gcc on windows generating garbage? windows vs linux

Question

I\'m trying to find out why in windows has so much more instructions for the same program than linux. So I just used int a=0xbeef; and printf(\"test\\n\");

Answer 1

You seem to be compiling with old 3.x series gcc, you'd better upgrade. Newer versions don't invoke alloca. I suspect the particular version of alloca might use register convention so the mov 0x10,%eax is probably setting up the argument for that call.

__main is a startup function defined in crtbegin.o that executes global constructors and registers a function using atexit that will run the global destructors.

Also note that main gets special treatment, like the stack alignment code and the above-mentioned initialization. It may be a good idea to instead compare a "plain" function if you are just interested in code generation issues.