rtl.def (DEFINE_CPU_UNIT, [...]): New RTL constructions.

2001-08-27  Vladimir Makarov  <vmakarov@touchme.toronto.redhat.com>

        * rtl.def (DEFINE_CPU_UNIT, DEFINE_QUERY_CPU_UNIT, EXCLUSION_SET,
	PRESENCE_SET, ABSENCE_SET, DEFINE_BYPASS, DEFINE_AUTOMATON,
	AUTOMATA_OPTION, DEFINE_RESERVATION, DEFINE_INSN_RESERVATION): New
	RTL constructions.

	* genattr.c (main): New variable num_insn_reservations.  Increase
	it if there is DEFINE_INSN_RESERVATION.  Output automaton based
	pipeline hazard recognizer interface.

	* genattrtab.h: New file.

	* genattrtab.c: Include genattrtab.h.
	(attr_printf, check_attr_test, make_internal_attr,
	make_numeric_value): Move protypes into genattrtab.h.  Define them
	as external.
	(num_dfa_decls): New global variable.
	(main): Process DEFINE_CPU_UNIT, DEFINE_QUERY_CPU_UNIT,
	DEFINE_BYPASS, EXCLUSION_SET, PRESENCE_SET, ABSENCE_SET,
	DEFINE_AUTOMATON, AUTOMATA_OPTION, DEFINE_RESERVATION,
	DEFINE_INSN_RESERVATION.  Call expand_automata and write_automata.

	* genautomata.c: New file.

	* rtl.h (LINK_COST_ZERO, LINK_COST_FREE): Remove them.

        * sched-int.h: (curr_state): Add the external definition for
	automaton pipeline interface.
	(haifa_insn_data): Add comments for members blockage and units.

	* target-def.h (TARGET_SCHED_USE_DFA_PIPELINE_INTERFACE,
	TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN,
	TARGET_SCHED_DFA_PRE_CYCLE_INSN,
	TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN,
	TARGET_SCHED_DFA_POST_CYCLE_INSN,
	TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD,
	TARGET_SCHED_INIT_DFA_BUBBLES, TARGET_SCHED_DFA_BUBBLE): New
	macros.
	(TARGET_SCHED): Use the new macros.

	* target.h (use_dfa_pipeline_interface, init_dfa_pre_cycle_insn,
	dfa_pre_cycle_insn, init_dfa_post_cycle_insn, dfa_post_cycle_insn,
	first_cycle_multipass_dfa_lookahead, init_dfa_bubbles,
	dfa_bubble): New members in gcc_target.sched.

        * haifa-sched.c (insert_schedule_bubbles_p): New variable.
	(MAX_INSN_QUEUE_INDEX): New macro for automaton interface.
	(insn_queue): Redefine it as pointer to array.
	(NEXT_Q, NEXT_Q_AFTER): Use MAX_INSN_QUEUE_INDEX instead of
	INSN_QUEUE_SIZE.
	(max_insn_queue_index_macro_value): New variable.
	(curr_state, dfa_state_size, ready_try): New varaibles for
	automaton interface.
	(ready_element, ready_remove, max_issue): New function prototypes
	for automaton interface.
	(choose_ready): New function prototype.
	(insn_unit, blockage_range): Add comments.
	(unit_last_insn, unit_tick, unit_n_insns): Define them for case
	FUNCTION_UNITS_SIZE == 0.
	(insn_issue_delay, actual_hazard_this_instance, schedule_unit,
	actual_hazard, potential_hazard): Add comments.
	(insn_cost): Use cost -1 as undefined value.  Remove
	LINK_COST_ZERO and LINK_COST_FREE.  Add new code for automaton
	pipeline interface.
	(ready_element, ready_remove): New functions for automaton
	interface.
	(schedule_insn): Add new code for automaton pipeline interface.
	(queue_to_ready): Add new code for automaton pipeline interface.
	Use MAX_INSN_QUEUE_INDEX instead of INSN_QUEUE_SIZE.
	(debug_ready_list): Print newline when the queue is empty.
	(max_issue): New function for automaton pipeline interface.
	(choose_ready): New function.
	(schedule_block): Add new code for automaton pipeline interface.
	Print ready list before scheduling each insn.
	(sched_init): Add new code for automaton pipeline interface.
	Initiate insn cost by -1.
	(sched_finish): Free the current automaton state and finalize
	automaton pipeline interface.

