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Move all the frequently occurring layout structures and components of layout
structures into arrays where possible. By replacing N global variables holding
individual layout structures or layout structure components with one global
variable holding an array of them, we reduce the sizes of the symbol tables
stored in object files, which should speed up both the C compiler and the
linker.
Measured on the modules of the library, mdbcomp and compiler directories
compiled in grade asm_fast.gc.debug, this diff reduces the size of the
generated C source files by 7.8%, the size of the generated object files
by 10.4%, and the number of symbols in the symbol tables of those object files
by a whopping 42.8%. (These improvements include, and are not on top of,
the improvements in my previous similar diff.)
runtime/mercury_stack_layout.h:
Each label layout structure has information about the type and
location of every variable that is live at that label. We store
this information in three arrays: an array of pseudo-typeinfos giving
the types of all these variables, and two arrays MR_ShortLvals and
MR_LongLvals respectively giving their locations. (Most of the time,
the location's encoded form fits into one byte (the MR_ShortLval)
but sometimes it needs more bits (this is when we use MR_LongLval)).
We used to store these three arrays, whose elements are different
types, in a single occurrence-specific common structure,
one after the other, with a cumbersome mechanism being required
to access them. We now store them as segments of three separate arrays,
of pseudo-typeinfos, MR_ShortLvals and MR_LongLvals respectively.
This makes access simpler and faster (which will matter more to any
accurate garbage collector than it does to the debugger). It also
allows more scope for compression, since reusing an existing segment of
one of the three arrays is easier than reusing an entire common
structure, which would require the equivalent of exact matches
on all three arrays.
Since most label layout structures that have information about
variables can encode the variables' locations using only MR_ShortLvals,
create a version of the label layout structure type that omits the
field used to record the whereabouts of the long location descriptors.
Add macros now generated by the compiler to initialize layout
structures.
Simplify a one-field struct.
runtime/mercury_grade.h:
Increment the binary compatibility version number for debuggable
executables, since .c and .o files from before and after the change
to label layout structures are NOT compatible.
runtime/mercury_type_info.h:
Fix some binary-compatibility-related bit rot.
runtime/mercury_misc.h:
Move here the existing macros used by the compiler when generating
references to layout arrays, and add new ones.
runtime/mercury_goto.h:
Delete the macros moved to mercury_misc.h.
Conform to the changes in mercury_stack_layout.h.
runtime/Mmakefile:
Prevent the unnecessary rebuilding of mercury_conf.h.
runtime/mercury_accurate_gc.c:
runtime/mercury_agc_debug.c:
runtime/mercury_layout_util.c:
runtime/mercury_stack_trace.c:
runtime/mercury_types.h:
trace/mercury_trace.c:
trace/mercury_trace_vars.c:
Conform to the changes in mercury_stack_layout.h.
runtime/mercury_wrapper.c:
Improve the debug support a bit.
runtime/mercury_engine.h:
Fix style.
compiler/layout.m:
Make the change described at the top. Almost all layout structures
are now in arrays. The only exceptions are those that occur rarely,
and proc layouts, whose names need to be derivable from the name
of the procedure itself.
Instead of having a single type "layout_data" that can represent
different kinds of single global variables (not array slots), have
different kinds for different purposes. This makes the code clearer
and allows traversals that do not have to skip over inapplicable kinds
of layout structures.
compiler/layout_out.m:
Output the new arrays.
compiler/stack_layout.m:
Generate the new arrays. Previously, an individual term generated by
stack_layout.m could represent several components of a layout
structure, with the components separated by layout_out.m. We now
do the separation in stack_layout.m itself, adding each component
to the array to which it belongs.
Instead of passing around a single stack_layout_info structure,
pass around several smaller one. This is preferable, since I found out
the hard way that including everything in one structure would give the
structure 51 fields. Most parts of the module work with only one
or two of these structures, which makes their role clearer.
Cluster related predicates together.
compiler/options.m:
doc/user_guide.texi:
Add an option that control whether stack_layout.m will attempt to
compress the layout arrays that can meaningfully be comressed.
compiler/llds.m:
Remove the old distinction between a data_addr and a data_name,
replacing both types with a single new one: data_id. Since different
kinds of data_names were treated differently in many places,
the distinction in types (which was intended to allow us to process
data_addrs that wrapped data_names differently from other kinds of
data_addrs) wasn't buying us anything anymore.
The new data_id type allows for the possibility that the code generator
wants to generate a reference to an address it does not know yet,
because it is a slot in a layout array, and the slot has not been
allocated yet.
Add the information from which the new layout array structures
will be generated to the LLDS.
compiler/llds_out.m:
Call layout_out.m to output the new layout arrays.
Adapt the decl_id type to the replacement of data_addrs by data_ids.
Don't both keeping track of the have-vs-have-not-declared status
of structures that are always declared at the start.
When writing out a data_addr, for some kinds of data_addr, llds_out.m
would write out the name of the relevant variable, while for some other
kinds, it would write out its address. This diff separates out those
those things into separate predicates, each of which behaves
consistently.
compiler/mercury_compile_llds_back_end.m:
Convey the intended contents of the new layout arrays from
stack_layout.m to llds_out.m.
compiler/continuation_info.m:
Add a type required by the way we now generate proc_static structures
for deep profiling.
compiler/hlds_rtti.m:
Add distinguishing prefixes to the field names of the rtti_proc_label
type.
compiler/code_info.m:
compiler/code_util.m:
compiler/erl_rtti.m:
compiler/exprn_aux.m:
compiler/global_data.m:
compiler/ll_pseudo_type_info.m:
compiler/ml_code_util.m:
compiler/opt_debug.m:
compiler/proc_gen.m:
compiler/prog_rep.m:
compiler/rtti_out.m:
compiler/unify_gen.m:
Conform to the changes above.
tests/debugger/declarative/track_through_catch.exp:
Expect procedures to be listed in the proper order.
tests/EXPECT_FAIL_TESTS.asm_fast.gc.debug:
tests/EXPECT_FAIL_TESTS.asm_fast.gc.profdeep:
Add these files to ignore expected failues in these grades.
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