/* Sort the SCC of type, hash pairs so that when we mix in
all members of the SCC the hash value becomes independent on
- the order we visited the SCC. Disregard hashes equal to
- the hash of the tree we mix into because we cannot guarantee
- a stable sort for those across different TUs. */
+ the order we visited the SCC. Produce hash of the whole SCC as
+ combination of hashes of individual elements. Then combine that hash into
+ hash of each element, so othewise identically looking elements from two
+ different SCCs are distinguished. */
qsort (&sccstack[first], size, sizeof (scc_entry), scc_entry_compare);
- hashval_t *tem = XALLOCAVEC (hashval_t, size);
- for (unsigned i = 0; i < size; ++i)
- {
- hashval_t hash = sccstack[first+i].hash;
- hashval_t orig_hash = hash;
- unsigned j;
- /* Skip same hashes. */
- for (j = i + 1;
- j < size && sccstack[first+j].hash == orig_hash; ++j)
- ;
- for (; j < size; ++j)
- hash = iterative_hash_hashval_t (sccstack[first+j].hash, hash);
- for (j = 0; sccstack[first+j].hash != orig_hash; ++j)
- hash = iterative_hash_hashval_t (sccstack[first+j].hash, hash);
- tem[i] = hash;
- }
- hashval_t scc_hash = 0;
+
+ hashval_t scc_hash = sccstack[first].hash;
+ for (unsigned i = 1; i < size; ++i)
+ scc_hash = iterative_hash_hashval_t (scc_hash,
+ sccstack[first+i].hash);
for (unsigned i = 0; i < size; ++i)
- {
- sccstack[first+i].hash = tem[i];
- scc_hash = iterative_hash_hashval_t (tem[i], scc_hash);
- }
+ sccstack[first+i].hash = iterative_hash_hashval_t (sccstack[first+i].hash, scc_hash);
return scc_hash;
}