	* sched-rgn.c: Include target.h.
	(init_ready_list, new_ready, debug_dependencies): Add new code for
	automaton pipeline interface.

	* sched-vis.c: Include target.h.
	(get_visual_tbl_length): Add code for automaton interface.
	(target_units, print_block_visualization):  Add comments.

        * Makefile.in (GETRUNTIME, HASHTAB, HOST_GETRUNTIME, HOST_HASHTAB,
	USE_HOST_GETRUNTIME, USE_HOST_HASHTAB, HOST_VARRAY): New variables.
	(sched-rgn.o, sched-vis.o): Add new dependency file target.h.
	(getruntime.o, genautomata.o): New entries.
	(genattrtab.o): Add new dependency file genattrtab.h.
	(genattrtab): Add new dependencies.  Link it with `libm.a'.
	(getruntime.o, hashtab.o): New entries for canadian cross.

	* doc/md.texi: Description of automaton based model.

	* doc/tm.texi (TARGET_SCHED_ISSUE_RATE, TARGET_SCHED_ADJUST_COST):
	Add comments.
	(TARGET_SCHED_USE_DFA_PIPELINE_INTERFACE,
	TARGET_SCHED_DFA_PRE_CYCLE_INSN,
	TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN,
	TARGET_SCHED_DFA_POST_CYCLE_INSN,
	TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN,
	TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD,
	TARGET_SCHED_INIT_DFA_BUBBLES, TARGET_SCHED_DFA_BUBBLE): The new
	hook descriptions.
	(TRADITIONAL_PIPELINE_INTERFACE, DFA_PIPELINE_INTERFACE,
	MAX_DFA_ISSUE_RATE): New macro descriptions.

	* doc/contrib.texi: Add dfa based scheduler contribution.

	* doc/gcc.texi: Add more information about genattrtab.

From-SVN: r45202

1 files changed, 156 insertions, 9 deletions

diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 80e8e75..6368b43 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -5446,11 +5446,19 @@ hooks for this purpose.  It is usually enough to define just a few of
 them: try the first ones in this list first.
 
 @deftypefn {Target Hook} int TARGET_SCHED_ISSUE_RATE (void)
-This hook returns the maximum number of instructions that can ever issue
-at the same time on the target machine.  The default is one.  This value
-must be constant over the entire compilation.  If you need it to vary
-depending on what the instructions are, you must use
+This hook returns the maximum number of instructions that can ever
+issue at the same time on the target machine.  The default is one.
+Although the insn scheduler can define itself the possibility of issue
+an insn on the same cycle, the value can serve as an additional
+constraint to issue insns on the same simulated processor cycle (see
+hooks @samp{TARGET_SCHED_REORDER} and @samp{TARGET_SCHED_REORDER2}).
+This value must be constant over the entire compilation.  If you need
+it to vary depending on what the instructions are, you must use
 @samp{TARGET_SCHED_VARIABLE_ISSUE}.
+
+You could use the value of macro @samp{MAX_DFA_ISSUE_RATE} to return
+the value of the hook @samp{TARGET_SCHED_ISSUE_RATE} for the automaton
+based pipeline interface.
 @end deftypefn
 
 @deftypefn {Target Hook} int TARGET_SCHED_VARIABLE_ISSUE (FILE *@var{file}, int @var{verbose}, rtx @var{insn}, int @var{more})
@@ -5466,12 +5474,17 @@ instruction that was scheduled.
 @end deftypefn
 
