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mercury/compiler/code_gen.m
Zoltan Somogyi 0642a10ff8 Reduce the number of arguments of MR_trace() to one. 
Estimated hours taken: 24

WARNING: this change affects binary compatibility for debuggable code;
the debuggable modules of the program and the runtime linked into the
executable must either all come from before this change, or they must all
come from after this change. However, this change does *not* affect binary
compatibility for non-debuggable executables.

Reduce the number of arguments of MR_trace() to one. Two of the arguments,
the port and the goal path, move into the label layout structure, as 16-bit
numbers; the port as a simple enumeration type, and the goal path as an
index into the module-wide string table. (The latter will eventually allow the
debugger to support the placement of breakpoints on labels with specific goal
paths.) The third argument, the number of the highest-numbered rN register in
use at the label, has been moved into the proc layout structure. In theory,
this will require more register saves and restores, since the number in the
proc layout is conservative (it is the max of the numbers that would be
required at the individual labels). However, this is not important, for two
reasons. First, we always save and restore all the rM registers that
appear in the mrM array before the last special-purpose register, and in
most cases this dictates how many registers we save/restore. Second, we
save/restore registers only when the debugger starts interaction, so
save/restore is a time critical activity only for the external debugger.

This change reduces the execution time of debuggable executables by about
4-5% when executing outside mdb and 3-4% when executing under mdb. It also
reduces executable sizes, but only by about 0.7% on x86.

This change eliminates the --trace-just-in-case compiler option, since
we now have the best of both --trace-just-in-case and --no-trace-just-in-case.

The drawback of this scheme is slightly increased executable size with the
accurage garbage collector, but that seems a small enough price to pay.

compiler/code_gen.m:
compiler/code_info.m:
	Record the number of the highest numbered rN register live at a trace
	label.

compiler/continuation_info.m:
	Record the number of the highest numbered rN register live at a trace
	label, and the port and goal path associated with the labels of trace
	events.

compiler/stack_layout.m:
	Put the number of the highest numbered rN register live at a trace
	label into proc layouts, and the port and goal path into label layouts.

	Since we are breaking binary compatibility with old debuggable modules
	anyway, compress the procedure id parts of proc layouts by using
	only 16 bits to store the procedure's arity and mode number, instead
	of 32 or 64.

compiler/trace.m:
	Update the handling of ports, goal paths and max live register numbers,
	so that instead of being passed as MR_trace arguments, they are
	recorded in data structures.

	Generate separate labels and layouts for the fail and redo events.
	Although they still have the same layout information, they now record
	different ports.

compiler/llds.m:
	Since trace.m now generates a label layout structure for the redo
	event, we must include redo events in the llds goal path type.

compiler/hlds_goal.m:
	Since the code for handling the port type for nondet pragma events
	has moved from the nondet-pragma-specific to the generic part of
	trace.m, we must now include their event types in the hlds goal path
	type.

compiler/llds_out.m:
	Add a predicate for converting ports into numbers, now that we
	must store ports in static data. Using their symbolic names would
	be better, but that would require complications in the llds type
	system, which would be inadvisable just before the release.

compiler/options.m:
compiler/handle_options.m:
doc/user_guide.texi:
	Eliminate --trace-just-in-case.

compiler/llds.m:
compiler/llds_common.m:
compiler/llds_out.m:
	Eliminate the data structure needed by --trace-just-in-case.

compiler/optimize.m:
	Trivial update to conform to data structure changes.

library/exception.m:
	Update the call to MR_trace.

runtime/mercury_stack_layout.h:
	Update the C structure declarations for the layout structures
	as discussed above.

runtime/mercury_init.h:
	Update the declarations of MR_trace_real and MR_trace_fake
	to use only one argument.

runtime/mercury_wrapper.[ch]:
	Update the declaration of MR_trace_func to use only one argument.

runtime/mercury_trace_base.[ch]:
	Update the declarations of MR_trace, MR_trace_real and MR_trace_fake
	to use only one argument.

	Delete MR_trace_struct(); since we deleted --trace-just-in-case, there
	will not be calls to it anymore.

	Since we are breaking binary compatibility anyway, move the exception
	port to be with the other interface ports. This should speed up a
	frequently executed test in the debugger.

	Update the handling of redo events.

trace/mercury_trace.h:
	Simplify and speed up the macro that tests a port for being an
	interface port, now that exceptions are grouped with other interface
	events.

trace/mercury_trace.c:
	Update the definition of MR_trace_real to use only one argument.
	The port is pulled out of the label layout structure only when
	needed to perform the termination tests for the current debugger
	command, and the goal path and the max live register number are
	looked up only when the termination test succeeds.
1999-12-14 04:54:38 +00:00

