From 03c4d20cddbeb9bbc0c7cde982a538d40160eab6 Mon Sep 17 00:00:00 2001
From: "yu.dongliang" <maja_creater@qq.com>
Date: Wed, 19 Oct 2022 17:45:25 +0800
Subject: [PATCH] optimize: pointer dereference when the variable pointed can
be identified, such as: int a = 1; int* p = &a; int** pp = &p;
**pp += 2; // this will be instead of 'a += 2', and 'p = &a; pp = &p' will be deleted.
---
core/scf_3ac.c | 1 +
core/scf_optimizer_basic_block.c | 43 +++++++------
core/scf_optimizer_pointer_alias.c | 100 +++++++++++++++++++++++------
3 files changed, 104 insertions(+), 40 deletions(-)
diff --git a/core/scf_3ac.c b/core/scf_3ac.c
index 6089384..1d8f807 100644
--- a/core/scf_3ac.c
+++ b/core/scf_3ac.c
@@ -687,6 +687,7 @@ int scf_3ac_code_to_dag(scf_3ac_code_t* c, scf_list_t* dag)
return ret;
} else if (scf_type_is_assign_array_index(c->op->type)
+ || scf_type_is_assign_dereference(c->op->type)
|| scf_type_is_assign_pointer(c->op->type)) {
scf_3ac_operand_t* src;
diff --git a/core/scf_optimizer_basic_block.c b/core/scf_optimizer_basic_block.c
index 1c86111..81a1d07 100644
--- a/core/scf_optimizer_basic_block.c
+++ b/core/scf_optimizer_basic_block.c
@@ -55,15 +55,18 @@ static int _bb_dag_update(scf_basic_block_t* bb, scf_vector_t* dag, scf_list_t*
if (scf_type_is_assign_array_index(dn->type))
continue;
+ if (scf_type_is_assign_dereference(dn->type) || SCF_OP_DEREFERENCE == dn->type)
+ continue;
if (scf_type_is_assign_pointer(dn->type))
continue;
if (scf_type_is_assign(dn->type)
- || SCF_OP_INC == dn->type || SCF_OP_DEC == dn->type
- || SCF_OP_3AC_INC == dn->type || SCF_OP_3AC_DEC == dn->type
- || SCF_OP_3AC_SETZ == dn->type || SCF_OP_3AC_SETNZ == dn->type
- || SCF_OP_3AC_SETLT == dn->type || SCF_OP_3AC_SETLE == dn->type
- || SCF_OP_3AC_SETGT == dn->type || SCF_OP_3AC_SETGE == dn->type) {
+ || SCF_OP_INC == dn->type || SCF_OP_DEC == dn->type
+ || SCF_OP_3AC_INC == dn->type || SCF_OP_3AC_DEC == dn->type
+ || SCF_OP_3AC_SETZ == dn->type || SCF_OP_3AC_SETNZ == dn->type
+ || SCF_OP_3AC_SETLT == dn->type || SCF_OP_3AC_SETLE == dn->type
+ || SCF_OP_3AC_SETGT == dn->type || SCF_OP_3AC_SETGE == dn->type
+ || SCF_OP_ADDRESS_OF == dn->type) {
if (!dn->childs) {
scf_list_del(&dn->list);
@@ -84,24 +87,27 @@ static int _bb_dag_update(scf_basic_block_t* bb, scf_vector_t* dag, scf_list_t*
return -1;
}
- if (scf_vector_find(bb->dn_saves, dn_func)
- || scf_vector_find(bb->dn_resaves, dn_func))
- continue;
+ if (SCF_OP_ADDRESS_OF != dn->type) {
- assert(dn_bb->parents && dn_bb->parents->size > 0);
+ if (scf_vector_find(bb->dn_saves, dn_func)
+ || scf_vector_find(bb->dn_resaves, dn_func))
+ continue;
- if (dn != dn_bb->parents->data[dn_bb->parents->size - 1])
- continue;
+ assert(dn_bb->parents && dn_bb->parents->size > 0);
+
+ if (dn != dn_bb->parents->data[dn_bb->parents->size - 1])
