diff options
| author | Mostafa Hagog <mustafa@il.ibm.com> | 2003-09-04 02:10:32 +0000 |
|---|---|---|
| committer | Richard Henderson <rth@gcc.gnu.org> | 2003-09-03 19:10:32 -0700 |
| commit | b885908b11b9952ec25251e56ab7000d9349c163 (patch) | |
| tree | 707ffa5fd1ad06d1035bb2d6960ade72bcd2659e /gcc | |
| parent | bcfb807527a1ae01d056ce4a7e70ca0b4b86b35e (diff) | |
| download | gcc-b885908b11b9952ec25251e56ab7000d9349c163.zip gcc-b885908b11b9952ec25251e56ab7000d9349c163.tar.gz gcc-b885908b11b9952ec25251e56ab7000d9349c163.tar.bz2 | |
gcse.c (replace_one_set): New function.
* gcse.c (replace_one_set): New function.
(pre_insert_copy_insn): Change the order of copying
to make copy propagation discover additional PRE opportunities.
From-SVN: r71047
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/gcse.c | 43 |
2 files changed, 46 insertions, 3 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index d432719..bd78801 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2003-09-03 Mostafa Hagog <mustafa@il.ibm.com> + + * gcse.c (replace_one_set): New function. + (pre_insert_copy_insn): Change the order of copying + to make copy propagation discover additional PRE opportunities. + 2003-09-03 Roger Sayle <roger@eyesopen.com> PR optimization/11700. @@ -559,6 +559,7 @@ static void alloc_reg_set_mem (int); static void free_reg_set_mem (void); static int get_bitmap_width (int, int, int); static void record_one_set (int, rtx); +static void replace_one_set (int, rtx, rtx); static void record_set_info (rtx, rtx, void *); static void compute_sets (rtx); static void hash_scan_insn (rtx, struct hash_table *, int); @@ -1176,6 +1177,24 @@ free_reg_set_mem (void) obstack_free (®_set_obstack, NULL); } +/* An OLD_INSN that used to set REGNO was replaced by NEW_INSN. + Update the corresponding `reg_set_table' entry accordingly. + We assume that NEW_INSN is not already recorded in reg_set_table[regno]. */ + +static void +replace_one_set (int regno, rtx old_insn, rtx new_insn) +{ + struct reg_set *reg_info; + if (regno >= reg_set_table_size) + return; + for (reg_info = reg_set_table[regno]; reg_info; reg_info = reg_info->next) + if (reg_info->insn == old_insn) + { + reg_info->insn = new_insn; + break; + } +} + /* Record REGNO in the reg_set table. */ static void @@ -5327,7 +5346,14 @@ pre_edge_insert (struct edge_list *edge_list, struct expr **index_map) return did_insert; } -/* Copy the result of INSN to REG. INDX is the expression number. */ +/* Copy the result of INSN to REG. INDX is the expression number. + Given "old_reg <- expr" (INSN), instead of adding after it + reaching_reg <- old_reg + it's better to do the following: + reaching_reg <- expr + old_reg <- reaching_reg + because this way copy propagation can discover additional PRE + opportunuties. */ static void pre_insert_copy_insn (struct expr *expr, rtx insn) @@ -5337,14 +5363,25 @@ pre_insert_copy_insn (struct expr *expr, rtx insn) int indx = expr->bitmap_index; rtx set = single_set (insn); rtx new_insn; + rtx new_set; + rtx old_reg; if (!set) abort (); - new_insn = emit_insn_after (gen_move_insn (reg, copy_rtx (SET_DEST (set))), insn); + old_reg = SET_DEST (set); + new_insn = emit_insn_after (gen_move_insn (old_reg, + reg), + insn); + new_set = single_set (new_insn); + + if (!new_set) + abort(); + SET_DEST (set) = reg; /* Keep register set table up to date. */ - record_one_set (regno, new_insn); + replace_one_set (REGNO (old_reg), insn, new_insn); + record_one_set (regno, insn); gcse_create_count++; |