# Copyright 2012-2024 Free Software Foundation, Inc.

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.


# The in-memory cache.
array set gdb_data_cache {}

# Print pass message msg into gdb.log
proc ignore_pass { msg } {
    verbose -log "gdb_do_cache_wrap ignoring pass: $msg"
}

# Call proc real_name and return the result, while ignoring calls to pass.
proc gdb_do_cache_wrap {real_name args} {
    if { [info procs save_pass] != "" } {
	return [uplevel 2 $real_name]
    }

    rename pass save_pass
    rename ignore_pass pass

    set code [catch {uplevel 2 [list $real_name {*}$args]} result]

    rename pass ignore_pass
    rename save_pass pass

    if {$code == 1} {
	global errorInfo errorCode
	return -code error -errorinfo $errorInfo -errorcode $errorCode $result
    } elseif {$code > 1} {
	return -code $code $result
    }

    return $result
}

# Global written to by gdb_exit_called proc.  Is set to true to
# indicate that a caching proc has called gdb_exit.

set gdb_exit_called false

# This proc is called via TCL's trace mechanism whenever gdb_exit is
# called during the execution of a caching proc.  This sets the global
# flag to indicate that gdb_exit has been called.

proc gdb_exit_called { args } {
    set ::gdb_exit_called true
}

# While calling the implementation of a caching proc, that
# implementation might itself call additional caching procs.  We need
# to track all of the nested caching procs that are called and we do
# that in this list which is a list containing the names of any nested
# caching procs that are called.

set gdb_nested_caching_proc_calls {}

# Called before returning from gdb_do_cache.  NAME is the name of the
# caching proc that was called.
#
# When DO_EXIT is true then this proc should call gdb_exit before
# returning, otherwise gdb_exit is not called.
#
# ALSO_CALLED is a list of the names all the nested caching procs that
# the proc NAME called.  This proc appends NAME as well as everything
# in ALSO_CALLED to the global GDB_NESTED_CACHING_PROC_CALLS, this
# aids in tracking recursive caching proc calls.

proc gdb_cache_maybe_gdb_exit { name do_exit also_called } {

    # Record all the procs that have been called, but only if the exit
    # trace is in place (this is done in gdb_do_cache) and indicates
    # that we are in data gathering mode.
    if { [info exists ::gdb_exit_trace_in_place] } {
	set ::gdb_nested_caching_proc_calls \
	    [list {*}$::gdb_nested_caching_proc_calls $name {*}$also_called]
    }

    # The cache 'exit' entry will be true if this caching proc, or any
    # caching proc that is recursively called from this caching proc,
    # called exit.
    if { !$do_exit } {
	return
    }

    # To track if this proc has been called for NAME we create a
    # global variable.  In gdb_cleanup_globals (see gdb.exp) this
    # global will be deleted when the test has finished.
    set global_name __${name}__cached_gdb_exit_called
    if { ![info exists ::${global_name}] } {
	gdb_exit
	verbose -log "gdb_caching_proc $name caused gdb_exit to be called"
	set ::${global_name} true
	verbose -log "  gdb_caching_proc $name marked as called"

	foreach other_name $also_called {
	    verbose -log "  gdb_caching_proc $other_name marked as called"
	    set global_name __${other_name}__cached_gdb_exit_called
	    set ::${global_name} true
	}
    }
}

# A helper for gdb_caching_proc that handles the caching.

proc gdb_do_cache {name args} {
    global gdb_data_cache objdir
    global GDB_PARALLEL

    verbose -log "gdb_do_cache: $name ( $args )"

    # Normally, if we have a cached value, we skip computation and return
    # the cached value.  If set to 1, instead don't skip computation and
    # verify against the cached value.
    set cache_verify 0

    # Alternatively, set this to do cache_verify only for one proc.
    set cache_verify_proc ""
    if { $name == $cache_verify_proc } {
	set cache_verify 1
    }

    # See if some other process wrote the cache file.  Cache value per
    # "board" to handle runs with multiple options
    # (e.g. unix/{-m32,-64}) correctly.  We use "file join" here
    # because we later use this in a real filename.
    set cache_name [file join [target_info name] $name {*}$args]

    set is_cached 0
    if {[info exists gdb_data_cache(${cache_name},value)]} {
	set cached_value $gdb_data_cache(${cache_name},value)
	set cached_exit $gdb_data_cache(${cache_name},exit)
	set cached_also_called $gdb_data_cache(${cache_name},also_called)
	verbose "$name: returning '$cached_value' from cache" 2
	if { $cache_verify == 0 } {
	    gdb_cache_maybe_gdb_exit $name $cached_exit $cached_also_called
	    return $cached_value
	}
	set is_cached 1
    }

    if { $is_cached == 0 && [info exists GDB_PARALLEL] } {
	set cache_filename [make_gdb_parallel_path cache $cache_name]
	if {[file exists $cache_filename]} {
	    set fd [open $cache_filename]
	    set content [split [read -nonewline $fd] \n]
	    close $fd
	    set gdb_data_cache(${cache_name},value) [lindex $content 0]
	    set gdb_data_cache(${cache_name},exit) [lindex $content 1]
	    set gdb_data_cache(${cache_name},also_called) [lindex $content 2]
	    set cached_value $gdb_data_cache(${cache_name},value)
	    set cached_exit $gdb_data_cache(${cache_name},exit)
	    set cached_also_called $gdb_data_cache(${cache_name},also_called)
	    verbose "$name: returning '$cached_value' from file cache" 2
	    if { $cache_verify == 0 } {
		gdb_cache_maybe_gdb_exit $name $cached_exit $cached_also_called
		return $cached_value
	    }
	    set is_cached 1
	}
    }

