Estimated hours taken: 4
Branches: main
This diff contains no changes in algorithms whatsoever.
browser/*.m:
compiler/*.m:
library/*.m:
Replace old-style lambdas with new-style lambdas or with named
procedures.
Estimated hours taken: 4
Branches: main
This diff makes code_info.m and many callers of its predicates easier to read
and to maintain, but contains no changes in algorithms whatsoever.
compiler/code_info.m:
Bring this module into line with our current coding standards.
Use predmode declarations, functions, and state variable syntax
when appropriate.
Reorder arguments of predicates where necessary for the use of state
variable syntax, and where this improves readability.
Where a predicate returned its input code_info unchanged, purely
to allow the convenient use of DCG notation in the caller, delete the
unnecessary output argument. This should make the caller somewhat more
efficient, since it can avoid updating the stack slot holding the
current code_info.
Replace old-style lambdas with new-style lambdas or with partially
applied named procedures.
compiler/*.m:
Conform to the changes in code_info.m. This mostly means using the
new argument orders of predicates exported by hlds_pred.m, and
using state variable notation.
Estimated hours taken: 2
Branches: main
compiler/*.m:
Import only one compiler module per line. Sort the blocks of imports.
This makes it easier to merge in changes.
In a couple of places, remove unnecessary imports.
Estimated hours taken: 2
Branches: main
Hide the events associated with the goals inserted by tabling transformations,
since ordinary programmers shouldn't be exposed to the details of the
transformation. (A later diff will adjust the goal paths of the events
associated with the original code back to what they would have been without
the transformation.)
Add a new mdb command, unhide_events, that allows the programmer to expose
hidden events. This is intended for implementors only.
compiler/hlds_goal.m:
Add a new goal feature, hide_debug_event. If a nonatomic goal has this
feature, then the associated trace events will be hidden.
compiler/trace.m:
Respect the new goal feature.
compiler/table_gen.m:
Add the new goal feature to the compound goals created by tabling
transformations.
compiler/code_gen.m:
compiler/dense_switch.m:
compiler/disj_gen.m:
compiler/ite_gen.m:
compiler/string_switch.m:
compiler/switch_gen.m:
compiler/tag_switch.m:
Pass the required goal_info to trace.m, to allow it to hide events as
required.
runtime/mercury_trace_base.[ch]:
Add two global boolean variables. One says whether we are exposing
hidden events, the other says whether we have ever exposed hidden
events.
trace/mercury_trace.c:
Hide hidden events, unless the programmer has asked for them to be
exposed.
trace/mercury_trace_internal.c:
Implement the unhide_events command.
Make "dd" check whether we have ever exposed hidden events.
Fix some unclear code in "print_optionals".
doc/user_guide.texi:
Doument the unhide_events command.
doc/mdb_categories:
Mention the unhide_events command.
tests/debugger/mdb_command_test.inp:
Test the documentation of the unhide_events command.
Estimated hours taken: 400
Branches: main
This diff implements stack slot optimization for the LLDS back end based on
the idea that after a unification such as A = f(B, C, D), saving the
variable A on the stack indirectly also saves the values of B, C and D.
Figuring out what subset of {B,C,D} to access via A and what subset to access
via their own stack slots is a tricky optimization problem. The algorithm we
use to solve it is described in the paper "Using the heap to eliminate stack
accesses" by Zoltan Somogyi and Peter Stuckey, available in ~zs/rep/stackslot.
That paper also describes (and has examples of) the source-to-source
transformation that implements the optimization.
The optimization needs to know what variables are flushed at call sites
and at program points that establish resume points (e.g. entries to
disjunctions and if-then-elses). We already had code to compute this
information in live_vars.m, but this code was being invoked too late.
This diff modifies live_vars.m to allow it to be invoked both by the stack
slot optimization transformation and by the code generator, and allows its
function to be tailored to the requirements of each invocation.
The information computed by live_vars.m is specific to the LLDS back end,
since the MLDS back ends do not (yet) have the same control over stack
frame layout. We therefore store this information in a new back end specific
field in goal_infos. For uniformity, we make all the other existing back end
specific fields in goal_infos, as well as the similarly back end specific
store map field of goal_exprs, subfields of this new field. This happens
to significantly reduce the sizes of goal_infos.
To allow a more meaningful comparison of the gains produced by the new
optimization, do not save any variables across erroneous calls even if
the new optimization is not enabled.
compiler/stack_opt.m:
New module containing the code that performs the transformation
to optimize stack slot usage.
compiler/matching.m:
New module containing an algorithm for maximal matching in bipartite
graphs, specialized for the graphs needed by stack_opt.m.
compiler/mercury_compile.m:
Invoke the new optimization if the options ask for it.
compiler/stack_alloc.m:
New module containing code that is shared between the old,
non-optimizing stack slot allocation system and the new, optimizing
stack slot allocation system, and the code for actually allocating
stack slots in the absence of optimization.
Live_vars.m used to have two tasks: find out what variables need to be
saved on the stack, and allocating those variables to stack slots.
Live_vars.m now does only the first task; stack_alloc.m now does
the second, using code that used to be in live_vars.m.
compiler/trace_params:
Add a new function to test the trace level, which returns yes if we
want to preserve the values of the input headvars.
compiler/notes/compiler_design.html:
Document the new modules (as well as trace_params.m, which wasn't
documented earlier).
compiler/live_vars.m:
Delete the code that is now in stack_alloc.m and graph_colour.m.
Separate out the kinds of stack uses due to nondeterminism: the stack
slots used by nondet calls, and the stack slots used by resumption
points, in order to allow the reuse of stack slots used by resumption
points after execution has left their scope. This should allow the
same stack slots to be used by different variables in the resumption
point at the start of an else branch and nondet calls in the then
branch, since the resumption point of the else branch is not in effect
when the then branch is executed.
If the new option --opt-no-return-calls is set, then say that we do not
need to save any values across erroneous calls.
Use type classes to allow the information generated by this module
to be recorded in the way required by its invoker.
Package up the data structures being passed around readonly into a
single tuple.
compiler/store_alloc.m:
Allow this module to be invoked by stack_opt.m without invoking the
follow_vars transformation, since applying follow_vars before the form
of the HLDS code is otherwise final can be a pessimization.
Make the module_info a part of the record containing the readonly data
passed around during the traversal.
compiler/common.m:
Do not delete or move around unifications created by stack_opt.m.
compiler/call_gen.m:
compiler/code_info.m:
compiler/continuation_info.m:
compiler/var_locn.m:
Allow the code generator to delete its last record of the location
of a value when generating code to make an erroneous call, if the new
--opt-no-return-calls option is set.
compiler/code_gen.m:
Use a more useful algorithm to create the messages/comments that
we put into incr_sp instructions, e.g. by distinguishing between
predicates and functions. This is to allow the new scripts in the
tool directory to gather statistics about the effect of the
optimization on stack frame sizes.
library/exception.m:
Make a hand-written incr_sp follow the new pattern.
compiler/arg_info.m:
Add predicates to figure out the set of input, output and unused
arguments of a procedure in several different circumstances.
Previously, variants of these predicates were repeated in several
places.
compiler/goal_util.m:
Export some previously private utility predicates.
compiler/handle_options.m:
Turn off stack slot optimizations when debugging, unless
--trace-optimized is set.
Add a new dump format useful for debugging --optimize-saved-vars.
compiler/hlds_llds.m:
New module for handling all the stuff specific to the LLDS back end
in HLDS goal_infos.
compiler/hlds_goal.m:
Move all the relevant stuff into the new back end specific field
in goal_infos.
compiler/notes/allocation.html:
Update the documentation of store maps to reflect their movement
into a subfield of goal_infos.
compiler/*.m:
Minor changes to accomodate the placement of all back end specific
information about goals from goal_exprs and individual fields of
goal_infos into a new field in goal_infos that gathers together
all back end specific information.
compiler/use_local_vars.m:
Look for sequences in which several instructions use a fake register
or stack slot as a base register pointing to a cell, and make those
instructions use a local variable instead.
Without this, a key assumption of the stack slot optimization,
that accessing a field in a cell costs only one load or store
instruction, would be much less likely to be true. (With this
optimization, the assumption will be false only if the C compiler's
code generator runs out of registers in a basic block, which for
the code we generate should be unlikely even on x86s.)
compiler/options.m:
Make the old option --optimize-saved-vars ask for both the old stack
slot optimization (implemented by saved_vars.m) that only eliminates
the storing of constants in stack slots, and the new optimization.
