diff mbox series

[08/12] mode-switching: Pass set of live registers to the needed hook

Message ID mptsf5k6nos.fsf@arm.com
State New
Headers show
Series Tweaks and extensions to the mode-switching pass | expand

Commit Message

Richard Sandiford Nov. 5, 2023, 6:48 p.m. UTC 
The emit hook already takes the set of live hard registers as input.
This patch passes it to the needed hook too.  SME uses this to
optimise the mode choice based on whether state is live or dead.

The main caller already had access to the required info, but the
special handling of return values did not.

gcc/
	* target.def (mode_switching.needed): Add a regs_live parameter.
	* doc/tm.texi: Regenerate.
	* config/epiphany/epiphany-protos.h (epiphany_mode_needed): Update
	accordingly.
	* config/epiphany/epiphany.cc (epiphany_mode_needed): Likewise.
	* config/epiphany/mode-switch-use.cc (insert_uses): Likewise.
	* config/i386/i386.cc (ix86_mode_needed): Likewise.
	* config/riscv/riscv.cc (riscv_mode_needed): Likewise.
	* config/sh/sh.cc (sh_mode_needed): Likewise.
	* mode-switching.cc (optimize_mode_switching): Likewise.
	(create_pre_exit): Likewise, using the DF simulate functions
	to calculate the required information.
---
 gcc/config/epiphany/epiphany-protos.h  |  4 +++-
 gcc/config/epiphany/epiphany.cc        |  2 +-
 gcc/config/epiphany/mode-switch-use.cc |  2 +-
 gcc/config/i386/i386.cc                |  2 +-
 gcc/config/riscv/riscv.cc              |  2 +-
 gcc/config/sh/sh.cc                    |  4 ++--
 gcc/doc/tm.texi                        |  5 +++--
 gcc/mode-switching.cc                  | 14 ++++++++++++--
 gcc/target.def                         |  5 +++--
 9 files changed, 27 insertions(+), 13 deletions(-)

Comments

Jeff Law Nov. 7, 2023, 1:11 a.m. UTC | #1 
On 11/5/23 11:48, Richard Sandiford wrote:
> The emit hook already takes the set of live hard registers as input.
> This patch passes it to the needed hook too.  SME uses this to
> optimise the mode choice based on whether state is live or dead.
> 
> The main caller already had access to the required info, but the
> special handling of return values did not.
> 
> gcc/
> 	* target.def (mode_switching.needed): Add a regs_live parameter.
> 	* doc/tm.texi: Regenerate.
> 	* config/epiphany/epiphany-protos.h (epiphany_mode_needed): Update
> 	accordingly.
> 	* config/epiphany/epiphany.cc (epiphany_mode_needed): Likewise.
> 	* config/epiphany/mode-switch-use.cc (insert_uses): Likewise.
> 	* config/i386/i386.cc (ix86_mode_needed): Likewise.
> 	* config/riscv/riscv.cc (riscv_mode_needed): Likewise.
> 	* config/sh/sh.cc (sh_mode_needed): Likewise.
> 	* mode-switching.cc (optimize_mode_switching): Likewise.
> 	(create_pre_exit): Likewise, using the DF simulate functions
> 	to calculate the required information.
We should probably deprecate the epiphany port.  It's been too flakey to 
test for years at this point.  But anyway....

OK for the trunk.

jeff
diff mbox series

Patch

diff --git a/gcc/config/epiphany/epiphany-protos.h b/gcc/config/epiphany/epiphany-protos.h
index 72c141c1a6d..ef49a1e06a4 100644
--- a/gcc/config/epiphany/epiphany-protos.h
+++ b/gcc/config/epiphany/epiphany-protos.h
@@ -44,7 +44,9 @@  extern void emit_set_fp_mode (int entity, int mode, int prev_mode,
 #endif
 extern void epiphany_insert_mode_switch_use (rtx_insn *insn, int, int);
 extern void epiphany_expand_set_fp_mode (rtx *operands);
-extern int epiphany_mode_needed (int entity, rtx_insn *insn);
+#ifdef HARD_CONST
+extern int epiphany_mode_needed (int entity, rtx_insn *insn, HARD_REG_SET);
+#endif
 extern int epiphany_mode_after (int entity, int last_mode, rtx_insn *insn);
 extern bool epiphany_epilogue_uses (int regno);
 extern bool epiphany_optimize_mode_switching (int entity);
diff --git a/gcc/config/epiphany/epiphany.cc b/gcc/config/epiphany/epiphany.cc
index a5460dbf97f..60a9b49d8a4 100644
--- a/gcc/config/epiphany/epiphany.cc
+++ b/gcc/config/epiphany/epiphany.cc
@@ -2400,7 +2400,7 @@  epiphany_mode_priority (int entity, int priority)
 }
 
