http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44194
--- Comment #17 from Easwaran Raman <eraman at google dot com> 2011-04-21 00:20:51 UTC --- On Sun, Apr 17, 2011 at 3:45 AM, rguenther at suse dot de <gcc-bugzi...@gcc.gnu.org> wrote: > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44194 > > --- Comment #16 from rguenther at suse dot de <rguenther at suse dot de> > 2011-04-17 10:44:02 UTC --- > On Fri, 15 Apr 2011, eraman at google dot com wrote: > >> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44194 >> >> --- Comment #15 from Easwaran Raman <eraman at google dot com> 2011-04-15 >> 22:22:15 UTC --- >> (In reply to comment #14) >> > On Fri, 15 Apr 2011, eraman at google dot com wrote: >> > >> > > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44194 >> > > >> > > Easwaran Raman <eraman at google dot com> changed: >> > > >> > > What |Removed |Added >> > > ---------------------------------------------------------------------------- >> > > CC| |eraman at google dot com >> > > >> > > --- Comment #13 from Easwaran Raman <eraman at google dot com> >> > > 2011-04-15 19:18:25 UTC --- >> > > Richard, did you mean to write >> > > >> > > static bool >> > > can_escape (tree expr) >> > > { >> > > tree base; >> > > if (!expr) >> > > return true; >> > > base = get_base_address (expr); >> > > if (DECL_P (base) >> > > && (!may_be_aliased (base) >> > > && !pt_solution_includes (&cfun->gimple_df->escaped, base))) >> > > return false; >> > > return true; >> > > } >> > > >> > > Only case when we know it doesn't escape is if bas is a DECL_P and is >> > > not in >> > > cfun->gimple_df->escaped and not aliased, right? Actually, I'm wondering >> > > if it >> > > is sufficient to test just >> > > DECL_P (base) && !pt_solution_includes (&cfun->gimple_df->escaped, base). >> > >> > No, because if the escaped solution for example includes ANYTHING then >> > the test will return true. That !may-aliased variables are not >> > contained in ANYTHING isn't known w/o context. >> > >> > Richard. >> >> Correct me if I am wrong. If I understand you right, just using DECL_P (base) >> && !pt_solution_includes is conservative since pt_solution_includes may >> return >> true if the escaped solution contains ANYTHING. To make it less conservative, >> you're suggesting >> >> if (DECL_P (base) >> && (!may_be_aliased (base) >> || !pt_solution_includes (&cfun->gimple_df->escaped, base))) >> return false; >> >> I tried that and most Fortran tests are failing. One of the tests >> (default_format_1.f90) has the following RTL sequence: >> >> >> (insn 30 29 32 4 (set (mem/s/c:SI (plus:DI (reg/f:DI 20 frame) >> (const_int -608 [0xfffffffffffffda0])) [2 >> dt_parm.0.common.flags+0 S4 A64]) >> (const_int 16512 [0x4080])) default_format_1.inc:56 64 >> {*movsi_internal} >> (nil)) >> >> (insn 32 30 33 4 (set (reg:DI 5 di) >> (reg/f:DI 106)) default_format_1.inc:56 62 {*movdi_internal_rex64} >> (expr_list:REG_EQUAL (plus:DI (reg/f:DI 20 frame) >> (const_int -608 [0xfffffffffffffda0])) >> (nil))) >> >> (call_insn 33 32 36 4 (call (mem:QI (symbol_ref:DI ("_gfortran_st_write") >> [flags 0x41] <function_decl 0x7f301ed12e00 _gfortran_st_write>) [0 >> _gfortran_st_write S1 A8]) >> (const_int 0 [0])) default_format_1.inc:56 618 {*call_0} >> (expr_list:REG_DEAD (reg:DI 5 di) >> (nil)) >> (expr_list:REG_DEP_TRUE (use (reg:DI 5 di)) >> (nil))) >> >> For the DECL dt_parm, pt_solution_includes (&cfun->gimple_df->escaped, base) >> returns false, even though its location is passed as a parameter to >> _gfortran_st_write. >> >> I did test with >> if (DECL_P (base) >> && (!may_be_aliased (base) >> && !pt_solution_includes (&cfun->gimple_df->escaped, base))) >> >> which has no regressions. Is that what you suggest? > > No, the version with || should be ok. The dt_parm argument does > not escape at the _gfortran_st_write call site because this > intrinsic function has a ".wW" fnspec attribute which specifies > the arguments do not escape. What you indeed need to do in > addition to the escaped solution query is walk over all function > arguments and see if there is one that aliases 'base'. That > may not be easily possible on RTL though. On the tree level > we have a separate points-to set for such call clobbers/uses > but we do not preserve it for RTL. Is it ok to make calls whose arg(s) have EAF_NOESCAPE kill all locations off the frame in addition to killing all locations that potentially escape (using the || case you suggested)? Will it be better or worse than just checking !may_be_aliased (base) alone? Thanks, Easwaran > -- > Configure bugmail: http://gcc.gnu.org/bugzilla/userprefs.cgi?tab=email > ------- You are receiving this mail because: ------- > You are on the CC list for the bug. >
