Hi Jakub I have run it on 4.6, it passes the following testing:
x86-64 bootstrap x86-64 regression test regression test on arm qemu Is it OK for gcc4.6? Ahmad, is it OK for google/gcc-4_6/ and google/gcc-4_6-mobile ? thanks Carrot On Wed, Sep 12, 2012 at 2:01 PM, Carrot Wei <car...@google.com> wrote: > Hi Jakub > > The same problem also affects gcc4.6, > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54398. Could this be > ported to 4.6 branch? > > thanks > Carrot > > On Mon, Feb 13, 2012 at 11:54 AM, Jakub Jelinek <ja...@redhat.com> wrote: >> >> On Wed, Jan 04, 2012 at 05:21:38PM +0000, Marcus Shawcroft wrote: >> > Alias analysis by DSE based on CSELIB expansion assumes that >> > references to the stack frame from different base registers (ie FP, SP) >> > never alias. >> > >> > The comment block in cselib explains that cselib does not allow >> > substitution of FP, SP or SFP specifically in order not to break DSE. >> >> Looks reasonable, appart from coding style (no spaces around -> and >> no {} around return p->loc;), I just wonder if having a separate >> loop in expand_loc just for this isn't too expensive. On sane targets >> IMHO hard frame pointer in the prologue should be initialized from sp, not >> the other way around, thus hard frame pointer based VALUEs should have >> hard frame pointer earlier in the locs list (when there is >> hfp = sp (+ optionally some const) >> insn, we first cselib_lookup_from_insn the rhs and add to locs >> of the new VALUE (plus (VALUE of sp) (const_int)), then process the >> lhs and add it to locs, moving the plus to locs->next). >> So I think the following patch could be enough (bootstrapped/regtested >> on x86_64-linux and i686-linux). >> There is AVR though, which has really weirdo prologue - PR50063, >> but I think it should just use UNSPEC for that or something similar, >> setting sp from hfp seems unnecessary and especially for values with long >> locs chains could make cselib more expensive. >> >> Richard, what do you think about this? >> >> 2012-02-13 Jakub Jelinek <ja...@redhat.com> >> >> * cselib.c (expand_loc): Return sp, fp, hfp or cfa base reg right >> away if seen. >> >> --- gcc/cselib.c.jj 2012-02-13 11:07:15.000000000 +0100 >> +++ gcc/cselib.c 2012-02-13 18:15:17.531776145 +0100 >> @@ -1372,8 +1372,18 @@ expand_loc (struct elt_loc_list *p, stru >> unsigned int regno = UINT_MAX; >> struct elt_loc_list *p_in = p; >> >> - for (; p; p = p -> next) >> + for (; p; p = p->next) >> { >> + /* Return these right away to avoid returning stack pointer based >> + expressions for frame pointer and vice versa, which is something >> + that would confuse DSE. See the comment in >> cselib_expand_value_rtx_1 >> + for more details. */ >> + if (REG_P (p->loc) >> + && (REGNO (p->loc) == STACK_POINTER_REGNUM >> + || REGNO (p->loc) == FRAME_POINTER_REGNUM >> + || REGNO (p->loc) == HARD_FRAME_POINTER_REGNUM >> + || REGNO (p->loc) == cfa_base_preserved_regno)) >> + return p->loc; >> /* Avoid infinite recursion trying to expand a reg into a >> the same reg. */ >> if ((REG_P (p->loc)) >> >> >> Jakub
