[LLVMdev] llvm jit acting at runtime, like libgccjit ?

[Dibyendu Majumdar]

On 9 July 2015 at 15:53, James Molloy <james at jamesmolloy.co.uk> wrote:

> You can do this by writing a trivial function with a
> loop in Clang and running:
>
> clang -O0 -emit-llvm -S -o - my-trivial-program.c
>
> Clang, like any frontend, produces deliberately poor code and expects LLVM
> to clean it up - if you want more cleaned up code use -O2.

I find it is more useful to use this:

clang -cc1 -O1 -disable-llvm-optzns -S -emit-llvm  prog.c


-O0 produces some extra rubbish that is just noise.
-O1 and above can get rid of the code altogether - so using the
disable optimizations flag appears to help.


Regards
Dibyendu