optimize_mode_switching passes an entity's current mode (if known)
to the emit hook. However, the mode that it passed ignored the
effect of the after hook. Instead, the mode for the first emit
call in a block was taken from the incoming mode, whereas the
mode for each subsequent emit call was taken from the result
of the previous call.
The previous pass through the insns already calculated the
correct mode, so this patch records it in the seginfo structure.
(There was a 32-bit hole on 64-bit hosts, so this doesn't increase
the size of the structure for them.)
gcc/
* mode-switching.cc (seginfo): Add a prev_mode field.
(new_seginfo): Take and initialize the prev_mode.
(optimize_mode_switching): Update calls accordingly.
Use the recorded modes during the emit phase, rather than
computing one on the fly.
---
gcc/mode-switching.cc | 30 +++++++++++++++++-------------
1 file changed, 17 insertions(+), 13 deletions(-)
On 11/5/23 11:47, Richard Sandiford wrote:
> optimize_mode_switching passes an entity's current mode (if known)
> to the emit hook. However, the mode that it passed ignored the
> effect of the after hook. Instead, the mode for the first emit
> call in a block was taken from the incoming mode, whereas the
> mode for each subsequent emit call was taken from the result
> of the previous call.
>
> The previous pass through the insns already calculated the
> correct mode, so this patch records it in the seginfo structure.
> (There was a 32-bit hole on 64-bit hosts, so this doesn't increase
> the size of the structure for them.)
>
> gcc/
> * mode-switching.cc (seginfo): Add a prev_mode field.
> (new_seginfo): Take and initialize the prev_mode.
> (optimize_mode_switching): Update calls accordingly.
> Use the recorded modes during the emit phase, rather than
> computing one on the fly.
OK
jeff
@@ -68,6 +68,7 @@ along with GCC; see the file COPYING3. If not see
NEXT is the next insn in the same basic block. */
struct seginfo
{
+ int prev_mode;
int mode;
rtx_insn *insn_ptr;
struct seginfo *next;
@@ -140,20 +141,22 @@ commit_mode_sets (struct edge_list *edge_list, int e, struct bb_info *info)
return need_commit;
}
-/* Allocate a new BBINFO structure, initialized with the MODE, INSN,
- and REGS_LIVE parameters.
+/* Allocate a new BBINFO structure, initialized with the PREV_MODE, MODE,
+ INSN, and REGS_LIVE parameters.
INSN may not be a NOTE_INSN_BASIC_BLOCK, unless it is an empty
basic block; that allows us later to insert instructions in a FIFO-like
manner. */
static struct seginfo *
-new_seginfo (int mode, rtx_insn *insn, const HARD_REG_SET ®s_live)
+new_seginfo (int prev_mode, int mode, rtx_insn *insn,
+ const HARD_REG_SET ®s_live)
{
struct seginfo *ptr;
gcc_assert (!NOTE_INSN_BASIC_BLOCK_P (insn)
|| insn == BB_END (NOTE_BASIC_BLOCK (insn)));
ptr = XNEW (struct seginfo);
+ ptr->prev_mode = prev_mode;
ptr->mode = mode;
ptr->insn_ptr = insn;
ptr->next = NULL;
@@ -590,7 +593,7 @@ optimize_mode_switching (void)
gcc_assert (NOTE_INSN_BASIC_BLOCK_P (ins_pos));
if (ins_pos != BB_END (bb))
ins_pos = NEXT_INSN (ins_pos);
- ptr = new_seginfo (no_mode, ins_pos, live_now);
+ ptr = new_seginfo (no_mode, no_mode, ins_pos, live_now);
add_seginfo (&tail_ptr, ptr);
for (i = 0; i < no_mode; i++)
clear_mode_bit (transp[bb->index], j, i);
@@ -606,12 +609,12 @@ optimize_mode_switching (void)
if (mode != no_mode && mode != last_mode)
{
- any_set_required = true;
- last_mode = mode;
- ptr = new_seginfo (mode, insn, live_now);
+ ptr = new_seginfo (last_mode, mode, insn, live_now);
add_seginfo (&tail_ptr, ptr);
for (i = 0; i < no_mode; i++)
clear_mode_bit (transp[bb->index], j, i);
+ any_set_required = true;
+ last_mode = mode;
}
if (targetm.mode_switching.after)
@@ -637,7 +640,7 @@ optimize_mode_switching (void)
mark the block as nontransparent. */
if (!any_set_required)
{
- ptr = new_seginfo (no_mode, BB_END (bb), live_now);
+ ptr = new_seginfo (last_mode, no_mode, BB_END (bb), live_now);
add_seginfo (&tail_ptr, ptr);
if (last_mode != no_mode)
for (i = 0; i < no_mode; i++)
@@ -778,9 +781,9 @@ optimize_mode_switching (void)
FOR_EACH_BB_FN (bb, cfun)
{
struct seginfo *ptr, *next;
- int cur_mode = bb_info[j][bb->index].mode_in;
+ struct seginfo *first = bb_info[j][bb->index].seginfo;
- for (ptr = bb_info[j][bb->index].seginfo; ptr; ptr = next)
+ for (ptr = first; ptr; ptr = next)
{
next = ptr->next;
if (ptr->mode != no_mode)
@@ -790,14 +793,15 @@ optimize_mode_switching (void)
rtl_profile_for_bb (bb);
start_sequence ();
+ int cur_mode = (ptr == first && ptr->prev_mode == no_mode
+ ? bb_info[j][bb->index].mode_in
+ : ptr->prev_mode);
+
targetm.mode_switching.emit (entity_map[j], ptr->mode,
cur_mode, ptr->regs_live);
mode_set = get_insns ();
end_sequence ();
- /* modes kill each other inside a basic block. */
- cur_mode = ptr->mode;
-
/* Insert MODE_SET only if it is nonempty. */
if (mode_set != NULL_RTX)
{