Cleanup and improve multipass_dfa_lookahead_guard

	* config/i386/i386.c (core2i7_first_cycle_multipass_filter_ready_try,)
	(core2i7_first_cycle_multipass_begin,)
	(core2i7_first_cycle_multipass_issue,)
	(core2i7_first_cycle_multipass_backtrack): Update signature.
	* config/ia64/ia64.c
	(ia64_first_cycle_multipass_dfa_lookahead_guard_spec): Remove.
	(ia64_first_cycle_multipass_dfa_lookahead_guard): Update signature.
	(TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD_SPEC): Remove
	hook definition.
	(ia64_first_cycle_multipass_dfa_lookahead_guard): Merge logic from
	ia64_first_cycle_multipass_dfa_lookahead_guard_spec.  Update return
	values.
	* config/rs6000/rs6000.c (rs6000_use_sched_lookahead_guard): Update
	return values.
	* doc/tm.texi: Regenerate.
	* doc/tm.texi.in
	(TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD_SPEC): Remove.
	* haifa-sched.c (ready_try): Make signed to allow negative values.
	(rebug_ready_list_1): Update.
	(choose_ready): Simplify.
	(sched_extend_ready_list): Update.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@210747 138bc75d-0d04-0410-961f-82ee72b054a4

10 files changed, 136 insertions, 124 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 7c169f67d17..c86e5a8b9a6 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,30 @@
 2014-05-22  Maxim Kuvyrkov  <maxim.kuvyrkov@linaro.org>
 
+	Cleanup and improve multipass_dfa_lookahead_guard
+        * config/i386/i386.c (core2i7_first_cycle_multipass_filter_ready_try,)
+        (core2i7_first_cycle_multipass_begin,)
+        (core2i7_first_cycle_multipass_issue,)
+        (core2i7_first_cycle_multipass_backtrack): Update signature.
+        * config/ia64/ia64.c
+        (ia64_first_cycle_multipass_dfa_lookahead_guard_spec): Remove.
+        (ia64_first_cycle_multipass_dfa_lookahead_guard): Update signature.
+        (TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD_SPEC): Remove
+        hook definition.
+        (ia64_first_cycle_multipass_dfa_lookahead_guard): Merge logic from
+        ia64_first_cycle_multipass_dfa_lookahead_guard_spec.  Update return
+        values.
+        * config/rs6000/rs6000.c (rs6000_use_sched_lookahead_guard): Update
+        return values.
+        * doc/tm.texi: Regenerate.
+        * doc/tm.texi.in
+        (TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD_SPEC): Remove.
+        * haifa-sched.c (ready_try): Make signed to allow negative values.
+        (rebug_ready_list_1): Update.
+        (choose_ready): Simplify.
+        (sched_extend_ready_list): Update.
+
+2014-05-22  Maxim Kuvyrkov  <maxim.kuvyrkov@linaro.org>
+
 	Remove IA64 speculation tweaking flags
         * config/ia64/ia64.c (ia64_set_sched_flags): Delete handling of
         speculation tuning flags.
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 415e31b5606..24c6f82c4b2 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -26383,7 +26383,7 @@ static int min_insn_size (rtx);
 static void
 core2i7_first_cycle_multipass_filter_ready_try
 (const_ix86_first_cycle_multipass_data_t data,
- char *ready_try, int n_ready, bool first_cycle_insn_p)
+ signed char *ready_try, int n_ready, bool first_cycle_insn_p)
 {
   while (n_ready--)
     {
@@ -26415,7 +26415,8 @@ core2i7_first_cycle_multipass_filter_ready_try
 
