clang optimizations


I am trying to apply level 3 of optimizations to a simple program. If I run:

clang -S -O3 -emit-llvm test.cpp -o testo.ll

all seems OK, the result testo.ll is highly optimized.

However if I attempt the same using:

clang -S -emit-llvm test.cpp -o a.ll

opt-10 -S --O3 a.ll -o test.ll

then there is no optimization performed.

The test program that I am using is:


attribute((always_inline)) void ADD(bool en, int x, int y, bool &ok, int &r)




ok = true;

r = x + y;




ok = false;

r = 0;



void test()


bool en = true;

int x = 123;

int y = 321;

int z;

bool ok;

ADD(en, x, y, ok, z);

std::cout << z;


Best regards,



Hi Florian,

Thank you for your quick response. This fixes the optimization.

Best regards,