Proposal: Run the Control Flow Graph pass twice

ext/opcache/Optimizer/block_pass.c

@@ -22,6 +22,7 @@
 #include "php.h"
 #include "Optimizer/zend_optimizer.h"
 #include "Optimizer/zend_optimizer_internal.h"
+#include "Optimizer/zend_call_graph.h"
 #include "zend_API.h"
 #include "zend_constants.h"
 #include "zend_execute.h"
@@ -924,12 +925,14 @@ static void zend_optimize_block(zend_basic_block *block, zend_op_array *op_array
 /* Rebuild plain (optimized) op_array from CFG */
 static void assemble_code_blocks(zend_cfg *cfg, zend_op_array *op_array, zend_optimizer_ctx *ctx)
 {
+	zend_func_info *func_info;
 	zend_basic_block *blocks = cfg->blocks;
 	zend_basic_block *end = blocks + cfg->blocks_count;
 	zend_basic_block *b;
 	zend_op *new_opcodes;
 	zend_op *opline;
 	uint32_t len = 0;
+	size_t opline_delta;
 	int n;
 
 	for (b = blocks; b < end; b++) {
@@ -970,6 +973,7 @@ static void assemble_code_blocks(zend_cfg *cfg, zend_op_array *op_array, zend_op
 	}
 
 	new_opcodes = emalloc(len * sizeof(zend_op));
+	opline_delta = ((uint8_t *)new_opcodes) - ((uint8_t *)op_array->opcodes);
 	opline = new_opcodes;
 
 	/* Copy code of reachable blocks into a single buffer */
@@ -1095,6 +1099,17 @@ static void assemble_code_blocks(zend_cfg *cfg, zend_op_array *op_array, zend_op
 			zend_build_delayed_early_binding_list(op_array);
 	}
 
+	/* update call graph (needed in second run of pass 5) */
+	func_info = ZEND_FUNC_INFO(op_array);
+	if (func_info) {
+		zend_call_info *call_info = func_info->callee_info;
+		while (call_info) {
+			call_info->caller_init_opline = (zend_op *)(((uint8_t *)call_info->caller_init_opline) + opline_delta);
+			call_info->caller_call_opline = (zend_op *)(((uint8_t *)call_info->caller_call_opline) + opline_delta);
+			call_info = call_info->next_callee;
+		}
+	}
+
 	/* rebuild map (just for printing) */
 	memset(cfg->map, -1, sizeof(int) * op_array->last);
 	for (n = 0; n < cfg->blocks_count; n++) {

ext/opcache/Optimizer/zend_optimizer.c

@@ -1300,6 +1300,16 @@ static void zend_optimize_op_array(zend_op_array      *op_array,
 	/* Redo pass_two() */
 	zend_redo_pass_two(op_array);
 
+	/* pass 5:
+	 * - CFG optimization (again) after converting code to no-ops.
+	 */
+	if (ZEND_OPTIMIZER_PASS_5 & ctx->optimization_level) {
+		zend_optimize_cfg(op_array, ctx);
+		if (ctx->debug_level & ZEND_DUMP_AFTER_PASS_5) {
+			zend_dump_op_array(op_array, 0, "after repeating pass 5", NULL);
+		}
+	}
+
 	if (op_array->live_range) {
 		zend_recalc_live_ranges(op_array, NULL);
 	}
@@ -1417,6 +1427,15 @@ int zend_optimize_script(zend_script *script, zend_long optimization_level, zend
 			}
 		}
 
+		if (ZEND_OPTIMIZER_PASS_5 & optimization_level) {
+			for (i = 0; i < call_graph.op_arrays_count; i++) {
+				zend_optimize_cfg(call_graph.op_arrays[i], &ctx);
+				if (debug_level & ZEND_DUMP_AFTER_PASS_5) {
+					zend_dump_op_array(call_graph.op_arrays[i], 0, "after repeating pass 5", NULL);
+				}
+			}
+		}
+
 		if (ZEND_OPTIMIZER_PASS_11 & optimization_level) {
 			for (i = 0; i < call_graph.op_arrays_count; i++) {
 				zend_optimizer_compact_literals(call_graph.op_arrays[i], &ctx);

ext/opcache/tests/opt/sccp_002.phpt

@@ -28,10 +28,9 @@ $_main: ; (lines=1, args=0, vars=0, tmps=0)
     ; %ssccp_002.php:1-14
 L0 (14):    RETURN int(1)
 