 /* Prepare for a new round of multipass lookahead scheduling.  */
 static void
-core2i7_first_cycle_multipass_begin (void *_data, char *ready_try, int n_ready,
+core2i7_first_cycle_multipass_begin (void *_data,
+				     signed char *ready_try, int n_ready,
 				     bool first_cycle_insn_p)
 {
   ix86_first_cycle_multipass_data_t data
@@ -26436,7 +26437,8 @@ core2i7_first_cycle_multipass_begin (void *_data, char *ready_try, int n_ready,
 /* INSN is being issued in current solution.  Account for its impact on
    the decoder model.  */
 static void
-core2i7_first_cycle_multipass_issue (void *_data, char *ready_try, int n_ready,
+core2i7_first_cycle_multipass_issue (void *_data,
+				     signed char *ready_try, int n_ready,
 				     rtx insn, const void *_prev_data)
 {
   ix86_first_cycle_multipass_data_t data
@@ -26474,7 +26476,7 @@ core2i7_first_cycle_multipass_issue (void *_data, char *ready_try, int n_ready,
 /* Revert the effect on ready_try.  */
 static void
 core2i7_first_cycle_multipass_backtrack (const void *_data,
-					 char *ready_try,
+					 signed char *ready_try,
 					 int n_ready ATTRIBUTE_UNUSED)
 {
   const_ix86_first_cycle_multipass_data_t data
diff --git a/gcc/config/ia64/ia64.c b/gcc/config/ia64/ia64.c
index 7118146998a..d6e4cf4961f 100644
--- a/gcc/config/ia64/ia64.c
+++ b/gcc/config/ia64/ia64.c
@@ -169,8 +169,7 @@ static int ia64_first_cycle_multipass_dfa_lookahead (void);
 static void ia64_dependencies_evaluation_hook (rtx, rtx);
 static void ia64_init_dfa_pre_cycle_insn (void);
 static rtx ia64_dfa_pre_cycle_insn (void);
-static int ia64_first_cycle_multipass_dfa_lookahead_guard (rtx);
-static bool ia64_first_cycle_multipass_dfa_lookahead_guard_spec (const_rtx);
+static int ia64_first_cycle_multipass_dfa_lookahead_guard (rtx, int);
 static int ia64_dfa_new_cycle (FILE *, int, rtx, int, int, int *);
 static void ia64_h_i_d_extended (void);
 static void * ia64_alloc_sched_context (void);
@@ -496,10 +495,6 @@ static const struct attribute_spec ia64_attribute_table[] =
 #undef TARGET_SCHED_GEN_SPEC_CHECK
 #define TARGET_SCHED_GEN_SPEC_CHECK ia64_gen_spec_check
 
-#undef TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD_SPEC
-#define TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD_SPEC\
-  ia64_first_cycle_multipass_dfa_lookahead_guard_spec
-
 #undef TARGET_SCHED_SKIP_RTX_P
 #define TARGET_SCHED_SKIP_RTX_P ia64_skip_rtx_p
 
@@ -7531,32 +7526,28 @@ ia64_variable_issue (FILE *dump ATTRIBUTE_UNUSED,
   return 1;
 }
 
-/* We are choosing insn from the ready queue.  Return nonzero if INSN
+/* We are choosing insn from the ready queue.  Return zero if INSN
    can be chosen.  */
 
 static int
-ia64_first_cycle_multipass_dfa_lookahead_guard (rtx insn)
+ia64_first_cycle_multipass_dfa_lookahead_guard (rtx insn, int ready_index)
 {
   gcc_assert (insn && INSN_P (insn));
-  return ((!reload_completed
-	   || !safe_group_barrier_needed (insn))
-	  && ia64_first_cycle_multipass_dfa_lookahead_guard_spec (insn)
-	  && (!mflag_sched_mem_insns_hard_limit
-	      || !is_load_p (insn)
-	      || mem_ops_in_group[current_cycle % 4] < ia64_max_memory_insns));
-}
 
-/* We are choosing insn from the ready queue.  Return nonzero if INSN
-   can be chosen.  */
+  /* Size of ALAT is 32.  As far as we perform conservative
+     data speculation, we keep ALAT half-empty.  */
+  if ((TODO_SPEC (insn) & BEGIN_DATA) && pending_data_specs >= 16)
+    return ready_index == 0 ? -1 : 1;
 
