Estimated hours taken: 4
Implement `recursive' and `non_recursive' pragma c_code declarations.
This allows the compiler to optimize cases when the C code
is known to not call Mercury code. It's also necessary
to allow C code which modifies the hp register to work
(such code must be declared `non_recursive', otherwise
the registers will be saved and restored over it).
To make things bootstrap OK, the old pragma c_code declarations
default to `non_recursive'.
prog_data.m, hlds_goal.m:
Add new field c_is_recursive to pragma c_code goals.
prog_io.m:
Parse the new `recursive' and `non_recursive' pragma c_code
declarations.
make_hlds.m:
Pass the c_is_recursive field from the parse tree to the HLDS.
live_vars.m:
For non-recursive C code, don't save variables on the stack.
code_gen.pp:
For non-recursive C code, don't save variables on the stack,
don't mark the succip as needing to be saved, and don't
call save_registers() and restore_registers().
*.m:
Change c_code/5 to c_code/6.
Estimated hours taken: 12
Implement higher-order functions.
Add higher-order function terms
(function lambda expressions, e.g. `Func = (func(X) = Y :- Y is 2 * X)'
and higher-order function calls (apply/N, e.g. `Z = apply(Func, 42)').
Add higher-order function insts and modes.
hlds_goal.m:
Add a new field pred_or_func to lambda_goal.
prog_data.m:
Add a new field pred_or_func to pred_inst_info.
prog_io.m:
Add support for parsing higher-order function terms and
higher-order function insts and modes.
make_hlds.m:
Add support for parsing higher-order function terms.
typecheck.m:
Add support for type-checking higher-order function calls
and higher-order function terms.
modes.m, mode_errors.m:
Add support for mode-checking higher-order function calls
and higher-order function terms.
higher_order.m:
Handle higher-order function types and insts.
hlds_pred.m:
Add new predicate pred_args_to_func_args, for extracting the
function arguments and function return from the arguments
of a predicate that is really a function.
*.m:
Minor changes to handle new pred_or_func field in lambda_goals
and pred_inst_infos.
Estimated hours taken: 24
Treat higher-order predicate calls as a new sort of goal,
rather than as calls to the special predicate call/N, in order to
remove the fixed limit on the number of arguments and on the modes
for call/N.
Also, remove the restriction on output arguments preceding input arguments
in lambda expressions.
hlds_goal.m:
Add new functor higher_order_call/6 to the hlds__goal type.
*.m:
Handle new functor higher_order_call/6.
arg_info.m:
Abstract things a bit more: the argument passing convention
for a procedure may be affected by that procedure's types,
modes, and code_model, as well as the arg_method.
follow_vars.m:
Pass down the args_method, since it is now needed for figuring
out the arg_info for unifications and higher-order calls.
follow_code.m:
Treat complicated unifications in the same way as calls.
lambda.m:
When creating lambda predicates, permute the arguments so
that all input arguments come before all output arguments.
call_gen.m:
When generating higher-order predicate calls, don't abort
if outputs precede inputs; instead, generate code assuming
that the called predicate's args have been permuted so that
the inputs to come before all the outputs.
Estimated hours taken: 1.5
Split llds into two parts. llds.m defines the data types, while llds_out.m
has the predicates for printing the code.
Removed the call_closure instruction. Instead, we use calls to the
system-defined addresses do_call_{det,semidet,nondet}_closure. This is
how call_closure was implemented already. The advantage of the new
implementation is that it allows jump optimization of what used to be
call_closures, without new code in jumpopt.
Estimated hours taken: 8
options.m:
Rename branch_delay_slot to have_delay_slot.
Set optimize_delay_slot in -O2 only if have_delay_slot was set earlier.
This is possible now because the default optimization level is now
set in mc.
mercury_compile:
Change verbose output a bit to be more consistent.
dead_proc_elim:
Export the predicates that will eventually be needed by inlining.m.
inlining.m:
Use the information about the number of times each procedure is called
to inline local nonrecursive procedures that are called exactly once.
EXCEPT that this is turned off at the moment, since the inlining of
parse_dcg_goal_2 in prog_io, which this change enables, causes the
compiler to emit incorrect code.
prog_io:
Moved the data type definitions to prog_data. (Even though prog_io.m
is ten times the size of prog_data.m, the sizes of the .c files are
not too dissimilar.)
Estimated hours taken: 3
options:
Add a new option, --branch-delay-slot, intended for use by mc on
the basis of the configuattion script. It says whether the machine
architecture has delays slots on branches.
