Hi, For loop2-invariant pass, when flag_ira_loop_pressure is enabled, function gain_for_invariant checks the pressures of all register classes. This does not make sense since one invariant might impact only one register class.
The patch enhances functions get_inv_cost and gain_for_invariant to check only the register pressure of the invariant if possible. Bootstrap and no make check regression on X86-64. Bootstrap and no make check regression on X86-64 with flag_ira_loop_pressure = true. OK for trunk? Thanks! -Zhenqiang ChangeLog: 2014-06-10 Zhenqiang Chen <zhenqiang.c...@linaro.org> * loop-invariant.c (get_inv_cost): Handle register class. (gain_for_invariant): Check the register pressure of the inv, other than all. diff --git a/gcc/loop-invariant.c b/gcc/loop-invariant.c index 100a2c1..e822bb6 100644 --- a/gcc/loop-invariant.c +++ b/gcc/loop-invariant.c @@ -1058,16 +1058,22 @@ get_pressure_class_and_nregs (rtx insn, int *nregs) } /* Calculates cost and number of registers needed for moving invariant INV - out of the loop and stores them to *COST and *REGS_NEEDED. */ + out of the loop and stores them to *COST and *REGS_NEEDED. *CL will be + the REG_CLASS of INV. Return + 0: if INV is invalid. + 1: if INV and its depends_on have same reg_class + > 1: if INV and its depends_on have different reg_classes. */ -static void -get_inv_cost (struct invariant *inv, int *comp_cost, unsigned *regs_needed) +static int +get_inv_cost (struct invariant *inv, int *comp_cost, unsigned *regs_needed, + enum reg_class *cl) { int i, acomp_cost; unsigned aregs_needed[N_REG_CLASSES]; unsigned depno; struct invariant *dep; bitmap_iterator bi; + int ret = 2; /* Find the representative of the class of the equivalent invariants. */ inv = invariants[inv->eqto]; @@ -1083,7 +1089,7 @@ get_inv_cost (struct invariant *inv, int *comp_cost, unsigned *regs_needed) if (inv->move || inv->stamp == actual_stamp) - return; + return 0; inv->stamp = actual_stamp; if (! flag_ira_loop_pressure) @@ -1095,6 +1101,8 @@ get_inv_cost (struct invariant *inv, int *comp_cost, unsigned *regs_needed) pressure_class = get_pressure_class_and_nregs (inv->insn, &nregs); regs_needed[pressure_class] += nregs; + *cl = pressure_class; + ret = 1; } if (!inv->cheap_address @@ -1135,10 +1143,12 @@ get_inv_cost (struct invariant *inv, int *comp_cost, unsigned *regs_needed) EXECUTE_IF_SET_IN_BITMAP (inv->depends_on, 0, depno, bi) { bool check_p; + enum reg_class dep_cl = NO_REGS; + int dep_ret; dep = invariants[depno]; - get_inv_cost (dep, &acomp_cost, aregs_needed); + dep_ret = get_inv_cost (dep, &acomp_cost, aregs_needed, &dep_cl); if (! flag_ira_loop_pressure) check_p = aregs_needed[0] != 0; @@ -1148,6 +1158,11 @@ get_inv_cost (struct invariant *inv, int *comp_cost, unsigned *regs_needed) if (aregs_needed[ira_pressure_classes[i]] != 0) break; check_p = i < ira_pressure_classes_num; + + if (dep_ret > 1) + ret += dep_ret; + else if ((dep_ret == 1) && (*cl != dep_cl)) + ret++; } if (check_p /* We need to check always_executed, since if the original value of @@ -1181,6 +1196,7 @@ get_inv_cost (struct invariant *inv, int *comp_cost, unsigned *regs_needed) } (*comp_cost) += acomp_cost; } + return ret; } /* Calculates gain for eliminating invariant INV. REGS_USED is the number @@ -1195,10 +1211,12 @@ gain_for_invariant (struct invariant *inv, unsigned *regs_needed, bool speed, bool call_p) { int comp_cost, size_cost; + enum reg_class cl; + int ret; actual_stamp++; - get_inv_cost (inv, &comp_cost, regs_needed); + ret = get_inv_cost (inv, &comp_cost, regs_needed, &cl); if (! flag_ira_loop_pressure) { @@ -1207,6 +1225,24 @@ gain_for_invariant (struct invariant *inv, unsigned *regs_needed, - estimate_reg_pressure_cost (new_regs[0], regs_used, speed, call_p)); } + else if (ret == 0) + return -1; + else if (ret == 1) + { + /* Hoist it anyway since it does not impact register pressure. */ + if (cl == NO_REGS) + return 1; + + size_cost = (int) new_regs[cl] + + (int) regs_needed[cl] + + LOOP_DATA (curr_loop)->max_reg_pressure[cl] + + IRA_LOOP_RESERVED_REGS + - ira_class_hard_regs_num[cl]; + if (size_cost > 0) + return -1; + else + size_cost = 0; + } else { int i;