Add two new options --optimize-saved-vars-{const,cell} to turn on
the two optimizations separately.
Add a bunch of options to specify the parameters of the new
optimizations, both in stack_opt.m and use_local_vars.m. These are
for implementors only; they are deliberately not documented.
Add a new option, --opt-no-return-cells, that governs whether we avoid
saving variables on the stack at calls that cannot return, either by
succeeding or by failing. This is for implementors only, and thus
deliberately documented only in comments. It is enabled by default.
compiler/optimize.m:
Transmit the value of a new option to use_local_vars.m.
doc/user_guide.texi:
Update the documentation of --optimize-saved-vars.
library/tree234.m:
Undo a previous change of mine that effectively applied this
optimization by hand. That change complicated the code, and now
the compiler can do the optimization automatically.
tools/extract_incr_sp:
A new script for extracting stack frame sizes and messages from
stack increment operations in the C code for LLDS grades.
tools/frame_sizes:
A new script that uses extract_incr_sp to extract information about
stack frame sizes from the C files saved from a stage 2 directory
by makebatch and summarizes the resulting information.
tools/avg_frame_size:
A new script that computes average stack frame sizes from the files
created by frame_sizes.
tools/compare_frame_sizes:
A new script that compares the stack frame size information
extracted from two different stage 2 directories by frame_sizes,
reporting on both average stack frame sizes and on specific procedures
that have different stack frame sizes in the two versions.
The main aim of this change is to make the overall, high-level structure
of the compiler clearer, and to encourage better encapsulation of the
major components.
compiler/libs.m:
compiler/backend_libs.m:
compiler/parse_tree.m:
compiler/hlds.m:
compiler/check_hlds.m:
compiler/transform_hlds.m:
compiler/bytecode_backend.m:
compiler/aditi_backend.m:
compiler/ml_backend.m:
compiler/ll_backend.m:
compiler/top_level.m:
New files. One module for each of the major components of the
Mercury compiler. These modules contain (as separate sub-modules)
all the other modules in the Mercury compiler, except gcc.m and
mlds_to_gcc.m.
Mmakefile:
compiler/Mmakefile:
Handle the fact that the top-level module is now `top_level',
not `mercury_compile' (since `mercury_compile' is a sub-module
of `top_level').
compiler/Mmakefile:
Update settings of *FLAGS-<modulename> to use the appropriate
nested module names.
compiler/recompilation_check.m:
compiler/recompilation_version.m:
compiler/recompilation_usage.m:
compiler/recompilation.check.m:
compiler/recompilation.version.m:
compiler/recompilation.version.m:
Convert the `recompilation_*' modules into sub-modules of the
`recompilation' module.
compiler/*.m:
compiler/*.pp:
Module-qualify the module names in `:- module', `:- import_module',
and `:- use_module' declarations.
compiler/base_type_info.m:
compiler/base_type_layout.m:
Deleted these unused empty modules.
compiler/prog_data.m:
compiler/globals.m:
Move the `foreign_language' type from prog_data to globals.
compiler/mlds.m:
compiler/ml_util.m:
compiler/mlds_to_il.m:
Import `globals', for `foreign_language'.
Mmake.common.in:
trace/Mmakefile:
runtime/Mmakefile:
Rename the %.check.c targets as %.check_hdr.c,
to avoid conflicts with compiler/recompilation.check.c.
Estimated hours taken: 6
Eliminated a lot of the dependencies on the the `code_model' type,
and move that type from llds.m into a new module `code_model'.
The aim of this change is to improve the modularity of the compiler by
reducing the number of places in the compiler front-end that depend
on back-end concepts and the number of places in the MLDS back-end
which depend on the LLDS.
compiler/code_model.m:
New module. Contains the code_model type and associated
procedures.
compiler/llds.m:
Move the code_model type into code_model.m.
compiler/hlds_goal.m:
Move the goal_info_get_code_model procedure into code_model.m,
to avoid having the HLDS modules import code_model.
compiler/hlds_out.m:
Delete `hlds_out__write_code_model', since it wasn't being used.
compiler/hlds_pred.m:
Move the proc_info_interface_code_model procedure into code_model.m,
to avoid having the HLDS modules import code_model.
compiler/goal_path.m:
When computing the `maybe_cut' field for `some' goals,
compute it by comparing the determinism rather than by
comparing the goal_infos.
compiler/unique_modes.m:
Use determinism and test for soln_count = at_most_many
rather than using code_model and testing for model_non.
compiler/inlining.m:
Test for determinism nondet/multi rather than testing
for code_model model_non.
compiler/hlds_pred.m:
compiler/det_report.m:
Change valid_code_model_for_eval_method, which succeeded unless
the eval_method was minimal_model and the code_model was model_det,
to valid_determinism_for_eval_method, which succeeds unless the
eval_method is minimal_model and the determinism cannot fail.
As well as avoiding a dependency on code_model in the HLDS
modules, this also fixes a bug where det_report could give
misleading error messages, saying that `multi' was a valid
determinism for `minimal_model' predicates, when in fact the
compiler will always report a determinism error if you declare
a `minimal_model' predicate with determinism `multi'.
(Actually the code in which this bug occurs is in fact
unreachable, but this is no doubt also a bug... I'll address
that one in a separate change.)
compiler/lookup_switch.m:
Simplify the code a bit by using globals__lookup_*_option
rather than globals__get_option and then getopt__lookup_option.
compiler/*.m:
Add `import_module' declarations for `code_model', and in some
cases remove `import_module' declarations for `llds'.
Estimated hours taken: 2
Reorganize the code for handling switches in the MLDS and
LLDS back-ends to reduce code duplication.
compiler/switch_util.m:
New file. Contains stuff for switches that is shared
between the MLDS and LLDS back-ends.
compiler/ml_switch_gen.m:
compiler/ml_string_switch.m:
compiler/ml_tag_switch.m:
compiler/switch_gen.m:
compiler/string_switch.m:
compiler/tag_switch.m:
Move code that was duplicated in the LLDS and MLDS back-ends
into string_util.m. Change some names and import_module
declarations to match the new organization.
compiler/notes/compiler_design.html:
Document the new module switch_util.m.
Also mention ml_tag_switch.m.
Estimated hours taken: 140
Add an alternative to code_exprn that does eager code generation (code_exprn
always does lazy code generation). Its main advantages are that the new code
is significantly simpler, and that it does not generate unnecessary shuffling
code. Its main disadvantage, which is that it does not eliminate the creation
of unneeded cells, can be eliminated by switching on --unneeded-code.
For now, you can select the use of the new code generator with the
--no-lazy-code option (which was previously present but unused).
This will be made the default later, after I do more performance tests.
Var_locn contains stricter self-checks than code_exprn does. This required
modifications to some other parts of the code generator to ensure that the
self-checks do not fail unnecessarily. (This mostly took the form of explicitly
killing off dead variables before calling code_info__clear_all_registers, which
would complain about losing the last record of the value of a variable that was
alive as far as it knew.) To make my changes simpler, also took the opportunity
to simplify parts of the code generator which were handing around rvals that
in fact had to be wrappers around lvals, by handing around the lvals directly.
Testing this change also required fixing an old bug which prevented compiling
the library with -O1 --trace deep, together with the usual intermodule
optimization. The bug is that a library module reads predicates from
builtin.opt or private_builtin.opt, does not eliminate them because of the -O1,
and then tries to generate traced code for them. However, this fails because
the builtin modules contain some predicates that cannot be made to conform to
typeinfo-liveness, which is required by tracing.
compiler/var_locn.m:
The new module that implements eager code generation.
compiler/follow_vars.m:
Improve the follow_vars pass, since eager code generation requires
better follow_vars information. We now generate correct information
for generic calls, and record not only where some vars (e.g. those
which appear as input arguments of following calls) should be put,
but also which registers are not reserved for those variables and
are thus available for other variables.
compiler/hlds_goal.m:
Modify the follow_vars field of the goal_info to record the number
of the first non-reserved register.
compiler/code_info.m:
Replace the general-purpose predicate code_info__cache_exprn, which
associated a variable with an rval without generating code, with a set
of special-purpose predicates such as code_info__assign_const_to_var
and code_info__assign_cell_to_var, some of which can generate code.
These new predicates and some older ones (e.g. code_info__setup_call)
now choose at runtime whether to call code_exprn or var_locn. The
basis for the decision is checking whether the code_info structure
contains an exprn_info or a var_locn_info. This is decided in
code_info__init based on the value of the lazy_code option, and
maintained unchanged from then on.
