + break; + } + case Intrinsic::powi: if (ConstantInt *Power = dyn_cast<ConstantInt>(II->getArgOperand(1))) { // powi(x, 0) -> 1.0 diff --git a/llvm/test/Transforms/InstCombine/bitreverse-fold.ll b/llvm/test/Transforms/InstCombine/bitreverse-fold.ll new file mode 100644 index 00000000000..ad7fc3a7464 --- /dev/null +++ b/llvm/test/Transforms/InstCombine/bitreverse-fold.ll @@ -0,0 +1,11 @@ +; RUN: opt < %s -instcombine -S | FileCheck %s + +define i32 @test1(i32 %p) { +; CHECK-LABEL: @test1 +; CHECK-NEXT: ret i32 %p + %a = call i32 @llvm.bitreverse.i32(i32 %p) + %b = call i32 @llvm.bitreverse.i32(i32 %a) + ret i32 %b +} + +declare i32 @llvm.bitreverse.i32(i32) readnone |