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%---------------------------------------------------------------------------%
% Copyright (C) 1994-1999 The University of Melbourne.
% This file may only be copied under the terms of the GNU General
% Public License - see the file COPYING in the Mercury distribution.
%---------------------------------------------------------------------------%
%
% Code generation - convert from HLDS to LLDS.
%
% Main authors: conway, zs.
%
% The two main tasks of this module are
%
% 1 to look after the aspects of generating code for a procedure
% that do not involve generating code for a specific goal, and
%
% 2 to provide a generic predicate that can be called from anywhere in
% the code generator to generate code for a goal.
%
% Code_gen forwards most of the actual construction of code for particular
% goals to other modules. The generation of code for unifications is done
% by unify_gen, for calls, higher-order calls and method calls by call_gen,
% for commits by commit_gen, for if-then-elses and negations by ite_gen,
% for switches by switch_gen and its subsidiary modules, for disjunctions
% by disj_gen, and for pragma_c_codes by pragma_c_gen. The only kind of goal
% handled directly by code_gen is the conjunction.
%
%---------------------------------------------------------------------------%
:- module code_gen.
:- interface.
:- import_module hlds_module, hlds_pred, hlds_goal, llds, code_info.
:- import_module globals.
:- import_module list, io.
% Translate a HLDS module to LLDS.
:- pred generate_code(module_info::in, module_info::out,
global_data::in, global_data::out, list(c_procedure)::out,
io__state::di, io__state::uo) is det.
% Translate a HLDS procedure to LLDS, threading through
% the data structure that records information about layout
% structures and the counter for ensuring the uniqueness
% of cell numbers.
:- pred generate_proc_code(pred_info::in, proc_info::in,
proc_id::in, pred_id::in, module_info::in, globals::in,
global_data::in, global_data::out, int::in, int::out,
c_procedure::out) is det.
% Translate a HLDS goal to LLDS.
:- pred code_gen__generate_goal(code_model::in, hlds_goal::in, code_tree::out,
code_info::in, code_info::out) is det.
%---------------------------------------------------------------------------%
%---------------------------------------------------------------------------%
:- implementation.
:- import_module call_gen, unify_gen, ite_gen, switch_gen, disj_gen.
:- import_module par_conj_gen, pragma_c_gen, commit_gen.
:- import_module continuation_info, trace, options, hlds_out.
:- import_module code_aux, middle_rec, passes_aux, llds_out.
:- import_module code_util, type_util, mode_util.
:- import_module prog_data, prog_out, instmap.
:- import_module bool, char, int, string.
:- import_module map, assoc_list, set, term, tree, std_util, require, varset.
%---------------------------------------------------------------------------%
generate_code(ModuleInfo0, ModuleInfo, GlobalData0, GlobalData, Procedures) -->
% get a list of all the predicate ids
% for which we are going to generate code.
{ module_info_predids(ModuleInfo0, PredIds) },
% now generate the code for each predicate
generate_pred_list_code(ModuleInfo0, ModuleInfo,
GlobalData0, GlobalData, PredIds, Procedures).
% Translate a list of HLDS predicates to LLDS.
:- pred generate_pred_list_code(module_info::in, module_info::out,
global_data::in, global_data::out,
list(pred_id)::in, list(c_procedure)::out,
io__state::di, io__state::uo) is det.
generate_pred_list_code(ModuleInfo, ModuleInfo, GlobalData, GlobalData,
[], []) --> [].
generate_pred_list_code(ModuleInfo0, ModuleInfo, GlobalData0, GlobalData,
[PredId | PredIds], Predicates) -->
{ module_info_preds(ModuleInfo0, PredInfos) },
% get the pred_info structure for this predicate
{ map__lookup(PredInfos, PredId, PredInfo) },
% extract a list of all the procedure ids for this
% predicate and generate code for them
{ pred_info_non_imported_procids(PredInfo, ProcIds) },
(
{ ProcIds = []
; hlds_pred__pred_info_is_aditi_relation(PredInfo)
}
->
{ Predicates0 = [] },
{ ModuleInfo1 = ModuleInfo0 },
{ GlobalData1 = GlobalData0 }
;
generate_pred_code(ModuleInfo0, ModuleInfo1,
GlobalData0, GlobalData1,
PredId, PredInfo, ProcIds, Predicates0)
),
{ list__append(Predicates0, Predicates1, Predicates) },
% and generate the code for the rest of the predicates
generate_pred_list_code(ModuleInfo1, ModuleInfo,
GlobalData1, GlobalData, PredIds, Predicates1).
% Translate a HLDS predicate to LLDS.
:- pred generate_pred_code(module_info::in, module_info::out,
global_data::in, global_data::out,
