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- From aab54373e9406ee2a154b8d6166b3045aa3484ee Mon Sep 17 00:00:00 2001
- From: Muh Muhten <muh.muhten@gmail.com>
- Date: Sat, 9 Feb 2019 17:24:18 -0500
- Subject: [PATCH 2/9] Reimplement block_drop_unreferenced in linear time
-
- ---
- src/compile.c | 50 +++++++++++++++++++++++++++++---------------------
- 1 file changed, 29 insertions(+), 21 deletions(-)
-
- --- a/src/compile.c
- +++ b/src/compile.c
- @@ -53,6 +53,7 @@ struct inst {
- struct inst* bound_by;
- char* symbol;
- int any_unbound;
- + int referenced;
-
- int nformals;
- int nactuals;
- @@ -75,6 +76,7 @@ static inst* inst_new(opcode op) {
- i->bound_by = 0;
- i->symbol = 0;
- i->any_unbound = 0;
- + i->referenced = 0;
- i->nformals = -1;
- i->nactuals = -1;
- i->subfn = gen_noop();
- @@ -465,30 +467,36 @@ block block_bind_referenced(block binder
- return block_join(refd, body);
- }
-
- +static void block_mark_referenced(block body) {
- + int saw_top = 0;
- + for (inst* i = body.last; i; i = i->prev) {
- + if (saw_top && i->bound_by == i && !i->referenced)
- + continue;
- + if (i->op == TOP) {
- + saw_top = 1;
- + }
- + if (i->bound_by) {
- + i->bound_by->referenced = 1;
- + }
- +
- + block_mark_referenced(i->arglist);
- + block_mark_referenced(i->subfn);
- + }
- +}
- +
- block block_drop_unreferenced(block body) {
- - inst* curr;
- + block_mark_referenced(body);
- +
- block refd = gen_noop();
- - block unrefd = gen_noop();
- - int drop;
- - do {
- - drop = 0;
- - while ((curr = block_take(&body)) && curr->op != TOP) {
- - block b = inst_block(curr);
- - if (block_count_refs(b,refd) + block_count_refs(b,body) == 0) {
- - unrefd = BLOCK(unrefd, b);
- - drop++;
- - } else {
- - refd = BLOCK(refd, b);
- - }
- - }
- - if (curr && curr->op == TOP) {
- - body = BLOCK(inst_block(curr),body);
- + inst* curr;
- + while ((curr = block_take(&body))) {
- + if (curr->bound_by == curr && !curr->referenced) {
- + inst_free(curr);
- + } else {
- + refd = BLOCK(inst_block(curr), refd);
- }
- - body = BLOCK(refd, body);
- - refd = gen_noop();
- - } while (drop != 0);
- - block_free(unrefd);
- - return body;
- + }
- + return refd;
- }
-
- jv block_take_imports(block* body) {
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