Memory usage explodes

[RalfJung]

Some seemingly harmless changes can make the impala memory usage explode. See the branch https://github.com/AnyDSL/imbatracer/commits/memleak of imbatracer. The last commit adds a simple (10-line) file that's not even used, which triggers the problem. Another example triggering the problem is adding an external function call as in https://github.com/AnyDSL/imbatracer/commit/b2eaa4a7295f8a275030b74fe915e230a74f6970.

[leissa]

The code is not first-order recursive. We are going to address this in a future version of Thorin.

[richardmembarth]

Same problem here: https://github.com/AnyDSL/imbatracer/commits/forever

[leissa]

Test case: https://github.com/AnyDSL/impala/blob/master/test/codegen/endless_mangling.impala

[wizzard0]

btw what does "!" means in the endless_mangling example?

[leissa]

A function fn foo(x: int) -> ! has type fn(int) -> ! which means that the function is a continuation. Calling this function does not return. An expression, calling a continuation has type <no-return>.

fn foo(x: int) -> int is syntactic sugar for fn foo(x: int, return: fn(int) -> !) -> !.

[leissa]

see also:

• https://github.com/AnyDSL/anydsl/wiki/For-Expression
• https://github.com/AnyDSL/anydsl/wiki/While-Expression
• https://github.com/AnyDSL/anydsl/wiki/With-Expression