-static bool
-ia64_first_cycle_multipass_dfa_lookahead_guard_spec (const_rtx insn)
-{
-  gcc_assert (insn  && INSN_P (insn));
-  /* Size of ALAT is 32.  As far as we perform conservative data speculation,
-     we keep ALAT half-empty.  */
-  return (pending_data_specs < 16
-	  || !(TODO_SPEC (insn) & BEGIN_DATA));
+  if (ready_index == 0)
+    return 0;
+
+  if ((!reload_completed
+       || !safe_group_barrier_needed (insn))
+      && (!mflag_sched_mem_insns_hard_limit
+	  || !is_load_p (insn)
+	  || mem_ops_in_group[current_cycle % 4] < ia64_max_memory_insns))
+    return 0;
 }
 
 /* The following variable value is pseudo-insn used by the DFA insn
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index cd7b8c1f49d..f58ccd0936c 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -26796,22 +26796,25 @@ rs6000_use_sched_lookahead (void)
     }
 }
 
-/* We are choosing insn from the ready queue.  Return nonzero if INSN can be chosen.  */
+/* We are choosing insn from the ready queue.  Return zero if INSN can be
+   chosen.  */
 static int
-rs6000_use_sched_lookahead_guard (rtx insn)
+rs6000_use_sched_lookahead_guard (rtx insn, int ready_index)
 {
+  if (ready_index == 0)
+    return 0;
+
   if (rs6000_cpu_attr != CPU_CELL)
-    return 1;
+    return 0;
 
-   if (insn == NULL_RTX || !INSN_P (insn))
-     abort ();
+  gcc_assert (insn != NULL_RTX && INSN_P (insn));
 
   if (!reload_completed
       || is_nonpipeline_insn (insn)
       || is_microcoded_insn (insn))
-    return 0;
+    return 1;
 
-  return 1;
+  return 0;
 }
 
 /* Determine if PAT refers to memory. If so, set MEM_REF to the MEM rtx
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 1a26bcd0448..05342b3d8ac 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -6716,26 +6716,32 @@ schedules to choose the best one.
 The default is no multipass scheduling.
 @end deftypefn
 
-@deftypefn {Target Hook} int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD (rtx @var{insn})
+@deftypefn {Target Hook} int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD (rtx @var{insn}, int @var{ready_index})
 
 This hook controls what insns from the ready insn queue will be
 considered for the multipass insn scheduling.  If the hook returns
-zero for @var{insn}, the insn will be not chosen to
-be issued.
+zero for @var{insn}, the insn will be considered in multipass scheduling.
+Positive return values will remove @var{insn} from consideration on
+the current round of multipass scheduling.
+Negative return values will remove @var{insn} from consideration for given
+number of cycles.
+Backends should be careful about returning non-zero for highest priority
+instruction at position 0 in the ready list.  @var{ready_index} is passed
+to allow backends make correct judgements.
 
 The default is that any ready insns can be chosen to be issued.
 @end deftypefn
 
-@deftypefn {Target Hook} void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN (void *@var{data}, char *@var{ready_try}, int @var{n_ready}, bool @var{first_cycle_insn_p})
+@deftypefn {Target Hook} void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN (void *@var{data}, signed char *@var{ready_try}, int @var{n_ready}, bool @var{first_cycle_insn_p})
 This hook prepares the target backend for a new round of multipass
 scheduling.
 @end deftypefn
 
-@deftypefn {Target Hook} void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE (void *@var{data}, char *@var{ready_try}, int @var{n_ready}, rtx @var{insn}, const void *@var{prev_data})
+@deftypefn {Target Hook} void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE (void *@var{data}, signed char *@var{ready_try}, int @var{n_ready}, rtx @var{insn}, const void *@var{prev_data})
 This hook is called when multipass scheduling evaluates instruction INSN.
 @end deftypefn
 
