diff options
| -rw-r--r-- | llvm/lib/Analysis/InstructionSimplify.cpp | 7 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstSimplify/rem.ll | 16 |
2 files changed, 11 insertions, 12 deletions
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp index 6c6b1cfe720..245133fb912 100644 --- a/llvm/lib/Analysis/InstructionSimplify.cpp +++ b/llvm/lib/Analysis/InstructionSimplify.cpp @@ -1040,6 +1040,13 @@ static Value *simplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, match(Op0, m_URem(m_Value(), m_Specific(Op1))))) return Op0; + // (X << Y) % X -> 0 + if ((Opcode == Instruction::SRem && + match(Op0, m_NSWShl(m_Specific(Op1), m_Value()))) || + (Opcode == Instruction::URem && + match(Op0, m_NUWShl(m_Specific(Op1), m_Value())))) + return Constant::getNullValue(Op0->getType()); + // If the operation is with the result of a select instruction, check whether // operating on either branch of the select always yields the same value. if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) diff --git a/llvm/test/Transforms/InstSimplify/rem.ll b/llvm/test/Transforms/InstSimplify/rem.ll index d949d6ea353..a015d4c43e0 100644 --- a/llvm/test/Transforms/InstSimplify/rem.ll +++ b/llvm/test/Transforms/InstSimplify/rem.ll @@ -189,9 +189,7 @@ define i32 @rem4() { define i32 @rem5(i32 %x, i32 %y) { ; CHECK-LABEL: @rem5( -; CHECK-NEXT: [[SHL:%.*]] = shl nsw i32 [[X:%.*]], [[Y:%.*]] -; CHECK-NEXT: [[MOD:%.*]] = srem i32 [[SHL]], [[X]] -; CHECK-NEXT: ret i32 [[MOD]] +; CHECK-NEXT: ret i32 0 ; %shl = shl nsw i32 %x, %y %mod = srem i32 %shl, %x @@ -200,9 +198,7 @@ define i32 @rem5(i32 %x, i32 %y) { define <2 x i32> @rem6(<2 x i32> %x, <2 x i32> %y) { ; CHECK-LABEL: @rem6( -; CHECK-NEXT: [[SHL:%.*]] = shl nsw <2 x i32> [[X:%.*]], [[Y:%.*]] -; CHECK-NEXT: [[MOD:%.*]] = srem <2 x i32> [[SHL]], [[X]] -; CHECK-NEXT: ret <2 x i32> [[MOD]] +; CHECK-NEXT: ret <2 x i32> zeroinitializer ; %shl = shl nsw <2 x i32> %x, %y %mod = srem <2 x i32> %shl, %x @@ -224,9 +220,7 @@ define i32 @rem7(i32 %x, i32 %y) { define i32 @rem8(i32 %x, i32 %y) { ; CHECK-LABEL: @rem8( -; CHECK-NEXT: [[SHL:%.*]] = shl nuw i32 [[X:%.*]], [[Y:%.*]] -; CHECK-NEXT: [[MOD:%.*]] = urem i32 [[SHL]], [[X]] -; CHECK-NEXT: ret i32 [[MOD]] +; CHECK-NEXT: ret i32 0 ; %shl = shl nuw i32 %x, %y %mod = urem i32 %shl, %x @@ -235,9 +229,7 @@ define i32 @rem8(i32 %x, i32 %y) { define <2 x i32> @rem9(<2 x i32> %x, <2 x i32> %y) { ; CHECK-LABEL: @rem9( -; CHECK-NEXT: [[SHL:%.*]] = shl nuw <2 x i32> [[X:%.*]], [[Y:%.*]] -; CHECK-NEXT: [[MOD:%.*]] = urem <2 x i32> [[SHL]], [[X]] -; CHECK-NEXT: ret <2 x i32> [[MOD]] +; CHECK-NEXT: ret <2 x i32> zeroinitializer ; %shl = shl nuw <2 x i32> %x, %y %mod = urem <2 x i32> %shl, %x |
