Remove dead JMP/JMPZ/JMPNZ/JMPZNZ (DCE pass can't remove them)

diff --git a/ext/opcache/Optimizer/dfa_pass.c b/ext/opcache/Optimizer/dfa_pass.c
index 642e0d3eadc9e359af5aa6ff2c172f5cd3ee00de..532597713d50ac2eaab528c0d4b71b9c9cd591dd 100644 (file)
--- a/ext/opcache/Optimizer/dfa_pass.c
+++ b/ext/opcache/Optimizer/dfa_pass.c
@@ -450,6 +450,84 @@ int zend_dfa_optimize_calls(zend_op_array *op_array, zend_ssa *ssa)
        return removed_ops;
 }
 
+static int zend_dfa_optimize_jmps(zend_op_array *op_array, zend_ssa *ssa)
+{
+       int removed_ops = 0;
+       int block_num = 0;
+
+       while (block_num < ssa->cfg.blocks_count
+               && !(ssa->cfg.blocks[block_num].flags & ZEND_BB_REACHABLE)) {
+               block_num++;
+       }
+       while (block_num < ssa->cfg.blocks_count) {
+               int next_block_num = block_num + 1;
+               zend_basic_block *block = &ssa->cfg.blocks[block_num];
+               uint32_t op_num;
+               zend_op *opline;
+               zend_ssa_op *op;
+
+               while (next_block_num < ssa->cfg.blocks_count
+                       && !(ssa->cfg.blocks[next_block_num].flags & ZEND_BB_REACHABLE)) {
+                       next_block_num++;
+               }
+
+               if (block->len) {
+                       if (block->successors_count == 2) {
+                               if (block->successors[0] == block->successors[1]) {
+                                       op_num = block->start + block->len - 1;
+                                       opline = op_array->opcodes + op_num;
+                                       switch (opline->opcode) {
+                                               case ZEND_JMPZ:
+                                               case ZEND_JMPNZ:
+                                               case ZEND_JMPZNZ:
+                                                       op = ssa->ops + op_num;
+                                                       if (block->successors[0] == next_block_num) {
+                                                               if (opline->op1_type & (IS_CV|IS_CONST)) {
+                                                                       zend_ssa_remove_instr(ssa, opline, op);
+                                                                       if (op->op1_use >= 0) {
+                                                                               zend_ssa_unlink_use_chain(ssa, op_num, op->op1_use);
+                                                                               op->op1_use = -1;
+                                                                               op->op1_use_chain = -1;
+                                                                       }
+                                                                       MAKE_NOP(opline);
+                                                                       removed_ops++;
+                                                               } else {
+                                                                       opline->opcode = ZEND_FREE;
+                                                                       opline->op2.num = 0;
+                                                               }
+                                                       } else {
+                                                               if (opline->op1_type & (IS_CV|IS_CONST)) {
+                                                                       if (op->op1_use >= 0) {
+                                                                               zend_ssa_unlink_use_chain(ssa, op_num, op->op1_use);
+                                                                               op->op1_use = -1;
+                                                                               op->op1_use_chain = -1;
+                                                                       }
+                                                                       opline->opcode = ZEND_JMP;
+                                                                       opline->op1_type = IS_UNUSED;
+                                                                       opline->op1.num = opline->op2.num;
+                                                               }
+                                                       }
+                                                       break;
+                                               default:
+                                                       break;
+                                       }
+                               }
+                       } else if (block->successors_count == 1 && block->successors[0] == next_block_num) {
+                               op_num = block->start + block->len - 1;
+                               opline = op_array->opcodes + op_num;
+                               if (opline->opcode == ZEND_JMP) {
+                                       MAKE_NOP(opline);
+                                       removed_ops++;
+                               }
+                   }
+               }
+
+               block_num = next_block_num;
+       }
+
+       return removed_ops;
+}
+
 void zend_dfa_optimize_op_array(zend_op_array *op_array, zend_optimizer_ctx *ctx, zend_ssa *ssa, zend_call_info **call_map)
 {
        if (ctx->debug_level & ZEND_DUMP_BEFORE_DFA_PASS) {
@@ -467,6 +545,11 @@ void zend_dfa_optimize_op_array(zend_op_array *op_array, zend_optimizer_ctx *ctx
                        if (sccp_optimize_op_array(ctx, op_array, ssa, call_map)) {
                                remove_nops = 1;
                        }
+
+                       if (zend_dfa_optimize_jmps(op_array, ssa)) {
+                               remove_nops = 1;
+                       }
+
 #if ZEND_DEBUG_DFA
                        ssa_verify_integrity(op_array, ssa, "after sccp");
 #endif