 int
-epiphany_mode_needed (int entity, rtx_insn *insn)
+epiphany_mode_needed (int entity, rtx_insn *insn, HARD_REG_SET)
 {
   enum attr_fp_mode mode;
 
diff --git a/gcc/config/epiphany/mode-switch-use.cc b/gcc/config/epiphany/mode-switch-use.cc
index 71530612658..183b9b7a394 100644
--- a/gcc/config/epiphany/mode-switch-use.cc
+++ b/gcc/config/epiphany/mode-switch-use.cc
@@ -58,7 +58,7 @@  insert_uses (void)
 	{
 	  if (!INSN_P (insn))
 	    continue;
-	  mode = epiphany_mode_needed (e, insn);
+	  mode = epiphany_mode_needed (e, insn, {});
 	  if (mode == no_mode)
 	    continue;
 	  if (target_insert_mode_switch_use)
diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index fdc9362cf5b..7a5a9a966e8 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -15061,7 +15061,7 @@  ix86_i387_mode_needed (int entity, rtx_insn *insn)
    prior to the execution of insn.  */
 
 static int
-ix86_mode_needed (int entity, rtx_insn *insn)
+ix86_mode_needed (int entity, rtx_insn *insn, HARD_REG_SET)
 {
   switch (entity)
     {
diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 08ff05dcc3f..f915de7ed56 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -9413,7 +9413,7 @@  riscv_frm_mode_needed (rtx_insn *cur_insn, int code)
    prior to the execution of insn.  */
 
 static int
-riscv_mode_needed (int entity, rtx_insn *insn)
+riscv_mode_needed (int entity, rtx_insn *insn, HARD_REG_SET)
 {
   int code = recog_memoized (insn);
 
diff --git a/gcc/config/sh/sh.cc b/gcc/config/sh/sh.cc
index 294faf7c0c3..c363490e852 100644
--- a/gcc/config/sh/sh.cc
+++ b/gcc/config/sh/sh.cc
@@ -195,7 +195,7 @@  static int calc_live_regs (HARD_REG_SET *);
 static HOST_WIDE_INT rounded_frame_size (int);
 static bool sh_frame_pointer_required (void);
 static void sh_emit_mode_set (int, int, int, HARD_REG_SET);
-static int sh_mode_needed (int, rtx_insn *);
+static int sh_mode_needed (int, rtx_insn *, HARD_REG_SET);
 static int sh_mode_after (int, int, rtx_insn *);
 static int sh_mode_entry (int);
 static int sh_mode_exit (int);
@@ -12531,7 +12531,7 @@  sh_emit_mode_set (int entity ATTRIBUTE_UNUSED, int mode,
 }
 
 static int
-sh_mode_needed (int entity ATTRIBUTE_UNUSED, rtx_insn *insn)
+sh_mode_needed (int entity ATTRIBUTE_UNUSED, rtx_insn *insn, HARD_REG_SET)
 {
   return recog_memoized (insn) >= 0  ? get_attr_fp_mode (insn) : FP_MODE_NONE;
 }
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 1a825c5004e..144b3f88c37 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -10414,12 +10414,13 @@  known.  Sets of a lower numbered entity will be emitted before
 sets of a higher numbered entity to a mode of the same or lower priority.
 @end deftypefn
 