pred_id::in, pred_info::in, list(proc_id)::in, list(c_procedure)::out,
io__state::di, io__state::uo) is det.
generate_pred_code(ModuleInfo0, ModuleInfo, GlobalData0, GlobalData,
PredId, PredInfo, ProcIds, Code) -->
globals__io_lookup_bool_option(very_verbose, VeryVerbose),
( { VeryVerbose = yes } ->
io__write_string("% Generating code for "),
hlds_out__write_pred_id(ModuleInfo0, PredId),
io__write_string("\n"),
globals__io_lookup_bool_option(statistics, Statistics),
maybe_report_stats(Statistics)
;
[]
),
{ module_info_get_cell_count(ModuleInfo0, CellCount0) },
globals__io_get_globals(Globals),
{ generate_proc_list_code(ProcIds, PredId, PredInfo, ModuleInfo0,
Globals, GlobalData0, GlobalData, CellCount0, CellCount,
[], Code) },
{ module_info_set_cell_count(ModuleInfo0, CellCount, ModuleInfo) }.
% Translate all the procedures of a HLDS predicate to LLDS.
:- pred generate_proc_list_code(list(proc_id)::in, pred_id::in, pred_info::in,
module_info::in, globals::in, global_data::in, global_data::out,
int::in, int::out, list(c_procedure)::in, list(c_procedure)::out)
is det.
generate_proc_list_code([], _PredId, _PredInfo, _ModuleInfo, _Globals,
GlobalData, GlobalData, CellCount, CellCount, Procs, Procs).
generate_proc_list_code([ProcId | ProcIds], PredId, PredInfo, ModuleInfo0,
Globals, GlobalData0, GlobalData, CellCount0, CellCount,
Procs0, Procs) :-
pred_info_procedures(PredInfo, ProcInfos),
map__lookup(ProcInfos, ProcId, ProcInfo),
generate_proc_code(PredInfo, ProcInfo, ProcId, PredId, ModuleInfo0,
Globals, GlobalData0, GlobalData1, CellCount0, CellCount1,
Proc),
generate_proc_list_code(ProcIds, PredId, PredInfo, ModuleInfo0,
Globals, GlobalData1, GlobalData, CellCount1, CellCount,
[Proc | Procs0], Procs).
%---------------------------------------------------------------------------%
% Values of this type hold information about stack frames that is
% generated when generating prologs and is used in generating epilogs
% and when massaging the code generated for the procedure.
:- type frame_info
---> frame(
int, % Number of slots in frame.
maybe(int), % Slot number of succip if succip is
% present in a general slot.
bool % Is this the frame of a model_non
% proc defined via pragma C code?
).
%---------------------------------------------------------------------------%
generate_proc_code(PredInfo, ProcInfo, ProcId, PredId, ModuleInfo, Globals,
GlobalData0, GlobalData, CellCount0, CellCount, Proc) :-
proc_info_interface_determinism(ProcInfo, Detism),
proc_info_interface_code_model(ProcInfo, CodeModel),
proc_info_goal(ProcInfo, Goal),
Goal = _ - GoalInfo,
goal_info_get_follow_vars(GoalInfo, MaybeFollowVars),
(
MaybeFollowVars = yes(FollowVars)
;
MaybeFollowVars = no,
map__init(FollowVars)
),
continuation_info__basic_stack_layout_for_proc(PredInfo, Globals,
BasicStackLayout, ForceProcId),
( BasicStackLayout = yes ->
SaveSuccip = yes
;
SaveSuccip = no
),
% Initialise the code_info structure. Generate_category_code
% below will use the returned OutsideResumePoint as the
% entry to the code that handles the failure of the procedure,
% if such code is needed. It is never needed for model_det
% procedures, always needed for model_semi procedures, and
% needed for model_non procedures only if we are doing
% execution tracing.
code_info__init(SaveSuccip, Globals, PredId, ProcId, ProcInfo,
FollowVars, ModuleInfo, CellCount0, OutsideResumePoint,
TraceSlotInfo, CodeInfo0),
% Generate code for the procedure.
generate_category_code(CodeModel, Goal, OutsideResumePoint,
TraceSlotInfo, CodeTree, MaybeTraceCallLabel, FrameInfo,
CodeInfo0, CodeInfo),
code_info__get_max_reg_in_use_at_trace(MaxTraceReg, CodeInfo, _),
code_info__get_cell_count(CellCount, CodeInfo, _),
% Turn the code tree into a list.
tree__flatten(CodeTree, FragmentList),
% Now the code is a list of code fragments (== list(instr)),
% so we need to do a level of unwinding to get a flat list.
list__condense(FragmentList, Instructions0),
FrameInfo = frame(TotalSlots, MaybeSuccipSlot, _),
(
MaybeSuccipSlot = yes(SuccipSlot)
->
% The set of recorded live values at calls (for value
% numbering) and returns (for accurate gc and execution
% tracing) do not yet record the stack slot holding the
% succip, so add it to those sets.
code_gen__add_saved_succip(Instructions0,
SuccipSlot, Instructions)
;
Instructions = Instructions0
),
( BasicStackLayout = yes ->
% Create the procedure layout structure.
code_info__get_layout_info(InternalMap, CodeInfo, _),
code_util__make_local_entry_label(ModuleInfo, PredId, ProcId,
no, EntryLabel),
ProcLayout = proc_layout_info(EntryLabel, Detism, TotalSlots,
MaybeSuccipSlot, MaybeTraceCallLabel, MaxTraceReg,
