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mercury/compiler/code_gen.m
Zoltan Somogyi ca0b3b7c6b Add an option that causes the compiler to pass information to the 
Estimated hours taken: 8

Add an option that causes the compiler to pass information to the
execution tracing system in one struct, rather than four separate arguments.

Two of these arguments are pointers, which each require two instructions
to set up on SPARC, MIPS and other RISCs that do not use a global pool.
The other two arguments are small constants. Therefore on 32-bit RISCs,
replacing MR_trace/4 with MR_trace_struct/1 will probably replace
six instructions with two, which saves four instructions' worth
of time and 16 bytes of code, at the cost of 12 bytes of data,
and possibly the cost of some instructions later loading the info
from the struct into registers. However, this loading cost does not have
to be paid if tracing is not enabled, and other optimizations may
reduce the cost even if tracing is enabled. For example, I strongly suspect
that on out-of-order machines, which means most CPUs you can buy today,
the load instructions are effectively free, because they happen while
the indirect jump to MR_trace_real takes place.

I intend to benchmark this option on our various platforms,
and have autoconfigure set it on the machines in which it is beneficial.

doc/user_guide.texi:
	Document the new --call-trace-struct option, and say it is not
	for general use.

compiler/options.m:
	Add the new option.

compiler/trace.m:
	If the option is set, call MR_trace_struct instead of MR_trace,
	and create a new kind of static (in both senses) global data structure
	to hold the arguments.

	Move the definition of trace_port to llds.m, and the procedure to
	convert it to string to llds_out.m

compiler/code_info.m:
	Add an extra code_info slot to hold this new kind of global data,
	and its access predicates.

compiler/code_gen.m:
	Transfer this new kind of global data from code_info to the global_data
	part of module_info.

compiler/hlds_module.m:
	Add a new field to the global_data data structure to hold this data.

compiler/mercury_compile.m:
	Include the new global data in the list of things we give to llds_out.

compiler/llds.m:
	Add a new kind of comp_gen_c_data to hold MR_trace_struct arguments.

	Also move the definition of trace_port from trace.m to here,
	since the new kind of comp_gen_c_data refers to this type.

compiler/llds_out.m:
	Add code to print the new kind of comp_gen_c_data.

	Move the code to print trace_ports from trace.m to here.

compiler/llds_common.m:
	Ignore the new kind of comp_gen_c_data, since by construction
	its contents are never common with anything else.

runtime/mercury_trace_base.[ch]:
	Add a new variant of MR_trace, MR_trace_struct, that consolidates
	the arguments into a single MR_Trace_Call_Info struct.

	Fix a bad variable name: the int argument to MR_trace is a max r
	register number, not a max mr register number.
1999-04-30 08:24:24 +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,
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, 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, PredIds, Procedures).
% Translate a list of HLDS predicates to LLDS.
:- pred generate_pred_list_code(module_info::in, module_info::out,
list(pred_id)::in, list(c_procedure)::out,
io__state::di, io__state::uo) is det.
generate_pred_list_code(ModuleInfo, ModuleInfo, [], []) --> [].
generate_pred_list_code(ModuleInfo0, ModuleInfo, [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 }
;
generate_pred_code(ModuleInfo0, ModuleInfo1, 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, PredIds, Predicates1).
% Translate a HLDS predicate to LLDS.
:- pred generate_pred_code(module_info::in, module_info::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, 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_global_data(ModuleInfo0, GlobalData0) },
{ 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, ModuleInfo1) },
{ module_info_set_global_data(ModuleInfo1, GlobalData,
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,
CodeTree, MaybeTraceCallLabel, FrameInfo, CodeInfo0, 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,
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, GlobalData),
predicate_name(ModuleInfo, PredId, Name),
predicate_arity(ModuleInfo, PredId, Arity),
% Construct a c_procedure structure with all the information.
Proc = c_procedure(Name, Arity, proc(PredId, ProcId), Instructions).
%---------------------------------------------------------------------------%
%---------------------------------------------------------------------------%
% 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, code_tree::out, maybe(label)::out,
frame_info::out, code_info::in, code_info::out) is det.
generate_category_code(model_det, Goal, ResumePoint, 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) }
;
code_info__get_maybe_trace_info(MaybeTraceInfo),
( { MaybeTraceInfo = yes(TraceInfo) } ->
trace__generate_external_event_code(call, TraceInfo,
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, _, ExitCode),
{ Code =
tree(EntryCode,
tree(TraceCallCode,
tree(BodyCode,
ExitCode)))
}
).
generate_category_code(model_semi, Goal, ResumePoint, 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"
]) },
code_info__get_maybe_trace_info(MaybeTraceInfo),
( { MaybeTraceInfo = yes(TraceInfo) } ->
trace__generate_external_event_code(call, TraceInfo,
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,
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),
trace__generate_external_event_code(fail, TraceInfo, _, _,
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,
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, Code,
MaybeTraceCallLabel, FrameInfo) -->
code_info__get_maybe_trace_info(MaybeTraceInfo),
( { MaybeTraceInfo = yes(TraceInfo) } ->
trace__generate_external_event_code(call, TraceInfo,
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, _, 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),
trace__generate_external_event_code(fail, TraceInfo, _, _,
TraceFailCode),
{ FailCode = node([
goto(do_fail) - "fail after fail trace port"
]) },
{ Code =
tree(EntryCode,
tree(TraceCallCode,
tree(BodyCode,
tree(ExitCode,
tree(ResumeCode,
tree(TraceFailCode,
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, _, 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)
- ""
]) },
{ 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 slots holding the call number and call depth for tracing.
%
% 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,
code_tree::out, code_tree::out, code_info::in, code_info::out) is det.
code_gen__generate_exit(CodeModel, FrameInfo, 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)
- ""
]) },
{ 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"
]) }
),
{ RestoreDeallocCode = tree(RestoreSuccipCode, DeallocCode ) },
code_info__get_maybe_trace_info(MaybeTraceInfo),
( { MaybeTraceInfo = yes(TraceInfo) } ->
trace__generate_external_event_code(exit, TraceInfo,
_, 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(higher_order_call(PredVar, Args, Types,
Modes, Det, _PredOrFunc), GoalInfo, CodeModel, Code) -->
call_gen__generate_higher_order_call(CodeModel, PredVar, Args,
Types, Modes, Det, GoalInfo, Code).
code_gen__generate_goal_2(class_method_call(TCVar, Num, Args, Types,
Modes, Det), GoalInfo, CodeModel, Code) -->
call_gen__generate_class_method_call(CodeModel, TCVar, Num, Args,
Types, 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).
%---------------------------------------------------------------------------%
% 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, CM)
->
map__init(Empty),
Instrn = call(Target, ReturnLabel,
[live_lvalue(direct(stackvar(StackLoc)),
succip, Empty) |
LiveVals0], CM)
;
Instrn = Instrn0
),
code_gen__add_saved_succip(Instrns0, StackLoc, Instrns).
%---------------------------------------------------------------------------%
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