diff options
Diffstat (limited to 'gcc/tree-ssa-copy.c')
| -rw-r--r-- | gcc/tree-ssa-copy.c | 49 |
1 files changed, 0 insertions, 49 deletions
diff --git a/gcc/tree-ssa-copy.c b/gcc/tree-ssa-copy.c index f582ed0..9dad1cd 100644 --- a/gcc/tree-ssa-copy.c +++ b/gcc/tree-ssa-copy.c @@ -78,55 +78,6 @@ may_propagate_copy (tree dest, tree orig) if (!useless_type_conversion_p (type_d, type_o)) return false; - /* FIXME. GIMPLE is allowing pointer assignments and comparisons of - pointers that have different alias sets. This means that these - pointers will have different memory tags associated to them. - - If we allow copy propagation in these cases, statements de-referencing - the new pointer will now have a reference to a different memory tag - with potentially incorrect SSA information. - - This was showing up in libjava/java/util/zip/ZipFile.java with code - like: - - struct java.io.BufferedInputStream *T.660; - struct java.io.BufferedInputStream *T.647; - struct java.io.InputStream *is; - struct java.io.InputStream *is.662; - [ ... ] - T.660 = T.647; - is = T.660; <-- This ought to be type-casted - is.662 = is; - - Also, f/name.c exposed a similar problem with a COND_EXPR predicate - that was causing DOM to generate and equivalence with two pointers of - alias-incompatible types: - - struct _ffename_space *n; - struct _ffename *ns; - [ ... ] - if (n == ns) - goto lab; - ... - lab: - return n; - - I think that GIMPLE should emit the appropriate type-casts. For the - time being, blocking copy-propagation in these cases is the safe thing - to do. */ - if (TREE_CODE (dest) == SSA_NAME - && TREE_CODE (orig) == SSA_NAME - && POINTER_TYPE_P (type_d) - && POINTER_TYPE_P (type_o)) - { - if (get_alias_set (TREE_TYPE (type_d)) - != get_alias_set (TREE_TYPE (type_o))) - return false; - else if (DECL_NO_TBAA_P (SSA_NAME_VAR (dest)) - != DECL_NO_TBAA_P (SSA_NAME_VAR (orig))) - return false; - } - /* Propagating virtual operands is always ok. */ if (TREE_CODE (dest) == SSA_NAME && !is_gimple_reg (dest)) { |