-@deftypefn {Target Hook} void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK (const void *@var{data}, char *@var{ready_try}, int @var{n_ready})
+@deftypefn {Target Hook} void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK (const void *@var{data}, signed char *@var{ready_try}, int @var{n_ready})
 This is called when multipass scheduling backtracks from evaluation of
 an instruction.
 @end deftypefn
@@ -6843,19 +6849,6 @@ a pattern for a branchy check corresponding to a simple check denoted by
 @var{insn} should be generated.  In this case @var{label} can't be null.
 @end deftypefn
 
-@deftypefn {Target Hook} bool TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD_SPEC (const_rtx @var{insn})
-This hook is used as a workaround for
-@samp{TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD} not being
-called on the first instruction of the ready list.  The hook is used to
-discard speculative instructions that stand first in the ready list from
-being scheduled on the current cycle.  If the hook returns @code{false},
-@var{insn} will not be chosen to be issued.
-For non-speculative instructions,
-the hook should always return @code{true}.  For example, in the ia64 backend
-the hook is used to cancel data speculative insns when the ALAT table
-is nearly full.
-@end deftypefn
-
 @deftypefn {Target Hook} void TARGET_SCHED_SET_SCHED_FLAGS (struct spec_info_def *@var{spec_info})
 This hook is used by the insn scheduler to find out what features should be
 enabled/used.
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index 9c81f201664..8a66842fd77 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -5019,8 +5019,6 @@ them: try the first ones in this list first.
 
 @hook TARGET_SCHED_GEN_SPEC_CHECK
 
-@hook TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD_SPEC
-
 @hook TARGET_SCHED_SET_SCHED_FLAGS
 
 @hook TARGET_SCHED_SMS_RES_MII
diff --git a/gcc/haifa-sched.c b/gcc/haifa-sched.c
index f39c0476f00..0e1800a6332 100644
--- a/gcc/haifa-sched.c
+++ b/gcc/haifa-sched.c
@@ -345,7 +345,7 @@ size_t dfa_state_size;
 
 /* The following array is used to find the best insn from ready when
    the automaton pipeline interface is used.  */
-char *ready_try = NULL;
+signed char *ready_try = NULL;
 
 /* The ready list.  */
 struct ready_list ready = {NULL, 0, 0, 0, 0};
@@ -5126,7 +5126,7 @@ early_queue_to_ready (state_t state, struct ready_list *ready)
    If READY_TRY is non-zero then only print insns that max_issue
    will consider.  */
 static void
-debug_ready_list_1 (struct ready_list *ready, char *ready_try)
+debug_ready_list_1 (struct ready_list *ready, signed char *ready_try)
 {
   rtx *p;
   int i;
@@ -5566,10 +5566,9 @@ choose_ready (struct ready_list *ready, bool first_cycle_insn_p,
     }
   else
     {
-      /* Try to choose the better insn.  */
+      /* Try to choose the best insn.  */
       int index = 0, i;
       rtx insn;
-      ds_t ts;
 
       insn = ready_element (ready, 0);
       if (INSN_CODE (insn) < 0)
@@ -5578,42 +5577,56 @@ choose_ready (struct ready_list *ready, bool first_cycle_insn_p,
 	  return 0;
 	}
 
-      ts = TODO_SPEC (insn);
-      if ((ts & SPECULATIVE)
-	  && (targetm.sched.first_cycle_multipass_dfa_lookahead_guard_spec
-	      && (!targetm.sched
-		  .first_cycle_multipass_dfa_lookahead_guard_spec (insn))))
-	/* Discard speculative instruction that stands first in the ready
-	   list.  */
+      /* Filter the search space.  */
+      for (i = 0; i < ready->n_ready; i++)
 	{
-	  change_queue_index (insn, 1);
-	  return 1;
-	}
+	  ready_try[i] = 0;
 
-      for (i = 0; i < ready->n_ready; i++)
-	ready_try [i] = 0;
+	  insn = ready_element (ready, i);
 
