Improved implementation of NOP removal pass from O(n^2) to O(n) (hnw)

diff --git a/ext/opcache/Optimizer/block_pass.c b/ext/opcache/Optimizer/block_pass.c
index b8c381406b38df07d3c5ce3d725ac7ee26a30cf6..7f874e7a4b89f3ddb7df099bb848e443c6836908 100644 (file)
--- a/ext/opcache/Optimizer/block_pass.c
+++ b/ext/opcache/Optimizer/block_pass.c
@@ -558,6 +558,52 @@ static void zend_rebuild_access_path(zend_cfg *cfg, zend_op_array *op_array, int
                convert_to_string((v)); \
        }
 
+static void strip_nop(zend_code_block *block)
+{
+       zend_op *opline = block->start_opline;
+       zend_op *end, *new_end;
+       int new_len = 0;
+
+       /* remove leading NOPs */
+       while (block->len > 0 && block->start_opline->opcode == ZEND_NOP) {
+               if (block->len == 1) {
+                       /* this block is all NOPs, join with following block */
+                       if (block->follow_to) {
+                               delete_code_block(block);
+                       }
+                       return;
+               }
+               block->start_opline++;
+               block->start_opline_no++;
+               block->len--;
+       }
+
+       /* strip the inside NOPs */
+       opline = new_end = block->start_opline;
+       end = opline + block->len;
+
+       while (opline < end) {
+               zend_op *src;
+               int len = 0;
+
+               while (opline < end && opline->opcode == ZEND_NOP) {
+                       opline++;
+               }
+               src = opline;
+
+               while (opline < end && opline->opcode != ZEND_NOP) {
+                       opline++;
+               }
+               len = opline - src;
+
+               /* move up non-NOP opcodes */
+               memmove(new_end, src, len*sizeof(zend_op));
+
+               new_end += len;
+       }
+       block->len = new_end - block->start_opline;
+}
+
 static void zend_optimize_block(zend_code_block *block, zend_op_array *op_array, char *used_ext TSRMLS_DC)
 {
        zend_op *opline = block->start_opline;
@@ -1168,45 +1214,7 @@ static void zend_optimize_block(zend_code_block *block, zend_op_array *op_array,
                opline++;
        }
 
-       /* remove leading NOPs */
-       while (block->len > 0 && block->start_opline->opcode == ZEND_NOP) {
-               if (block->len == 1) {
-                       /* this block is all NOPs, join with following block */
-                       if (block->follow_to) {
-                               delete_code_block(block);
-                       }
-                       if (op_array->T) {
-                               efree(Tsource);
-                       }
-                       return;
-               }
-               block->start_opline++;
-               block->start_opline_no++;
-               block->len--;
-       }
-
-       /* strip the inside NOPs */
-       opline = block->start_opline;
-       end = opline + block->len;
-       while (opline < end) {
-               if (opline->opcode == ZEND_NOP) {
-                       zend_op *nop = opline + 1;
-                       int noplen;
-                       while (nop < end && nop->opcode == ZEND_NOP) {
-                               nop++;
-                       }
-                       noplen = nop-opline;
-                       if (nop < end) {
-                               /* move up non-NOP opcodes */
-                               memmove(opline, nop, (end-nop)*sizeof(zend_op));
-                       } else {
-                               /* all NOPs up to the end, do nothing */
-                       }
-                       block->len -= noplen;
-                       end = block->start_opline + block->len;
-               }
-               opline++;
-       }
+       strip_nop(block);
 
        if (op_array->T) {
                efree(Tsource);