Currently, we treat predicates as "second-class" citizens: - assume any identifier as a valid predicate - cannot write more complex predicates than an identifier in match-op
I was wondering whether it would be a good idea to ave user-defined predicates, instead of hard-coding them as macros in gimple-match-head.c ? * Syntax A predicate is assumed to expect only one operand as input. (define_predicate <name> (c_expr)) and use it the same way we do currently. Example Use case: Consider following pattern: (simplify (foo @0 @1) (if (TYPE_UNSIGNED (TREE_TYPE (@1))) @0) The second operand (@1) is only captured for sake of testing it's type in if-expr. Instead, define a predicate: (define_predicate type_unsigned_p (TYPE_UNSIGNED (TREE_TYPE (@@))) @@ refers to the operand we use the predicate on. (simplify (foo @0 type_unsigned) @0) in this case @@ would be op21 (one of the generated temporaries during code-gen for match-op in decision tree). * code-gen We would generate predicates as macros in the generated file. so in gimple-match.c, there would be #define type_unsigned(op) (TYPE_UNSIGNED (TREE_TYPE (op))) (we also need this for generic-match.c, so maybe generate macros in separate file say genpreds.c and include it in both gimple-match.c and generic-match.c) and replace @@ by correct operand in the patterns the predicates are used. The current "predicates" in gimple-match-head.c can be written as: (define_predicate INTEGER_CST_P (TREE_CODE (@@) == INTEGER_CST))) (define_predicate integral_op_p (INTEGRAL_TYPE_P (TREE_TYPE (@@))) Not sure if this would have real benefit, just an idea... Thanks, Prathamesh