+ continue;
- if (2 == dn->childs->size) {
- dn_bb2 = dn->childs->data[1];
+ if (2 == dn->childs->size) {
+ dn_bb2 = dn->childs->data[1];
- assert(0 == scf_vector_del(dn->childs, dn_bb2));
- assert(0 == scf_vector_del(dn_bb2->parents, dn));
+ assert(0 == scf_vector_del(dn->childs, dn_bb2));
+ assert(0 == scf_vector_del(dn_bb2->parents, dn));
- if (0 == dn_bb2->parents->size) {
- scf_vector_free(dn_bb2->parents);
- dn_bb2->parents = NULL;
+ if (0 == dn_bb2->parents->size) {
+ scf_vector_free(dn_bb2->parents);
+ dn_bb2->parents = NULL;
+ }
}
}
@@ -355,7 +361,6 @@ static int _optimize_basic_block(scf_ast_t* ast, scf_function_t* f, scf_list_t*
|| bb->ret_flag
|| bb->end_flag
|| bb->call_flag
- || bb->dereference_flag
|| bb->varg_flag) {
scf_logd("bb: %p, jmp:%d,ret:%d, end: %d, call:%d, varg:%d, dereference_flag: %d\n",
bb, bb->jmp_flag, bb->ret_flag, bb->end_flag, bb->call_flag, bb->dereference_flag,
diff --git a/core/scf_optimizer_pointer_alias.c b/core/scf_optimizer_pointer_alias.c
index d73035e..583cdb1 100644
--- a/core/scf_optimizer_pointer_alias.c
+++ b/core/scf_optimizer_pointer_alias.c
@@ -1,13 +1,15 @@
#include"scf_optimizer.h"
#include"scf_pointer_alias.h"
-static int _filter_3ac_by_pointer_alias(scf_3ac_operand_t* pointer, scf_list_t* prev, scf_basic_block_t* bb)
+static int _filter_3ac_by_pointer_alias(scf_3ac_operand_t* pointer, scf_list_t* prev, scf_basic_block_t* bb, scf_list_t* bb_list_head)
{
- scf_3ac_code_t* c2;
- scf_3ac_code_t* c3;
- scf_list_t* l2;
- scf_list_t* l3;
- scf_list_t h;
+ scf_basic_block_t* bb2;
+ scf_basic_block_t* bb3;
+ scf_3ac_code_t* c2;
+ scf_3ac_code_t* c3;
+ scf_list_t* l2;
+ scf_list_t* l3;
+ scf_list_t h;
scf_list_init(&h);
@@ -17,31 +19,81 @@ static int _filter_3ac_by_pointer_alias(scf_3ac_operand_t* pointer, scf_list_t*
return ret;
}
- for (l2 = scf_list_head(&h); l2 != scf_list_sentinel(&h); ) {
+ l3 = prev;
+
+ for (l2 = scf_list_tail(&h); l2 != scf_list_sentinel(&h); ) {
c2 = scf_list_data(l2, scf_3ac_code_t, list);
- l2 = scf_list_next(l2);
- for (l3 = prev; l3 != scf_list_sentinel(&bb->code_list_head); ) {
+ for ( ; l3 != scf_list_sentinel(&bb->code_list_head); ) {
c3 = scf_list_data(l3, scf_3ac_code_t, list);
- l3 = scf_list_prev(l3);
if (scf_3ac_code_same(c2, c3)) {
+ l3 = scf_list_prev(l3);
+ l2 = scf_list_prev(l2);
+
scf_list_del(&c3->list);
+ scf_list_del(&c2->list);
+
scf_3ac_code_free(c3);
+ scf_3ac_code_free(c2);
break;
}
+
+ l3 = scf_list_prev(l3);
}
- scf_list_del(&c2->list);
- scf_3ac_code_free(c2);
+ if (l3 == scf_list_sentinel(&bb->code_list_head)) {
+
+ if (scf_list_prev(&bb->list) == scf_list_sentinel(bb_list_head))
+ break;
+
+ bb2 = scf_list_data(scf_list_prev(&bb->list), scf_basic_block_t, list);
+
+ if (!bb2->nexts || bb2->nexts->size != 1)
+ break;
+
