Richard, this patch makes canonical_type to be computed via the hash only for main variants of types. The idea is to save some lookups because most types are variants and should match.
I also added sanity checking about that. Bootstrapped/regtested ppc-linux, OK? Honza * lto.c (iterative_hash_canonical_type, gimple_register_canonical_type): only hash main variants of types * tree.c (verify_type_variant): Verify that type and variant is compatible. (gimple_canonical_types_compatible_p): Look for main variants. Index: lto/lto.c =================================================================== --- lto/lto.c (revision 223883) +++ lto/lto.c (working copy) @@ -413,6 +413,9 @@ static void iterative_hash_canonical_type (tree type, inchash::hash &hstate) { hashval_t v; + + /* All type variants have same TYPE_CANONICAL. */ + type = TYPE_MAIN_VARIANT (type); /* An already processed type. */ if (TYPE_CANONICAL (type)) { @@ -498,7 +501,15 @@ gimple_register_canonical_type (tree t) if (TYPE_CANONICAL (t) || !type_with_alias_set_p (t)) return; - gimple_register_canonical_type_1 (t, hash_canonical_type (t)); + /* Canonical types are same among all complete variants. */ + if (TYPE_CANONICAL (TYPE_MAIN_VARIANT (t))) + TYPE_CANONICAL (t) = TYPE_CANONICAL (TYPE_MAIN_VARIANT (t)); + else + { + gimple_register_canonical_type_1 (TYPE_MAIN_VARIANT (t), + hash_canonical_type (TYPE_MAIN_VARIANT (t))); + TYPE_CANONICAL (t) = TYPE_CANONICAL (TYPE_MAIN_VARIANT (t)); + } } /* Re-compute TYPE_CANONICAL for NODE and related types. */ Index: tree.c =================================================================== --- tree.c (revision 223883) +++ tree.c (working copy) @@ -12819,6 +12819,17 @@ verify_type_variant (const_tree t, tree debug_tree (TREE_TYPE (t)); return false; } + if (type_with_alias_set_p (t) + && !gimple_canonical_types_compatible_p (t, tv, false)) + { + error ("type is not compatible with its vairant"); + debug_tree (tv); + error ("type variant's TREE_TYPE"); + debug_tree (TREE_TYPE (tv)); + error ("type's TREE_TYPE"); + debug_tree (TREE_TYPE (t)); + return false; + } return true; #undef verify_variant_match } @@ -12843,7 +12854,13 @@ bool gimple_canonical_types_compatible_p (const_tree t1, const_tree t2, bool trust_type_canonical) { - /* Before starting to set up the SCC machinery handle simple cases. */ + /* Type variants should be same as the main variant. When not doing sanity + checking to verify this fact, go to main variants and save some work. */ + if (trust_type_canonical) + { + t1 = TYPE_MAIN_VARIANT (t1); + t2 = TYPE_MAIN_VARIANT (t2); + } /* Check first for the obvious case of pointer identity. */ if (t1 == t2)