Hi,
This patch has one significant change: cprop_insn would not iterate
after a successful copy propagation, assuming the uses found with
find_used_regs remain the same. This is not true in two cases:
* find_used_regs found multiple uses of the same register, but that
register was replaced by try_replace_reg.
* find_used_regs found regs that have been folded after substitution
in try_replace_reg (which ultimately tries simplify_replace_rtx if all
else fails)
After this patch, cprop_insn starts over after one successful copy
propagation replacement.
The rest of the patch just cleans up a single-member struct reg_use {
rtx reg }. An array of rtx is simpler, although it probably makes no
difference for the generated code for cprop.c.
Bootstrapped & tested on x86_64-unknown-linux-gnu. OK?
Ciao!
Steven
* cprop.c (struct reg_use): Remove.
(reg_use_table): Make an array of RTX.
(find_used_regs, constprop_register, local_cprop_pass,
bypass_block): Simplify users of reg_use_table.
(cprop_insn): Likewise. Iterate if copy propagation succeeded
on one of the uses found by find_used_regs.
Index: cprop.c
===================================================================
--- cprop.c (revision 171947)
+++ cprop.c (working copy)
@@ -53,8 +53,6 @@ along with GCC; see the file COPYING3.
/* An obstack for our working variables. */
static struct obstack cprop_obstack;
-struct reg_use {rtx reg_rtx; };
-
/* Occurrence of an expression.
There is one per basic block. If a pattern appears more than once the
last appearance is used. */
@@ -653,12 +651,12 @@ compute_cprop_data (void)
/* Maximum number of register uses in an insn that we handle. */
#define MAX_USES 8
-/* Table of uses found in an insn.
+/* Table of uses (registers, both hard and pseudo) found in an insn.
Allocated statically to avoid alloc/free complexity and overhead. */
-static struct reg_use reg_use_table[MAX_USES];
+static rtx reg_use_table[MAX_USES];
/* Index into `reg_use_table' while building it. */
-static int reg_use_count;
+static unsigned reg_use_count;
/* Set up a list of register numbers used in INSN. The found uses are stored
in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
@@ -687,7 +685,7 @@ find_used_regs (rtx *xptr, void *data AT
if (reg_use_count == MAX_USES)
return;
- reg_use_table[reg_use_count].reg_rtx = x;
+ reg_use_table[reg_use_count] = x;
reg_use_count++;
}
@@ -997,10 +995,12 @@ constprop_register (rtx insn, rtx from,
static int
cprop_insn (rtx insn)
{
- struct reg_use *reg_used;
- int changed = 0;
+ unsigned i;
+ int changed = 0, changed_this_round;
rtx note;
+retry:
+ changed_this_round = 0;
reg_use_count = 0;
note_uses (&PATTERN (insn), find_used_regs, NULL);
@@ -1009,16 +1009,16 @@ cprop_insn (rtx insn)
if (note)
find_used_regs (&XEXP (note, 0), NULL);
- for (reg_used = ®_use_table[0]; reg_use_count > 0;
- reg_used++, reg_use_count--)
+ for (i = 0; i < reg_use_count; i++)
{
- unsigned int regno = REGNO (reg_used->reg_rtx);
+ rtx reg_used = reg_use_table[i];
+ unsigned int regno = REGNO (reg_used);
rtx src;
struct expr *set;
/* If the register has already been set in this block, there's
nothing we can do. */
- if (! reg_not_set_p (reg_used->reg_rtx, insn))
+ if (! reg_not_set_p (reg_used, insn))
continue;
/* Find an assignment that sets reg_used and is available
@@ -1032,9 +1032,9 @@ cprop_insn (rtx insn)
/* Constant propagation. */
if (cprop_constant_p (src))
{
- if (constprop_register (insn, reg_used->reg_rtx, src))
+ if (constprop_register (insn, reg_used, src))
{
- changed = 1;
+ changed_this_round = changed = 1;
global_const_prop_count++;
if (dump_file != NULL)
{
@@ -1051,9 +1051,9 @@ cprop_insn (rtx insn)
&& REGNO (src) >= FIRST_PSEUDO_REGISTER
&& REGNO (src) != regno)
{
- if (try_replace_reg (reg_used->reg_rtx, src, insn))
+ if (try_replace_reg (reg_used, src, insn))
{
- changed = 1;
+ changed_this_round = changed = 1;
global_copy_prop_count++;
if (dump_file != NULL)
{
@@ -1069,6 +1069,11 @@ cprop_insn (rtx insn)
and made things worse. */
}
}
+
+ /* If try_replace_reg simplified the insn, the regs found
+ by find_used_regs may not be valid anymore. Start over. */
+ if (changed_this_round)
+ goto retry;
}
if (changed && DEBUG_INSN_P (insn))
@@ -1195,8 +1200,8 @@ local_cprop_pass (void)
{
basic_block bb;
rtx insn;
- struct reg_use *reg_used;
bool changed = false;
+ unsigned i;
cselib_init (0);
FOR_EACH_BB (bb)
@@ -1214,10 +1219,9 @@ local_cprop_pass (void)
if (note)
local_cprop_find_used_regs (&XEXP (note, 0), NULL);
- for (reg_used = ®_use_table[0]; reg_use_count > 0;
- reg_used++, reg_use_count--)
+ for (i = 0; i < reg_use_count; i++)
{
- if (do_local_cprop (reg_used->reg_rtx, insn))
+ if (do_local_cprop (reg_use_table[i], insn))
{
changed = true;
break;
@@ -1226,7 +1230,7 @@ local_cprop_pass (void)
if (INSN_DELETED_P (insn))
break;
}
- while (reg_use_count);
+ while (i < reg_use_count);
}
cselib_process_insn (insn);
}
@@ -1461,9 +1465,10 @@ bypass_block (basic_block bb, rtx setcc,
{
rtx insn, note;
edge e, edest;
- int i, change;
+ int change;
int may_be_loop_header;
unsigned removed_p;
+ unsigned i;
edge_iterator ei;
insn = (setcc != NULL) ? setcc : jump;
@@ -1513,8 +1518,8 @@ bypass_block (basic_block bb, rtx setcc,
for (i = 0; i < reg_use_count; i++)
{
- struct reg_use *reg_used = ®_use_table[i];
- unsigned int regno = REGNO (reg_used->reg_rtx);
+ rtx reg_used = reg_use_table[i];
+ unsigned int regno = REGNO (reg_used);
basic_block dest, old_dest;
struct expr *set;
rtx src, new_rtx;
@@ -1525,7 +1530,7 @@ bypass_block (basic_block bb, rtx setcc,
continue;
/* Check the data flow is valid after edge insertions. */
- if (e->insns.r && reg_killed_on_edge (reg_used->reg_rtx, e))
+ if (e->insns.r && reg_killed_on_edge (reg_used, e))
continue;
src = SET_SRC (pc_set (jump));
@@ -1535,8 +1540,7 @@ bypass_block (basic_block bb, rtx setcc,
SET_DEST (PATTERN (setcc)),
SET_SRC (PATTERN (setcc)));
- new_rtx = simplify_replace_rtx (src, reg_used->reg_rtx,
- set->src);
+ new_rtx = simplify_replace_rtx (src, reg_used, set->src);
/* Jump bypassing may have already placed instructions on
edges of the CFG. We can't bypass an outgoing edge that
