diff options
Diffstat (limited to 'gcc/alias.c')
| -rw-r--r-- | gcc/alias.c | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/gcc/alias.c b/gcc/alias.c index 2ef13cc..21daa5f 100644 --- a/gcc/alias.c +++ b/gcc/alias.c @@ -2236,11 +2236,20 @@ nonoverlapping_component_refs_p (const_rtx rtlx, const_rtx rtly) return false; found: - /* If we're left with accessing different fields of a structure, - then no overlap. */ - if (TREE_CODE (typex) == RECORD_TYPE - && fieldx != fieldy) - return true; + /* If we're left with accessing different fields of a structure, then no + possible overlap, unless they are both true bitfields, i.e. bitfields + for which the size isn't a multiple of the (memory) unit. */ + if (TREE_CODE (typex) == RECORD_TYPE && fieldx != fieldy) + { + if (!DECL_BIT_FIELD (fieldx) || !DECL_BIT_FIELD (fieldy)) + return true; + + if ((tree_low_cst (DECL_SIZE (fieldx), 1) % BITS_PER_UNIT) == 0 + || (tree_low_cst (DECL_SIZE (fieldy), 1) % BITS_PER_UNIT) == 0) + return true; + + return false; + } /* The comparison on the current field failed. If we're accessing a very nested structure, look at the next outer level. */ |