> - If I patch in this code, actually I get the same results I did
> before where the constants are propagated. It seems that in 4.3.2,
> every part of the compiler is trying to do that.
There are at least two forward propagation passes, one before and
another after GCSE. I haven't tried to tackle those passes, but I
believe they already have a cost model in place.
This patch will prevent partial sums involving registers and
constants from being combined during GCSE.
> - Just for testing I turned off the GCSE pass and it still
> propagated and folded the constants...
GCSE won't help with your trimmed down example
int main(void)
{
long a = 0xcafecafe;
printf("Final: %lx %lx %lx\n", a, a+5, a+15);
return EXIT_SUCCESS;
}
I believe Paolo's canon_reg solution together with tweaking
rtx_cost of constants with outer code PLUS might help. Any
luck with that pass?