Rename some predicates to better reflect their current possible
behaviors.
compiler/unify_gen.m:
Call the new special-purpose predicates in code_info instead of
code_info__cache_exprn.
Replace an incorrect clause with a call to error, since that clause
could never be invoked.
compiler/call_gen.m:
Hand over the task of generating the args of generic calls to
code_info, since it already has code to do the right thing, which
includes reserving the registers to be used for the input args.
Notify the rest of the code generator after the last use of
non-forward-live variables, in order to avoid spurious calls to error
(it is an error to clobber the last location of a live variable).
Notify the rest of the code generator when generic calls overwrite
registers, to allow the proper consistency checks to be made.
If an output variable is singleton, then do not make it known to the
code generator. It never will never become dead, and may thus cause a
spurious compiler abort if its storage is ever clobbered.
Export a predicate for use by follow_vars.
Factor out some common code.
Call the new preds in code_info where necessary.
compiler/pragma_c_gen.m:
Notify the rest of the code generator after the last use of
non-forward-live variables, in order to avoid spurious calls to error
(it is an error to clobber the last location of a live variable).
If an output variable is singleton, then do not make it known to the
code generator. It never will never become dead, and may thus cause a
spurious compiler abort if its storage is ever clobbered.
When using var_locn, ensure that none of the input arguments of a
model_semi pragma_c_code is assigned to r1. If we did, and the last
reference to the value of that argument was after an assignment to
SUCCESS_INDICATOR, the C compiler would be forced to generate code
to shuffle the value of the argument out of the way.
compiler/code_exprn.m:
Minor changes to return lvals directly instead of lvals wrapped inside
rvals and to conform the new format of follow_vars.
Do not include the registers reserved by follow_vars in the
search for a spare register.
compiler/lookup_switch.m:
compiler/switch_gen.m:
Fix an old bug that did not matter with code_exprn but does matter with
var_locn: the branch end structure was being computed in the wrong
place.
compiler/disj_gen.m:
At the ends of non-last disjuncts, kill off the variables that we
needed to know inside the disjunct but won't need to know after the
disjunct, in order to avoid error messages about throwing away their
state. The variables affected are those which are needed only by the
resumption point of the next disjunct, not by enclosing resumption
points or forward execution.
compiler/arg_info.m:
Associate an lval, not an rval, with each argument.
compiler/*.m:
Minor changes to conform to (a) the new format of follow_vars, (b)
the replacement of rvals containing lvals by lvals.
compiler/code_util.m:
Add some utility predicates for var_locn.m.
compiler/exprn_aux.m:
Add some utility functions for var_locn.m.
Export a predicate for var_locn.m.
compiler/handle_options.m:
If --no-lazy-code is set, switch on the "optimizations" on whose
presence it depends.
compiler/mercury_compile.m:
compiler/code_gen.m:
Turn off tracing for predicates that don't obey typeinfo liveness
for backend_by_preds and backend_by_phases respectively.
Look up options in the globals structure in the module_info, not in the
globals structure in the I/O state, since this is where we turn off
tracing. (We should later make sure that other parts of the compiler
are also consistent on this issue.)
compiler/stack_layout.m:
Throw away any continuation_info structures that belong to predicates
that don't obey typeinfo liveness.
Estimated hours taken: 2.5
Some more changes to minimize the complexity of the intermodule dependencies.
In particular, ensure that bytecode.m does not need to import llds.m.
compiler/llds.m:
compiler/builtin_ops.m:
Move the definitions of the unary_op and binary_op types into
a new module `builtin_ops'. These types are used by three of the
different back-ends (bytecode, llds, and mlds) and therefore deserve
to be in their own module.
compiler/bytecode.m:
Define a type `byte_reg_type' and use that instead of llds__reg_type.
Delete the import of module llds.
compiler/notes/compiler_design.html:
Document the new module builtin_ops.
compiler/rl_exprn.m:
Add a comment explaining why we need to import llds (and builtin_ops).
compiler/base_type_layout.m:
compiler/bytecode.m:
compiler/code_util.m:
compiler/dense_switch.m:
compiler/ite_gen.m:
compiler/jumpopt.m:
compiler/llds_out.m:
compiler/lookup_switch.m:
compiler/middle_rec.m:
compiler/opt_debug.m:
compiler/opt_util.m:
compiler/rl_exprn.m:
compiler/string_switch.m:
compiler/tag_switch.m:
compiler/transform_llds.m:
compiler/unify_gen.m:
compiler/value_number.m:
compiler/vn_block.m:
compiler/vn_cost.m:
compiler/vn_flush.m:
compiler/vn_type.m:
compiler/vn_util.m:
compiler/vn_verify.m:
Add imports of module builtin_ops to lots of modules that
imported llds.
Estimated hours taken: 5
This change does some renaming to match the new nomenclature introduced
in the RTTI paper.
Rename simple tags as unshared tags, complicated tags as shared
remote tags and complicated constant tags as shared local.
Also rename "simple vector" as "functor descriptor",
"functors vector" as "enum vector".
compiler/base_type_layout.m:
compiler/bytecode.m:
compiler/bytecode_gen.m:
compiler/hlds_data.m:
compiler/make_tags.m:
compiler/switch_gen.m:
compiler/tag_switch.m:
compiler/unify_gen.m:
Perform these renamings in the compiler, renaming a few
functors and data structures.
library/std_util.m:
runtime/mercury_deep_copy_body.h:
runtime/mercury_tabling.c:
runtime/mercury_type_info.c:
runtime/mercury_type_info.h:
Perform these renamings in the library and runtime, renaming
macros and variables.
Estimated hours taken: 20
These changes make `var' and `term' polymorphic. This allows us to make
variables and terms representing types of a different type to those
representing program terms and those representing insts.
These changes do not *fix* any existing problems (for instance
there was a messy conflation of program variables and inst variables,
and where necessary I've just called varset__init(InstVarSet) with
an XXX comment).
NEWS:
Mention the changes to the standard library.
library/term.m:
Make term, var and var_supply polymorphic.
Add new predicates:
term__generic_term/1
term__coerce/2
term__coerce_var/2
term__coerce_var_supply/2
library/varset.m:
Make varset polymorphic.
Add the new predicate:
varset__coerce/2
compiler/prog_data.m:
Introduce type equivalences for the different kinds of
vars, terms, and varsets that we use (tvar and tvarset
were already there but have been changed to use the
polymorphic var and term).
Also change the various kinds of items to use the appropriate
kinds of var/varset.
compiler/*.m:
Thousands of boring changes to make the compiler type correct
with the different types for type, program and inst vars and
varsets.
Estimated hours taken: 260
Implement new methods of handling failures and the end points of branched
control structures.
compiler/notes/failure.html:
Fix an omission about the handling of resume_is_known in if-then-elses.
(This omission lead to a bug in the implementation.)
Optimize cuts across multi goals when curfr is known to be equal
to maxfr.
Clarify the wording in several places.
compiler/code_info.m:
Completely rewrite the methods for handling failure.
Separate the fields of code_info into three classes: those which
do not change after initialization, those which record state that
depends on where in the HLDS goal we are, and those which contain
persistent data such as label and cell counters.
Rename grab_code_info and slap_code_info as remember_position
and reset_to_position, and add a wrapper around the remembered
code_info to make it harder to make mistakes in its use.
(Only the location-dependent fields of the remembered code_info
are used, but putting only them into a separate data structure would
result in more, not less, memory being allocated.)
Gather the predicates that deal with handling branched control
structures into a submodule.
Reorder the declarations and definitions of access predicates
to conform to the new order of fields.
Reorder the declarations and definitions of the failure handling
submodule to better reflect the separation of higher-level and
lower-level predicates.
compiler/code_gen.m:
Replace code_gen__generate_{det,semi,non}_goal_2 with a single
predicate, since for most HLDS constructs the code here is the same
anyway (the called preds check the code model when needed).
Move classification of the various kinds of unifications to unify_gen,
since that is where it belongs.
Move responsibility for initializing the code generator's trace
info to code_info.
Move the generation of code for negations to ite_gen, since the
handling of negations is a cut-down version of the handling of
negations. This should make the required double maintenance easier,
and more likely to happen.
compiler/disj_gen.m:
compiler/ite_gen.m:
These are the two modules that handle most failures; they have
undergone a significant rewrite. As part of this rewrite, factor
out the remaining common code between model_non and model_{det,semi}
goals.
compiler/unify_gen.m:
Move classification of the various kinds of unifications here from
code_gen. This allows us to keep several previously exported
predicates private.
compiler/call_gen.m:
Factor out some code that was common to ordinary calls, higher order
calls and method calls. Move the common code that checks whether
we are doing tracing to trace.m.
