From 48ecbf60ab9a84a4f49a015bbf797486f9e89987 Mon Sep 17 00:00:00 2001
From: Sven Verdoolaege <skimo@kotnet.org>
Date: Tue, 10 May 2011 10:56:01 +0200
Subject: [PATCH] cloog_loop_constant: don't drop constraints on outer loop
 iterators

9802965 (cloog_loop_generate_general: add special treatment for loops
with constant value, Sat Dec 4 17:57:26 2010 +0100) improved code
generation in presence of the -noscalars option, but did so by creating
loops with domains that only had constraints on the current loop iterator
and not on any previous loop iterator.
This broke a fundamental assumption of the CLooG internals.

We already introduced a bandaid in b130274 (fix backtracking in presence
of constant loops, Thu Mar 24 21:48:27 2011 +0100) for backtracking,
but cloog_loop_stop was also affected.
Rather than introducing a new bandaid, let's just play by the rules
in cloog_loop_constant and remove the backtracking bandaid.
The fallout appears to be relatively minor.

Signed-off-by: Sven Verdoolaege <skimo@kotnet.org>
---
 source/loop.c             | 20 ++++++--------------
 test/reservoir/lim-lam3.c |  8 +++++---
 2 files changed, 11 insertions(+), 17 deletions(-)

diff --git a/source/loop.c b/source/loop.c
index 47c698e..e73904d 100644
--- a/source/loop.c
+++ b/source/loop.c
@@ -1520,10 +1520,6 @@ CloogLoop *cloog_loop_generate_backtrack(CloogLoop *loop,
       else
       new_loop = cloog_loop_project(inner, level);
 
-      domain = cloog_domain_intersection(new_loop->domain, temp->domain);
-      cloog_domain_free(new_loop->domain);
-      new_loop->domain = domain;
-
       cloog_loop_free_parts(inner,0,0,0,0) ;
       cloog_loop_add(&l,&now2,new_loop) ;
       inner = next ;
@@ -1600,28 +1596,24 @@ int cloog_loop_is_constant(CloogLoop *loop, int level)
 CloogLoop *cloog_loop_constant(CloogLoop *loop, int level)
 {
     CloogLoop *res, *inner, *tmp;
-    CloogDomain *domain, *context, *t;
+    CloogDomain *domain, *t;
 
     if (!loop)
 	return loop;
 
     inner = loop->inner;
-    for (tmp = loop->next; tmp; tmp = tmp->next)
+    domain = loop->domain;
+    for (tmp = loop->next; tmp; tmp = tmp->next) {
 	inner = cloog_loop_concat(inner, tmp->inner);
+	domain = cloog_domain_union(domain, tmp->domain);
+    }
 
-    domain = cloog_domain_copy(loop->domain);
     domain = cloog_domain_simple_convex(t = domain);
     cloog_domain_free(t);
-    context = cloog_domain_project(domain, level - 1);
-    context = cloog_domain_extend(t = context, level);
-    cloog_domain_free(t);
-    domain = cloog_domain_simplify(t = domain, context);
-    cloog_domain_free(t);
-    cloog_domain_free(context);
 
     res = cloog_loop_alloc(loop->state, domain, 0, NULL, NULL, inner, NULL);
 
-    cloog_loop_free_parts(loop, 1, 0, 0, 1);
+    cloog_loop_free_parts(loop, 0, 0, 0, 1);
 
     return res;
 }
diff --git a/test/reservoir/lim-lam3.c b/test/reservoir/lim-lam3.c
index 313b319..c68a629 100644
--- a/test/reservoir/lim-lam3.c
+++ b/test/reservoir/lim-lam3.c
@@ -1,4 +1,4 @@
-/* Generated from ../../../git/cloog/test/reservoir/lim-lam3.cloog by CLooG 0.16.1-1-g6af50a0 gmp bits in 0.01s. */
+/* Generated from ../../../git/cloog/test/reservoir/lim-lam3.cloog by CLooG 0.16.2-8-g1421b58 gmp bits in 0.03s. */
 S4(1);
 for (c2=9;c2<=min(13,5*M-1);c2++) {
   if (c2 <= M+7) {
@@ -7,8 +7,10 @@ for (c2=9;c2<=min(13,5*M-1);c2++) {
   if (c2 == 10) {
     S4(2);
   }
-  if (c2%3 == 0) {
-    S3((c2-3)/3,1);
+  if (c2 <= 3*M+3) {
+    if (c2%3 == 0) {
+      S3((c2-3)/3,1);
+    }
   }
 }
 for (c2=14;c2<=5*M-1;c2++) {
-- 
2.11.4.GIT