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compiler.cfg.representations.selection: some initial docs from comments

db4
Björn Lindqvist 2015-07-26 18:14:59 +02:00 committed by John Benediktsson
parent 31aae02916
commit cdf9a8535b
2 changed files with 19 additions and 9 deletions
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19
basis/compiler/cfg/representations/selection/selection-docs.factor Normal file
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@ -0,0 +1,19 @@
USING: help.markup help.syntax math sequences ;
IN: compiler.cfg.representations.selection
HELP: costs
{ $var-description "Maps vreg to representation to cost." } ;
HELP: increase-cost
{ $values { "rep" "representation symbol" } { "scc" "?" } { "factor" integer } }
{ $description "Increase cost of keeping vreg in rep, making a choice of rep less likely. If the rep is not in the cost alist, it means this representation is prohibited." } ;
HELP: init-costs
{ $description "Initialize cost as 0 for each possibility." } ;
HELP: minimize-costs
{ $values { "costs" sequence } { "representations" sequence } }
{ $description "For every vreg, compute preferred representation, that minimizes costs." } ;
HELP: tagged-vregs
{ $var-description "Vregs which must be tagged at the definition site because there is at least one usage that is not int-rep. If all usages are int-rep it is safe to untag at the definition site." } ;

9
basis/compiler/cfg/representations/selection/selection.factor
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@ -12,9 +12,6 @@ FROM: assocs => change-at ;
FROM: namespaces => set ;
IN: compiler.cfg.representations.selection
! vregs which must be tagged at the definition site because
! there is at least one usage that is not int-rep. If all usages
! are int-rep it is safe to untag at the definition site.
SYMBOL: tagged-vregs
SYMBOL: vreg-reps
@ -62,17 +59,12 @@ SYMBOL: possibilities
! For every vreg, compute the cost of keeping it in every possible
! representation.
! Cost map maps vreg to representation to cost.
SYMBOL: costs
: init-costs ( -- )
! Initialize cost as 0 for each possibility.
possibilities get [ [ 0 ] H{ } map>assoc ] assoc-map costs set ;
: increase-cost ( rep scc factor -- )
! Increase cost of keeping vreg in rep, making a choice of rep less
! likely. If the rep is not in the cost alist, it means this
! representation is prohibited.
[ costs get at 2dup key? ] dip
'[ [ current-loop-nesting 10^ _ * + ] change-at ] [ 2drop ] if ;
@ -137,7 +129,6 @@ M: vreg-insn compute-insn-costs
[ [ compute-insn-costs ] each-non-phi ] bi
] each-basic-block ;
! For every vreg, compute preferred representation, that minimizes costs.
: minimize-costs ( costs -- representations )
[ nip assoc-empty? ] assoc-reject
[ >alist alist-min first ] assoc-map ;