TraceSlotInfo, ForceProcId, InternalMap),
global_data_add_new_proc_layout(GlobalData0,
proc(PredId, ProcId), ProcLayout, GlobalData1)
;
GlobalData1 = GlobalData0
),
code_info__get_non_common_static_data(NonCommonStatics, CodeInfo, _),
global_data_add_new_non_common_static_datas(GlobalData1,
NonCommonStatics, GlobalData2),
maybe_add_tabling_pointer_var(ModuleInfo, PredId, ProcId, ProcInfo,
GlobalData2, GlobalData),
pred_info_name(PredInfo, Name),
pred_info_arity(PredInfo, Arity),
% Construct a c_procedure structure with all the information.
Proc = c_procedure(Name, Arity, proc(PredId, ProcId), Instructions).
:- pred maybe_add_tabling_pointer_var(module_info, pred_id, proc_id, proc_info,
global_data, global_data).
:- mode maybe_add_tabling_pointer_var(in, in, in, in, in, out) is det.
maybe_add_tabling_pointer_var(ModuleInfo, PredId, ProcId, ProcInfo,
GlobalData0, GlobalData) :-
proc_info_eval_method(ProcInfo, EvalMethod),
(
EvalMethod \= eval_normal
->
code_util__make_proc_label(ModuleInfo, PredId, ProcId,
ProcLabel),
module_info_name(ModuleInfo, ModuleName),
Var = tabling_pointer_var(ModuleName, ProcLabel),
global_data_add_new_proc_var(GlobalData0,
proc(PredId, ProcId), Var, GlobalData)
;
GlobalData = GlobalData0
).
%---------------------------------------------------------------------------%
%---------------------------------------------------------------------------%
% Generate_category_code generates code for an entire procedure.
% Its algorithm has three or four main stages:
%
% - generate code for the body goal
% - generate code for the procedure entry
% - generate code for the procedure exit
% - generate code for the procedure fail (if needed)
%
% The first three tasks are forwarded to other procedures.
% The fourth task, if needed, is done by generate_category_code.
%
% The only caller of generate_category_code, generate_proc_code,
% has set up the code generator state to reflect what the machine
% state will be on entry to the procedure. Ensuring that the
% machine state at exit will conform to the expectation
% of the caller is the job of code_gen__generate_exit.
%
% The reason why we generate the entry code after the body is that
% information such as the total number of stack slots needed,
% which is needed in the procedure entry prologue, cannot be
% conveniently obtained before generating the body, since the
% code generator may allocate temporary variables to hold values
% such as saved heap and trail pointers.
%
% Code_gen__generate_entry cannot depend on the code generator
% state, since when it is invoked this state is not appropriate
% for the procedure entry. Nor can it change the code generator state,
% since that would confuse code_gen__generate_exit.
%
% Generating CALL trace events is done by generate_category_code,
% since only on entry to generate_category_code is the code generator
% state set up right. Generating EXIT trace events is done by
% code_gen__generate_exit. Generating FAIL trace events is done
% by generate_category_code, since this requires modifying how
% we generate code for the body of the procedure (failures must
% now branch to a different place). Since FAIL trace events are
% part of the failure continuation, generate_category_code takes
% care of the failure continuation as well. (Model_det procedures
% of course have no failure continuation. Model_non procedures have
% a failure continuation, but in the absence of tracing this
% continuation needs no code. Only model_semi procedures need code
% for the failure continuation at all times.)
:- pred generate_category_code(code_model::in, hlds_goal::in,
resume_point_info::in, trace_slot_info::in, code_tree::out,
maybe(label)::out, frame_info::out, code_info::in, code_info::out)
is det.
generate_category_code(model_det, Goal, ResumePoint, TraceSlotInfo, Code,
MaybeTraceCallLabel, FrameInfo) -->
% generate the code for the body of the clause
(
code_info__get_globals(Globals),
{ globals__lookup_bool_option(Globals, middle_rec, yes) },
middle_rec__match_and_generate(Goal, MiddleRecCode)
->
{ Code = MiddleRecCode },
{ MaybeTraceCallLabel = no },
{ FrameInfo = frame(0, no, no) }
;
{ Goal = _ - GoalInfo },
{ goal_info_get_context(GoalInfo, BodyContext) },
code_info__get_maybe_trace_info(MaybeTraceInfo),
( { MaybeTraceInfo = yes(TraceInfo) } ->
trace__generate_external_event_code(call, TraceInfo,
BodyContext, TraceCallLabel, _TypeInfos,
TraceCallCode),
{ MaybeTraceCallLabel = yes(TraceCallLabel) }
;
{ TraceCallCode = empty },
{ MaybeTraceCallLabel = no }
),
code_gen__generate_goal(model_det, Goal, BodyCode),
code_gen__generate_entry(model_det, Goal, ResumePoint,
FrameInfo, EntryCode),