+ if (!bb->prevs || bb->prevs->size != 1)
+ break;
+
+ if (bb2->nexts->data[0] != bb || bb->prevs->data[0] != bb2)
+ break;
+
+ if (scf_list_empty(&bb->code_list_head)) {
+
+ SCF_XCHG(bb2->nexts, bb->nexts);
+
+ int i;
+ int j;
+
+ for (i = 0; i < bb2->nexts->size; i++) {
+ bb3 = bb2->nexts->data[i];
+
+ for (j = 0; j < bb3->prevs->size; j++) {
+
+ if (bb3->prevs->data[j] == bb) {
+ bb3->prevs->data[j] = bb2;
+ break;
+ }
+ }
+ }
+
+ scf_list_del(&bb->list);
+
+ scf_basic_block_free(bb);
+ bb = NULL;
+ }
+
+ bb = bb2;
+ l3 = scf_list_tail(&bb->code_list_head);
+ }
}
return 0;
}
-static int _3ac_pointer_alias(scf_dag_node_t* alias, scf_3ac_code_t* c, scf_basic_block_t* bb)
+static int _3ac_pointer_alias(scf_dag_node_t* alias, scf_3ac_code_t* c, scf_basic_block_t* bb, scf_list_t* bb_list_head)
{
scf_3ac_operand_t* pointer;
@@ -58,7 +110,7 @@ static int _3ac_pointer_alias(scf_dag_node_t* alias, scf_3ac_code_t* c, scf_basi
}
#if 1
- ret = _filter_3ac_by_pointer_alias(pointer, scf_list_prev(&c->list), bb);
+ ret = _filter_3ac_by_pointer_alias(pointer, scf_list_prev(&c->list), bb, bb_list_head);
if (ret < 0)
return ret;
#endif
@@ -160,13 +212,16 @@ static int _alias_assign_dereference(scf_vector_t** paliases, scf_dag_node_t* dn
status = aliases->data[0];
if (SCF_DN_ALIAS_VAR == status->alias_type) {
- ret = _3ac_pointer_alias(status->alias, c, bb);
+
+ ret = _3ac_pointer_alias(status->alias, c, bb, bb_list_head);
+
scf_vector_free(aliases);
+ aliases = NULL;
+
if (ret < 0)
return ret;
return scf_basic_block_inited_vars(bb, bb_list_head);
}
- return 0;
}
*paliases = aliases;
@@ -196,7 +251,6 @@ static int __optimize_alias_dereference(scf_3ac_operand_t* pointer, scf_3ac_code
return ret;
if (aliases) {
- flag = 1;
if (1 == aliases->size) {
ds = aliases->data[0];
@@ -217,7 +271,7 @@ static int __optimize_alias_dereference(scf_3ac_operand_t* pointer, scf_3ac_code
l = scf_list_prev(&c->list);
}
- ret = _filter_3ac_by_pointer_alias(pointer, l, bb2);
+ ret = _filter_3ac_by_pointer_alias(pointer, l, bb2, bb_list_head);
if (ret < 0)
return ret;
@@ -227,7 +281,9 @@ static int __optimize_alias_dereference(scf_3ac_operand_t* pointer, scf_3ac_code
if (ret < 0)
return ret;
- flag = 0;
+ scf_vector_free(aliases);
+ aliases = NULL;
+ return 0;
}
}
@@ -238,6 +294,8 @@ static int __optimize_alias_dereference(scf_3ac_operand_t* pointer, scf_3ac_code
if (ret < 0)
return ret;
+
+ flag = 1;
}
return flag;
@@ -301,13 +359,13 @@ static int __optimize_alias_bb(scf_list_t** pend, scf_list_t* start, scf_basic_b
flag += ret;
} else if (SCF_OP_DEREFERENCE == c->op->type) {
-
+#if 0
assert(c->dsts && 1 == c->dsts->size);
dst = c->dsts->data[0];
dn_dereference = dst->dag_node;
ret = _alias_dereference(&aliases, dn_pointer, c, bb, bb_list_head);
-
+#endif
} else {
if (i > 0)
break;
--
2.25.1