------- Comment #7 from anemo at mba dot ocn dot ne dot jp 2006-07-21 16:34 ------- (In reply to comment #6) > Thanks. With this patch, gcc 4.1.1 produces expected output. > It seems gcc 4.2 does not move rdhwr before branch without this patch, but I > can not see why.
I tried to find the reason of this difference between 4.1.1 and 4.2, and found that the change happend on r108713. The changelog is: > 2005-12-17 Danny Berlin <[EMAIL PROTECTED]> > Kenneth Zadeck <[EMAIL PROTECTED]> > > * basic-block.h: Changed basic block numbering so that the entry > block is 0 and the exit block is 1. Changed insn iterators so > that they are tolerant of blocks with no insns. > * regrename.c (copyprop_hardreg_forward): Changed basic block > numbering so that the entry block is 0 and the exit block is 1. > ... While it is too complex for me, I'm still not sure gcc 4.2 really do not need the patch in comment #2. Looking at comment #1, it seems gcc 4.2 still need the patch, but I could not reproduce the same result by daney with 4.2. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28126
