}

    # TODO: We can't analyze [lsort -command] yet, but we could. What it would
    #       take is to generate bytecode for the command prefix with two dummy
    #       arguments, and then determine the effect of the bytecode on the
    #       callframe.

    # error "lsort -command is not supported yet"
    return {
	error "lsort -command is not supported yet"
	nre {} reads 0 writes 0 readsNonLocal {} writesNonLocal {}
    }

}

# quadcode::specializer method frameEffect___regexp --
#

    #	         processed further.
    #   frameEffect - Dictionary whose keys are instance names and whose
    #	              values are dictionaries describing the procedure
    #		      instances' effect on the caller's callframe.
    #   instanceBeingAnalyzed - Holds the instance name of the current procedure
    #	                        during a call to type analysis in the quadcode
    #		                database.
    #	nreActive - Dictionary whose keys are instance names of procedures
    #	            being analyzed for NRE requirement, and whose values
    #	            are immaterial. A procedure is present if it is currently
    #	            being analyzed; this flag is used to check whether the
    #	            procedure is recursive.
    #   onWorklist - Dictionary whose keys are the instance names of the
    #	             procedures on the worklist for analysis and whose values
    #	             are their positions in the heap.
    #   precedence - Dictionary whose keys are fully qualified procedure names
    #	             (without types) and whose values are the positions of
    #	             those procedures in depth-first numbering and hence
    #		     the order in which they should be analyzed.
    #   requiredInstances - Two level dictionary. The first level keys are
    #		            fully qualified procedure names (without types)
    #	                    and the second level keys are lists of types.
    #			    The values are immaterial. This dictionary tracks
    #                       procedure instances explicity requested by an
    #	                    external caller
    #   returnType - Dictionary whose keys are instance names and whose values
    #	             are the return types of those procedure instances.
    #	typeInf - Dictionary whose keys are instance names and whose values
    #	          are quadcode databases for the instances

    variable canInline cmdAttr database dependencies dependents \
	diagnostics diagnosticSeq failed frameEffect nreActive \
	instanceBeingAnalyzed onWorklist precedence requiredInstances \
	returnType typeInf

    # Local commands:
    #   worklist - List of procedures awaiting type analysis. This list is
    #	           organized as a binary heap in order by precedence of the
    #	           procedure, and within that, in lexicographic order by

	}
    }

    # Once all the procedures are fully typed, there's a final pass needed
    # to determine which ones can be called directly, and which ones must
    # be NRE.

    my debug-specializer {
	puts "Analyze NRE requirements"
    }
    my nreRequired
}

# quadcode::specializer method searchForInlines --
#
#	Try to find opportunities to inline procedure instances into their
#	callers.
#

	
    my debug-inline {
	puts "Can $inst be inlined? [dict get $canInline $inst]"
    }
    return [dict get $canInline $inst]
}

# quadcode::specializer nreRequired --
#
#	Determines which procedure instances in the call graph require
#	non-recursive evaluation.
#
# Results:
#	None.
#
# Side effects:
#	Calls the translator instance to set the 'NRE' flag on any procedure
#	requiring non-recursive evaluation
#
# A procedure requires NRE for any of the following reasons:
#
#	1. It does anything that might change the active coroutine.
#	2. It invokes unknown, non-compiled commands.
#	3. It invokes any Core command that requires NRE.
#	4. It is directly or indirectly recursive.
#	5. It invokes, directly or indirectly, any other command that
#	   might require NRE.
#
# We perform a depth-first traversal of the call graph to analyze NRE.
# This is done with the help of the quadcode::transformer object. We call
# the transformer's 'needsNRE' method for each required instance, and it
# calls back to the specializer's 'needsNRE' method for each invoked command.

oo::define quadcode::specializer method nreRequired {} {

    set nreActive {}

    dict for {instance db} $typeInf {
	my debug-specializer {
	    puts "NRE: $instance"
	}
	dict set nreActive $instance {}
	set needs [$db needsNRE]
	my debug-specializer {
	    puts [format {NRE: %s %s NRE} $instance \
		      [expr {$needs ? "needs" : "does not need"}]]
	}
	dict unset nreActive $instance
    }
}