code_gen__generate_exit(model_det, FrameInfo, TraceSlotInfo,
BodyContext, _, ExitCode),
{ Code =
tree(EntryCode,
tree(TraceCallCode,
tree(BodyCode,
ExitCode)))
}
).
generate_category_code(model_semi, Goal, ResumePoint, TraceSlotInfo, Code,
MaybeTraceCallLabel, FrameInfo) -->
{ set__singleton_set(FailureLiveRegs, reg(r, 1)) },
{ FailCode = node([
assign(reg(r, 1), const(false)) - "Fail",
livevals(FailureLiveRegs) - "",
goto(succip) - "Return from procedure call"
]) },
{ Goal = _ - GoalInfo },
{ goal_info_get_context(GoalInfo, BodyContext) },
code_info__get_maybe_trace_info(MaybeTraceInfo),
( { MaybeTraceInfo = yes(TraceInfo) } ->
trace__generate_external_event_code(call, TraceInfo,
BodyContext, TraceCallLabel, _TypeInfos,
TraceCallCode),
{ MaybeTraceCallLabel = yes(TraceCallLabel) },
code_gen__generate_goal(model_semi, Goal, BodyCode),
code_gen__generate_entry(model_semi, Goal, ResumePoint,
FrameInfo, EntryCode),
code_gen__generate_exit(model_semi, FrameInfo, TraceSlotInfo,
BodyContext, RestoreDeallocCode, ExitCode),
code_info__generate_resume_point(ResumePoint, ResumeCode),
{ code_info__resume_point_vars(ResumePoint, ResumeVarList) },
{ set__list_to_set(ResumeVarList, ResumeVars) },
code_info__set_forward_live_vars(ResumeVars),
% XXX A context that gives the end of the procedure
% definition would be better than BodyContext.
trace__generate_external_event_code(fail, TraceInfo,
BodyContext, _, _, TraceFailCode),
{ Code =
tree(EntryCode,
tree(TraceCallCode,
tree(BodyCode,
tree(ExitCode,
tree(ResumeCode,
tree(TraceFailCode,
tree(RestoreDeallocCode,
FailCode)))))))
}
;
{ MaybeTraceCallLabel = no },
code_gen__generate_goal(model_semi, Goal, BodyCode),
code_gen__generate_entry(model_semi, Goal, ResumePoint,
FrameInfo, EntryCode),
code_gen__generate_exit(model_semi, FrameInfo, TraceSlotInfo,
BodyContext, RestoreDeallocCode, ExitCode),
code_info__generate_resume_point(ResumePoint, ResumeCode),
{ Code =
tree(EntryCode,
tree(BodyCode,
tree(ExitCode,
tree(ResumeCode,
tree(RestoreDeallocCode,
FailCode)))))
}
).
generate_category_code(model_non, Goal, ResumePoint, TraceSlotInfo, Code,
MaybeTraceCallLabel, FrameInfo) -->
code_info__get_maybe_trace_info(MaybeTraceInfo),
{ Goal = _ - GoalInfo },
{ goal_info_get_context(GoalInfo, BodyContext) },
( { MaybeTraceInfo = yes(TraceInfo) } ->
trace__generate_external_event_code(call, TraceInfo,
BodyContext, TraceCallLabel, _TypeInfos,
TraceCallCode),
{ MaybeTraceCallLabel = yes(TraceCallLabel) },
code_gen__generate_goal(model_non, Goal, BodyCode),
code_gen__generate_entry(model_non, Goal, ResumePoint,
FrameInfo, EntryCode),
code_gen__generate_exit(model_non, FrameInfo, TraceSlotInfo,
BodyContext, _, ExitCode),
code_info__generate_resume_point(ResumePoint, ResumeCode),
{ code_info__resume_point_vars(ResumePoint, ResumeVarList) },
{ set__list_to_set(ResumeVarList, ResumeVars) },
code_info__set_forward_live_vars(ResumeVars),
% XXX A context that gives the end of the procedure
% definition would be better than BodyContext.
trace__generate_external_event_code(fail, TraceInfo,
BodyContext, _, _, TraceFailCode),
{ TraceSlotInfo = trace_slot_info(_, _, yes(_)) ->
DiscardTraceTicketCode = node([
discard_ticket - "discard retry ticket"
])
;
DiscardTraceTicketCode = empty
},
{ FailCode = node([
goto(do_fail) - "fail after fail trace port"
]) },
{ Code =
tree(EntryCode,
tree(TraceCallCode,
tree(BodyCode,
tree(ExitCode,
tree(ResumeCode,
tree(TraceFailCode,
tree(DiscardTraceTicketCode,
FailCode)))))))
}
;
{ MaybeTraceCallLabel = no },
code_gen__generate_goal(model_non, Goal, BodyCode),
code_gen__generate_entry(model_non, Goal, ResumePoint,
FrameInfo, EntryCode),
code_gen__generate_exit(model_non, FrameInfo, TraceSlotInfo,
BodyContext, _, ExitCode),
{ Code =
tree(EntryCode,
tree(BodyCode,
ExitCode))
}
).
%---------------------------------------------------------------------------%
% Generate the prologue for a procedure.
%
% The prologue will contain
%
% a comment to mark prologue start
% a comment explaining the stack layout
% the procedure entry label
% code to allocate a stack frame
% code to fill in some special slots in the stack frame
% a comment to mark prologue end
%
% At the moment the only special slots are the succip slot, and
% the slots holding the call number and call depth for tracing.
%
% Not all frames will have all these components. For example, the code
% to allocate a stack frame will be missing if the procedure doesn't
% need a stack frame, and if the procedure is nondet, then the code
% to fill in the succip slot is subsumed by the mkframe.
:- pred code_gen__generate_entry(code_model::in, hlds_goal::in,