Replace call_gen__generate_{det,semi,nondet}_builtin with a single
predicate.
Delete the commented out call_gen__generate_complicated_unify,
since it will never be needed and in any case suffered from
significant code rot.
compiler/llds.m:
Change the mkframe instruction so that depending on one of its
arguments, it can create either ordinary frames, or the cut-down
frames used by the new failure handling algorithm (they have only
three fixed fields: prevfr, redoip and redofr).
compiler/llds_out.m:
Emit a #define MR_USE_REDOFR before including mercury_imp.h, to
tell the runtime we are using the new failure handling scheme.
This effectively changes the grade of the compiled module.
Emit MR_stackvar and MR_framevar instead of detstackvar and framevar.
This is a step towards cleaning up the name-space, and a step towards
making both start numbering at 0. For the time being, the compiler
internally still starts counting framevars at 0; the code in llds_out.m
adds a +1 offset.
compiler/trace.m:
Change the way trace info is initialized to fit in with the new
requirements of code_info.m.
Move the "are we tracing" check from the callers to the implementation
of trace__prepare_for_call.
compiler/*.m:
Minor changes in accordance with the major ones above.
compiler/options.m:
Introduce a new option, allow_hijacks, which is set to "yes" by
default. It is not used yet, but the idea is that when it is set to no,
the code generator will not generate code that hijacks the nondet
stack frame of another procedure invocation; instead, it will create
a new temporary nondet stack frame. If the current procedure is
model_non, it will have three fields: prevfr, redoip and redofr.
If the current procedure is model_det or model_semi, it will have
a fourth field that is set to the value of MR_sp. The idea is that
the runtime system, which will be able to distinguish between
ordinary frames (whose size is at least 5 words), 3-word and 4-word
temporary frames, will now be able to use the redofr slots of
all three kinds of frames and the fourth slot values of 4-word
temporary frames as the addresses relative to which framevars
and detstackvars respectively ought to be offset in stack layouts.
compiler/handle_options.m:
Turn off allow_hijacks if the gc method is accurate.
runtime/mercury_stacks.h:
Change the definitions for the nondet stack handling macros
to accommodate the new nondet stack handling discipline.
Define a new macro for creating temp nondet frames.
Define MR_based_stackvar and MR_based_framevar (both of which start
numbering slots at 1), and express other references, including
MR_stackvar and MR_framevar and backward compatible definitions of
detstackvar and framevar for hand-written C code, in terms of those
two.
runtime/mercury_stack_trace.[ch]:
Add a new function to print a dump of the fixed elements nondet stack,
for debugging my changes. (The dump does not include variable values.)
runtime/mercury_trace_internal.c:
Add a new undocumented command "D" for dumping the nondet stack
(users should not know about this command, since the output is
intelligible only to implementors).
Add a new command "toggle_echo" that can cause the debugger to echo
all commands. When the input to the debugger is redirected, this
echo causes the output of the session to be much more readable.
runtime/mercury_wrapper.c:
Save the address of the artificial bottom nondet stack frame,
so that the new function in mercury_stack_trace.c can find out
where to stop.
runtime/mercury_engine.c:
runtime/mercury_wrapper.c:
Put MR_STACK_TRACE_THIS_MODULE at the tops of these modules, so that
the labels they define (e.g. do_fail and global_success) are registered
in the label table when their module initialization functions are
called. This is necessary for a meaningful nondet stack dump.
runtime/mercury_grade.h:
Add a new component to the grade string that specifies whether
the code was compiled with the old or the new method of handling
the nondet stack. This is important, because modules compiled
with different nondet stack handling disciplines are not compatible.
This component depends on whether MR_USE_REDOFR is defined or not.
runtime/mercury_imp.h:
If MR_DISABLE_REDOFR is defined, undefine off MR_USE_REDOFR before
including mercury_grade.h. This is to allow people to continue
working on un-updated workspaces after this change is installed;
they should put "EXTRA_CFLAGS = -DMR_DISABLE_REDOFR" into
Mmake.stage.params. (This way their stage1 will use the new method
of handling failure, while their stage2 2&3 will use the old one.)
This change should be undone once all our workspaces have switched
over to the new failure handling method.
tests/hard_coded/cut_test.{m,exp}:
A new test case to tickle the various ways of handling cuts in the
new code generator.
tests/hard_coded/Mmakefile:
Enable the new test case.
Estimated hours taken: 50
Add support for nested modules.
- module names may themselves be module-qualified
- modules may contain `:- include_module' declarations
which name sub-modules
- a sub-module has access to all the declarations in the
parent module (including its implementation section).
This support is not yet complete; see the BUGS and LIMITATIONS below.
LIMITATIONS
- source file names must match module names
(just as they did previously)
- mmc doesn't allow path names on the command line any more
(e.g. `mmc --make-int ../library/foo.m').
- import_module declarations must use the fully-qualified module name
- module qualifiers must use the fully-qualified module name
- no support for root-qualified module names
(e.g. `:parent:child' instead of `parent:child').
- modules may not be physically nested (only logical nesting, via
`include_module').
BUGS
- doesn't check that the parent module is imported/used before allowing
import/use of its sub-modules.
- doesn't check that there is an include_module declaration in the
parent for each module claiming to be a child of that parent
- privacy of private modules is not enforced
-------------------
NEWS:
Mention that we support nested modules.
library/ops.m:
library/nc_builtin.nl:
library/sp_builtin.nl:
compiler/mercury_to_mercury.m:
Add `include_module' as a new prefix operator.
Change the associativity of `:' from xfy to yfx
(since this made parsing module qualifiers slightly easier).
compiler/prog_data.m:
Add new `include_module' declaration.
Change the `module_name' and `module_specifier' types
from strings to sym_names, so that module names can
themselves be module qualified.
compiler/modules.m:
Add predicates module_name_to_file_name/2 and
file_name_to_module_name/2.
Lots of changes to handle parent module dependencies,
to create parent interface (`.int0') files, to read them in,
to output correct dependencies information for them to the
`.d' and `.dep' files, etc.
Rewrite a lot of the code to improve the readability
(add comments, use subroutines, better variable names).
Also fix a couple of bugs:
- generate_dependencies was using the transitive implementation
dependencies rather than the transitive interface dependencies
to compute the `.int3' dependencies when writing `.d' files
(this bug was introduced during crs's changes to support
`.trans_opt' files)
- when creating the `.int' file, it was reading in the
interfaces for modules imported in the implementation section,
not just those in the interface section.
This meant that the compiler missed a lot of errors.
library/graph.m:
library/lexer.m:
library/term.m:
library/term_io.m:
library/varset.m:
compiler/*.m:
Add `:- import_module' declarations to the interface needed
by declarations in the interface. (The previous version
of the compiler did not detect these missing interface imports,
due to the above-mentioned bug in modules.m.)
compiler/mercury_compile.m:
compiler/intermod.m:
Change mercury_compile__maybe_grab_optfiles and
intermod__grab_optfiles so that they grab the opt files for
parent modules as well as the ones for imported modules.
compiler/mercury_compile.m:
Minor changes to handle parent module dependencies.
(Also improve the wording of the warning about trans-opt
dependencies.)
compiler/make_hlds.m:
compiler/module_qual.m:
Ignore `:- include_module' declarations.
compiler/module_qual.m:
A couple of small changes to handle nested module names.
compiler/prog_out.m:
compiler/prog_util.m:
Add new predicates string_to_sym_name/3 (prog_util.m) and
sym_name_to_string/{2,3} (prog_out.m).
compiler/*.m:
Replace many occurrences of `string' with `module_name'.
Change code that prints out module names or converts
them to strings or filenames to handle the fact that
module names are now sym_names intead of strings.
Also change a few places (e.g. in intermod.m, hlds_module.m)
where the code assumed that any qualified symbol was
fully-qualified.
compiler/prog_io.m:
compiler/prog_io_goal.m:
Move sym_name_and_args/3, parse_qualified_term/4 and
parse_qualified_term/5 preds from prog_io_goal.m to prog_io.m,
since they are very similar to the parse_symbol_name/2 predicate
already in prog_io.m. Rewrite these predicates, both
to improve maintainability, and to handle the newly
allowed syntax (module-qualified module names).
Rename parse_qualified_term/5 as `parse_implicit_qualified_term'.
compiler/prog_io.m:
Rewrite the handling of `:- module' and `:- end_module'
declarations, so that it can handle nested modules.