The setting of option should affect whether we set
--optimize-delay-slots at -O2, but this doesn't work yet.
hlds_goal:
Add an extra field to hold follow_vars infromation to disjunctions,
switches and if-then-elses. I intend to use this information to
generate better code.
*.m:
Changes to accommodate the extra field.
Estimated hours taken: 10
hlds, hlds_module, hlds_pred, hlds_goal, hlds_data:
Divided the old hlds.m into four files:
hlds_module.m defines the data structures that deal with issues
that are wider than a single predicate. These data structures are
the module_info structure, dependency_info, the predicate table
and the shape table.
hlds_pred.m defined pred_info and proc_info, pred_id and proc_id.
hlds_goal.m defines hlds__goal, hlds__goal_{expr,info}, and the
other parts of goal structures.
hlsd_data.m defines the HLDS types that deal with issues related
to data and its representation: function symbols, types, insts, modes.
It also defines the types related to determinism.
hlds.m is now an empty module. I have not removed it from CVS
because we may need the name hlds.m again, and CVS does not like
the reuse of a name once removed.
other modules:
Import the necessary part of hlds.
det_analysis:
Define a type that was up to now improperly defined in hlds.m.
prog_io:
Move the definition of type determinism to hlds_data. This decision
may need to be revisited when prog_io is broken up.
dnf, lambda:
Simplify the task of defining predicates.
llds:
Fix some comments.
mercury_compile:
If the option -d all is given, dump all HLDS stages.
shape, unused_args:
Fix formatting.
Estimated hours taken: 12
Implement functional syntax. You can now use `:- func' in a similar manner
to `:- pred'. For example, `:- func foo(int, int) = int.' declares a function,
and `:- mode foo(in, in) = out.' defines a mode for it. You can write clauses
for functions, such as `foo(X, Y) = Z :- Z is 2*X + Y.' Any term in the
head or body of a clause can be a function call, e.g. `bar(X, Y, foo(X, Y))'.
Until we have implemented a proper Mercury debugger, this syntax
should not be used (except that I might reimplement the functions
provided by Prolog's is/2 predicate using this syntax, rather than
the current special-case hack in the parser).
prog_io.m:
Add syntax for declaring and defining functions.
Disallow the use of `=' to define modes, as in `:- mode foo = bar.'
(Instead, you should use `::'. `==' is also allowed.)
Also, use higher-order predicates to simplify some of the rather
repetitious parsing code.
mercury_to_mercury.m, mercury_to_goedel.m, make_hlds.m, modules.m:
Handle new functional syntax.
typecheck.m:
Add support for functions, function types such as `func(int) = int',
and currying. (But there's currently no equivalent to call/N for
functions, so function types and currying aren't very useful yet.)
undef_types.m:
Add support for function types.
modes.m:
Convert function calls into predicate calls.
(This must be done after typechecking is complete,
so I put it in mode analysis.)
hlds.m:
Add new field `pred_or_func' to the pred_info.
hlds_out.m:
Print out the `pred_or_func' field.
higher_order.m, unused_args.m, lambda.m, dnf.m:
Pass extra pred_or_func argument to pred_info_init to specify that
the thing being created is a predicate, not a function.
constraint.m, dependency_graph.m, hlds_out.m:
`mercury_output_mode_subdecl' has been renamed
`mercury_output_pred_mode_subdecl'.
prog_util.m:
Add new predicate split_type_and_mode/3.
llds.m:
Print out
/* code for predicate '*'/3 in mode 0 */
rather than
/* code for predicate */3 in mode 0 */
to avoid a syntax error in the generated C code.
Estimated hours taken: 8
mercury_compile:
Fix the pass structure, and start using a loose sequence of stage
numbers, to make it easier to add new stages without having to fiddle
stage numbers.
THIS DOES MEAN THAT ALL STAGE NUMBERS HAVE CHANGED NOW.
The stage number assignment scheme assigns 1 to 25 to the front end,
26 to 50 to the middle passes, and 51 to 99 to the back end.
hlds:
We had two types that combined a pred_id and a proc_id. One,
pred_proc_id, used a simple pair; the other, procedure_id, had a better
definition using a specific function symbol but was not used
anywhere else. I standardized on the name pred_proc_id, but using the
definition with a dedicated function symbol (proc).
I also defined a type pred_proc_list as a list of pred_proc_id.
To prepare for memoing, I added a new field to pred_info, which is
a list of markers, each requesting a specific transformation on the
predicate or indicating that the transformation has been done.
