stack-overflow at quickjs.c:31754 about quickjs

[moqi2011]

我在v2ex上面看到一个人头像和名字都和你一样，是你吗？

[kvenux]

@moqi2011 Yes....

[HelloAlone]

refer this repo (support msvc 2017 or 2019): https://github.com/c-smile/quickjs/

[kvenux]

refer this repo (support msvc 2017 or 2019): https://github.com/c-smile/quickjs/

another official repo?

[alexdowad]

This evals a 1.4MB string in such a way that QuickJS generates an enormous number of OP_with_get_var opcodes when compiling that source string. When compiling a function (or eval'd string), QuickJS must determine how much space it needs for its evaluation stack. Since OP_with_get_var does a conditional forward jump, compute_stack_size_rec recurses to check what the maximum required evaluation stack size is both when the conditional jump is taken, and when it is not taken.

Generate a function with lots and lots of OP_with_get_var opcodes, and the recursion tree for compute_stack_size_rec will be enormous.

This is unfortunate, since the recursive code for compute_stack_size_rec is quite simple and straightforward. From a cursory examination, it looks like any fix will make the function significantly less readable.

[bellard]

fixed

[alexdowad]

OK, so explicit recursion is no longer used to explore different paths through a function and calculate the required stack size. Instead, paths which still need to be searched are pushed onto a queue.

I must say that the fix is simpler and less intrusive than what I had imagined. Nice!