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Properly unlinking dead blocks from predecessors/successors and dominators

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This commit is contained in:
Dmitry Stogov 2017-07-10 16:22:47 +03:00
parent 502002aa6e
commit 07f45d8a3d
1 changed files with 43 additions and 13 deletions
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56
ext/opcache/Optimizer/zend_ssa.c
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@ -1262,22 +1262,26 @@ static inline void zend_ssa_remove_defs_of_instr(zend_ssa *ssa, zend_ssa_op *ssa
}
/* }}} */
static inline void zend_ssa_remove_phi_source(zend_ssa *ssa, zend_ssa_phi *phi, int i) /* {{{ */
static inline void zend_ssa_remove_phi_source(zend_ssa *ssa, zend_ssa_phi *phi, int pred_offset, int predecessors_count) /* {{{ */
{
int j, var_num = phi->sources[i];
int j, var_num = phi->sources[pred_offset];
predecessors_count--;
if (pred_offset < predecessors_count) {
memmove(phi->sources + pred_offset, phi->sources + pred_offset + 1, (predecessors_count - pred_offset) * sizeof(uint32_t));
}
/* Check if they same var is used in a different phi operand as well, in this case we don't
* need to adjust the use chain (but may have to move the next pointer). */
for (j = 0; j < ssa->cfg.blocks[phi->block].predecessors_count; j++) {
for (j = 0; j < predecessors_count; j++) {
if (phi->sources[j] == var_num) {
if (j < i) {
phi->sources[i] = -1;
if (j < pred_offset) {
ZEND_ASSERT(phi->use_chains[pred_offset] == NULL);
return;
}
if (j > i) {
phi->use_chains[j] = phi->use_chains[i];
phi->use_chains[i] = NULL;
phi->sources[i] = -1;
if (j >= pred_offset) {
phi->use_chains[j] = phi->use_chains[pred_offset];
phi->use_chains[pred_offset] = NULL;
return;
}
}
@ -1285,8 +1289,7 @@ static inline void zend_ssa_remove_phi_source(zend_ssa *ssa, zend_ssa_phi *phi,
/* Variable only used in one operand, remove the phi from the use chain. */
zend_ssa_remove_use_of_phi_source(ssa, phi, var_num);
phi->sources[i] = -1;
phi->use_chains[i] = NULL;
phi->use_chains[pred_offset] = NULL;
}
/* }}} */
@ -1387,13 +1390,17 @@ void zend_ssa_remove_block(zend_op_array *op_array, zend_ssa *ssa, int i) /* {{{
}
} else {
if (phi->sources[pred_offset] >= 0) {
zend_ssa_remove_phi_source(ssa, phi, pred_offset);
zend_ssa_remove_phi_source(ssa, phi, pred_offset, next_block->predecessors_count);
}
}
}
/* Remove this predecessor */
predecessors[pred_offset] = -1;
next_block->predecessors_count--;
if (pred_offset < next_block->predecessors_count) {
predecessors = &ssa->cfg.predecessors[next_block->predecessor_offset + pred_offset];
memmove(predecessors, predecessors + 1, (next_block->predecessors_count - pred_offset) * sizeof(uint32_t));
}
}
/* Remove successors of predecessors */
@ -1413,6 +1420,29 @@ void zend_ssa_remove_block(zend_op_array *op_array, zend_ssa *ssa, int i) /* {{{
}
}
}
block->successors_count = 0;
block->predecessors_count = 0;
/* Remove from dominators tree */
if (block->idom >= 0) {
j = ssa->cfg.blocks[block->idom].children;
if (j == i) {
ssa->cfg.blocks[block->idom].children = block->next_child;
} else if (j >= 0) {
while (ssa->cfg.blocks[j].next_child >= 0) {
if (ssa->cfg.blocks[j].next_child == i) {
ssa->cfg.blocks[j].next_child = block->next_child;
break;
}
j = ssa->cfg.blocks[j].next_child;
}
}
}
block->idom = -1;
block->level = -1;
block->children = -1;
block->next_child = -1;
}
/* }}} */