39 lines
1.7 KiB
Factor
39 lines
1.7 KiB
Factor
USING: compiler.cfg compiler.cfg.instructions compiler.cfg.stacks.padding
|
|
help.markup help.syntax sequences strings ;
|
|
IN: compiler.cfg.stacks.vacant
|
|
|
|
ARTICLE: "compiler.cfg.stacks.vacant" "Uninitialized/overinitialized stack location analysis"
|
|
"Consider the following sequence of instructions:"
|
|
{ $code
|
|
"##inc D: 2"
|
|
"..."
|
|
"##allot"
|
|
"##replace ... D: 0"
|
|
"##replace ... D: 1"
|
|
}
|
|
"The GC check runs before stack locations 0 and 1 have been initialized, and so the GC needs to scrub them so that they don't get traced. This is achieved by computing uninitialized locations with a dataflow analysis, and recording the information in GC maps. The call_frame_slot_visitor object in vm/slot_visitor.hpp reads this information from GC maps and performs the scrubbing." ;
|
|
|
|
HELP: fill-gc-maps
|
|
{ $values { "cfg" cfg } }
|
|
{ $description "Populates the scrub-d, check-d, scrub-r and check-r slots of all gc maps in the cfg." } ;
|
|
|
|
HELP: state>gc-data
|
|
{ $values { "state" sequence } { "gc-data" sequence } }
|
|
{ $description "Takes a stack state on the format given by " { $link trace-stack-state2 } " and emits an array containing two bit-patterns with locations on the data and retain stacks to scrub." } ;
|
|
|
|
HELP: vacant>bits
|
|
{ $values
|
|
{ "vacant" "sequence of uninitialized stack locations" }
|
|
{ "bits" "sequence of 1:s and 0:s" }
|
|
}
|
|
{ $description "Converts a sequence of uninitialized stack locations to the pattern of 1:s and 0:s that can be put in the " { $slot "scrub-d" } " and " { $slot "scrub-r" } " slots of a " { $link gc-map } ". 0:s are uninitialized locations and 1:s are initialized." }
|
|
{ $examples
|
|
{ $example
|
|
"USING: compiler.cfg.stacks.vacant prettyprint ;"
|
|
"{ 0 1 3 } vacant>bits ."
|
|
"{ 0 0 1 0 }"
|
|
}
|
|
} ;
|
|
|
|
ABOUT: "compiler.cfg.stacks.vacant"
|