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Bug #56103 optimizer hang, taking up 40% cpu usage
Submitted: 2004-06-19 01:06 UTC Modified: 2013-02-05 05:39 UTC
From: xuefer at 21cn dot com Assigned:
Status: Wont fix Package: APC (PECL)
PHP Version: 4.3.3 OS: linux
Private report: No CVE-ID: None
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From: xuefer at 21cn dot com
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 [2004-06-19 01:06 UTC] xuefer at 21cn dot com 
Description:
------------
apc.optimization=1

i have tested on my code, but i don't have a stripped down testcase script
this patch solved the problem.
logically, RESTART_PEEPHOLE_LOOP should be done only when opcode is modified
apc is still SEGV with this patch for my script, but at least it won't hang

Index: apc_optimizer.c
===================================================================
RCS file: /repository/pecl/apc/apc_optimizer.c,v
retrieving revision 3.24
diff -u -r3.24 apc_optimizer.c
--- apc_optimizer.c     20 Jul 2003 00:07:02 -0000      3.24
+++ apc_optimizer.c     19 Jun 2004 05:09:40 -0000
@@ -790,15 +790,15 @@
         if ((p = peephole_inc(op_array->opcodes, i, op_array->last))) {
             if (!are_branch_targets(cdr(p), jumps)) {
                 rewrite_inc(op_array->opcodes, p);
+                RESTART_PEEPHOLE_LOOP;
             }
-            RESTART_PEEPHOLE_LOOP;
         }
         
         if ((p = peephole_print(op_array->opcodes, i, op_array->last))) {
             if (!are_branch_targets(cdr(p), jumps)) {
                 rewrite_print(op_array->opcodes, p);
+                RESTART_PEEPHOLE_LOOP;
             }
-            RESTART_PEEPHOLE_LOOP;
         }
         
         if ((p = peephole_multiple_echo(op_array->opcodes, i, op_array->last))) {
@@ -810,27 +810,27 @@
         if ((p = peephole_constant_fold(op_array->opcodes, i, op_array->last))) {
             if (!are_branch_targets(cdr(p), jumps)) {
                 rewrite_constant_fold(op_array->opcodes, p);
+                RESTART_PEEPHOLE_LOOP;
             }
-            RESTART_PEEPHOLE_LOOP;
         }
         
         if ((p = peephole_fcall(op_array->opcodes, i, op_array->last))) {
             if (!are_branch_targets(cdr(p), jumps)) {
                 rewrite_fcall(op_array->opcodes, p);
+                RESTART_PEEPHOLE_LOOP;
             }
-            RESTART_PEEPHOLE_LOOP;
         }
         if ((p = peephole_add_string(op_array->opcodes, i, op_array->last))) {
             if (!are_branch_targets(cdr(p), jumps)) {
                 rewrite_add_string(op_array->opcodes, p);
+                RESTART_PEEPHOLE_LOOP;
             }
-            RESTART_PEEPHOLE_LOOP;
         }
         if ((p = peephole_needless_bool(op_array->opcodes, i, op_array->last))) {
             if (!are_branch_targets(cdr(p), jumps)) {
                 rewrite_needless_bool(op_array->opcodes, p);
+                RESTART_PEEPHOLE_LOOP;
             }
-            RESTART_PEEPHOLE_LOOP;
         }
     }

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 [2004-06-23 12:35 UTC] xuefer at 21cn dot com 
this patch
1. fixed for http://pecl.php.net/bugs/bug.php?id=1679
2. improved "Cannot break/continue***", tell which file which line
3. fixed previous patch's memory leak: do pair_destroy(p);
4. comment out "constant_fold", it's not stable, without it all my scripts work fine

Index: apc_optimizer.c
===================================================================
RCS file: /repository/pecl/apc/apc_optimizer.c,v
retrieving revision 3.24
diff -u -r3.24 apc_optimizer.c
--- apc_optimizer.c	20 Jul 2003 00:07:02 -0000	3.24
+++ apc_optimizer.c	23 Jun 2004 16:29:21 -0000
@@ -139,7 +139,10 @@
                 if (ops[j].opcode != ZEND_NOP) {
                     break;
                 }
-                j++;
+                if (++ j >= num_ops) {
+                    j --;
+                    break;
+                }
             }
 
