From 41429e3f1e4d72ee4f7d4df786b5b0c87405f5b0 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Thu, 17 Feb 2011 02:23:02 +0000 Subject: [PATCH] preserve NUW/NSW when transforming add x,x git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125711 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/InstCombine/InstCombineAddSub.cpp | 9 +++++++-- test/Transforms/InstCombine/add2.ll | 8 ++++++++ 2 files changed, 15 insertions(+), 2 deletions(-) diff --git a/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/lib/Transforms/InstCombine/InstCombineAddSub.cpp index 4ff005e26c2..89cc540da71 100644 --- a/lib/Transforms/InstCombine/InstCombineAddSub.cpp +++ b/lib/Transforms/InstCombine/InstCombineAddSub.cpp @@ -147,8 +147,13 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) { return BinaryOperator::CreateXor(LHS, RHS); // X + X --> X << 1 - if (LHS == RHS && I.getType()->isIntegerTy()) - return BinaryOperator::CreateShl(LHS, ConstantInt::get(I.getType(), 1)); + if (LHS == RHS && I.getType()->isIntegerTy()) { + BinaryOperator *New = + BinaryOperator::CreateShl(LHS, ConstantInt::get(I.getType(), 1)); + New->setHasNoSignedWrap(I.hasNoSignedWrap()); + New->setHasNoUnsignedWrap(I.hasNoUnsignedWrap()); + return New; + } // -A + B --> B - A // -A + -B --> -(A + B) diff --git a/test/Transforms/InstCombine/add2.ll b/test/Transforms/InstCombine/add2.ll index a382142d73a..c5109c52885 100644 --- a/test/Transforms/InstCombine/add2.ll +++ b/test/Transforms/InstCombine/add2.ll @@ -33,3 +33,11 @@ define i32 @test3(i32 %A) { ; CHECK-NEXT: ret i32 } +define i32 @test4(i32 %A) { + %B = add nuw i32 %A, %A + ret i32 %B +; CHECK: @test4 +; CHECK-NEXT: %B = shl nuw i32 %A, 1 +; CHECK-NEXT: ret i32 %B +} +