Add code to parse `include_module' declarations.
compiler/prog_util.m:
compiler/*.m:
Add new predicates mercury_public_builtin_module/1 and
mercury_private_builtin_module/1 in prog_util.m.
Change most of the hard-coded occurrences of "mercury_builtin"
to call mercury_private_builtin_module/1 or
mercury_public_builtin_module/1 or both.
compiler/llds_out.m:
Add llds_out__sym_name_mangle/2, for mangling module names.
compiler/special_pred.m:
compiler/mode_util.m:
compiler/clause_to_proc.m:
compiler/prog_io_goal.m:
compiler/lambda.m:
compiler/polymorphism.m:
Move the predicates in_mode/1, out_mode/1, and uo_mode/1
from special_pred.m to mode_util.m, and change various
hard-coded definitions to instead call these predicates.
compiler/polymorphism.m:
Ensure that the type names `type_info' and `typeclass_info' are
module-qualified in the generated code. This avoids a problem
where the code generated by polymorphism.m was not considered
type-correct, due to the type `type_info' not matching
`mercury_builtin:type_info'.
compiler/check_typeclass.m:
Simplify the code for check_instance_pred and
get_matching_instance_pred_ids.
compiler/mercury_compile.m:
compiler/modules.m:
Disallow directory names in command-line arguments.
compiler/options.m:
compiler/handle_options.m:
compiler/mercury_compile.m:
compiler/modules.m:
Add a `--make-private-interface' option.
The private interface file `<module>.int0' contains
all the declarations in the module; it is used for
compiling sub-modules.
scripts/Mmake.rules:
scripts/Mmake.vars.in:
Add support for creating `.int0' and `.date0' files
by invoking mmc with `--make-private-interface'.
doc/user_guide.texi:
Document `--make-private-interface' and the `.int0'
and `.date0' file extensions.
doc/reference_manual.texi:
Document nested modules.
util/mdemangle.c:
profiler/demangle.m:
Demangle names with multiple module qualifiers.
tests/general/Mmakefile:
tests/general/string_format_test.m:
tests/general/string_format_test.exp:
tests/general/string__format_test.m:
tests/general/string__format_test.exp:
tests/general/.cvsignore:
Change the `:- module string__format_test' declaration in
`string__format_test.m' to `:- module string_format_test',
because with the original declaration the `__' was taken
as a module qualifier, which lead to an error message.
Hence rename the file accordingly, to avoid the warning
about file name not matching module name.
tests/invalid/Mmakefile:
tests/invalid/missing_interface_import.m:
tests/invalid/missing_interface_import.err_exp:
Regression test to check that the compiler reports
errors for missing `import_module' in the interface section.
tests/invalid/*.err_exp:
tests/warnings/unused_args_test.exp:
tests/warnings/unused_import.exp:
Update the expected diagnostics output for the test cases to
reflect a few minor changes to the warning messages.
tests/hard_coded/Mmakefile:
tests/hard_coded/parent.m:
tests/hard_coded/parent.child.m:
tests/hard_coded/parent.exp:
tests/hard_coded/parent2.m:
tests/hard_coded/parent2.child.m:
tests/hard_coded/parent2.exp:
Two simple tests case for the use of nested modules with
separate compilation.
Estimated hours taken: 10
compiler/tag_switch.m:
Add a new way of generating code for switches, binary searches.
These have the form:
if (tag(var)) > 1) goto L23
if (tag(var)) != 0) goto L1
code for tag 0
goto end
L1: code for tag 1
goto end
L23: if (tag(var)) != 2) goto L3
code for tag 2
goto end
L3: code for tag 3
goto end
These have a lower number of expected comparisons than try chains,
especially for machines with three tag bits, although some of the
tests, requiring a subtraction, may be slightly more expensive.
They can be useful for switches where the number of alternatives is
not high enough to justify the overhead of using a jump table.
Make the use of the --dense-switch-size and --try-switch-size options
conform to their documentation. Their arguments are inclusive lower
bounds; they were used as exclusive lower bounds.
compiler/options.m:
Add a new option --binary-switch-size, that controls when we use
the new method.
doc/user_guide.texi:
Document the new option.
Estimated hours taken: 20
Give duplicate code elimination more teeth in dealing with similar arguments
of different function symbols. For the source code
:- type t1 ---> f(int)
; g(int, int).
:- pred p1(t1::in, int::out) is det.
p1(f(Y), Y).
p1(g(Y, _), Y).
we now generate the C code
Define_entry(mercury__xdup__p1_2_0);
r1 = const_mask_field(r1, (Integer) 0);
proceed();
thus avoiding the cost of testing the function symbol.
runtime/mercury_tags.h:
Add two new macros, mask_field and const_mask_field, that behave
just like field and const_field except that instead of stripping
off a known tag from the pointer, they strip (mask) off an unknown
tag.
compiler/llds.m:
Change the first argument of the lval field/3 from tag to maybe(tag).
Make the comments on some types more readable.
compiler/llds_out.m:
If the first arg of the lval field/3 is no, emit a (const_)mask_field
macro; otherwise, emit a (const_)field macro.
compiler/basic_block.m:
New module to convert sequences of instructions to sequences of
basic blocks and vice versa. Used in the new dupelim.m.
compiler/dupelim.m:
Complete rewrite to give duplicate code elimination more teeth.
Whereas previously we eliminated blocks of code only if they exactly
duplicated other blocks of code, we now look for blocks that can be
"anti-unified". For example, the blocks
r1 = field(mktag(0), r2, 0)
goto L1
and
r1 = field(mktag(1), r2, 0)
<fall through to L1>
anti-unify, with the most specific common generalization being
r1 = mask_field(r2, 0)
goto L1
If several basic blocks antiunify, we replace one copy with the
antiunified block and try to eliminate the others. We do not
eliminate blocks that can be fallen into, since eliminating them
would require introducing a goto, which would slow the code down.
compiler/peephole,m:
If a conditional branch to a label is followed by that label or
by an unconditional branch to that label, eliminate the branch.
Dupelim produces this kind of code.
compiler/{code_exprn,exprn_aux,lookup_switch,opt_debug,unify_gen}.m:
Minor changes required by the change to field/3.
compiler/{frameopt,jumpopt,labelopt,mercury_compile,optimize,value_number}.m:
s/__main/_main/ in predicate names.
compiler/jumpopt.m:
Add some documentation.
compiler/unify_gen.m:
Fix a module qualified predicate name reference that would not
work in Prolog.
compiler/notes/compiler_design.html:
Document the new file basic_block.m.
Estimated hours taken: 5
When generating code that raises trace events at runtime, trace not just
procedure calls, exits and failures, but also entries to switch arms,
disjunction arms and to the then and else parts of if-then-elses.
These new trace ports are exactly what is needed to let the trace analyzer
figure out what path execution took inside a procedure. (This includes
knowing at what point forward execution resumes after backtracking.)
The new ports correspond to the UNIFY port in the Opium debugger, which
signified entry to a clause.
These new ports complete the set of ports required for generating traces
whose information content is approximately equivalent to Opium (i.e. as
close to Opium functionality as we can get in Mercury).
compiler/trace.m:
Add code to handle the new ports.
compiler/hlds_goal.m:
Add an extra slot to each hlds_goal_info structure. This slot
holds information about the position of the goal within the
procedure, in the form of a description of the path from the
root of the main goal to this goal. This info is included in
the new trace ports. It is likely that this info will also be
used by optimizations (such as loop invariant removal) to be
implemented later.
compiler/goal_path.m:
A new module whose job it is to fill the new goal_info slot;
later it may also contain code to e.g. check whether one goal
is before, after, or parallel to another.
compiler/hlds_out.m:
Include the new slot in HLDS dumps.
compiler/mercury_compile.m:
Invoke code in goal_path.m to fill in the new slot just before
code generation when generating traces.
compiler/dense_switch.m:
compiler/disj_gen.m:
compiler/ite_gen.m:
compiler/string_switch.m:
compiler/switch_gen.m:
compiler/tag_switch.m:
Emit code for invoking the new trace ports.
runtime/mercury_trace.c:
runtime/mercury_trace.h:
Implement the new ports.
Estimated hours taken: 30
Implement support for types with user-defined equality predicates.
Types with user-defined equality predicates are called "non-canonical types";
they may have more than one representation for the same abstract value.
That means that any attempt to deconstruct a value of a non-canonical
type, i.e. any attempt to peek at the representation, must be cc_multi.