resume_point_info::in, frame_info::out, code_tree::out,
code_info::in, code_info::out) is det.
code_gen__generate_entry(CodeModel, Goal, OutsideResumePoint, FrameInfo,
EntryCode) -->
code_info__get_stack_slots(StackSlots),
code_info__get_varset(VarSet),
{ code_aux__explain_stack_slots(StackSlots, VarSet, SlotsComment) },
{ StartComment = node([
comment("Start of procedure prologue") - "",
comment(SlotsComment) - ""
]) },
code_info__get_total_stackslot_count(MainSlots),
code_info__get_pred_id(PredId),
code_info__get_proc_id(ProcId),
code_info__get_module_info(ModuleInfo),
{ code_util__make_local_entry_label(ModuleInfo, PredId, ProcId, no,
Entry) },
{ LabelCode = node([
label(Entry) - "Procedure entry point"
]) },
code_info__get_succip_used(Used),
(
% Do we need to save the succip across calls?
{ Used = yes },
% Do we need to use a general slot for storing succip?
{ CodeModel \= model_non }
->
{ SuccipSlot is MainSlots + 1 },
{ SaveSuccipCode = node([
assign(stackvar(SuccipSlot), lval(succip)) -
"Save the success ip"
]) },
{ TotalSlots = SuccipSlot },
{ MaybeSuccipSlot = yes(SuccipSlot) }
;
{ SaveSuccipCode = empty },
{ TotalSlots = MainSlots },
{ MaybeSuccipSlot = no }
),
code_info__get_maybe_trace_info(MaybeTraceInfo),
( { MaybeTraceInfo = yes(TraceInfo) } ->
trace__generate_slot_fill_code(TraceInfo, TraceFillCode)
;
{ TraceFillCode = empty }
),
{ predicate_module(ModuleInfo, PredId, ModuleName) },
{ predicate_name(ModuleInfo, PredId, PredName) },
{ predicate_arity(ModuleInfo, PredId, Arity) },
{ prog_out__sym_name_to_string(ModuleName, ModuleNameString) },
{ string__int_to_string(Arity, ArityStr) },
{ string__append_list([ModuleNameString, ":", PredName, "/", ArityStr],
PushMsg) },
(
{ CodeModel = model_non }
->
{ code_info__resume_point_stack_addr(OutsideResumePoint,
OutsideResumeAddress) },
(
{ Goal = pragma_c_code(_,_,_,_,_,_, PragmaCode) - _},
{ PragmaCode = nondet(Fields, FieldsContext,
_,_,_,_,_,_,_) }
->
{ pragma_c_gen__struct_name(ModuleName, PredName,
Arity, ProcId, StructName) },
{ Struct = pragma_c_struct(StructName,
Fields, FieldsContext) },
{ string__format("#define\tMR_ORDINARY_SLOTS\t%d\n",
[i(TotalSlots)], DefineStr) },
{ DefineComponents = [pragma_c_raw_code(DefineStr)] },
{ NondetFrameInfo = ordinary_frame(PushMsg, TotalSlots,
yes(Struct)) },
{ AllocCode = node([
mkframe(NondetFrameInfo, OutsideResumeAddress)
- "Allocate stack frame",
pragma_c([], DefineComponents,
will_not_call_mercury, no, no, no)
- ""
]) },
{ NondetPragma = yes }
;
{ NondetFrameInfo = ordinary_frame(PushMsg, TotalSlots,
no) },
{ AllocCode = node([
mkframe(NondetFrameInfo, OutsideResumeAddress)
- "Allocate stack frame"
]) },
{ NondetPragma = no }
)
;
{ TotalSlots > 0 }
->
{ AllocCode = node([
incr_sp(TotalSlots, PushMsg) -
"Allocate stack frame"
]) },
{ NondetPragma = no }
;
{ AllocCode = empty },
{ NondetPragma = no }
),
{ FrameInfo = frame(TotalSlots, MaybeSuccipSlot, NondetPragma) },
{ EndComment = node([
comment("End of procedure prologue") - ""
]) },
{ EntryCode =
tree(StartComment,
tree(LabelCode,
tree(AllocCode,
tree(SaveSuccipCode,
tree(TraceFillCode,
EndComment)))))
}.
%---------------------------------------------------------------------------%
% Generate the success epilogue for a procedure.
%
% The success epilogue will contain
%
% a comment to mark epilogue start
% code to place the output arguments where their caller expects
% code to restore registers from some special slots
% code to deallocate the stack frame
% code to set r1 to TRUE (for semidet procedures only)
% a jump back to the caller, including livevals information
% a comment to mark epilogue end
%
% The parts of this that restore registers and deallocate the stack
% frame are also part of the failure epilog, which is handled by
% our caller; this is why we return RestoreDeallocCode.
%
% At the moment the only special slots are the succip slot, and
% the tracing slots (holding the call sequence number, call event
% number, call depth, from-full indication, and trail state).
%
% Not all frames will have all these components. For example, for
% nondet procedures we don't deallocate the stack frame before
% success.
%
% Epilogues for procedures defined by nondet pragma C codes do not
% follow the rules above. For such procedures, the normal functions
% of the epilogue are handled when traversing the pragma C code goal;
% we need only #undef a macro defined by the procedure prologue.
:- pred code_gen__generate_exit(code_model::in, frame_info::in,
trace_slot_info::in, prog_context::in, code_tree::out, code_tree::out,
code_info::in, code_info::out) is det.
code_gen__generate_exit(CodeModel, FrameInfo, TraceSlotInfo, BodyContext,
