Avoid live range references in opcodes

Don't store the live range of the freed variable for FREE_ON_RETURN
frees, instead look it up at runtime. As this is an extremely
unlikely codepath (in particular, it requires a loop variable with
a throwing destructor), saving the runtime lookup of the live range
is not worth the extra complexity this adds everywhere else.

3 files changed, 4 insertions, 44 deletions

diff --git a/ext/opcache/Optimizer/block_pass.c b/ext/opcache/Optimizer/block_pass.c
index 97e44fe0b2..b402cce276 100644
--- a/ext/opcache/Optimizer/block_pass.c
+++ b/ext/opcache/Optimizer/block_pass.c
@@ -347,10 +347,6 @@ static void zend_optimize_block(zend_basic_block *block, zend_op_array *op_array
 					    src->opcode != ZEND_FETCH_DIM_R &&
 					    src->opcode != ZEND_FETCH_OBJ_R &&
 					    src->opcode != ZEND_NEW) {
-						if (opline->extended_value & ZEND_FREE_ON_RETURN) {
-							/* mark as removed (empty live range) */
-							op_array->live_range[opline->op2.num].var = (uint32_t)-1;
-						}
 						src->result_type = IS_UNUSED;
 						MAKE_NOP(opline);
 					}
@@ -1040,10 +1036,6 @@ static void assemble_code_blocks(zend_cfg *cfg, zend_op_array *op_array, zend_op
 	/* adjust loop jump targets & remove unused live range entries */
 	if (op_array->last_live_range) {
 		int i, j;
-		uint32_t *map;
-		ALLOCA_FLAG(use_heap);
-
-		map = (uint32_t *)do_alloca(sizeof(uint32_t) * op_array->last_live_range, use_heap);
 
 		for (i = 0, j = 0; i < op_array->last_live_range; i++) {
 			if (op_array->live_range[i].var == (uint32_t)-1) {
@@ -1062,7 +1054,6 @@ static void assemble_code_blocks(zend_cfg *cfg, zend_op_array *op_array, zend_op
 				}
 				op_array->live_range[i].start = start_op;
 				op_array->live_range[i].end = end_op;
-				map[i] = j;
 				if (i != j) {
 					op_array->live_range[j]  = op_array->live_range[i];
 				}
@@ -1071,23 +1062,12 @@ static void assemble_code_blocks(zend_cfg *cfg, zend_op_array *op_array, zend_op
 		}
 
 		if (i != j) {
-			if ((op_array->last_live_range = j)) {
-				zend_op *opline = new_opcodes;
-				zend_op *end = opline + len;
-				while (opline != end) {
-					if ((opline->opcode == ZEND_FREE || opline->opcode == ZEND_FE_FREE) &&
-							opline->extended_value == ZEND_FREE_ON_RETURN) {
-						ZEND_ASSERT(opline->op2.num < (uint32_t) i);
-						opline->op2.num = map[opline->op2.num];
-					}
-					opline++;
-				}
-			} else {
+			op_array->last_live_range = j;
+			if (j == 0) {
 				efree(op_array->live_range);
 				op_array->live_range = NULL;
 			}
 		}
-		free_alloca(map, use_heap);
 	}
 
 	/* adjust early binding list */
diff --git a/ext/opcache/Optimizer/zend_dump.c b/ext/opcache/Optimizer/zend_dump.c
index 7fb55355fd..e4516b59cc 100644
--- a/ext/opcache/Optimizer/zend_dump.c
+++ b/ext/opcache/Optimizer/zend_dump.c
@@ -118,10 +118,6 @@ static void zend_dump_unused_op(const zend_op *opline, znode_op op, uint32_t fla
 		if (op.num != (uint32_t)-1) {
 			fprintf(stderr, " try-catch(%u)", op.num);
 		}
-	} else if (ZEND_VM_OP_LIVE_RANGE == (flags & ZEND_VM_OP_MASK)) {
-		if (opline->extended_value & ZEND_FREE_ON_RETURN) {
-			fprintf(stderr, " live-range(%u)", op.num);
-		}
 	} else if (ZEND_VM_OP_THIS == (flags & ZEND_VM_OP_MASK)) {
 		fprintf(stderr, " THIS");
 	} else if (ZEND_VM_OP_NEXT == (flags & ZEND_VM_OP_MASK)) {
diff --git a/ext/opcache/Optimizer/zend_optimizer.c b/ext/opcache/Optimizer/zend_optimizer.c
index 07860f3998..ffc04854e2 100644
--- a/ext/opcache/Optimizer/zend_optimizer.c
+++ b/ext/opcache/Optimizer/zend_optimizer.c
@@ -566,14 +566,9 @@ void zend_optimizer_remove_live_range(zend_op_array *op_array, uint32_t var)
 	if (op_array->last_live_range) {
 		int i = 0;
 		int j = 0;
-		uint32_t *map;
-		ALLOCA_FLAG(use_heap);
-
-		map = (uint32_t *)do_alloca(sizeof(uint32_t) * op_array->last_live_range, use_heap);
 
 		do {
 			if ((op_array->live_range[i].var & ~ZEND_LIVE_MASK) != var) {
-				map[i] = j;
 				if (i != j) {
 					op_array->live_range[j] = op_array->live_range[i];
 				}
@@ -582,23 +577,12 @@ void zend_optimizer_remove_live_range(zend_op_array *op_array, uint32_t var)
 			i++;
 		} while (i < op_array->last_live_range);
 		if (i != j) {
-			if ((op_array->last_live_range = j)) {
-				zend_op *opline = op_array->opcodes;
-				zend_op *end = opline + op_array->last;
-
-				while (opline != end) {
-					if ((opline->opcode == ZEND_FREE || opline->opcode == ZEND_FE_FREE) &&
-							opline->extended_value == ZEND_FREE_ON_RETURN) {
-						opline->op2.num = map[opline->op2.num];
-					}
-					opline++;
-				}
-			} else {
+			op_array->last_live_range = j;
+			if (j == 0) {
 				efree(op_array->live_range);
 				op_array->live_range = NULL;
 			}
 		}
-		free_alloca(map, use_heap);
 	}
 }