This also implies that conceptually speaking, non-canonical types are not
members of the type classes `comparable' (compare/3) or `deconstructible'
(index/2, argument/3, functor/3, deconstruct/5). Since we don't support
type classes yet, that just means that the type-class checking is done
at runtime, i.e. any call to one of those functions for a non-canonical
type will call error/1 or fatal_error().
To make non-canonical types useful, we really need type classes,
so that the user can provide instance definitions for `comparable'
and `deconstructible' for such types. It might also be a good idea
to have a type-class `canonicalizable' which provides a function
to convert its argument to some canonical type (that would
require existential types to do nicely, but alternatively we could
just use `univ').
Note that currently the only mechanism for promising that things are
unique is via the C interface.
compiler/det_analysis.m:
Add code to check unifications that examine the
representation of a type with a user-defined equality predicate.
Any such unification must occur in a single-solution context and
must not be able to fail. Such unifications determinism have
determinism cc_multi.
compiler/det_report.m:
Add code to report errors for misuse of types with user-defined
equality predicates. (Also some other stylistic improvements:
split up a complicated predicate into subroutines, and
avoid some unnecessary code duplication.)
compiler/prog_data.m:
compiler/hlds_data.m:
Add a new `maybe(sym_name)' field to the du_type/3 constructor
to hold the name of the user-defined equality pred for the
type, if any.
compiler/prog_io.m:
Add code to parse the new `... where equality is <name>.' syntax.
Delete the old support for `... where <condition>'.
compiler/hlds_out.m:
compiler/mercury_to_mercury.m:
compiler/mercury_to_goedel.m:
Print out the new field.
compiler/base_type_layout.m:
compiler/code_util.m:
compiler/dense_switch.m:
compiler/equiv_type.m:
compiler/intermod.m:
compiler/make_hlds.m:
compiler/mode_util.m:
compiler/module_qual.m:
compiler/modules.m:
compiler/switch_detection.m:
compiler/tag_switch.m:
compiler/type_util.m:
compiler/typecheck.m:
compiler/unify_gen.m:
Trivial changes to ignore (or leave unchanged)
the new field in `du_type'.
compiler/modecheck_unify.m:
Pass the term__context to unify_proc__request_unify.
compiler/typecheck.m:
Typecheck the compiler-generated unify predicates for types
with user-defined equality preds.
compiler/unify_proc.m:
For d.u. types, if the type has a user-defined equality predicate
then generate code for the compiler-generated unify predicate
that just calls the specified predicate, and generate
code for the compiler-generated compare and index predicates
that just calls some procedures in mercury_builtin.m that
report appropriate error messages.
Ensure that the automatically-generated predicates
have appropriate term__contexts everywhere, so that if
the user-defined equality predicate name is ambiguous,
non-existent, or has the wrong type, mode, or determinism,
then the error messages from type checking, mode checking,
or determinism checking refer to the type declaration.
library/mercury_builtin.m:
Add predicates builtin_index_non_canonical_type/2
and builtin_compare_non_canonical_type/2, used by
the code generated by compiler/unify_proc.m.
doc/reference_manual.texi:
Document the support for user-defined equality predicates.
library/std_util.m:
Change ML_expand() to return an indication of whether or not
the type is a non-canonical type (one with a user-defined
equality predicate). Change argument/2, functor/2, and
deconstruct/4 to abort if called for a non-canonical type.
Estimated hours taken: 14
Implemented a :- use_module directive. This is the same as
:- import_module, except all uses of the imported items
must be explicitly module qualified.
:- use_module is implemented by ensuring that unqualified versions
of items only get added to the HLDS symbol tables if they were imported
using import_module.
Indirectly imported items (from `.int2' files) and items declared in `.opt'
files are treated as if they were imported with use_module, since all uses
of them should be module qualified.
compiler/module_qual.m
Keep two sets of type, mode and inst ids, those which can
be used without qualifiers and those which can't.
Renamed some predicates which no longer have unique names since
'__' became a synonym for ':'.
Made mq_info_set_module_used check whether the current item is in
the interface, rather than relying on its caller to do the check.
Removed init_mq_info_module, since make_hlds.m now uses the
mq_info built during the module qualification pass.
compiler/prog_data.m
Added a pseudo-declaration `used', same as `imported' except uses of
the following items must be module qualified.
Added a type need_qualifier to describe whether uses of an item
need to be module qualified.
compiler/make_hlds.m
Keep with the import_status whether current item was imported
using a :- use_module directive.
Use the mq_info structure passed in instead of building a new one.
Ensure unqualified versions of constructors only get added to the
cons_table if they can be used without qualification.
compiler/hlds_module.m
Added an extra argument to predicate_table_insert of type
need_qualifier.
Only add predicates to the name and name-arity indices if they
can be used without qualifiers.
Changed the structure of the module-name-arity index, so that
lookups can be made without an arity, such as when type-checking
module qualified higher-order predicate constants. This does not
change the interface to the module_name_arity index.
Factored out some common code in predicate_table_insert which
applies to both predicates and functions.
compiler/hlds_pred.m
Removed the opt_decl import_status. It isn't needed any more
since all uses of items declared in .opt files must now be
module qualified.
Added some documentation about when the clauses_info is valid.
compiler/intermod.m
Ensure that predicate and function calls in the `.opt' file are
module qualified. Use use_module instead of import_module in
`.opt' files.
compiler/modules.m
Handle use_module directives.
Report a warning if both use_module and import_module declarations
exist for the same module.
compiler/mercury_compile.m
Collect inter-module optimization information before module
qualification, since it can't cause conflicts any more. This means
that the mq_info structure built in module_qual.m can be reused in
make_hlds.m, instead of building a new one.
compiler/prog_out.m
Add a predicate prog_out__write_module_list, which was moved
here from module_qual.m.
compiler/typecheck.m
Removed code to check that predicates declared in `.opt' files
were being used appropriately, since this is now handled by
use_module.
compiler/*.m
Added missing imports, mostly for prog_data and term.
NEWS
compiler/notes/todo.html
doc/reference_manual.texi
Document `:- use_module'.
tests/valid/intermod_lambda_test.m
tests/valid/intermod_lambda_test2.m
tests/invalid/errors.m
tests/invalid/errors2.m
Test cases.
Estimated hours taken: 3
Enable --warn-interface-imports by default. This was turned off while
list and term were defined in mercury_builtin.m, since it caused many
warnings.
Fix all the unused interface imports that have been added since then.
compiler/options.m:
Enable --warn-interface-imports by default.
compiler/module_qual.m:
Fix formatting inconsistencies with module names in warning
messages. (".m" was not appended to module names if there was
only one module).
compiler/*.m:
library/*.m:
tests/invalid/type_loop.m:
tests/warnings/*.m:
Remove usused interface imports, or move them into
implementation (mostly bool, list and std_util).
Estimated hours taken: 4
Fix a bug where tag_switch.m was generating references to non-existent
labels for det switches that don't cover the full range of the type.
llds.m:
Add new alternative `do_not_reached' to the code_addr type.
exprn_aux.m:
dupelim.m:
livemap.m:
llds_out.m:
opt_util.m:
opt_debug.m:
Add new code to handle `do_not_reached'.
tag_switch.m:
When generating tag switch jump tables for det switches that do
not cover the whole type, which can happen if the initial inst of
the switch variable is a bound(...) inst that represents a
subtype, make sure that we don't generate references to
undefined labels for cases that occur in the switch var's type
but not in the switch var's initial inst. Instead, make such
references refer to a label that jumps to `do_not_reached'.
Estimated hours taken: 3
Replace calls to map__set with calls to either map__det_insert or
map__det_update. In some cases this required a small amount of code
reorganization.
Estimated hours taken: 6
tag_switch:
So far the switches on the primary and secondary tags have been
implemented either as try-me-else chains or jump tables. I have
added a new alternative, try chains, that should be more efficient
than try-me-else chains for small-medium sized switches.
options:
Add an option, --try-switch-size, giving the size threshold for
the new switch method.
