gcc/ChangeLog:

PR middle-end/31127
* cse.c (cse_find_path): Do not bail out if a basic block that
we already visited now becomes part of a path that starts at a
different basic block.  Just disallow this, to make sure we
visit each basic block at most once.
gcc/testsuite/ChangeLog:
PR middle-end/31127
* gcc.dg/pr31127.c: New.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@122900 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b90b689..9d2fc89 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2007-03-13  Steven Bosscher  <steven@gcc.gnu.org>
+
+       PR middle-end/31127
+       * cse.c (cse_find_path): Do not bail out if a basic block that
+       we already visited now becomes part of a path that starts at a
+       different basic block.  Just disallow this, to make sure we
+       visit each basic block at most once.
+
 2007-03-13  Jan Hubicka  <jh@suse.cz>
 
        * ipa-inline.c (cgraph_maybe_hot_edge_p): Look for hot/cold attributes,

diff --git a/gcc/cse.c b/gcc/cse.c
index 6976d45..cdc5ebe 100644 (file)
--- a/gcc/cse.c
+++ b/gcc/cse.c
@@ -5876,13 +5876,20 @@ cse_find_path (basic_block first_bb, struct cse_basic_block_data *data,
            {
              bb = FALLTHRU_EDGE (previous_bb_in_path)->dest;
              if (bb != EXIT_BLOCK_PTR
-                 && single_pred_p (bb))
+                 && single_pred_p (bb)
+                 /* We used to assert here that we would only see blocks
+                    that we have not visited yet.  But we may end up
+                    visiting basic blocks twice if the CFG has changed
+                    in this run of cse_main, because when the CFG changes
+                    the topological sort of the CFG also changes.  A basic
+                    blocks that previously had more than two predecessors
+                    may now have a single predecessor, and become part of
+                    a path that starts at another basic block.
+
+                    We still want to visit each basic block only once, so
+                    halt the path here if we have already visited BB.  */
+                 && !TEST_BIT (cse_visited_basic_blocks, bb->index))
                {
-#if ENABLE_CHECKING
-                 /* We should only see blocks here that we have not
-                    visited yet.  */
-                 gcc_assert (!TEST_BIT (cse_visited_basic_blocks, bb->index));
-#endif
                  SET_BIT (cse_visited_basic_blocks, bb->index);
                  data->path[path_size++].bb = bb;
                  break;
@@ -5921,14 +5928,12 @@ cse_find_path (basic_block first_bb, struct cse_basic_block_data *data,
            e = NULL;
 
          if (e && e->dest != EXIT_BLOCK_PTR
-             && single_pred_p (e->dest))
+             && single_pred_p (e->dest)
+             /* Avoid visiting basic blocks twice.  The large comment
+                above explains why this can happen.  */
+             && !TEST_BIT (cse_visited_basic_blocks, e->dest->index))
            {
              basic_block bb2 = e->dest;
-
-             /* We should only see blocks here that we have not
-                visited yet.  */
-             gcc_assert (!TEST_BIT (cse_visited_basic_blocks, bb2->index));
-
              SET_BIT (cse_visited_basic_blocks, bb2->index);
              data->path[path_size++].bb = bb2;
              bb = bb2;

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index c0358cf..3007d98 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2007-03-13  Alexandre Oliva  <aoliva@redhat.com>
+
+       PR middle-end/31127
+       * gcc.dg/pr31127.c: New.
+
 2007-03-13  Zdenek Dvorak  <dvorakz@suse.cz>
 
        * gcc.dg/tree-ssa/loop-26.c: New test.

diff --git a/gcc/testsuite/gcc.dg/pr31127.c b/gcc/testsuite/gcc.dg/pr31127.c
new file mode 100644 (file)
index 0000000..f45b10e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr31127.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+void ParseStringSidToSid(char *s, int* p) {
+    int i = 0;
+
+    while (*s) {
+        while (*s && *s != '-')
+            s++;
+        if (*s== '-')
+            s++;
+
+        p[i++] = *s;
+    }
+}