From 454c2f245bab13b75f8518ac45416f6ee744566d Mon Sep 17 00:00:00 2001
From: Alex Vondrak <ajvondrak@csupomona.edu>
Date: Thu, 23 Jun 2011 17:39:46 -0700
Subject: [PATCH] compiler.cfg.gvn: preparing for avail-based redundancy
 elimination

---
 extra/compiler/cfg/gvn/graph/graph.factor | 12 ++++++++++--
 extra/compiler/cfg/gvn/gvn.factor         | 11 ++++++++---
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/extra/compiler/cfg/gvn/graph/graph.factor b/extra/compiler/cfg/gvn/graph/graph.factor
index bcdd2bea00..080acf6e0c 100644
--- a/extra/compiler/cfg/gvn/graph/graph.factor
+++ b/extra/compiler/cfg/gvn/graph/graph.factor
@@ -15,6 +15,10 @@ SYMBOL: exprs>vns
 ! assoc mapping value numbers to instructions
 SYMBOL: vns>insns
 
+! assoc mapping basic blocks to the set of value numbers that
+! are defined in the block
+SYMBOL: bbs>defns
+
 ! boolean to track whether vregs>vns changes
 SYMBOL: changed?
 
@@ -27,12 +31,16 @@ SYMBOL: changed?
 
 : vreg>insn ( vreg -- insn ) vreg>vn vn>insn ;
 
+: defined ( bb -- vns ) bbs>defns get at ;
+
 : clear-exprs ( -- )
     exprs>vns get clear-assoc
-    vns>insns get clear-assoc ;
+    vns>insns get clear-assoc
+    bbs>defns get clear-assoc ;
 
 : init-value-graph ( -- )
     0 input-expr-counter set
     H{ } clone vregs>vns set
     H{ } clone exprs>vns set
-    H{ } clone vns>insns set ;
+    H{ } clone vns>insns set
+    H{ } clone bbs>defns set ;
diff --git a/extra/compiler/cfg/gvn/gvn.factor b/extra/compiler/cfg/gvn/gvn.factor
index 685de8bd7a..f2317f6dca 100644
--- a/extra/compiler/cfg/gvn/gvn.factor
+++ b/extra/compiler/cfg/gvn/gvn.factor
@@ -1,7 +1,7 @@
 ! Copyright (C) 2008, 2010 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: namespaces arrays assocs kernel accessors fry grouping
-sorting sets sequences locals
+USING: namespaces arrays assocs hashtables kernel accessors fry
+grouping sorting sets sequences locals
 cpu.architecture
 sequences.deep
 compiler.cfg
@@ -29,6 +29,7 @@ GENERIC: process-instruction ( insn -- insn' )
     vn vn set-vn
     vn expr exprs>vns get set-at
     insn vn vns>insns get set-at
+    vn vn basic-block get bbs>defns get [ ?set-at ] change-at
     insn ;
 
 : check-redundancy ( insn -- insn' )
@@ -62,6 +63,10 @@ M: array process-instruction
         changed? get
     ] loop ;
 
+! FIXME can't just do a pass through the cfg to rewrite---not
+! all canonical leaders are necessarily available in a
+! particular rewrite
+
 : eliminate-redundancies ( cfg -- )
     final-iteration? on
     clear-exprs
@@ -69,5 +74,5 @@ M: array process-instruction
 
 : value-numbering ( cfg -- cfg )
     dup identify-redundancies
-    dup eliminate-redundancies
+    ! dup eliminate-redundancies
     cfg-changed predecessors-changed ;