From: Nikita Popov <nikita.ppv@gmail.com>
Date: Wed, 29 May 2019 09:48:40 +0000 (+0200)
Subject: Don't JIT functions with many blocks
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=b7a6430a52da182646844860a03fc6befbac8012;p=php

Don't JIT functions with many blocks

Avoids a stack overflow in Zend/tests/runtime_compile_time_binary_operands.php
that happens in recursive RPO calculation. We could make that code
non-recursive, but I don't think it makes sense to JIT this kind of
function in the first place.
---

diff --git a/ext/opcache/jit/zend_jit.c b/ext/opcache/jit/zend_jit.c
index 0d43576ed3..c6849cd3ac 100644
--- a/ext/opcache/jit/zend_jit.c
+++ b/ext/opcache/jit/zend_jit.c
@@ -599,6 +599,13 @@ static int zend_jit_build_cfg(zend_op_array *op_array, zend_cfg *cfg)
 		return FAILURE;
 	}
 
+	/* Don't JIT huge functions. Apart from likely being detrimental due to the amount of
+	 * generated code, some of our analysis is recursive and will stack overflow with many
+	 * blocks. */
+	if (cfg->blocks_count > 100000) {
+		return FAILURE;
+	}
+
 	if (zend_cfg_build_predecessors(&CG(arena), cfg) != SUCCESS) {
 		return FAILURE;
 	}