diff --git a/lib/Transforms/InstCombine/InstCombineShifts.cpp b/lib/Transforms/InstCombine/InstCombineShifts.cpp index a7f800587bb..8143b257b30 100644 --- a/lib/Transforms/InstCombine/InstCombineShifts.cpp +++ b/lib/Transforms/InstCombine/InstCombineShifts.cpp @@ -644,7 +644,14 @@ Instruction *InstCombiner::visitShl(BinaryOperator &I) { return &I; } } - + + // (C1 << A) << C2) -> (C1 << C2) << A) + Constant *C1, *C2; + Value *A; + if (match(I.getOperand(0), m_OneUse(m_Shl(m_Constant(C1), m_Value(A)))) && + match(I.getOperand(1), m_Constant(C2))) + return BinaryOperator::CreateShl(ConstantExpr::getShl(C1, C2), A); + return 0; } diff --git a/test/Transforms/InstCombine/shift.ll b/test/Transforms/InstCombine/shift.ll index 7fab1d2cab5..bded68ac475 100644 --- a/test/Transforms/InstCombine/shift.ll +++ b/test/Transforms/InstCombine/shift.ll @@ -485,3 +485,24 @@ entry: ; CHECK: ret i8 %tmp551 ret i8 %tmp55 } + +; PR9809 +define i32 @test40(i32 %a, i32 %b) nounwind { + %shl1 = shl i32 1, %b + %shl2 = shl i32 %shl1, 2 + %div = udiv i32 %a, %shl2 + ret i32 %div +; CHECK: @test40 +; CHECK-NEXT: add i32 %b, 2 +; CHECK-NEXT: lshr i32 %a +; CHECK-NEXT: ret i32 +} + +define i32 @test41(i32 %a, i32 %b) nounwind { + %1 = shl i32 1, %b + %2 = shl i32 %1, 3 + ret i32 %2 +; CHECK: @test41 +; CHECK-NEXT: shl i32 8, %b +; CHECK-NEXT: ret i32 +}