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optimizer: preserve implied properties from a let RHS

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In an expression such as

 (let ([x (car y)])
   ....)

the information that `y` must be a pair didn't reach the body of the
`let` in most cases.
This commit is contained in:
Matthew Flatt 2014-11-02 19:44:57 -07:00
parent 89106b6708
commit edd50a24a8
2 changed files with 29 additions and 2 deletions
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8
pkgs/racket-pkgs/racket-test/tests/racket/optimize.rktl
View File

@ -2357,6 +2357,14 @@
(- (expt 2 31) 2))
#f)
;; Propagate type impliciations from RHS:
(test-comp '(lambda (x)
(let ([y (car x)])
(list (cdr x) y (car x) y)))
'(lambda (x)
(let ([y (car x)])
(list (unsafe-cdr x) y (unsafe-car x) y))))
;; don't duplicate an operation by moving it into a lambda':
(test-comp '(lambda (x)
(let ([y (unsafe-flvector-length x)])

23
racket/src/racket/src/optimize.c
View File

@ -115,6 +115,7 @@ static Scheme_Object *optimize_info_mutated_lookup(Optimize_Info *info, int pos,
static void optimize_info_used_top(Optimize_Info *info);
static Scheme_Object *optimize_get_predicate(int pos, Optimize_Info *info);
static void add_type(Optimize_Info *info, int pos, Scheme_Object *pred);
static void merge_types(Optimize_Info *src_info, Optimize_Info *info, int delta);
static void optimize_mutated(Optimize_Info *info, int pos);
static void optimize_produces_local_type(Optimize_Info *info, int pos, int ct);
@ -3725,6 +3726,23 @@ static void add_type(Optimize_Info *info, int pos, Scheme_Object *pred)
info->types = new_types;
}
static void merge_types(Optimize_Info *src_info, Optimize_Info *info, int delta)
{
Scheme_Hash_Tree *types = src_info->types;
Scheme_Object *pos, *pred;
intptr_t i;
if (!types)
return;
i = scheme_hash_tree_next(types, -1);
while (i != -1) {
scheme_hash_tree_index(types, i, &pos, &pred);
add_type(info, SCHEME_INT_VAL(pos)+delta, pred);
i = scheme_hash_tree_next(types, i);
}
}
static int relevant_predicate(Scheme_Object *pred)
{
/* Relevant predicates need to be disjoint for check_known2_pred()
@ -5682,9 +5700,10 @@ scheme_optimize_lets(Scheme_Object *form, Optimize_Info *info, int for_inline, i
optimize_info_seq_done(rhs_info, &info_seq);
if (post_bind)
if (post_bind) {
optimize_info_done(rhs_info, body_info);
else if (split_shift)
merge_types(rhs_info, body_info, head->count);
} else if (split_shift)
optimize_info_done(rhs_info, body_info);
body = scheme_optimize_expr(body, body_info, scheme_optimize_tail_context(context));