    # Add a trace hook to gdb_exit.  In the case of recursive calls to
    # gdb_do_cache we only want to install the trace hook once, so we
    # set a global to indicate that the trace is in place.
    #
    # We also set a local flag to indicate that this is the scope in
    # which the debug trace needs to be removed.
    if { ![info exists ::gdb_exit_trace_in_place] } {
	trace add execution gdb_exit enter gdb_exit_called
	set ::gdb_exit_trace_in_place true
	set gdb_exit_trace_created true
    } else {
	set gdb_exit_trace_created false
    }

    # As above, we need to consider recursive calls into gdb_do_cache.
    # Store the old value of gdb_exit_called global and then set the
    # flag to false.  Initially gdb_exit_called is always false, but
    # for recursive calls to gdb_do_cache we can't know the state of
    # gdb_exit_called.
    #
    # Before starting a recursive gdb_do_cache call we need
    # gdb_exit_called to be false, that way the inner call can know if
    # it invoked gdb_exit or not.
    #
    # Once the recursive call completes, if it did call gdb_exit then
    # the outer, parent call to gdb_do_cache should also be considered
    # as having called gdb_exit.
    set old_gdb_exit_called $::gdb_exit_called
    set ::gdb_exit_called false

    # As with the exit tracking above we also need to track any nested
    # caching procs that this proc might call.  To do this we backup
    # the current global list of nested caching proc calls and reset
    # the global back ot the empty list.  As nested caching procs are
    # called their names are added to the global list, see
    # gdb_cache_maybe_gdb_exit for where this is done.
    set old_gdb_nested_caching_proc_calls $::gdb_nested_caching_proc_calls
    set ::gdb_nested_caching_proc_calls {}

    set real_name gdb_real__$name
    set gdb_data_cache(${cache_name},value) [gdb_do_cache_wrap $real_name {*}$args]
    set gdb_data_cache(${cache_name},exit) $::gdb_exit_called
    set gdb_data_cache(${cache_name},also_called) \
	[lsort -unique $::gdb_nested_caching_proc_calls]

    # Now that the actual implementation of this caching proc has been
    # executed the gdb_nested_caching_proc_calls global will contain
    # the names of any nested caching procs that were called.  We
    # append this new set of names onto the set of names we backed up
    # above.
    set ::gdb_nested_caching_proc_calls \
	[list {*}$old_gdb_nested_caching_proc_calls \
	     {*}$::gdb_nested_caching_proc_calls]

    # See comment above where OLD_GDB_EXIT_CALLED is set: if
    # GDB_EXIT_CALLED was previously true then this is a recursive
    # call and the outer caching proc set the global true, so restore
    # the true value now.
    if { $old_gdb_exit_called } {
	set ::gdb_exit_called true
    }

    # See comment above where GDB_EXIT_TRACE_CREATED is set: this is
    # the frame in which the trace was installed.  This must be the
    # outer caching proc call (if an recursion occurred).
    if { $gdb_exit_trace_created } {
	trace remove execution gdb_exit enter gdb_exit_called
	unset ::gdb_exit_trace_in_place
	set ::gdb_exit_called false
	set ::gdb_nested_caching_proc_calls {}
    }

    # If a value being stored in the cache contains a newline then
    # when we try to read the value back from an on-disk cache file
    # we'll interpret the second line of the value as the ',exit' value.
    if { [regexp "\[\r\n\]" $gdb_data_cache(${cache_name},value)] } {
	set computed_value $gdb_data_cache(${cache_name},value)
	error "Newline found in value for $cache_name: $computed_value"
    }

    if { $cache_verify == 1 && $is_cached == 1 } {
	set computed_value $gdb_data_cache(${cache_name},value)
	set computed_exit $gdb_data_cache(${cache_name},exit)
	set computed_also_called $gdb_data_cache(${cache_name},also_called)
	if { $cached_value != $computed_value } {
	    error [join [list "Inconsistent value results for $cache_name:"
			 "cached: $cached_value vs. computed: $computed_value"]]
	}
	if { $cached_exit != $computed_exit } {
	    error [join [list "Inconsistent exit results for $cache_name:"
			 "cached: $cached_exit vs. computed: $computed_exit"]]
	}
	if { $cached_also_called != $computed_also_called } {
	    error [join [list "Inconsistent also_called results for $cache_name:"
			 "cached: $cached_also_called vs. computed: $computed_also_called"]]
	}
    }

    if {[info exists GDB_PARALLEL]} {
	verbose "$name: returning '$gdb_data_cache(${cache_name},value)' and writing file" 2
	file mkdir [file dirname $cache_filename]
	# Make sure to write the results file atomically.
	set fd [open $cache_filename.[pid] w]
	puts $fd $gdb_data_cache(${cache_name},value)
	puts $fd $gdb_data_cache(${cache_name},exit)
	puts $fd $gdb_data_cache(${cache_name},also_called)
	close $fd
	file rename -force -- $cache_filename.[pid] $cache_filename
    }
    gdb_cache_maybe_gdb_exit $name $gdb_data_cache(${cache_name},exit) \
	$gdb_data_cache(${cache_name},also_called)
    return $gdb_data_cache(${cache_name},value)
}

# Define a new proc named NAME, with optional args ARGS.  BODY is the body of
# the proc.  The proc will evaluate BODY and cache the results, both in memory
# and, if GDB_PARALLEL is defined, in the filesystem for use across
# invocations of dejagnu.
#

proc gdb_caching_proc {name arglist body} {
    # Define the underlying proc that we'll call.
    set real_name gdb_real__$name
    proc $real_name $arglist $body

    # Define the advertised proc.
    set caching_proc_body [list gdb_do_cache $name]
    foreach arg $arglist {
	lappend caching_proc_body $$arg
    }
    set caching_proc_body [join $caching_proc_body]
    proc $name $arglist $caching_proc_body
}