-      /* Let the target filter the search space.  */
-      for (i = 1; i < ready->n_ready; i++)
-	if (!ready_try[i])
-	  {
-	    insn = ready_element (ready, i);
-
-	    /* If this insn is recognizable we should have already
-	       recognized it earlier.
-	       ??? Not very clear where this is supposed to be done.
-	       See dep_cost_1.  */
-	    gcc_checking_assert (INSN_CODE (insn) >= 0
-				 || recog_memoized (insn) < 0);
-
-	    ready_try [i]
-	      = (/* INSN_CODE check can be omitted here as it is also done later
-		    in max_issue ().  */
-		 INSN_CODE (insn) < 0
-		 || (targetm.sched.first_cycle_multipass_dfa_lookahead_guard
-		     && !targetm.sched.first_cycle_multipass_dfa_lookahead_guard
-		     (insn)));
-	  }
+	  /* If this insn is recognizable we should have already
+	     recognized it earlier.
+	     ??? Not very clear where this is supposed to be done.
+	     See dep_cost_1.  */
+	  gcc_checking_assert (INSN_CODE (insn) >= 0
+			       || recog_memoized (insn) < 0);
+	  if (INSN_CODE (insn) < 0)
+	    {
+	      /* Non-recognized insns at position 0 are handled above.  */
+	      gcc_assert (i > 0);
+	      ready_try[i] = 1;
+	      continue;
+	    }
+
+	  if (targetm.sched.first_cycle_multipass_dfa_lookahead_guard)
+	    {
+	      ready_try[i]
+		= (targetm.sched.first_cycle_multipass_dfa_lookahead_guard
+		    (insn, i));
+
+	      if (ready_try[i] < 0)
+		/* Queue instruction for several cycles.
+		   We need to restart choose_ready as we have changed
+		   the ready list.  */
+		{
+		  change_queue_index (insn, -ready_try[i]);
+		  return 1;
+		}
+
+	      /* Make sure that we didn't end up with 0'th insn filtered out.
+		 Don't be tempted to make life easier for backends and just
+		 requeue 0'th insn if (ready_try[0] == 0) and restart
+		 choose_ready.  Backends should be very considerate about
+		 requeueing instructions -- especially the highest priority
+		 one at position 0.  */
+	      gcc_assert (ready_try[i] == 0 || i > 0);
+	      if (ready_try[i])
+		continue;
+	    }
+
+	  gcc_assert (ready_try[i] == 0);
+	  /* INSN made it through the scrutiny of filters!  */
+	}
 
       if (max_issue (ready, 1, curr_state, first_cycle_insn_p, &index) == 0)
 	{
@@ -7193,8 +7206,9 @@ sched_extend_ready_list (int new_sched_ready_n_insns)
 
   gcc_assert (new_sched_ready_n_insns >= sched_ready_n_insns);
 
-  ready_try = (char *) xrecalloc (ready_try, new_sched_ready_n_insns,
-                                  sched_ready_n_insns, sizeof (*ready_try));
+  ready_try = (signed char *) xrecalloc (ready_try, new_sched_ready_n_insns,
+					 sched_ready_n_insns,
+					 sizeof (*ready_try));
 
   /* We allocate +1 element to save initial state in the choice_stack[0]
      entry.  */
diff --git a/gcc/sched-int.h b/gcc/sched-int.h
index 6e024c29f42..ffe618cc67d 100644
--- a/gcc/sched-int.h
+++ b/gcc/sched-int.h
@@ -170,7 +170,7 @@ struct ready_list
   int n_debug;
 };
 
-extern char *ready_try;
+extern signed char *ready_try;
 extern struct ready_list ready;
 
 extern int max_issue (struct ready_list *, int, state_t, bool, int *);
diff --git a/gcc/sel-sched.c b/gcc/sel-sched.c
index e255d62c7c3..0c864acd7f7 100644
--- a/gcc/sel-sched.c
+++ b/gcc/sel-sched.c
@@ -4225,7 +4225,7 @@ invoke_dfa_lookahead_guard (void)
       if (! have_hook || i == 0)
         r = 0;
       else
-        r = !targetm.sched.first_cycle_multipass_dfa_lookahead_guard (insn);
+        r = targetm.sched.first_cycle_multipass_dfa_lookahead_guard (insn, i);
 
