Ensure no entry predecessors for SSA construction

diff --git a/Zend/tests/entry_block_with_predecessors.phpt b/Zend/tests/entry_block_with_predecessors.phpt
new file mode 100644 (file)
index 0000000..ffc3147
--- /dev/null
+++ b/Zend/tests/entry_block_with_predecessors.phpt
@@ -0,0 +1,33 @@
+--TEST--
+For SSA form the entry block should have no predecessors
+--FILE--
+<?php
+
+function test() {
+    while (true) {
+        var_dump($a + 1);
+        $a = 1;
+        if (@$i++) {
+            break;
+        }
+    }
+}
+
+function test2() {
+    while (true) {
+        $a = 42;
+        if (@$i++ > 1) {
+            break;
+        }
+        $a = new stdClass;
+    }
+}
+
+test();
+test2();
+
+?>
+--EXPECTF--
+Notice: Undefined variable: a in %s on line %d
+int(1)
+int(2)

diff --git a/ext/opcache/Optimizer/dfa_pass.c b/ext/opcache/Optimizer/dfa_pass.c
index f7cae772fbb1600930e8f77bf2de3b2a954fed38..3be638eb927df626f9183525a360762ddd97a9b8 100644 (file)
--- a/ext/opcache/Optimizer/dfa_pass.c
+++ b/ext/opcache/Optimizer/dfa_pass.c
@@ -43,7 +43,8 @@ int zend_dfa_analyze_op_array(zend_op_array *op_array, zend_optimizer_ctx *ctx,
     /* Build SSA */
        memset(ssa, 0, sizeof(zend_ssa));
 
-       if (zend_build_cfg(&ctx->arena, op_array, 0, &ssa->cfg, flags) != SUCCESS) {
+       if (zend_build_cfg(&ctx->arena, op_array,
+                       ZEND_CFG_NO_ENTRY_PREDECESSORS, &ssa->cfg, flags) != SUCCESS) {
                return FAILURE;
        }
 

diff --git a/ext/opcache/Optimizer/zend_cfg.c b/ext/opcache/Optimizer/zend_cfg.c
index 2bf43fe9c5ac14eb04351c2641166579198a862e..9701f586067c2e39b12683efd8566f503fb94d45 100644 (file)
--- a/ext/opcache/Optimizer/zend_cfg.c
+++ b/ext/opcache/Optimizer/zend_cfg.c
@@ -240,9 +240,22 @@ static void record_successor(zend_basic_block *blocks, int pred, int n, int succ
        blocks[pred].successors[n] = succ;
 }
 
+static void initialize_block(zend_basic_block *block) {
+       block->flags = 0;
+       block->successors[0] = -1;
+       block->successors[1] = -1;
+       block->predecessors_count = 0;
+       block->predecessor_offset = -1;
+       block->idom = -1;
+       block->loop_header = -1;
+       block->level = -1;
+       block->children = -1;
+       block->next_child = -1;
+}
+
 #define BB_START(i) do { \
                if (!block_map[i]) { blocks_count++;} \
-               block_map[i] = 1; \
+               block_map[i]++; \
        } while (0)
 
 int zend_build_cfg(zend_arena **arena, const zend_op_array *op_array, uint32_t build_flags, zend_cfg *cfg, uint32_t *func_flags) /* {{{ */
@@ -255,6 +268,7 @@ int zend_build_cfg(zend_arena **arena, const zend_op_array *op_array, uint32_t b
        int blocks_count = 0;
        zend_basic_block *blocks;
        zval *zv;
+       zend_bool extra_entry_block = 0;
 
        cfg->split_at_live_ranges = (build_flags & ZEND_CFG_SPLIT_AT_LIVE_RANGES) != 0;
        cfg->map = block_map = zend_arena_calloc(arena, op_array->last, sizeof(uint32_t));
@@ -407,6 +421,12 @@ int zend_build_cfg(zend_arena **arena, const zend_op_array *op_array, uint32_t b
                }
        }
 
+       /* If the entry block has predecessors, we may need to split it */
+       if ((build_flags & ZEND_CFG_NO_ENTRY_PREDECESSORS)
+                       && op_array->last > 0 && block_map[0] > 1) {
+               extra_entry_block = 1;
+       }
+
        if (cfg->split_at_live_ranges) {
                for (j = 0; j < op_array->last_live_range; j++) {
                        BB_START(op_array->live_range[j].start);
@@ -429,6 +449,7 @@ int zend_build_cfg(zend_arena **arena, const zend_op_array *op_array, uint32_t b
                }
        }
 
+       blocks_count += extra_entry_block;
        cfg->blocks_count = blocks_count;
 
        /* Build CFG, Step 2: Build Array of Basic Blocks */
@@ -437,23 +458,23 @@ int zend_build_cfg(zend_arena **arena, const zend_op_array *op_array, uint32_t b
                return FAILURE;
        }
 
-       for (i = 0, blocks_count = -1; i < op_array->last; i++) {
+       blocks_count = -1;
+
+       if (extra_entry_block) {
+               initialize_block(&blocks[0]);
+               blocks[0].start = 0;
+               blocks[0].len = 0;
+               blocks_count++;
+       }
+
+       for (i = 0; i < op_array->last; i++) {
                if (block_map[i]) {
                        if (blocks_count >= 0) {
                                blocks[blocks_count].len = i - blocks[blocks_count].start;
                        }
                        blocks_count++;
-                       blocks[blocks_count].flags = 0;
+                       initialize_block(&blocks[blocks_count]);
                        blocks[blocks_count].start = i;
-                       blocks[blocks_count].successors[0] = -1;
-                       blocks[blocks_count].successors[1] = -1;
-                       blocks[blocks_count].predecessors_count = 0;
-                       blocks[blocks_count].predecessor_offset = -1;
-                       blocks[blocks_count].idom = -1;
-                       blocks[blocks_count].loop_header = -1;
-                       blocks[blocks_count].level = -1;
-                       blocks[blocks_count].children = -1;
-                       blocks[blocks_count].next_child = -1;
                }
                block_map[i] = blocks_count;
        }

diff --git a/ext/opcache/Optimizer/zend_cfg.h b/ext/opcache/Optimizer/zend_cfg.h
index 244a2ade97420fade2eb9e12e4efebb011d59705..da908fdbe3750f40edde0d77193397b3529b3eaa 100644 (file)
--- a/ext/opcache/Optimizer/zend_cfg.h
+++ b/ext/opcache/Optimizer/zend_cfg.h
@@ -96,6 +96,7 @@ typedef struct _zend_cfg {
 #define ZEND_SSA_DEBUG_PHI_PLACEMENT   (1<<28)
 #define ZEND_SSA_RC_INFERENCE          (1<<27)
 #define ZEND_CFG_SPLIT_AT_LIVE_RANGES  (1<<26)
+#define ZEND_CFG_NO_ENTRY_PREDECESSORS (1<<25)
 
 #define CRT_CONSTANT_EX(op_array, node, rt_constants) \
        ((rt_constants) ? \