RestoreDeallocCode, ExitCode) -->
{ StartComment = node([
comment("Start of procedure epilogue") - ""
]) },
{ EndComment = node([
comment("End of procedure epilogue") - ""
]) },
{ FrameInfo = frame(TotalSlots, MaybeSuccipSlot, NondetPragma) },
( { NondetPragma = yes } ->
{ UndefStr = "#undef\tMR_ORDINARY_SLOTS\n" },
{ UndefComponents = [pragma_c_raw_code(UndefStr)] },
{ UndefCode = node([
pragma_c([], UndefComponents,
will_not_call_mercury, no, no, no)
- ""
]) },
{ RestoreDeallocCode = empty }, % always empty for nondet code
{ ExitCode =
tree(StartComment,
tree(UndefCode,
EndComment))
}
;
code_info__get_instmap(Instmap),
code_info__get_arginfo(ArgModes),
code_info__get_headvars(HeadVars),
{ assoc_list__from_corresponding_lists(HeadVars, ArgModes,
Args)},
(
{ instmap__is_unreachable(Instmap) }
->
{ FlushCode = empty }
;
code_info__setup_call(Args, callee, FlushCode)
),
{
MaybeSuccipSlot = yes(SuccipSlot)
->
RestoreSuccipCode = node([
assign(succip, lval(stackvar(SuccipSlot))) -
"restore the success ip"
])
;
RestoreSuccipCode = empty
},
{
( TotalSlots = 0 ; CodeModel = model_non )
->
DeallocCode = empty
;
DeallocCode = node([
decr_sp(TotalSlots) - "Deallocate stack frame"
])
},
{
TraceSlotInfo = trace_slot_info(_, _, yes(_)),
CodeModel \= model_non
->
DiscardTraceTicketCode = node([
discard_ticket - "discard retry ticket"
])
;
DiscardTraceTicketCode = empty
},
{ RestoreDeallocCode =
tree(RestoreSuccipCode,
tree(DeallocCode,
DiscardTraceTicketCode))
},
code_info__get_maybe_trace_info(MaybeTraceInfo),
( { MaybeTraceInfo = yes(TraceInfo) } ->
% XXX A context that gives the end of the
% procedure definition would be better than
% CallContext.
trace__generate_external_event_code(exit, TraceInfo,
BodyContext, _, TypeInfoDatas, TraceExitCode),
{ map__values(TypeInfoDatas, TypeInfoLocnSets) },
{ FindBaseLvals = lambda([Lval::out] is nondet, (
list__member(LocnSet, TypeInfoLocnSets),
set__member(Locn, LocnSet),
(
Locn = direct(Lval)
;
Locn = indirect(Lval, _)
)
)) },
{ solutions(FindBaseLvals, TypeInfoLvals) }
;
{ TraceExitCode = empty },
{ TypeInfoLvals = [] }
),
% Find out which locations should be mentioned
% in the success path livevals(...) annotation,
% so that value numbering doesn't optimize them away.
{ code_gen__select_args_with_mode(Args, top_out, _OutVars,
OutLvals) },
{ list__append(TypeInfoLvals, OutLvals, LiveArgLvals) },
{ set__list_to_set(LiveArgLvals, LiveArgs) },
(
{ CodeModel = model_det },
{ SuccessCode = node([
livevals(LiveArgs) - "",
goto(succip) - "Return from procedure call"
]) },
{ AllSuccessCode =
tree(TraceExitCode,
tree(RestoreDeallocCode,
SuccessCode))
}
;
{ CodeModel = model_semi },
{ set__insert(LiveArgs, reg(r, 1), SuccessLiveRegs) },
{ SuccessCode = node([
assign(reg(r, 1), const(true)) - "Succeed",
livevals(SuccessLiveRegs) - "",
goto(succip) - "Return from procedure call"
]) },
{ AllSuccessCode =
tree(TraceExitCode,
tree(RestoreDeallocCode,
SuccessCode))
}
;
{ CodeModel = model_non },
{ MaybeTraceInfo = yes(TraceInfo2) ->
trace__maybe_setup_redo_event(TraceInfo2,
SetupRedoCode)
;
SetupRedoCode = empty
},
{ SuccessCode = node([
livevals(LiveArgs) - "",
goto(do_succeed(no))
- "Return from procedure call"
]) },
{ AllSuccessCode =
tree(SetupRedoCode,
tree(TraceExitCode,
SuccessCode))
}
),
{ ExitCode =
tree(StartComment,
tree(FlushCode,
tree(AllSuccessCode,
EndComment)))
}
).
%---------------------------------------------------------------------------%
% Generate a goal. This predicate arranges for the necessary updates of
% the generic data structures before and after the actual code generation,
% which is delegated to goal-specific predicates.
code_gen__generate_goal(ContextModel, Goal - GoalInfo, Code) -->
% Make any changes to liveness before Goal
{ goal_is_atomic(Goal) ->
IsAtomic = yes
;
IsAtomic = no
},
code_info__pre_goal_update(GoalInfo, IsAtomic),
code_info__get_instmap(Instmap),
(
{ instmap__is_reachable(Instmap) }
->
{ goal_info_get_code_model(GoalInfo, CodeModel) },
% sanity check: code of some code models
% should occur only in limited contexts
{
CodeModel = model_det
;
CodeModel = model_semi,
( ContextModel \= model_det ->
true
;
error("semidet model in det context")
)
;
CodeModel = model_non,
( ContextModel = model_non ->
true
;
error("nondet model in det/semidet context")
)
},
code_gen__generate_goal_2(Goal, GoalInfo, CodeModel, Code),
% Make live any variables which subsequent goals
% will expect to be live, but were not generated
code_info__set_instmap(Instmap),
code_info__post_goal_update(GoalInfo)
;
{ Code = empty }
),
!.
%---------------------------------------------------------------------------%
