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[factor.git] / basis / compiler / cfg / ssa / destruction / destruction-docs.factor

diff --git a/basis/compiler/cfg/ssa/destruction/destruction-docs.factor b/basis/compiler/cfg/ssa/destruction/destruction-docs.factor
index 2fea4ed3ca536343c1bd79944b2779921dd5b4b0..86ea0fa06f06c706f51055c7b83d05dd9bf44a22 100644 (file)
--- a/basis/compiler/cfg/ssa/destruction/destruction-docs.factor
+++ b/basis/compiler/cfg/ssa/destruction/destruction-docs.factor
@@ -3,50 +3,25 @@ compiler.cfg.ssa.destruction.private compiler.cfg.ssa.destruction.leaders
 compiler.cfg.ssa.interference help.markup help.syntax kernel sequences ;
 IN: compiler.cfg.ssa.destruction
 
-HELP: class-element-map
-{ $var-description "Maps leaders to equivalence class elements which are sequences of " { $link vreg-info } " instances." } ;
-
 HELP: cleanup-cfg
 { $values { "cfg" cfg } }
-{ $description "In this step, " { $link ##parallel-copy } " instructions are substituted with more concreete " { $link ##copy } " instructions. " { $link ##phi } " instructions are removed here." } ;
-
-HELP: coalesce-elements
-{ $values { "merged" "??" } { "follower" "vreg" } { "leader" "vreg" } }
-{ $description "Delete follower's class, and set leaders's class to merged." } ;
-
-HELP: coalesce-vregs
-{ $values { "merged" "??" } { "follower" "vreg" } { "leader" "vreg" } }
-{ $description "Sets 'leader' as the leader of 'follower'." } ;
-
-HELP: copies
-{ $var-description "Sequence of copies (tuples of { vreg-dst vreg-src}) that maybe can be eliminated later." }
-{ $see-also init-coalescing } ;
+{ $description "In this pass, useless copies are eliminated. " { $link ##phi } " instructions are removed and " { $link ##parallel-copy } " are transformed into regular " { $link ##copy } " instructions. Then for the copy instructions, which are ##copy and " { $link ##tagged>integer } " it is checked to see if the copy is useful. If it is not, the instruction is removed from the cfg." } ;
 
-HELP: try-eliminate-copy
-{ $values { "follower" "vreg" } { "leader" "vreg" } { "must?" boolean } }
-{ $description "Tries to eliminate a vreg copy from 'leader' to 'follower'. If 'must?' is " { $link t } " then a " { $link vregs-shouldn't-interfere } " error is thrown if the vregs interfere." }
-{ $see-also try-eliminate-copies vregs-interfere? } ;
-
-HELP: try-eliminate-copies
-{ $values { "pairs" "a sequence of vreg pairs" } { "must?" boolean } }
-{ $description "Tries to eliminate the vreg copies in the " { $link sequence } " 'pairs'. If 'must?' is " { $link t } " then a " { $link vregs-shouldn't-interfere } " error is thrown if any of the vregs interfere." }
-{ $see-also try-eliminate-copy } ;
+HELP: destruct-ssa
+{ $values { "cfg" cfg } }
+{ $description "Main entry point for the SSA destruction compiler pass." } ;
 
 ARTICLE: "compiler.cfg.ssa.destruction" "SSA Destruction"
+"SSA destruction compiler pass. It is preceded by " { $vocab-link "compiler.cfg.save-contexts" } " and followed by " { $vocab-link "compiler.cfg.linear-scan" } "."
+$nl
 "Because of the design of the register allocator, this pass has three peculiar properties."
 { $list
-  "Instead of renaming vreg usages in the CFG, a map from vregs to canonical representatives is computed. This allows the register allocator to use the original SSA names to get reaching definitions."
+  { "Instead of renaming vreg usages in the CFG, a map from vregs to canonical representatives is computed. This allows the register allocator to use the original SSA names to get reaching definitions. See " { $link leader-map } "." }
   { "Useless " { $link ##copy } " instructions, and all " { $link ##phi } " instructions, are eliminated, so the register allocator does not have to remove any redundant operations." }
   { "This pass computes live sets and fills out the " { $slot "gc-roots" } " slots of GC maps with " { $vocab-link "compiler.cfg.liveness" } ", so the linear scan register allocator does not need to compute liveness again." }
 }
 $nl
 "Main entry point:"
-{ $subsections destruct-ssa }
-"Vreg copy elimination:"
-{ $subsections
-  perform-coalescing
-  try-eliminate-copies
-  try-eliminate-copy
-} ;
+{ $subsections destruct-ssa } ;
 
 ABOUT: "compiler.cfg.ssa.destruction"