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Diffstat (limited to 'gcc/tree-ssa-scopedtables.c')
| -rw-r--r-- | gcc/tree-ssa-scopedtables.c | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/gcc/tree-ssa-scopedtables.c b/gcc/tree-ssa-scopedtables.c index 6e1fd58..27e0c68 100644 --- a/gcc/tree-ssa-scopedtables.c +++ b/gcc/tree-ssa-scopedtables.c @@ -258,15 +258,24 @@ avail_exprs_stack::lookup_avail_expr (gimple *stmt, bool insert, bool tbaa_p) { /* If we did not find the expression in the hash table, we may still be able to produce a result for some expressions. */ - tree alt = avail_exprs_stack::simplify_binary_operation (stmt, element); - if (alt) - return alt; + tree retval = avail_exprs_stack::simplify_binary_operation (stmt, + element); + /* We have, in effect, allocated *SLOT for ELEMENT at this point. + We must initialize *SLOT to a real entry, even if we found a + way to prove ELEMENT was a constant after not finding ELEMENT + in the hash table. + + An uninitialized or empty slot is an indication no prior objects + entered into the hash table had a hash collection with ELEMENT. + + If we fail to do so and had such entries in the table, they + would become unreachable. */ class expr_hash_elt *element2 = new expr_hash_elt (element); *slot = element2; record_expr (element2, NULL, '2'); - return NULL_TREE; + return retval; } /* If we found a redundant memory operation do an alias walk to |