The inline request is now represented using such a marker. However,
the interface is backwards compatible.
constraint, dead_proc_elim, dependency_graph, det_analysis, det_report,
higher_order, unused_args:
Changes to conform to the new definition of pred_proc_id.
In two places removed definitions of predproclist, whose
equivalent pred_proc_list is now defined in hlds.m.
hlds_out, make_hlds, mercury_to_mercury, prog_io:
Add code to handle memo pragma declarations, using whenever possible
a version of the existing code for handling inline requests, but
generalized for handling any pragma that sets a marker.
switch_detection:
Rename the type cases_list to sorted_cases_list. This avoids a
name clash that creates a duplicate label and therefore screws up
the profiler, and is a better name anyway.
options:
Add a new option, --opt-space, that turns on optimizations that save
space and turns off optimizations that squander space.
handle_options:
Pass the special option handler to getopt.
frameopt:
For each labelled code sequence that tears down the stack frame but
does not use it, we used to create a parallel code sequence that omits
the teardown code, for use by gotos from locations that did not have
a stack frame. However, peepholing may discover that it is better
not to tear down the stack frame at the site of the goto after all,
so we need the original code sequence as well.
The current change fixes a bug that occurs if the original code
sequence is modified by another part of frameopt to omit teardown
code. In such cases, which are produced by --pred-value-number,
peepholing redirects a goto to a code sequence that it thinks tears
down the stack frame, but actually doesn't.
With this change, --pred-value-number now works.
llds:
Fix typos in a comment.
Estimated hours taken: _2___
Change names with badly placed double underscores (ie where the part of
a name before a double underscore is not the same as the module name.)
Reflect changes in the library interface.
compiler/*:
Use the newer, more correct form of the term and bool names.
Predicates "bool__" are now "std_util__bool" and labels of
the term ADT are now "term_" instead of "term__".
compiler/vn*.m:
change all names "vn__*" to a correct module prefix. All the
names remain qualified.
compiler/hlds.m:
s/\<is_builtin__/hlds__is_builtin_/g
s/\<dependency_info__/hlds__dependency_info_/g
compiler/unify_proc.m:
s/\<unify_proc_info__/unify_proc__info_/g
compiler/transform.m:
s/\<reschedule__conj/transform__reschedule_conj/g
The changes made allow declarations of the form:
:- pragma(c_code, predname(Varname1::mode1, Varname2::mode2, ...),
"Some C code to execute instead of a mercury clause;").
There are still a couple of minor problems to be fixed in the near future:
If there is a regular clause given as well as a pragma(c_code, ...) dec, it
is not handled well, and variables names '_' are not handled well.
prog_io.m:
parse the pragma(c_code, ...) dec.
hlds.m:
define a new hlds__goal_expr 'pragma_c_code'.
make_hlds.m:
insert the pragma(c_code, ...) dec. as a pragma_c_code into the hlds.
det_analysis.m:
infer that pragma_c_code goals are det.
modes.m:
convince the mode checker that the correct pragma variables are bound
etc.
quantification.m:
quantify the variables in the pragma(c_code, ...) dec.
code_gen.pp:
convert pragma_c_code into pragma_c (in the llds).
llds.m:
define a new instr, pragma_c. Output the pragma_c
hlds_out.m:
mercury_to_mercury.m:
mercury_to_goedel.m:
spit out pragma(c_code, ...) decs properly
*.m: handle the new pragma_c_code in the hlds or the new pragma_c in the llds
dependency_graph.m:
Ensure that the dependency graph is available when I want to output it
for profiling.
mercury_compile.pp:
Option -p, --profiling now output's the static call graph for the
profiler into a file called <module_name>.prof
context of the unification from which call was made. We we use this to generate
significantly better error messages. (There should be no more messages of the
form "call to __Unify__(blah blah blah) can fail".) Most of the files are
changed just to reflect this.
An unrelated change in det_analysis is that we now ensure the absence of
cycles by modifying the new inferred determinism in the light of the old
one, ensuring that any changes are monotonic.
In hlds_out, inhibit the printing of pseudo-imported predicates (unifications)
since nobody cares about them except sometimes Fergus.
options.m:
Added the profiling option, which generates a file <module>.prof, which
contains the static call graph.
dependency_graph.m:
Predicate to output the static call graph in a form useful for the
profiler.
prof.m:
Scan's through the LLDS marking all labels that are continuation
labels. eg All label's cont_type field should be unknown now.
llds.m, code_info.m:
Minor changes so that the above stuff works.