             /* update jump table IFF ops[j] is a branch */
@@ -392,8 +395,10 @@
         array_offset = opline->op1.u.opline_num;
         do {
             if (array_offset < 0) {
-                zend_error(E_ERROR, "Cannot break/continue %d level", 
-                           original_nest_levels);
+                zend_error(E_ERROR, "Cannot break/continue %d level (%s#%d)", 
+                           original_nest_levels,
+                           op_array->filename,
+                           opline->lineno);
             }
             jmp_to = &op_array->brk_cont_array[array_offset];
             if (nest_levels>1) {
@@ -763,6 +768,22 @@
 zend_op_array* apc_optimize_op_array(zend_op_array* op_array)
 {
 #define RESTART_PEEPHOLE_LOOP { pair_destroy(p); i = -1; continue; }
+#define OPTIMIZE1(name) { \
+        if ((p = peephole_ ## name(op_array->opcodes, i, op_array->last))) { \
+            rewrite_ ## name(op_array->opcodes, p); \
+            pair_destroy(p); \
+        } \
+}
+
+#define OPTIMIZE2(name) { \
+        if ((p = peephole_ ## name(op_array->opcodes, i, op_array->last))) { \
+            if (!are_branch_targets(cdr(p), jumps)) { \
+                rewrite_ ## name(op_array->opcodes, p); \
+                RESTART_PEEPHOLE_LOOP; \
+            } \
+            pair_destroy(p); \
+        } \
+}
 
     Pair** jumps;
     int i;
@@ -777,61 +798,17 @@
     for (i = 0; i < op_array->last; i++) {
         Pair* p;
         
-        if ((p = peephole_cast(op_array->opcodes, i, op_array->last))) {
-            rewrite_const_cast(op_array->opcodes, p);
-            RESTART_PEEPHOLE_LOOP;
-        }
-
-        if ((p = peephole_is_equal_bool(op_array->opcodes, i, op_array->last))) {
-            rewrite_is_equal_bool(op_array->opcodes, p);
-            RESTART_PEEPHOLE_LOOP;
-        } 
-        
-        if ((p = peephole_inc(op_array->opcodes, i, op_array->last))) {
-            if (!are_branch_targets(cdr(p), jumps)) {
-                rewrite_inc(op_array->opcodes, p);
-            }
-            RESTART_PEEPHOLE_LOOP;
-        }
-        
-        if ((p = peephole_print(op_array->opcodes, i, op_array->last))) {
-            if (!are_branch_targets(cdr(p), jumps)) {
-                rewrite_print(op_array->opcodes, p);
-            }
-            RESTART_PEEPHOLE_LOOP;
-        }
-        
-        if ((p = peephole_multiple_echo(op_array->opcodes, i, op_array->last))) {
-            if (!are_branch_targets(cdr(p), jumps)) {
-                rewrite_multiple_echo(op_array->opcodes, p);
-            }
-        } 
-        
-        if ((p = peephole_constant_fold(op_array->opcodes, i, op_array->last))) {
-            if (!are_branch_targets(cdr(p), jumps)) {
-                rewrite_constant_fold(op_array->opcodes, p);
-            }
-            RESTART_PEEPHOLE_LOOP;
-        }
-        
-        if ((p = peephole_fcall(op_array->opcodes, i, op_array->last))) {
-            if (!are_branch_targets(cdr(p), jumps)) {
-                rewrite_fcall(op_array->opcodes, p);
-            }
-            RESTART_PEEPHOLE_LOOP;
-        }
-        if ((p = peephole_add_string(op_array->opcodes, i, op_array->last))) {
-            if (!are_branch_targets(cdr(p), jumps)) {
-                rewrite_add_string(op_array->opcodes, p);
-            }
-            RESTART_PEEPHOLE_LOOP;
-        }
-        if ((p = peephole_needless_bool(op_array->opcodes, i, op_array->last))) {
-            if (!are_branch_targets(cdr(p), jumps)) {
-                rewrite_needless_bool(op_array->opcodes, p);
-            }
-            RESTART_PEEPHOLE_LOOP;
-        }
+        OPTIMIZE1(cast);
+        OPTIMIZE1(is_equal_bool);
+        OPTIMIZE2(inc);
+        OPTIMIZE2(print);
+        OPTIMIZE2(multiple_echo);
+        /* not stable
+        OPTIMIZE2(constant_fold);
+        */
+        OPTIMIZE2(fcall);
+        OPTIMIZE2(add_string);
+        OPTIMIZE2(needless_bool);
     }
 
     op_array->last = compress_ops(op_array, jumps);
@@ -839,6 +816,8 @@
     
     return op_array;
 
+#undef OPTIMIZE1
+#undef OPTIMIZE2
 #undef RESTART_PEEPHOLE_LOOP
 }
 /* }}} */
 [2004-06-23 12:42 UTC] xuefer at 21cn dot com 
OPTIMIZE1(cast); should be OPTIMIZE1(const_cast);
and:
@@ -518,7 +523,7 @@
 
 /* {{{ peephole match functions */
 
-static Pair* peephole_cast(zend_op* ops, int i, int num_ops)
+static Pair* peephole_const_cast(zend_op* ops, int i, int num_ops)
 {
     if (ops[i].opcode == ZEND_CAST &&
         ops[i].op1.op_type == IS_CONST &&
 [2013-02-05 05:39 UTC] gopalv@php.net 
Optimizer removed from codebase
 [2013-02-05 05:39 UTC] gopalv@php.net
-Status: Open +Status: Wont fix
 
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