JIT: Fix incorrect FETCH_THIS elimination

Fizex oss-fuzz #43159

Author: dstogov

ext/opcache/jit/zend_jit_trace.c

@@ -3147,8 +3147,9 @@ static void zend_jit_trace_setup_ret_counter(const zend_op *opline, size_t offse
 	}
 }
 
-static zend_bool zend_jit_may_delay_fetch_this(zend_ssa *ssa, const zend_op **ssa_opcodes, int var)
+static zend_bool zend_jit_may_delay_fetch_this(const zend_op_array *op_array, zend_ssa *ssa, const zend_op **ssa_opcodes, const zend_ssa_op *ssa_op)
 {
+	int var = ssa_op->result_def;
 	int i;
 	int use = ssa->vars[var].use_chain;
 	const zend_op *opline;
@@ -3189,6 +3190,19 @@ static zend_bool zend_jit_may_delay_fetch_this(zend_ssa *ssa, const zend_op **ss
 		return 0;
 	}
 
+	if (opline->opcode == ZEND_ASSIGN_OBJ_OP) {
+		if (opline->op1_type == IS_CV
+		 && (opline+1)->op1_type == IS_CV
+		 && (opline+1)->op1.var == opline->op1.var) {
+			/* skip $a->prop += $a; */
+			return 0;
+		}
+		if (!zend_jit_supported_binary_op(
+				opline->extended_value, MAY_BE_ANY, OP1_DATA_INFO())) {
+			return 0;
+		}
+	}
+
 	for (i = ssa->vars[var].definition; i < use; i++) {
 		if (ssa_opcodes[i]->opcode == ZEND_DO_UCALL
 		 || ssa_opcodes[i]->opcode == ZEND_DO_FCALL_BY_NAME
@@ -5610,7 +5624,7 @@ static const void *zend_jit_trace(zend_jit_trace_rec *trace_buffer, uint32_t par
 					case ZEND_FETCH_THIS:
 						delayed_fetch_this = 0;
 						if (ssa_op->result_def >= 0 && opline->result_type != IS_CV) {
-							if (zend_jit_may_delay_fetch_this(ssa, ssa_opcodes, ssa_op->result_def)) {
+							if (zend_jit_may_delay_fetch_this(op_array, ssa, ssa_opcodes, ssa_op)) {
 								ssa->var_info[ssa_op->result_def].delayed_fetch_this = 1;
 								delayed_fetch_this = 1;
 							}

ext/opcache/tests/jit/assign_obj_op_001.phpt

@@ -0,0 +1,19 @@
+--TEST--
+JIT ASSIGN_OBJ_OP: Unsupported types
+--INI--
+opcache.enable=1
+opcache.enable_cli=1
+opcache.file_update_protection=0
+opcache.jit_buffer_size=1M
+--FILE--
+<?php
+class Test{
+}
+
+$test = new Test;
+(function(){$this->y.=[];})->call($test);
+?>
+--EXPECTF--
+Warning: Undefined property: Test::$y in %sassign_obj_op_001.php on line 6
+
+Warning: Array to string conversion in %sassign_obj_op_001.php on line 6