-@deftypefn {Target Hook} int TARGET_MODE_NEEDED (int @var{entity}, rtx_insn *@var{insn})
+@deftypefn {Target Hook} int TARGET_MODE_NEEDED (int @var{entity}, rtx_insn *@var{insn}, HARD_REG_SET @var{regs_live})
 @var{entity} is an integer specifying a mode-switched entity.
 If @code{OPTIMIZE_MODE_SWITCHING} is defined, you must define this hook
 to return the mode that @var{entity} must be switched into prior to the
 execution of @var{insn}, or the number of modes if @var{insn} has no
-such requirement.
+such requirement.  @var{regs_live} contains the set of hard registers
+that are live before @var{insn}.
 @end deftypefn
 
 @deftypefn {Target Hook} int TARGET_MODE_AFTER (int @var{entity}, int @var{mode}, rtx_insn *@var{insn})
diff --git a/gcc/mode-switching.cc b/gcc/mode-switching.cc
index b8a887d81f7..c5fe90ba449 100644
--- a/gcc/mode-switching.cc
+++ b/gcc/mode-switching.cc
@@ -254,6 +254,9 @@  create_pre_exit (int n_entities, int *entity_map, const int *num_modes)
 	    && GET_CODE (PATTERN (last_insn)) == USE
 	    && GET_CODE ((ret_reg = XEXP (PATTERN (last_insn), 0))) == REG)
 	  {
+	    auto_bitmap live;
+	    df_simulate_initialize_backwards (src_bb, live);
+
 	    int ret_start = REGNO (ret_reg);
 	    int nregs = REG_NREGS (ret_reg);
 	    int ret_end = ret_start + nregs;
@@ -262,6 +265,8 @@  create_pre_exit (int n_entities, int *entity_map, const int *num_modes)
 	    bool forced_late_switch = false;
 	    rtx_insn *before_return_copy;
 
+	    df_simulate_one_insn_backwards (src_bb, last_insn, live);
+
 	    do
 	      {
 		rtx_insn *return_copy = PREV_INSN (last_insn);
@@ -269,6 +274,8 @@  create_pre_exit (int n_entities, int *entity_map, const int *num_modes)
 		int copy_start, copy_num;
 		int j;
 
+		df_simulate_one_insn_backwards (src_bb, return_copy, live);
+
 		if (NONDEBUG_INSN_P (return_copy))
 		  {
 		    /* When using SJLJ exceptions, the call to the
@@ -368,11 +375,14 @@  create_pre_exit (int n_entities, int *entity_map, const int *num_modes)
 		       the case for floating point on SH4 - then it might
 		       be set by an arithmetic operation that needs a
 		       different mode than the exit block.  */
+		    HARD_REG_SET hard_regs_live;
+		    REG_SET_TO_HARD_REG_SET (hard_regs_live, live);
 		    for (j = n_entities - 1; j >= 0; j--)
 		      {
 			int e = entity_map[j];
 			int mode =
-			  targetm.mode_switching.needed (e, return_copy);
+			  targetm.mode_switching.needed (e, return_copy,
+							 hard_regs_live);
 
 			if (mode != num_modes[e]
 			    && mode != targetm.mode_switching.exit (e))
@@ -610,7 +620,7 @@  optimize_mode_switching (void)
 	    {
 	      if (INSN_P (insn))
 		{
-		  int mode = targetm.mode_switching.needed (e, insn);
+		  int mode = targetm.mode_switching.needed (e, insn, live_now);
 		  rtx link;
 
 		  if (mode != no_mode && mode != last_mode)
diff --git a/gcc/target.def b/gcc/target.def
index a70275b8abd..50bad184aca 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -7031,8 +7031,9 @@  DEFHOOK
 If @code{OPTIMIZE_MODE_SWITCHING} is defined, you must define this hook\n\
 to return the mode that @var{entity} must be switched into prior to the\n\
 execution of @var{insn}, or the number of modes if @var{insn} has no\n\
-such requirement.",
- int, (int entity, rtx_insn *insn), NULL)
+such requirement.  @var{regs_live} contains the set of hard registers\n\
+that are live before @var{insn}.",
+ int, (int entity, rtx_insn *insn, HARD_REG_SET regs_live), NULL)
 
 DEFHOOK
 (after,