# quadcode::specializer method needsNRE --
#
#	Tests whether an individual procedure instance requires NRE.
#
# Parameters:
#	name - Name of the command to analyze
#	alist - List of quadcode values for the command's arguments
#	atypes - List of typecodes of the types of the arguments.
#
# Results:
#	Returns 1 if the command needs NRE, 0 otherwise.

oo::define quadcode::specializer method needsNRE {q atypes} {

    set name [lindex $q 3 1]
    my debug-specializer {
	puts [format "%*sDoes %s(%s) need NRE?" [dict size $nreActive] {} \
		  $name $atypes]
    }
    set instance [list $name $atypes]
    if {[dict exists $nreActive $instance]} {
	my debug-specializer {
	    puts [format "%*s  Yes. It's recursive" [dict size $nreActive] {}]
	}
	return 1;		# The procedure is recursive.
    }
    
    if {[dict exists $typeInf $instance]} {
	# The instance is a compiled command that we have not
	# visited. Find out whether it needs NRE
	set db [dict get $typeInf $instance]
	dict set nreActive $instance {}
	set result [$db needsNRE]
	dict unset nreActive $instance
	my debug-specializer {
	    puts [format "%*s  %s. Translator says so." \
		      [dict size $nreActive] {} \
		      [expr {$result ? "Yes" : "No"}]]
	}
	return $result
    }

    # The instance is not a compiled command. It may be a builtin.

    if {[dict exists $cmdAttr $name]} {
	set attrs [dict get $cmdAttr $name]
	if {[dict exists $attrs special]} {
	    set method frameEffect_[string map {:: __} $name]
	    set attrs [my $method $q]
	}
	if {! [dict exists $attrs nre]} {
	    my debug-specializer {
		puts [format "%*s  No. It's builtin" [dict size $nreActive] {}]
	    }
	    return 0
	}
    }

    # We don't know what the instance is, so require NRE

    my debug-specializer {
	puts [format "%*s  Yes. It's not understood." [dict size $nreActive] {}]
    }

    return 1
}


# quadcode::specializer method frameEffect --
#
#	Looks up what the effect of a command is on the callframe.
#
# Parameters:
#	q - Quadcode instruction that invokes the command

    #			3 - the variable has been analyzed, and might or
    #			    might not exist depending on code path.
    #
    #				TYPE INFERENCE
    #
    #	types - Dictionary whose keys are variable names and whose values
    #		are the numeric codes for the variable types.
    #
    #	nre - Flag that is 1 if this procedure requires non-recursive
    #	      evaluation, and 0 otherwise

    variable bytecode quadindex fixup
    variable debugged specializer originProc sourcefile ns
    variable quads vars links bbstart
    variable bbcontent bbpred
    variable bbidom bbkids bblevel bbnlevels varcount
    variable duchain udchain
    variable varExists
    variable types
    variable nre
    variable ptype ns_counters

    # Constructor -
    #
    # Keyword arguments (following the positional arguments):
    #	-debug {list}
    #		Accepts a list of keys. For each key in the list, a

source [file join $quadcode::libdir flatten.tcl]
source [file join $quadcode::libdir fqcmd.tcl]
source [file join $quadcode::libdir inline.tcl]
source [file join $quadcode::libdir invoke.tcl]
source [file join $quadcode::libdir liveranges.tcl]
source [file join $quadcode::libdir narrow.tcl]
source [file join $quadcode::libdir nodesplit.tcl]
source [file join $quadcode::libdir nre.tcl]
source [file join $quadcode::libdir renameTemps.tcl]
source [file join $quadcode::libdir ssa.tcl]
source [file join $quadcode::libdir translate.tcl]
source [file join $quadcode::libdir typecheck.tcl]
source [file join $quadcode::libdir types.tcl]
source [file join $quadcode::libdir upvar.tcl]
source [file join $quadcode::libdir varargs.tcl]
source [file join $quadcode::libdir widen.tcl]

#source [file join $quadcode::libdir exists.tcl]
#source [file join $quadcode::libdir interval.tcl]