Estimated hours taken: 8
Enable the code to treat `__' as an alternative syntax for module
qualification, after fixing various places in the compiler where
we use `__' in ways that are incompatible with this.
compiler/prog_io.m:
compiler/prog_io_goal.m:
Uncomment the code to handle `__' as module qualification.
compiler/intermod.m:
compiler/hlds_module.m:
compiler/modecheck_unify.m:
Fix bugs in the handling of module qualified higher-order terms.
compiler/*.m:
s/hlds__/hlds_/g
compiler/passes_aux.m:
s/process__/process_/g
compiler/pragma_c_gen.m:
compiler/code_gen.m:
s/code_gen__/pragma_c_gen__/ for the predicates defined in
pragma_c_gen.m (this ought to have been done when the code
was first moved from code_gen.m to pragma_c_gen.m).
compiler/llds.m:
s/llds__proc_id/llds_proc_id/g
The reason for this was to avoid ambiguity between proc_id
in hlds_pred.m and llds__proc_id in llds.m.
compiler/quantification.m:
compiler/make_hlds.m:
compiler/mercury_to_c.m:
s/goal_vars/quantification__goal_vars/g
The reason for this was to avoid ambiguity between goal_vars
in quantification.m and goal_util__goal_vars in goal_util.m.
compiler/dupelim.m:
compiler/optimize.m:
s/dupelim__main/dupelim_main/g
The reason for this change is that a program can only
have one main/2 predicate.
compiler/prog_io_dcg.m:
Remove the old "temporary hack" to strip off and ignore
io__gc_call/1, since the new handling of `__' broke it.
It was only useful for optimizing NU-Prolog performance,
which we don't care about anymore.
compiler/mercury_compile.m:
compiler/modules.m:
compiler/intermod.m:
compiler/prog_io.m:
Remove occurrences of io__gc_call.
compiler/llds_out.m:
compiler/base_type_info.m:
Ensure that we properly handle the special hacks in mercury_builtin
where predicates from other modules (e.g. term__context_init)
are defined in mercury_builtin because they are needed for
type_to_term and term_to_type. llds_out.m: don't put
`mercury_builtin' in the mangled names for those symbols.
base_type_info.m: handle types whose status is "imported"
in their own module.
Estimated hours taken: 3
tag_switch:
If the number of primary tag values we select among is at least as
large as the dense switch threshold, then use a jump table indexed
by the primary tag value.
Estimated hours taken: 3
code_gen, pragma_c_code:
Move the code that generates code for pragma_c_codes to a new module.
llds:
Change the representation of reg and temp lvals, in order to create
the concept of a "register type" and to reduce memory requirements.
Also add a comment indicating a possible future extension dealing with
model_non pragma_c_codes.
code_exprn, code_info:
Add the ability to request registers of a given type, or a specific
register, when acquiring registers.
bytecode, bytecode_gen, call_gen, dupelim, exprn_aux, follow_vars, frameopt,
garbage_out, jumpopt, llds_out, middle_rec, opt_debug, opt_util, store_alloc,
string_switch, tag_switch, unify_gen, vn_block, vn_cost, vn_filter, vn_flush,
vn_order, vn_temploc, vn_type, vn_util, vn_verify:
Small changes to accommodate the new register representation.
hlds_goal:
Add a comment indicating a possible future extension dealing with
model_non pragma_c_codes.
inlining:
Add a comment indicating a how to deal with a possible future extension
dealing with model_non pragma_c_codes.
Estimated hours taken: _____
Take the code generator a big step closer to notes/ALLOCATION.
The new code generator emits code that is smaller and faster than
the code we used to emit.
Nondet liveness is no longer used; nondet live sets are always empty.
In code that was being modified anyway, remove its handling. Other
uses will be removed later (this keeps this change from being far too big;
as it is it is merely too big). Similarly for cont-lives.
In several places, clarify the code that gathers several code pieces together.
call_gen:
Unset the failure continuation and flush the resume vars to
their stack slots before nondet calls.
Move the code that decides whether a nondet call can be a tailcall
to code_info.
code_aux:
Remove the code to handle resume points, since these are now
handled in the specific constructs that need them. Replace it
with a sanity check.
code_exprn:
Add a predicate to place multiple vars.
code_gen:
Remove the predicate code_gen__generate_forced_goal, since it
packaged together some operations that should be executed at different
times.
Don't unset the failure continuation after every nondet goal;
this is now done in the constructs that need it.
Modify the handling of negation to use resume point info
according to notes/ALLOCATION.
Remove the predicate code_gen__ensure_vars_are_saved which was
use to save all lives variables to the stack before nondet
disjunctions and if-then-elses; we don't do that anymore.
code_info:
Significantly simplify and document the handling of failure
continuations, and make the types involved abstract types.
Factor out common code in the handling of det and semi commits.
Keep track of "zombies", variables that are dead wrt forward
execution but whose values we need because they may be needed
at a resume point we can reach.
Remove several now unneeded predicates, and introduce new
predicates to help other modules.
code_util:
Add a couple of predicates to check whether ia goal cannot fail before
flushing all variables to the stack, and whether a goal cannot flush
any variables to the stack. These are used in liveness to decide
which entry labels will be needed at resume points.
disj_gen:
Unify the handling of det and semi disjunctions. Model the code
handling of nondet disjunctions on the code handling pruned
disjunctions. It is possible that the handling of nondet and pruned
disjunctions can also be unified; the new code should make this
significantly easier.
Make the code conform to notes/ALLOCATION. This means saving
only the variables mentioned in the resume_point field, not
flushing all live variables to the stack at the start of a
nondet disjunction, handling zombies, and using the new method
of flushing variables at the ends of branched structures.
ite_gen:
Unify the handling of det and semi if-then-elses. Model the code
handling of nondet if-then-elses on the code handling det/semi
if-then-elses. It is possible that the handling of nondet and pruned
if-then-elses can also be unified; the new code should make this
significantly easier.
Make the code conform to notes/ALLOCATION. This means saving
only the variables mentioned in the resume_point field, not
flushing all live variables to the stack at the start of a
nondet if-then-else, handling zombies, and using the new method
of flushing variables at the ends of branched structures.
Apply the new rules about liveness in if-then-elses, which say that
the else part is parallel not to the then part but to the conjunction
of the condition and the then part.
dense_switch, lookup_switch, string_switch, switch_gen, tag_switch, middle_rec:
Use the new method of flushing variables at the ends of branched
structures. Don't call remake_with_store map; switch_gen will do so.
Fix an old bug in lookup_switch.
The code in switch_gen which looked for the special case of a two-way
switch used to use a heuristic to decide which one was recursive and
which one was a base case. We now check the codes of the cases.
hlds_goal:
Adjust the structure of the resume_point field to make it easier
to use. Add a more convenient access predicate.
hlds_out:
Don't print the nondet liveness and cont live fields, since they are
not used anymore. Comment out the printing of the context field,
which is rarely useful. Modify the printing of the resume_point field
to conform to its new definition.
live_vars:
Use the resume_point field, not the nondetlives field, to decide
which variables may be needed on backward execution. Remove some
code copied from liveness.m.
liveness:
Put the several pieces of information we thread through the traversal
predicates into a single tuple.
Don't put variables which are local to one branch of a branched
structure into the post-birth sets of other branches.
Apply the new rules about liveness in if-then-elses, which say that
the else part is parallel not to the then part but to the conjunction
of the condition and the then part. Variables that are needed in the
else part but not in the condition or the then part now die in at the
start of the condition (they will be protected by the resume point on
the condition).
We now treat pruned and non-pruned disjunctions the same way
wrt deadness; the old way was too conservative (it had to be).
We still mishandle branches which produce some variables but
can't succeed.
mercury_compile:
Liveness now prints its own progress message with -V; support this.
store_alloc:
When figuring out what variables need to be saved across calls,
make sure that we put in interference arcs between those variables
and those that are required by enclosing resume points.
Don't compute cont-lives, since they are not used anymore.
livemap:
Fix the starting comment.
Estimated hours taken: 2.5
Switch from using a stack of store_maps in the code_info to govern what
goes where at the end of each branched structure to using the store map
fields of the goal expressions of those structures.
Fix variable names where they resembled the wrong kind of map(var, lval).
code_info:
Remove the operations on stacks of store maps.
Modify the generate_forced_saves and remake_with_store_map operations
to take a store_map parameter.
When making variables magically live, pick random unused variables
to hold them, since we can no longer use the guidance of the top
store map stack entry. This may lead to the generation of some
excess move instructions at non-reachable points in the code;
this will be fixed later.
code_gen:
Remove the store map push and pop invocations.
Modify the generate_forced_goal operation to take a store_map parameter.
code_exprn:
Export a predicate for use by code_info.
middle_rec, disj_gen, ite_gen, switch_gen,
dense_switch, lookup_switch, string_switch, tag_switch:
Pass the store map around to get it to invocations of the primitives
in code_gen and code_info that now need it.
goal_util:
Name apart the new follow_vars field in hlds__goal_infos.
