SCCP: Fix leak when determining TYPE_CHECK from type info

As TYPE_CHECK is the only opcode where we do something like this,
I'm adding this hack.

Author: nikic

ext/opcache/Optimizer/sccp.c

@@ -2203,6 +2203,14 @@ static int try_remove_definition(sccp_ctx *ctx, int var_num, zend_ssa_var *var,
 				zend_ssa_remove_result_def(ssa, ssa_op);
 				if (opline->opcode == ZEND_DO_ICALL) {
 					removed_ops = remove_call(ctx, opline, ssa_op);
+				} else if (opline->opcode == ZEND_TYPE_CHECK
+						&& !value_known(&ctx->values[ssa_op->op1_use])) {
+					/* For TYPE_CHECK we may compute the result value without knowing the
+					 * operand, based on type inference information. Make sure the operand is
+					 * freed and leave further cleanup to DCE. */
+					opline->opcode = ZEND_FREE;
+					opline->result_type = IS_UNUSED;
+					removed_ops++;
 				} else {
 					zend_ssa_remove_instr(ssa, opline, ssa_op);
 					removed_ops++;

ext/opcache/tests/opt/sccp_030.phpt

@@ -0,0 +1,17 @@
+--TEST--
+SCCP 030: TYPE_CHECK inferred from type inference info
+--INI--
+opcache.enable=1
+opcache.enable_cli=1
+opcache.optimization_level=-1
+opcache.opt_debug_level=0
+--SKIPIF--
+<?php require_once('skipif.inc'); ?>
+--FILE--
+<?php
+
+var_dump(is_string(sys_get_temp_dir()));
+
+?>
+--EXPECT--
+bool(true)