 @deftypefn {Target Hook} int TARGET_SCHED_ADJUST_COST (rtx @var{insn}, rtx @var{link}, rtx @var{dep_insn}, int @var{cost})
-This function corrects the value of @var{cost} based on the relationship
-between @var{insn} and @var{dep_insn} through the dependence @var{link}.
-It should return the new value.  The default is to make no adjustment to
-@var{cost}.  This can be used for example to specify to the scheduler
+This function corrects the value of @var{cost} based on the
+relationship between @var{insn} and @var{dep_insn} through the
+dependence @var{link}.  It should return the new value.  The default
+is to make no adjustment to @var{cost}.  This can be used for example
+to specify to the scheduler using the traditional pipeline description
 that an output- or anti-dependence does not incur the same cost as a
-data-dependence.
+data-dependence.  If the scheduler using the automaton based pipeline
+description, the cost of anti-dependence is zero and the cost of
+output-dependence is maximum of one and the difference of latency
+times of the first and the second insns.  If these values are not
+acceptable, you could use the hook to modify them too.
 @end deftypefn
 
 @deftypefn {Target Hook} int TARGET_SCHED_ADJUST_PRIORITY (rtx @var{insn}, int @var{priority})
@@ -5537,6 +5550,140 @@ RTL dumps and assembly output.  Define this hook only if you need this
 level of detail about what the scheduler is doing.
 @end deftypefn
 
