[PATCH] Fix PR51775

[Richard Guenther]

This fixes PR51775, we do not need to avoid value-numbering for
stmts that can throw.  PRE already ensures to not enter anything
into the EXP/TMP_GEN sets for those so it won't ever end up
trying to insert throwing expressions.

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.

Richard.

2012-01-09  Richard Guenther  <rguent...@suse.de>

        PR tree-optimization/51775
        * tree-ssa-sccvn.c (visit_use): Value-number throwing stmts.
        * tree-ssa-pre.c (eliminate): Properly fixup EH info.

Index: gcc/tree-ssa-sccvn.c
===================================================================
--- gcc/tree-ssa-sccvn.c        (revision 183007)
+++ gcc/tree-ssa-sccvn.c        (working copy)
@@ -3178,8 +3178,7 @@ visit_use (tree use)
       if (gimple_code (stmt) == GIMPLE_PHI)
        changed = visit_phi (stmt);
       else if (!gimple_has_lhs (stmt)
-              || gimple_has_volatile_ops (stmt)
-              || stmt_could_throw_p (stmt))
+              || gimple_has_volatile_ops (stmt))
        changed = defs_to_varying (stmt);
       else if (is_gimple_assign (stmt))
        {
Index: gcc/tree-ssa-pre.c
===================================================================
--- gcc/tree-ssa-pre.c  (revision 183007)
+++ gcc/tree-ssa-pre.c  (working copy)
@@ -4194,6 +4194,7 @@ eliminate (void)
              tree sprime = NULL;
              pre_expr lhsexpr = get_or_alloc_expr_for_name (lhs);
              pre_expr sprimeexpr;
+             gimple orig_stmt = stmt;
 
              sprimeexpr = bitmap_find_leader (AVAIL_OUT (b),
                                               get_expr_value_id (lhsexpr),
@@ -4231,6 +4232,16 @@ eliminate (void)
                  propagate_tree_value_into_stmt (&gsi, sprime);
                  stmt = gsi_stmt (gsi);
                  update_stmt (stmt);
+
+                 /* If we removed EH side-effects from the statement, clean
+                    its EH information.  */
+                 if (maybe_clean_or_replace_eh_stmt (orig_stmt, stmt))
+                   {
+                     bitmap_set_bit (need_eh_cleanup,
+                                     gimple_bb (stmt)->index);
+                     if (dump_file && (dump_flags & TDF_DETAILS))
+                       fprintf (dump_file, "  Removed EH side-effects.\n");
+                   }
                  continue;
                }
 
@@ -4286,7 +4297,7 @@ eliminate (void)
 
                  /* If we removed EH side-effects from the statement, clean
                     its EH information.  */
-                 if (maybe_clean_or_replace_eh_stmt (stmt, stmt))
+                 if (maybe_clean_or_replace_eh_stmt (orig_stmt, stmt))
                    {
                      bitmap_set_bit (need_eh_cleanup,
                                      gimple_bb (stmt)->index);