diff options
Diffstat (limited to 'gcc/tree-ssa-loop-ch.c')
| -rw-r--r-- | gcc/tree-ssa-loop-ch.c | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/gcc/tree-ssa-loop-ch.c b/gcc/tree-ssa-loop-ch.c index 3033c90..e2e272b2 100644 --- a/gcc/tree-ssa-loop-ch.c +++ b/gcc/tree-ssa-loop-ch.c @@ -1,5 +1,5 @@ /* Loop header copying on trees. - Copyright (C) 2004, 2005 Free Software Foundation, Inc. + Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc. This file is part of GCC. @@ -200,6 +200,27 @@ copy_loop_headers (void) continue; } + /* If the loop has the form "for (i = j; i < j + 10; i++)" then + this copying can introduce a case where we rely on undefined + signed overflow to eliminate the preheader condition, because + we assume that "j < j + 10" is true. We don't want to warn + about that case for -Wstrict-overflow, because in general we + don't warn about overflow involving loops. Prevent the + warning by setting TREE_NO_WARNING. */ + if (warn_strict_overflow > 0) + { + unsigned int i; + + for (i = 0; i < n_bbs; ++i) + { + tree last; + + last = last_stmt (copied_bbs[i]); + if (TREE_CODE (last) == COND_EXPR) + TREE_NO_WARNING (last) = 1; + } + } + /* Ensure that the latch and the preheader is simple (we know that they are not now, since there was the loop exit condition. */ split_edge (loop_preheader_edge (loop)); |