+@deftypefn {Target Hook} int TARGET_SCHED_USE_DFA_PIPELINE_INTERFACE (void)
+This hook is called many times during insn scheduling.  If the hook
+returns nonzero, the automaton based pipeline description is used for
+insn scheduling.  Otherwise the traditional pipeline description is
+used.  The default is usage of the traditional pipeline description.
+
+You should also remember that to simplify the insn scheduler sources
+an empty traditional pipeline description interface is generated even
+if there is no a traditional pipeline description in the @file{.md}
+file.  The same is true for the automaton based pipeline description.
+That means that you should be accurate in defining the hook.
+@end deftypefn
+
+@deftypefn {Target Hook} int TARGET_SCHED_DFA_PRE_CYCLE_INSN (void)
+The hook returns an RTL insn.  The automaton state used in the
+pipeline hazard recognizer is changed as if the insn were scheduled
+when the new simulated processor cycle starts.  Usage of the hook may
+simplify the automaton pipeline description for some @acronym{VLIW}
+processors.  If the hook is defined, it is used only for the automaton
+based pipeline description.  The default is not to change the state
+when the new simulated processor cycle starts.
+@end deftypefn
+
+@deftypefn {Target Hook} void TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN (void)
+The hook can be used to initialize data used by the previous hook.
+@end deftypefn
+
+@deftypefn {Target Hook} int TARGET_SCHED_DFA_POST_CYCLE_INSN (void)
+The hook is analogous to @samp{TARGET_SCHED_DFA_PRE_CYCLE_INSN} but used
+to changed the state as if the insn were scheduled when the new
+simulated processor cycle finishes.
+@end deftypefn
+
+@deftypefn {Target Hook} void TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN (void)
+The hook is analogous to @samp{TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN} but
+used to initialize data used by the previous hook.
+@end deftypefn
+
+@deftypefn {Target Hook} int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD (void)
+This hook controls better choosing an insn from the ready insn queue
+for the @acronym{DFA}-based insn scheduler.  Usually the scheduler
+chooses the first insn from the queue.  If the hook returns a positive
+value, an additional scheduler code tries all permutations of
+@samp{TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD ()}
+subsequent ready insns to choose an insn whose issue will result in
+maximal number of issued insns on the same cycle.  For the
+@acronym{VLIW} processor, the code could actually solve the problem of
+packing simple insns into the @acronym{VLIW} insn.  Of course, if the
+rules of @acronym{VLIW} packing are described in the automaton.
+
+This code also could be used for superscalar @acronym{RISC}
+processors.  Let us consider a superscalar @acronym{RISC} processor
+with 3 pipelines.  Some insns can be executed in pipelines @var{A} or
+@var{B}, some insns can be executed only in pipelines @var{B} or
+@var{C}, and one insn can be executed in pipeline @var{B}.  The
+processor may issue the 1st insn into @var{A} and the 2nd one into
+@var{B}.  In this case, the 3rd insn will wait for freeing @var{B}
+until the next cycle.  If the scheduler issues the 3rd insn the first,
+the processor could issue all 3 insns per cycle.
+
+Actually this code demonstrates advantages of the automaton based
+pipeline hazard recognizer.  We try quickly and easy many insn
+schedules to choose the best one.
+
+The default is no multipass scheduling.
+@end deftypefn
+
+@deftypefn {Target Hook} void TARGET_SCHED_INIT_DFA_BUBBLES (void)
+The @acronym{DFA}-based scheduler could take the insertion of nop
+operations for better insn scheduling into account.  It can be done
+only if the multi-pass insn scheduling works (see hook
+@samp{TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD}).
+
+Let us consider a @acronym{VLIW} processor insn with 3 slots.  Each
+insn can be placed only in one of the three slots.  We have 3 ready
+insns @var{A}, @var{B}, and @var{C}.  @var{A} and @var{C} can be
+placed only in the 1st slot, @var{B} can be placed only in the 3rd
+slot.  We described the automaton which does not permit empty slot
+gaps between insns (usually such description is simpler).  Without
+this code the scheduler would place each insn in 3 separate
+@acronym{VLIW} insns.  If the scheduler places a nop insn into the 2nd
+slot, it could place the 3 insns into 2 @acronym{VLIW} insns.  What is
+the nop insn is returned by hook @samp{TARGET_SCHED_DFA_BUBBLE}.  Hook
+@samp{TARGET_SCHED_INIT_DFA_BUBBLES} can be used to initialize or
+create the nop insns.
+
+You should remember that the scheduler does not insert the nop insns.
+It is not wise because of the following optimizations.  The scheduler
+only considers such possibility to improve the result schedule.  The
+nop insns should be inserted lately, e.g. on the final phase.
+@end deftypefn
+
+@deftypefn {Target Hook} rtx TARGET_SCHED_DFA_BUBBLE (int @var{index})
+This hook @samp{FIRST_CYCLE_MULTIPASS_SCHEDULING} is used to insert
+nop operations for better insn scheduling when @acronym{DFA}-based
+scheduler makes multipass insn scheduling (see also description of
+hook @samp{TARGET_SCHED_INIT_DFA_BUBBLES}).  This hook
+returns a nop insn with given @var{index}.  The indexes start with
+zero.  The hook should return @code{NULL} if there are no more nop
+insns with indexes greater than given index.
+@end deftypefn
+
+Macros in the following table are generated by the program
+@file{genattr} and can be useful for writing the hooks.
+
+@table @code
+@findex TRADITIONAL_PIPELINE_INTERFACE
+@item TRADITIONAL_PIPELINE_INTERFACE
+The macro definition is generated if there is a traditional pipeline
+description in @file{.md} file. You should also remember that to
+simplify the insn scheduler sources an empty traditional pipeline
+description interface is generated even if there is no a traditional
+pipeline description in the @file{.md} file.  The macro can be used to
+distinguish the two types of the traditional interface.
+
+@findex DFA_PIPELINE_INTERFACE
+@item DFA_PIPELINE_INTERFACE
+The macro definition is generated if there is an automaton pipeline
+description in @file{.md} file.  You should also remember that to
+simplify the insn scheduler sources an empty automaton pipeline
+description interface is generated even if there is no an automaton
+pipeline description in the @file{.md} file.  The macro can be used to
+distinguish the two types of the automaton interface.
+
+@findex MAX_DFA_ISSUE_RATE
+@item MAX_DFA_ISSUE_RATE
+The macro definition is generated in the automaton based pipeline
+description interface.  Its value is calculated from the automaton
+based pipeline description and is equal to maximal number of all insns
+described in constructions @samp{define_insn_reservation} which can be
+issued on the same processor cycle.
+
+@end table
+
 @node Sections
 @section Dividing the Output into Sections (Texts, Data, @dots{})
 @c the above section title is WAY too long.  maybe cut the part between