-foo: ; (lines=4, args=1, vars=1, tmps=0)
+foo: ; (lines=3, args=1, vars=1, tmps=0)
     ; (after optimizer)
     ; %ssccp_002.php:2-12
 L0 (2):     CV0($x) = RECV 1
-L1 (9):     ECHO int(1)
-L2 (11):    ECHO int(1)
-L3 (12):    RETURN null
+L1 (11):    ECHO string("11")
+L2 (12):    RETURN null

ext/opcache/tests/opt/sccp_003.phpt

@@ -28,9 +28,8 @@ $_main: ; (lines=1, args=0, vars=0, tmps=0)
     ; %ssccp_003.php:1-14
 L0 (14):    RETURN int(1)
 
-foo: ; (lines=3, args=0, vars=0, tmps=0)
+foo: ; (lines=2, args=0, vars=0, tmps=0)
     ; (after optimizer)
     ; %ssccp_003.php:2-12
-L0 (9):     ECHO int(1)
-L1 (11):    ECHO int(1)
-L2 (12):    RETURN null
+L0 (11):    ECHO string("11")
+L1 (12):    RETURN null

ext/opcache/tests/opt/sccp_004.phpt

@@ -31,10 +31,9 @@ $_main: ; (lines=1, args=0, vars=0, tmps=0)
     ; %ssccp_004.php:1-17
 L0 (17):    RETURN int(1)
 
-foo: ; (lines=4, args=1, vars=1, tmps=0)
+foo: ; (lines=3, args=1, vars=1, tmps=0)
     ; (after optimizer)
     ; %ssccp_004.php:2-15
 L0 (2):     CV0($x) = RECV 1
-L1 (11):    ECHO bool(true)
-L2 (14):    ECHO int(1)
-L3 (15):    RETURN null
+L1 (14):    ECHO string("11")
+L2 (15):    RETURN null

ext/opcache/tests/opt/sccp_010.phpt

@@ -29,9 +29,8 @@ $_main: ; (lines=1, args=0, vars=0, tmps=0)
     ; %ssccp_010.php:1-15
 L0 (15):    RETURN int(1)
 
-foo: ; (lines=3, args=0, vars=0, tmps=0)
+foo: ; (lines=2, args=0, vars=0, tmps=0)
     ; (after optimizer)
     ; %ssccp_010.php:2-13
-L0 (10):    ECHO int(1)
-L1 (12):    ECHO int(1)
-L2 (13):    RETURN null
+L0 (12):    ECHO string("11")
+L1 (13):    RETURN null

ext/opcache/tests/opt/sccp_012.phpt

@@ -31,9 +31,8 @@ $_main: ; (lines=1, args=0, vars=0, tmps=0)
     ; %ssccp_012.php:1-17
 L0 (17):    RETURN int(1)
 
-foo: ; (lines=3, args=0, vars=0, tmps=0)
+foo: ; (lines=2, args=0, vars=0, tmps=0)
     ; (after optimizer)
     ; %ssccp_012.php:2-15
-L0 (10):    ECHO int(1)
-L1 (14):    ECHO int(4)
-L2 (15):    RETURN null
+L0 (14):    ECHO string("14")
+L1 (15):    RETURN null

ext/opcache/tests/opt/sccp_026.phpt

@@ -15,7 +15,7 @@ function test($var) {
         return;
     }
 
-    var_dump($username); 
+    var_dump($username);
 }
 ?>
 --EXPECTF--
@@ -24,15 +24,14 @@ $_main: ; (lines=1, args=0, vars=0, tmps=0)
     ; %s:1-10
 L0 (10):    RETURN int(1)
 
-test: ; (lines=9, args=1, vars=2, tmps=1)
+test: ; (lines=8, args=1, vars=2, tmps=1)
     ; (after optimizer)
     ; %s:2-8
 L0 (2):     CV0($var) = RECV 1
 L1 (3):     T2 = TYPE_CHECK (string) CV0($var)
-L2 (3):     JMPZ T2 L4
-L3 (3):     JMP L5
-L4 (4):     RETURN null
-L5 (7):     INIT_FCALL 1 %d string("var_dump")
-L6 (7):     SEND_VAR CV1($username) 1
-L7 (7):     DO_ICALL
-L8 (8):     RETURN null
+L2 (3):     JMPNZ T2 L4
+L3 (4):     RETURN null
+L4 (7):     INIT_FCALL 1 96 string("var_dump")
+L5 (7):     SEND_VAR CV1($username) 1
+L6 (7):     DO_ICALL
+L7 (8):     RETURN null