(This should have been in the change that introduced that field.)
common, constraint, cse_detection, det_analysis, dnf, excess, follow_code,
intermod, lambda, lco, liveness, make_hlds, mode_util, modes, polymorphism,
quantification, simplify, switch_detection, typecheck, unique_modes,
unused_args:
Fix variable names.
follow_vars, store_alloc:
Add comments.
Estimated hours taken: 15
hlds_data:
Rename address_const to code_addr_const, and add base_type_info_const
as a new alternative in cons_id, and make corresponding changes
to cons_tag.
Make hlds_type__defn an abstract type.
llds:
Rename address_const to code_addr_const, and add data_addr_const
as a new alternative in rval_const.
Change type "label" to have four alternatives, not three:
local/2 (for internal labels), c_local (local to a C module),
local/1 (local a Mercury module but not necessarily to a C module,
and exported.
llds_out:
Keep track of the things declared previously, and don't declare them
again unnecessarily. Associate indentation with the following item
rather than the previous item (the influence of 244); this results
in braces being put in different places than previously, but should be
easier to maintain. Handle the new forms of addresses and labels.
Refer to c_local labels as STATIC when not using --split-c-files.
code_info:
Use a presently junk field to store a cell counter, which is used
to allocate distinguishing numbers to create'd cells. Previously
we used the label counter, which meant that label numbers changed
when we optimized away some creates. Handle the new forms of
addresses and labels.
exprn_aux:
Handle the new forms of addresses and labels. We are now more
precise in figuring out what label address forms will be considered
constants by the C compilers.
others:
Changes to handle the new forms of addresses and labels, and/or to
access hlds_type__defn as an abstract type.
Estimated hours taken: 0.1
Spotted a bizzare piece of C code - a COMPUTED_GOTO with a single
label. Bug was a `>=' instead of a `<' when deciding whether or not
to use a computed goto in tag_switch.
compiler/tag_switch.m:
Fix a tiny bug which meant we were not using computed gotos
in some cases where we should.
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: 16
options:
Replace the word_size option with the two options bits_per_word and
bytes_per_word. The former is needed by lookup_switch, the latter by
value numbering.
lookup_switch:
Use the new option instead of word_size.
vn_type, vn_cost, vn_block, value_number:
Add a new type, vn_params, containing information such as the number
of bytes per word (from the option) and cost parameters. Use these
cost parameters to make more realistic decisions.
vn_filter:
New module to filter out unnecessary uses of temporary variables,
which gcc does unnecessarily badly on.
value_number, vn_verify:
Move verification completely to vn_verify. Tighten the verification
rules relating to tags where it concerns code sequences in which
the tag of an rval is taken in a statement before an if_val, but
loosen them to avoid spurious rejections of code sequences containing
arithmetic comparisons. Fix some missing cases from semidet switches
that may have lead to overly conservative decisions.
value_number, vn_order:
Vn_order was making an overly conservative assumption about where
to split an extended basic block if it couldn't be optimized together.
Move the decision to value_number and try to make it better. The new
heuristic is not enabled yet.
vn_debug:
Change the conditions under which one type of message is printed.
vn_flush:
Wrap some too long lines.
llds:
Fix a bug that would prevent profiling from working correctly on
value numbered code: we weren't scanning instructions inside blocks
when looking for return addresses.
peephole:
Enable an optimization previously left disabled by accident.
switch_detection, tag_switch:
Eliminate an unused argument.
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: 4
Changed the way configuration parameters are handled so that we
can avoid bootstrapping problems. Instead of getting configuration
paramters from `conf.m.in', they are now passed via the `mc' script.
Also renamed the `num_real_regs' option to `num_real_r_regs',
to avoid confusion with the NUM_REAL_REGS macro set in runtime/machdeps/*.h
(which has a different meaning).
compiler/conf.m.in:
Removed this module, which used to define the old
conf__low_tags_bits/1 predicate.
compiler/Mmake:
Removed references to conf.m*.
compiler/options.m:
Added conf_low_tag_bits option, to replace the old
conf__low_tag_bits/1 predicate.
Rename num_real_regs option as num_real_r_regs.
compiler/tag_switch.m:
Rename num_real_regs option as num_real_r_regs.
compiler/mercury_compile.pp:
Use the conf_low_tag_bits option rather than calling
the old conf__low_tag_bits/1 predicate.
excess:
A new pass to remove unnecessary assignment unifications.
mercury_compile:
Call the new excess assignment module.
options:
Add a new option, excess_assign, to control the new optimization.
Add another, num-real-regs, to specify how many of r1, r2 etc are
actually real registers. The default is now set to 5 for kryten;
later it should be supplied by the mc script, with a value determined
at configuration time.
tag_switch:
Use num-real-regs to figure out whether it is likely to be worthwhile
to eliminate the common subexpression of taking the primary tag of
a variable. Also fix an old performance bug: the test for when a
jump table is worthwhile was reversed.
value_number, vn_block:
Do value numbering on extended basic blocks, not basic blocks.
vn_debug:
Modify an information message.
labelopt:
Clean up an export an internal predicate for value numbering. Replace
bintree_set with set.
middle_rec:
Prepare for the generalization of middle recursion optimization
to include predicates with an if-then-else structure.
cse_detection:
Fix a bug: when hoisting a common desconstruction X = f(Yi), create
new variables for the Yi. This avoids problems with any of the Yis
appearing in other branches of the code.
goal_util:
Add a new predicate for use by cse_detection.
common:
Fix a bug: recompute instmap deltas, since they may be affected by the
optimization of common structures.
code_info:
Make an error message more explicit.
det_analysis:
Restrict import list to the needed modules.
*.m:
Import assoc_list.
code_info:
Expose the predicate for producing a variable not into an arbitrary
location, but into a register.
tag_switch:
Produce the switched-on variable into a register, since we will
need it several times (to extract the primary tag, probably to
extract a secondary tag, and then -usually- to get some of its
fields).
tag_switch:
Fixed two bugs. First, if a primary tag value did not have cases for
all its secondary tag values, we now emit a goto the failure label
if the secondary tag does not match any case; we used to just fall
through. Second, the failure code itself used to be generated in
the context of the end of one of the cases; this should now be fixed,
although I want to go over it with Tom to make sure.
The computation of the secondary tag is now done once, instead of
being repeated at every secondary tag test.
options:
Set tag_switch_size to 4 by default, reduced from 8. It was this change
that exposed the two bugs above. After the fix, the compiler is smaller
by about 2 Kb.
switch_gen:
Add some comments.
code_util:
Fixed nonstandard indentation.
llds:
Optionally generate while (1) loops instead of short backward branches.
This is faster in the absence of fast jumps.
options:
Add a new option, --no-emit-c-loops.
middle_rec:
We now check if the LLDS code after the recursive call is empty.
If yes, we don't generate the downward loop.
code_aux:
Minor cleanup associated with previous change.
frameopt:
Instead of blindly assuming that any code before an if_val will be
able to fill the delay slot, we check whether it computes a value
that is used in the condition. We now also allow a slightly wider
range of user instructions to fill delay slots.
opt_util:
Some new preds to support the new funcionality in frameopt.
tag_switch:
Compute the tag of the switched-on value into a register at the
start, instead of computing it in each if_val.
instructions, and the last argument from local labels. All these were
placeholders for info put in there by prof.m and used when emitting C
code.
The set of labels that serve as return points are now calculated in llds.m
just before each procedure has its C code generated. This set is passed to
output_instruction along with the label at the start of the procedure.
*.m:
Changed the way the extra field in the label type is defined. Now
all labels are initially assumed to be 'unknown' and a seperate
profiling pass (to be implemented) will determine whether the label can
be accessed externally.
tag_switch.m:
Fix a Zoltan bug! ;-)
This was the bug causing the "Software error: no failure continuation"
errors. The problem was that when Zoltan changed the field
in switches from a determism to can_fail/cannot_fail, he accidentally
inverted the sense of a test, causing the code to generate the
"fail" case only for tag switches which can never fail.
make_hlds:
Fix one-character bug that rejected all non-det modes.
tag_switch:
Minor cleanup.
det_analysis:
Prepare for error diagnosis.
hlds_out:
Print out determinisms, not code_models.
prog_io, hlds: Added the functor "multidet" to the type determinism.
Added types and predicates to relate determinism to its
two components, can_fail and soln_count.
Removed the functor "unspecified" from the type determinism,
substituting maybe(determinism) for determinism in proc_info.
Replaced the type category with the type code_model,
and added predicates to compute it from determinism.
det_analysis: Redone the analyses to work with determinism, not category
(or code_model). This should enable programmers to write
their own erroneous (and failure) predicates.
other files: Use the new and renamed types and access predicates.
