On Thu, Mar 24, 2011 at 11:03 AM, H.J. Lu <hjl.to...@gmail.com> wrote: > On Tue, Mar 22, 2011 at 6:28 AM, Ira Rosen <ira.ro...@linaro.org> wrote: >> On 17 March 2011 16:48, Richard Guenther <richard.guent...@gmail.com> wrote: >> >>>> + then_datarefs = VEC_alloc (data_reference_p, heap, 1); >>>> + else_datarefs = VEC_alloc (data_reference_p, heap, 1); >>>> + then_ddrs = VEC_alloc (ddr_p, heap, 1); >>>> + else_ddrs = VEC_alloc (ddr_p, heap, 1); >>>> + if (!compute_data_dependences_for_bb (then_bb, false, &then_datarefs, >>>> + &then_ddrs) >>> >>> Can we avoid computing dependencies if the other BB would have no >>> data-refs? Thus, split collecting datarefs and computing dependences? >> >> Done. >> >>> >>>> + || !compute_data_dependences_for_bb (else_bb, false, &else_datarefs, >>>> + &else_ddrs) >>>> + || !VEC_length (data_reference_p, then_datarefs) >>>> + || !VEC_length (data_reference_p, else_datarefs)) >>>> + { >>>> + free_data_refs (then_datarefs); >>>> + free_data_refs (else_datarefs); >>>> + free_dependence_relations (then_ddrs); >>>> + free_dependence_relations (else_ddrs); >>>> + return false; >>>> + } >>>> + >>>> + /* Check that there are no read-after-write or write-after-write >>>> dependencies >>>> + in THEN_BB. */ >>>> + FOR_EACH_VEC_ELT (ddr_p, then_ddrs, i, ddr) >>>> + { >>>> + struct data_reference *dra = DDR_A (ddr); >>>> + struct data_reference *drb = DDR_B (ddr); >>>> + >>>> + if (DDR_ARE_DEPENDENT (ddr) != chrec_known >>>> + && ((DR_IS_READ (dra) && DR_IS_WRITE (drb) >>>> + && gimple_uid (DR_STMT (dra)) > gimple_uid (DR_STMT (drb))) >>>> + || (DR_IS_READ (drb) && DR_IS_WRITE (dra) >>>> + && gimple_uid (DR_STMT (drb)) > gimple_uid (DR_STMT >>>> (dra))) >>>> + || (DR_IS_WRITE (dra) && DR_IS_WRITE (drb)))) >>> >>> The gimple_uids are not initialized here, you need to make sure to >>> call renumber_gimple_stmt_uids () before starting. Note that phiopt >>> incrementally changes the IL, so I'm not sure those uids will stay >>> valid as stmts are moved across blocks. >> >> I added a call to renumber_gimple_stmt_uids_in_blocks() before data >> dependence checks, and there are no code changes between that and the >> checks, so, I think, it should be OK. >> >>> >>>> + { >>>> + free_data_refs (then_datarefs); >>>> + free_data_refs (else_datarefs); >>>> + free_dependence_relations (then_ddrs); >>>> + free_dependence_relations (else_ddrs); >>>> + return false; >>>> + } >>>> + } >>>> + >>>> + /* Check that there are no read-after-write or write-after-write >>>> dependencies >>>> + in ELSE_BB. */ >>>> + FOR_EACH_VEC_ELT (ddr_p, else_ddrs, i, ddr) >>>> + { >>>> + struct data_reference *dra = DDR_A (ddr); >>>> + struct data_reference *drb = DDR_B (ddr); >>>> + >>>> + if (DDR_ARE_DEPENDENT (ddr) != chrec_known >>>> + && ((DR_IS_READ (dra) && DR_IS_WRITE (drb) >>>> + && gimple_uid (DR_STMT (dra)) > gimple_uid (DR_STMT (drb))) >>>> + || (DR_IS_READ (drb) && DR_IS_WRITE (dra) >>>> + && gimple_uid (DR_STMT (drb)) > gimple_uid (DR_STMT >>>> (dra))) >>>> + || (DR_IS_WRITE (dra) && DR_IS_WRITE (drb)))) >>>> + { >>>> + free_data_refs (then_datarefs); >>>> + free_data_refs (else_datarefs); >>>> + free_dependence_relations (then_ddrs); >>>> + free_dependence_relations (else_ddrs); >>>> + return false; >>>> + } >>>> + } >>>> + >>>> + /* Found pairs of stores with equal LHS. */ >>>> + FOR_EACH_VEC_ELT (data_reference_p, then_datarefs, i, then_dr) >>>> + { >>>> + if (DR_IS_READ (then_dr)) >>>> + continue; >>>> + >>>> + then_store = DR_STMT (then_dr); >>>> + then_lhs = gimple_assign_lhs (then_store); >>>> + found = false; >>>> + >>>> + FOR_EACH_VEC_ELT (data_reference_p, else_datarefs, j, else_dr) >>>> + { >>>> + if (DR_IS_READ (else_dr)) >>>> + continue; >>>> + >>>> + else_store = DR_STMT (else_dr); >>>> + else_lhs = gimple_assign_lhs (else_store); >>>> + >>>> + if (operand_equal_p (then_lhs, else_lhs, 0)) >>>> + { >>>> + found = true; >>>> + break; >>>> + } >>>> + } >>>> + >>>> + if (!found) >>>> + continue; >>>> + >>>> + res = cond_if_else_store_replacement_1 (then_bb, else_bb, join_bb, >>>> + then_store, else_store); >>> >>> So you are executing if-else store replacement for common data reference >>> pairs only. I think it's cheaper to collect those pairs before computing >>> dependences and only if there is at least one pair perform the optimization. >> >> OK, I changed the order. >> >>> >>> You basically perform store sinking, creating a PHI node for each store >>> you sink (that's then probably if-converted by if-conversion later, >>> eventually >>> redundant with -ftree-loop-if-convert-stores?) >>> >>> I am concerned that having no bound on the number of stores sunk will >>> increase register pressure and does not allow scheduling of the stores >>> in an optimal way. Consider two BBs similar to >>> >>> t = a + b; >>> *p = t; >>> t = c + d; >>> *q = t; >>> >>> where the transformation undoes a good schedule and makes fixing it >>> impossible if the remaining statements are not if-convertible. >>> >>> Thus, I'd rather make this transformation only if in the end the conditional >>> can be completely if-converted. >>> >>> I realize that we already do unbound and very aggressive if-conversion >>> in tree-ifcvt.c regardless of whether the loop will be vectorized or not >>> (including leaking the if-converted loops to the various loop versions >>> we create during vectorization, causing only code-size bloat). But it's >>> not a good reason to continue down this road ;) >>> >>> I suppose a simple maximum on the number of stores to sink >>> controllable by a param should do, eventually disabling this >>> extended transformation when vectorization is disabled? >> >> I added a param, and it's set to 0 if either vectorization or if-conversion >> is disabled. >> >>> >>> Otherwise the implementation looks good. >> >> Bootstrapped and tested on powerpc64-suse-linux. >> OK to apply? >> >> Thanks, >> Ira >> >> ChangeLog: >> >> * doc/invoke.texi (max-stores-to-sink): Document. >> * params.h (MAX_STORES_TO_SINK): Define. >> * opts.c (finish_options): Set MAX_STORES_TO_SINK to 0 >> if either vectorization or if-conversion is disabled. >> * tree-data-ref.c (dr_equal_offsets_p1): Moved and renamed from >> tree-vect-data-refs.c vect_equal_offsets. >> (dr_equal_offsets_p): New function. >> (find_data_references_in_bb): Remove static. >> * tree-data-ref.h (find_data_references_in_bb): Declare. >> (dr_equal_offsets_p): Likewise. >> * tree-vect-data-refs.c (vect_equal_offsets): Move to tree-data-ref.c. >> (vect_drs_dependent_in_basic_block): Update calls to vect_equal_offsets. >> (vect_check_interleaving): Likewise. >> * tree-ssa-phiopt.c: Include cfgloop.h and tree-data-ref.h. >> (cond_if_else_store_replacement): Rename to... >> (cond_if_else_store_replacement_1): ... this. Change arguments and >> documentation. >> (cond_if_else_store_replacement): New function. >> * Makefile.in (tree-ssa-phiopt.o): Adjust dependencies. >> * params.def (PARAM_MAX_STORES_TO_SINK): Define. >> >> testsuite/ChangeLog: >> >> * gcc.dg/vect/vect-cselim-1.c: New test. >> * gcc.dg/vect/vect-cselim-2.c: New test. >> > > This caused: > > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48270
Yep, I see FAIL: gcc.c-torture/execute/builtins/strlen-2.c compilation, -O3 -fomit-frame-p ointer (internal compiler error) on x86_64-linux with #0 0x0000000001f53253 in gimple_uid (g=0x0) at /space/rguenther/src/svn/trunk/gcc/gimple.h:1297 1297 return g->gsbase.uid; (gdb) Bottom (innermost) frame selected; you cannot go down. (gdb) up #1 0x0000000001f7753d in cond_if_else_store_replacement ( then_bb=0x7ffff533abc8, else_bb=0x7ffff533ac30, join_bb=0x7ffff533ac98) at /space/rguenther/src/svn/trunk/gcc/tree-ssa-phiopt.c:1511 1511 if (DDR_ARE_DEPENDENT (ddr) != chrec_known DR_STMT of dra is NULL. No idea how that can happen. Richard.