Hey all,
I am trying to run llvm's optimzation passes (basically as many as possible :p), but apparently there is no effect (dumped .ll-file before and after optimization -> identical).
I am wondering if the method is just not optimizable in *any* way or if I am not invoking the stuff correctly.
The system setup on a broad scale looks as follows:
- custom LLVM-module pass
- at some point inside the runOnModule(), it instantiates a PassManager, adds all kinds of optimizations ( PM.add(createXYZPass()) ) and runs them on a provided module.
- the module is provided by a bitcode file that is generated with llvm-g++ from a c++-file.
There are several problems with the bitcode generated by llvm-g++:
- I understand that in LLVM 2.5 all optimizations of gcc are disabled. this leads to horrible code with a lot of unnecessary alloc/gep/load/store stuff
- however, there seems to be one optimization that is particularly nasty and I do not know how to disable it: at certain points where a struct with three floats is supplied, the struct is split into a double and a float (for loading/storing, but this also affects function signatures!)
the functions I am running this on look like the following:
struct Point {
float x;
float y;
float z;
}
extern "C" void test
(
int a,
float f,
Point p0,
Point p1,
float x,
Point & result
);
only the result should be stored back (and is usually only used once at the end of the function), all other values should not invoke any allocations or loads/stores...
I hope someone can help me out here.
Regards,
Ralf