[buddy] get rid of many recursive algorithms

This patch addresses the BuDDy part of #396,
reported by Florian Renkin and Reed Oei.

* src/kernel.c, src/kernel.h: Declare a bddrecstack and
associated macros.  Resize it when new variable are declared.
* src/cache.h: Add a BddCache_index macro.
* src/bddop.c (not_rec, apply_rec, quant_rec, appquant_rec,
support_rec, ite_rec, compose_rec, restrict_rec, satone_rec,
satoneset_rec): Rewrite using this stack to get rid of the recursion.

buddy/src/cache.h

@@ -1,5 +1,5 @@
 /*========================================================================
-               Copyright (C) 1996-2002 by Jorn Lind-Nielsen
+               Copyright (C) 1996-2002, 2020 by Jorn Lind-Nielsen
                             All rights reserved
 
     Permission is hereby granted, without written agreement and without
@@ -67,7 +67,7 @@ extern int  BddCache_resize(BddCache *, int);
 extern void BddCache_reset(BddCache *);
 
 #define BddCache_lookup(cache, hash) (&(cache)->table[hash & ((cache)->tablesize - 1)])
-
+#define BddCache_index(cache, hash, index) (&(cache)->table[index = (hash & ((cache)->tablesize - 1))])
 
 #endif /* _CACHE_H */
 

buddy/src/kernel.c

@@ -45,7 +45,6 @@
 #include <assert.h>
 
 #include "kernel.h"
-#include "cache.h"
 #include "prime.h"
 
 /*************************************************************************
@@ -103,6 +102,8 @@ jmp_buf      bddexception;      /* Long-jump point for interrupting calc. */
 int          bddresized;        /* Flag indicating a resize of the nodetable */
 int          bddcachesize;      /* Size of the operator caches */
 int          bddhashsize;       /* Size of the BDD node hash */
+int*         bddrecstack;       /* Internal recursion stack */
+int*         bddrecstacktop;    /* Internal recursion stack top */
 
 bddCacheStat bddcachestats;
 
@@ -273,6 +274,7 @@ void bdd_done(void)
 
    free(bddnodes);
    free(bddrefstack);
+   free(bddrecstack);
    free(bddvarset);
    free(bddvar2level);
    free(bddlevel2var);
@@ -280,6 +282,7 @@ void bdd_done(void)
 
    bddnodes = NULL;
    bddrefstack = NULL;
+   bddrecstack = NULL;
    bddvarset = NULL;
 
    bdd_operator_done();
@@ -374,7 +377,11 @@ int bdd_setvarnum(int num)
 
    if (__likely(bddrefstack != NULL))
       free(bddrefstack);
-   bddrefstack = bddrefstacktop = (int*)malloc(sizeof(int)*(num*2+4));
+   bddrefstack = bddrefstacktop = (int*)malloc(sizeof(int)*((num+2)*2));
+
+   if (__likely(bddrecstack != NULL))
+      free(bddrecstack);
+   bddrecstack = bddrecstacktop = (int*)malloc(sizeof(int)*((num+1)*9));
 
    for(bdv=bddvarnum ; bddvarnum < num; bddvarnum++)
    {

buddy/src/kernel.h

@@ -43,6 +43,7 @@
 #include <limits.h>
 #include <setjmp.h>
 #include "bddx.h"
+#include "cache.h"
 #ifdef HAVE_CONFIG_H
 # include "config.h"
 #endif
@@ -133,6 +134,8 @@ extern int       bddreorderdisabled;
 extern int       bddresized;
 extern int       bddcachesize;
 extern bddCacheStat bddcachestats;
+extern int*      bddrecstack;
+extern int*      bddrecstacktop;
 
   /* from reorder.c */
 extern int bddreordermethod;
@@ -214,6 +217,28 @@ static inline int PUSHREF(int a)
 #define READREF(a) *(bddrefstacktop-(a))
 #define POPREF(a)  bddrefstacktop -= (a)
 
+#define PUSHREF_(a) *(localbddrefstacktop++) = (a)
+#define READREF_(a) *(localbddrefstacktop-(a))
+#define POPREF_(a)  localbddrefstacktop -= (a)
+
+#define PUSHINT_(a) *(localbddrecstacktop++) = (a)
+#define PUSH2INT_(a, b) {PUSHINT_(a); PUSHINT_(b);}
+#define PUSH3INT_(a, b, c) {PUSHINT_(a); PUSHINT_(b); PUSHINT_(c);}
+#define PUSH4INT_(a, b, c, d) {PUSHINT_(a); PUSHINT_(b); PUSHINT_(c); PUSHINT_(d);}
+#define POPINT_() *(--localbddrecstacktop)
+
+#define LOCAL_REC_STACKS                                \
+  int* restrict localbddrefstacktop = bddrefstacktop;   \
+  int* restrict localbddrecstacktop = bddrecstacktop;   \
+  int* localbddrecstackbot = bddrecstacktop;
+
+#define NONEMPTY_REC_STACK (localbddrecstacktop > localbddrecstackbot)
+
+
+#define SYNC_REC_STACKS                         \
+  bddrefstacktop = localbddrefstacktop;         \
+  bddrecstacktop = localbddrecstacktop;
+
 #define BDDONE 1
 #define BDDZERO 0