compiler.cfg.builder.*: docs and tests

basis/compiler/cfg/builder/blocks/blocks-docs.factor

@@ -67,8 +67,12 @@ HELP: emit-trivial-block
 { $examples { $unchecked-example $[ ex-emit-trivial-block ] } } ;
 
 HELP: end-branch
-{ $values { "block" basic-block } { "pair/f" "two-tuple" } }
-{ $description "pair is { final-bb final-height }" } ;
+{ $values
+  { "block/f" { $maybe basic-block } }
+  { "pair/f" "two-tuple" }
+}
+{ $description "The pair is a two tuple on the format { final-bb final-height }." }
+{ $see-also with-branch } ;
 
 HELP: set-basic-block
 { $values { "basic-block" basic-block } }

basis/compiler/cfg/builder/blocks/blocks.factor

@@ -39,7 +39,7 @@ SLOT: out-d
 : begin-branch ( block -- block' )
     height-state [ clone-height-state ] change (begin-basic-block) ;
 
-: end-branch ( block -- pair/f )
+: end-branch ( block/f -- pair/f )
     dup [
         ##branch,
         end-local-analysis

basis/compiler/cfg/builder/builder-tests.factor

@@ -270,6 +270,22 @@ SYMBOL: foo
     predecessors>> first instructions>>
 ] cfg-unit-test
 
+! emit-if
+{ V{ 3 2 } } [
+    <basic-block> dup set-basic-block ##branch,
+    T{ #if
+       { in-d { 9 } }
+       { children
+         {
+             { T{ #push { literal 3 } { out-d { 6 } } } }
+             { T{ #push { literal 2 } { out-d { 7 } } } }
+         }
+       }
+       { live-branches { t t } }
+    } emit-if
+    predecessors>> [ instructions>> first val>> ] map
+] cfg-unit-test
+
 ! emit-loop-call
 { 1 "good" } [
     V{ } 0 insns>block dup set-basic-block