       gcc_assert (INSN_CODE (insn) >= 0);
 
diff --git a/gcc/target.def b/gcc/target.def
index dd167bb6afb..5fe2e823e27 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -1174,11 +1174,17 @@ DEFHOOK
  "\n\
 This hook controls what insns from the ready insn queue will be\n\
 considered for the multipass insn scheduling.  If the hook returns\n\
-zero for @var{insn}, the insn will be not chosen to\n\
-be issued.\n\
+zero for @var{insn}, the insn will be considered in multipass scheduling.\n\
+Positive return values will remove @var{insn} from consideration on\n\
+the current round of multipass scheduling.\n\
+Negative return values will remove @var{insn} from consideration for given\n\
+number of cycles.\n\
+Backends should be careful about returning non-zero for highest priority\n\
+instruction at position 0 in the ready list.  @var{ready_index} is passed\n\
+to allow backends make correct judgements.\n\
 \n\
 The default is that any ready insns can be chosen to be issued.",
- int, (rtx insn), NULL)
+ int, (rtx insn, int ready_index), NULL)
 
 /* This hook prepares the target for a new round of multipass
    scheduling.
@@ -1193,7 +1199,7 @@ DEFHOOK
 (first_cycle_multipass_begin,
  "This hook prepares the target backend for a new round of multipass\n\
 scheduling.",
- void, (void *data, char *ready_try, int n_ready, bool first_cycle_insn_p),
+ void, (void *data, signed char *ready_try, int n_ready, bool first_cycle_insn_p),
  NULL)
 
 /* This hook is called when multipass scheduling evaluates instruction INSN.
@@ -1209,7 +1215,7 @@ scheduling.",
 DEFHOOK
 (first_cycle_multipass_issue,
  "This hook is called when multipass scheduling evaluates instruction INSN.",
- void, (void *data, char *ready_try, int n_ready, rtx insn,
+ void, (void *data, signed char *ready_try, int n_ready, rtx insn,
 	const void *prev_data), NULL)
 
 /* This hook is called when multipass scheduling backtracks from evaluation of
@@ -1225,7 +1231,7 @@ DEFHOOK
 (first_cycle_multipass_backtrack,
  "This is called when multipass scheduling backtracks from evaluation of\n\
 an instruction.",
- void, (const void *data, char *ready_try, int n_ready), NULL)
+ void, (const void *data, signed char *ready_try, int n_ready), NULL)
 
 /* This hook notifies the target about the result of the concluded current
    round of multipass scheduling.
@@ -1421,26 +1427,6 @@ a pattern for a branchy check corresponding to a simple check denoted by\n\
 @var{insn} should be generated.  In this case @var{label} can't be null.",
  rtx, (rtx insn, rtx label, unsigned int ds), NULL)
 
-/* The following member value is a pointer to a function controlling
-   what insns from the ready insn queue will be considered for the
-   multipass insn scheduling.  If the hook returns zero for the insn
-   passed as the parameter, the insn will not be chosen to be
-   issued.  This hook is used to discard speculative instructions,
-   that stand at the first position of the ready list.  */
-DEFHOOK
-(first_cycle_multipass_dfa_lookahead_guard_spec,
- "This hook is used as a workaround for\n\
-@samp{TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD} not being\n\
-called on the first instruction of the ready list.  The hook is used to\n\
-discard speculative instructions that stand first in the ready list from\n\
-being scheduled on the current cycle.  If the hook returns @code{false},\n\
-@var{insn} will not be chosen to be issued.\n\
-For non-speculative instructions,\n\
-the hook should always return @code{true}.  For example, in the ia64 backend\n\
-the hook is used to cancel data speculative insns when the ALAT table\n\
-is nearly full.",
- bool, (const_rtx insn), NULL)
-
 /* The following member value is a pointer to a function that provides
    information about the speculation capabilities of the target.
    The parameter is a pointer to spec_info variable.  */