On Wed, Aug 19, 2015 at 5:19 AM, Segher Boessenkool <seg...@kernel.crashing.org> wrote: > Hi, > > I've used this patch in the past for another port, and now again for > rs6000, and I think it is generally useful. It prints very verbose > information to the dump file about how ivopts comes up with its costs > for various forms of memory accesses, which tends to show problems in > the target's address cost functions and the legitimize functions. > > In this patch it is disabled by default -- it is very chatty.
Hi, I ran into back-end address cost issue before and this should be useful in such cases. Though there are a lot of dumps, it would be better to classify it into existing dump option (TDF_DETAILS?) and discard the use of macro. Also the address cost will be tuned/dumped later, we should differentiate between them by emphasizing this part of dump is the original cost from back-end. Maybe there will be some other comments. > > It also shows that the LAST_VIRTUAL_REGISTER trickery ivopts does > does not work (legitimize_address can create new registers, so now > a) we have new registers anyway, and b) we use some for multiple > purposes. Oops). Yes, that makes seq dump a little weird. Thanks, bin > > Is this okay for trunk? Bootstrapped and tested on powerpc64-linux. > > > Segher > > > 2015-08-18 Segher Boessenkool <seg...@kernel.crashing.org> > > * tree-ssa-loop-ivopts.c (IVOPTS_DEBUG_COSTS): New define. > (get_address_cost): Add address cost debug code. > > --- > gcc/tree-ssa-loop-ivopts.c | 50 > ++++++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 48 insertions(+), 2 deletions(-) > > diff --git a/gcc/tree-ssa-loop-ivopts.c b/gcc/tree-ssa-loop-ivopts.c > index 6bce3a1..ae29a6f 100644 > --- a/gcc/tree-ssa-loop-ivopts.c > +++ b/gcc/tree-ssa-loop-ivopts.c > @@ -17,6 +17,9 @@ You should have received a copy of the GNU General Public > License > along with GCC; see the file COPYING3. If not see > <http://www.gnu.org/licenses/>. */ > > +/* Define to 1 to debug how this pass comes up with its cost estimates. */ > +#define IVOPTS_DEBUG_COSTS 0 > + > /* This pass tries to find the optimal set of induction variables for the > loop. > It optimizes just the basic linear induction variables (although adding > support for other types should not be too hard). It includes the > @@ -3743,8 +3746,51 @@ get_address_cost (bool symbol_present, bool > var_present, > seq = get_insns (); > end_sequence (); > > - acost = seq_cost (seq, speed); > - acost += address_cost (addr, mem_mode, as, speed); > + unsigned acost1 = seq_cost (seq, speed); > + unsigned acost2 = address_cost (addr, mem_mode, as, speed); > + > + if (dump_file && IVOPTS_DEBUG_COSTS) > + { > + fprintf (dump_file, "======= sequence generated for "); > + if (sym_p) > + fprintf (dump_file, "sym + "); > + if (var_p) > + fprintf (dump_file, "var + "); > + if (off_p) > + fprintf (dump_file, "cst + "); > + if (rat_p) > + fprintf (dump_file, "rat * "); > + fprintf (dump_file, "index:\n"); > + > + print_rtl (dump_file, seq); > + > + fprintf (dump_file, "\n cost of seq is %u", acost1); > + > + if (seq && NEXT_INSN (seq)) > + { > + fprintf (dump_file, " (namely,"); > + > + for (rtx_insn *insn = seq; insn; insn = NEXT_INSN (insn)) > + { > + unsigned cost; > + rtx set = single_set (insn); > + if (set) > + cost = set_rtx_cost (set, speed); > + else > + cost = 1; > + fprintf (dump_file, " %u", cost); > + } > + > + fprintf (dump_file, ")"); > + } > + > + fprintf (dump_file, "\n\nremaining address is:\n"); > + print_rtl_single (dump_file, addr); > + > + fprintf (dump_file, "\n cost of that address is %u\n\n", > acost2); > + } > + > + acost = acost1 + acost2; > > if (!acost) > acost = 1; > -- > 1.8.1.4 >