:- pred code_gen__generate_goal_2(hlds_goal_expr::in, hlds_goal_info::in,
code_model::in, code_tree::out, code_info::in, code_info::out) is det.
code_gen__generate_goal_2(unify(_, _, _, Uni, _), _, CodeModel, Code) -->
unify_gen__generate_unification(CodeModel, Uni, Code).
code_gen__generate_goal_2(conj(Goals), _GoalInfo, CodeModel, Code) -->
code_gen__generate_goals(Goals, CodeModel, Code).
code_gen__generate_goal_2(par_conj(Goals, _SM), GoalInfo, CodeModel, Code) -->
par_conj_gen__generate_par_conj(Goals, GoalInfo, CodeModel, Code).
code_gen__generate_goal_2(disj(Goals, StoreMap), _, CodeModel, Code) -->
disj_gen__generate_disj(CodeModel, Goals, StoreMap, Code).
code_gen__generate_goal_2(not(Goal), _GoalInfo, CodeModel, Code) -->
ite_gen__generate_negation(CodeModel, Goal, Code).
code_gen__generate_goal_2(if_then_else(_Vars, Cond, Then, Else, StoreMap),
_GoalInfo, CodeModel, Code) -->
ite_gen__generate_ite(CodeModel, Cond, Then, Else, StoreMap, Code).
code_gen__generate_goal_2(switch(Var, CanFail, CaseList, StoreMap),
GoalInfo, CodeModel, Code) -->
switch_gen__generate_switch(CodeModel, Var, CanFail, CaseList,
StoreMap, GoalInfo, Code).
code_gen__generate_goal_2(some(_Vars, _, Goal), _GoalInfo, CodeModel, Code) -->
commit_gen__generate_commit(CodeModel, Goal, Code).
code_gen__generate_goal_2(generic_call(GenericCall, Args, Modes, Det),
GoalInfo, CodeModel, Code) -->
call_gen__generate_generic_call(CodeModel, GenericCall, Args,
Modes, Det, GoalInfo, Code).
code_gen__generate_goal_2(call(PredId, ProcId, Args, BuiltinState, _, _),
GoalInfo, CodeModel, Code) -->
(
{ BuiltinState = not_builtin }
->
call_gen__generate_call(CodeModel, PredId, ProcId, Args,
GoalInfo, Code)
;
call_gen__generate_builtin(CodeModel, PredId, ProcId, Args,
Code)
).
code_gen__generate_goal_2(pragma_c_code(Attributes,
PredId, ModeId, Args, ArgNames, OrigArgTypes, PragmaCode),
GoalInfo, CodeModel, Instr) -->
pragma_c_gen__generate_pragma_c_code(CodeModel, Attributes,
PredId, ModeId, Args, ArgNames, OrigArgTypes, GoalInfo,
PragmaCode, Instr).
code_gen__generate_goal_2(bi_implication(_, _), _, _, _) -->
% these should have been expanded out by now
{ error("code_gen__generate_goal_2: unexpected bi_implication") }.
%---------------------------------------------------------------------------%
% Generate a conjoined series of goals.
% Note of course, that with a conjunction, state information
% flows directly from one conjunct to the next.
:- pred code_gen__generate_goals(hlds_goals::in, code_model::in,
code_tree::out, code_info::in, code_info::out) is det.
code_gen__generate_goals([], _, empty) --> [].
code_gen__generate_goals([Goal | Goals], CodeModel, Instr) -->
code_gen__generate_goal(CodeModel, Goal, Instr1),
code_info__get_instmap(Instmap),
(
{ instmap__is_unreachable(Instmap) }
->
{ Instr = Instr1 }
;
code_gen__generate_goals(Goals, CodeModel, Instr2),
{ Instr = tree(Instr1, Instr2) }
).
%---------------------------------------------------------------------------%
:- pred code_gen__select_args_with_mode(assoc_list(prog_var, arg_info)::in,
arg_mode::in, list(prog_var)::out, list(lval)::out) is det.
code_gen__select_args_with_mode([], _, [], []).
code_gen__select_args_with_mode([Var - ArgInfo | Args], DesiredMode, Vs, Ls) :-
code_gen__select_args_with_mode(Args, DesiredMode, Vs0, Ls0),
ArgInfo = arg_info(Loc, Mode),
(
Mode = DesiredMode
->
code_util__arg_loc_to_register(Loc, Reg),
Vs = [Var | Vs0],
Ls = [Reg | Ls0]
;
Vs = Vs0,
Ls = Ls0
).
%---------------------------------------------------------------------------%
% Add the succip to the livevals before and after calls.
% Traverses the list of instructions looking for livevals and calls,
% adding succip in the stackvar number given as an argument.
:- pred code_gen__add_saved_succip(list(instruction)::in, int::in,
list(instruction)::out) is det.
code_gen__add_saved_succip([], _StackLoc, []).
code_gen__add_saved_succip([Instrn0 - Comment | Instrns0 ], StackLoc,
[Instrn - Comment | Instrns]) :-
(
Instrn0 = livevals(LiveVals0),
Instrns0 \= [goto(succip) - _ | _]
% XXX We should also test for tailcalls
% once we start generating them directly.
->
set__insert(LiveVals0, stackvar(StackLoc), LiveVals1),
Instrn = livevals(LiveVals1)
;
Instrn0 = call(Target, ReturnLabel, LiveVals0, Context, CM)
->
map__init(Empty),
LiveVals = [live_lvalue(direct(stackvar(StackLoc)),
succip, Empty) | LiveVals0],
Instrn = call(Target, ReturnLabel, LiveVals, Context, CM)
;
Instrn = Instrn0
),
code_gen__add_saved_succip(Instrns0, StackLoc, Instrns).
%---------------------------------------------------------------------------%
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