diff options
Diffstat (limited to 'gcc/tree-ssa-phiopt.cc')
| -rw-r--r-- | gcc/tree-ssa-phiopt.cc | 99 |
1 files changed, 77 insertions, 22 deletions
diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc index bf493e1..faecab6 100644 --- a/gcc/tree-ssa-phiopt.cc +++ b/gcc/tree-ssa-phiopt.cc @@ -3605,7 +3605,8 @@ cond_store_replacement (basic_block middle_bb, basic_block join_bb, static bool cond_if_else_store_replacement_1 (basic_block then_bb, basic_block else_bb, basic_block join_bb, gimple *then_assign, - gimple *else_assign) + gimple *else_assign, + gphi *vphi) { tree lhs_base, lhs, then_rhs, else_rhs, name; location_t then_locus, else_locus; @@ -3672,6 +3673,14 @@ cond_if_else_store_replacement_1 (basic_block then_bb, basic_block else_bb, add_phi_arg (newphi, else_rhs, EDGE_SUCC (else_bb, 0), else_locus); new_stmt = gimple_build_assign (lhs, gimple_phi_result (newphi)); + /* Update the vdef for the new store statement. */ + tree newvphilhs = make_ssa_name (gimple_vop (cfun)); + tree vdef = gimple_phi_result (vphi); + gimple_set_vuse (new_stmt, newvphilhs); + gimple_set_vdef (new_stmt, vdef); + gimple_phi_set_result (vphi, newvphilhs); + SSA_NAME_DEF_STMT (vdef) = new_stmt; + update_stmt (vphi); if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf(dump_file, "to use phi:\n"); @@ -3699,10 +3708,11 @@ cond_if_else_store_replacement_1 (basic_block then_bb, basic_block else_bb, } /* Return the single store in BB with VDEF or NULL if there are - other stores in the BB or loads following the store. */ + other stores in the BB or loads following the store. VPHI is + where the only use of the vdef should be. */ static gimple * -single_trailing_store_in_bb (basic_block bb, tree vdef) +single_trailing_store_in_bb (basic_block bb, tree vdef, gphi *vphi) { if (SSA_NAME_IS_DEFAULT_DEF (vdef)) return NULL; @@ -3717,17 +3727,62 @@ single_trailing_store_in_bb (basic_block bb, tree vdef) && gimple_code (SSA_NAME_DEF_STMT (gimple_vuse (store))) != GIMPLE_PHI) return NULL; - /* Verify there is no load or store after the store. */ + /* Verify there is no load or store after the store, the vdef of the store + should only be used by the vphi joining the 2 bbs. */ use_operand_p use_p; - imm_use_iterator imm_iter; - FOR_EACH_IMM_USE_FAST (use_p, imm_iter, gimple_vdef (store)) - if (USE_STMT (use_p) != store - && gimple_bb (USE_STMT (use_p)) == bb) - return NULL; + gimple *use_stmt; + if (!single_imm_use (gimple_vdef (store), &use_p, &use_stmt)) + return NULL; + if (use_stmt != vphi) + return NULL; return store; } +/* Limited Conditional store replacement. We already know + that the recognized pattern looks like so: + + split: + if (cond) goto THEN_BB; else goto ELSE_BB (edge E1) + THEN_BB: + ... + ONLY_STORE = Y; + ... + goto JOIN_BB; + ELSE_BB: + ... + ONLY_STORE = Z; + ... + fallthrough (edge E0) + JOIN_BB: + some more + + Handles only the case with single store in THEN_BB and ELSE_BB. That is + cheap enough due to in phiopt and not worry about heurstics. Moving the store + out might provide an opportunity for a phiopt to happen. */ + +static bool +cond_if_else_store_replacement_limited (basic_block then_bb, basic_block else_bb, + basic_block join_bb) +{ + gphi *vphi = get_virtual_phi (join_bb); + if (!vphi) + return false; + + tree then_vdef = PHI_ARG_DEF_FROM_EDGE (vphi, single_succ_edge (then_bb)); + gimple *then_assign = single_trailing_store_in_bb (then_bb, then_vdef, vphi); + if (!then_assign) + return false; + + tree else_vdef = PHI_ARG_DEF_FROM_EDGE (vphi, single_succ_edge (else_bb)); + gimple *else_assign = single_trailing_store_in_bb (else_bb, else_vdef, vphi); + if (!else_assign) + return false; + + return cond_if_else_store_replacement_1 (then_bb, else_bb, join_bb, + then_assign, else_assign, vphi); +} + /* Conditional store replacement. We already know that the recognized pattern looks like so: @@ -3764,25 +3819,20 @@ cond_if_else_store_replacement (basic_block then_bb, basic_block else_bb, /* Handle the case with single store in THEN_BB and ELSE_BB. That is cheap enough to always handle as it allows us to elide dependence checking. */ - gphi *vphi = NULL; - for (gphi_iterator si = gsi_start_phis (join_bb); !gsi_end_p (si); - gsi_next (&si)) - if (virtual_operand_p (gimple_phi_result (si.phi ()))) - { - vphi = si.phi (); - break; - } + gphi *vphi = get_virtual_phi (join_bb); if (!vphi) return false; tree then_vdef = PHI_ARG_DEF_FROM_EDGE (vphi, single_succ_edge (then_bb)); - tree else_vdef = PHI_ARG_DEF_FROM_EDGE (vphi, single_succ_edge (else_bb)); - gimple *then_assign = single_trailing_store_in_bb (then_bb, then_vdef); + gimple *then_assign = single_trailing_store_in_bb (then_bb, then_vdef, vphi); if (then_assign) { - gimple *else_assign = single_trailing_store_in_bb (else_bb, else_vdef); + tree else_vdef = PHI_ARG_DEF_FROM_EDGE (vphi, single_succ_edge (else_bb)); + gimple *else_assign = single_trailing_store_in_bb (else_bb, else_vdef, + vphi); if (else_assign) return cond_if_else_store_replacement_1 (then_bb, else_bb, join_bb, - then_assign, else_assign); + then_assign, else_assign, + vphi); } /* If either vectorization or if-conversion is disabled then do @@ -3921,7 +3971,7 @@ cond_if_else_store_replacement (basic_block then_bb, basic_block else_bb, then_store = store_pair.first; else_store = store_pair.second; res = cond_if_else_store_replacement_1 (then_bb, else_bb, join_bb, - then_store, else_store); + then_store, else_store, vphi); ok = ok || res; } @@ -4456,6 +4506,11 @@ pass_phiopt::execute (function *) && !predictable_edge_p (EDGE_SUCC (bb, 0)) && !predictable_edge_p (EDGE_SUCC (bb, 1))) hoist_adjacent_loads (bb, bb1, bb2, bb3); + + /* Try to see if there are only one store in each side of the if + and try to remove that. */ + if (EDGE_COUNT (bb3->preds) == 2) + cond_if_else_store_replacement_limited (bb1, bb2, bb3); } gimple_stmt_iterator gsi; |