From 0efec0eff12ecab579cc125e5218d3a73dd743f5 Mon Sep 17 00:00:00 2001
From: Slava Pestov <slava@slava-pestovs-macbook-pro.local>
Date: Mon, 18 Aug 2008 21:30:10 -0500
Subject: [PATCH] DCE fixes

---
 basis/compiler/generator/generator.factor     |  2 +-
 basis/compiler/tree/builder/builder.factor    |  3 ---
 basis/compiler/tree/cleanup/cleanup.factor    |  8 +++++++
 .../tree/dead-code/branches/branches.factor   | 22 ++++++++++---------
 .../tree/dead-code/dead-code-tests.factor     |  2 ++
 basis/compiler/tree/tree.factor               |  3 +++
 6 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/basis/compiler/generator/generator.factor b/basis/compiler/generator/generator.factor
index 4d826c40d2..35ad0656cd 100755
--- a/basis/compiler/generator/generator.factor
+++ b/basis/compiler/generator/generator.factor
@@ -92,7 +92,7 @@ M: node generate-node drop iterate-next ;
     %jump-label ;
 
 : generate-call ( label -- next )
-    ! dup maybe-compile
+    dup maybe-compile
     end-basic-block
     dup compiling-loops get at [
         %jump-label f
diff --git a/basis/compiler/tree/builder/builder.factor b/basis/compiler/tree/builder/builder.factor
index 8a59f82bcf..8bc0f72ac9 100644
--- a/basis/compiler/tree/builder/builder.factor
+++ b/basis/compiler/tree/builder/builder.factor
@@ -22,9 +22,6 @@ IN: compiler.tree.builder
     ] with-tree-builder nip
     unclip-last in-d>> ;
 
-: ends-with-terminate? ( nodes -- ? )
-    dup empty? [ drop f ] [ peek #terminate? ] if ;
-
 : build-sub-tree ( #call quot -- nodes )
     [ [ out-d>> ] [ in-d>> ] bi ] dip build-tree-with
     over ends-with-terminate?
diff --git a/basis/compiler/tree/cleanup/cleanup.factor b/basis/compiler/tree/cleanup/cleanup.factor
index 3f530effd3..ff42a08818 100644
--- a/basis/compiler/tree/cleanup/cleanup.factor
+++ b/basis/compiler/tree/cleanup/cleanup.factor
@@ -117,11 +117,19 @@ M: #branch cleanup*
         [ live-branches>> live-branches set ]
     } cleave ;
 
+: eliminate-phi ( #phi -- node )
+    dup phi-in-d>> length {
+        { 0 [ drop f ] }
+        { 1 [ [ phi-in-d>> first ] [ out-d>> ] bi #copy ] }
+        [ drop ]
+    } case ;
+
 M: #phi cleanup*
     #! Remove #phi function inputs which no longer exist.
     live-branches get
     [ '[ , select-children sift ] change-phi-in-d ]
     [ '[ , select-children sift ] change-phi-info-d ] bi
+    eliminate-phi
     live-branches off ;
 
 : >copy ( node -- #copy ) [ in-d>> ] [ out-d>> ] bi #copy ;
diff --git a/basis/compiler/tree/dead-code/branches/branches.factor b/basis/compiler/tree/dead-code/branches/branches.factor
index 7bff7aa148..bbae02b4ff 100644
--- a/basis/compiler/tree/dead-code/branches/branches.factor
+++ b/basis/compiler/tree/dead-code/branches/branches.factor
@@ -1,9 +1,10 @@
 ! Copyright (C) 2008 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: sequences namespaces kernel accessors assocs sets fry
-arrays combinators columns stack-checker.backend compiler.tree
-compiler.tree.combinators compiler.tree.dead-code.liveness
-compiler.tree.dead-code.simple ;
+arrays combinators columns stack-checker.backend
+stack-checker.branches compiler.tree compiler.tree.combinators
+compiler.tree.dead-code.liveness compiler.tree.dead-code.simple
+;
 IN: compiler.tree.dead-code.branches
 
 M: #if mark-live-values* look-at-inputs ;
@@ -26,10 +27,9 @@ M: #branch remove-dead-code*
     bi ;
 
 : remove-phi-inputs ( #phi -- )
-    dup [ out-d>> ] [ phi-in-d>> flip ] bi
-    filter-corresponding
-    flip >>phi-in-d
-    drop ;
+    if-node get children>>
+    [ dup ends-with-terminate? [ drop f ] [ peek out-d>> ] if ] map
+    pad-with-bottom >>phi-in-d drop ;
 
 : live-value-indices ( values -- indices )
     [ length ] keep live-values get
@@ -42,7 +42,10 @@ M: #branch remove-dead-code*
     #shuffle ;
 
 : insert-drops ( nodes values indices -- nodes' )
-    '[ , drop-values suffix ] 2map ;
+    '[
+        over ends-with-terminate?
+        [ drop ] [ , drop-values suffix ] if
+    ] 2map ;
 
 : hoist-drops ( #phi -- )
     if-node get swap
@@ -50,8 +53,7 @@ M: #branch remove-dead-code*
     '[ , , insert-drops ] change-children drop ;
 
 : remove-phi-outputs ( #phi -- )
-    [ filter-live ] change-out-d
-    drop ;
+    [ filter-live ] change-out-d drop ;
 
 M: #phi remove-dead-code*
     {
diff --git a/basis/compiler/tree/dead-code/dead-code-tests.factor b/basis/compiler/tree/dead-code/dead-code-tests.factor
index 14e66fa648..8804a9417e 100644
--- a/basis/compiler/tree/dead-code/dead-code-tests.factor
+++ b/basis/compiler/tree/dead-code/dead-code-tests.factor
@@ -98,3 +98,5 @@ IN: compiler.tree.dead-code.tests
 [ ] [ [ dup [ 3 throw ] [ ] if ] optimize-quot drop ] unit-test
 
 [ [ [ . ] [ drop ] if ] ] [ [ [ dup . ] [ ] if drop ] optimize-quot ] unit-test
+
+[ [ f ] ] [ [ f dup [ ] [ ] if ] optimize-quot ] unit-test
diff --git a/basis/compiler/tree/tree.factor b/basis/compiler/tree/tree.factor
index b994ce8bfc..40a35e66d4 100755
--- a/basis/compiler/tree/tree.factor
+++ b/basis/compiler/tree/tree.factor
@@ -183,6 +183,9 @@ M: #return-recursive inputs/outputs [ in-d>> ] [ out-d>> ] bi ;
 : recursive-phi-in ( #enter-recursive -- seq )
     [ label>> calls>> [ in-d>> ] map ] [ in-d>> ] bi suffix ;
 
+: ends-with-terminate? ( nodes -- ? )
+    dup empty? [ drop f ] [ peek #terminate? ] if ;
+
 M: vector child-visitor V{ } clone ;
 M: vector #introduce, #introduce node, ;
 M: vector #call, #call node, ;