JIT: provide Garbage Collector callback if run out of stubs

[edwintorok]

Bugzilla Link	3083
Resolution	WONTFIX
Resolved on	Nov 20, 2008 17:51
Version	unspecified
OS	Linux
Blocks	llvm/llvm-bugzilla-archive#3084
Attachments	testcase to show problem

Extended Description

Apply the attached patch to example/HowToUseJIT, and run:

"We just constructed this LLVM module:

; ModuleID = 'test'

define i32 @​add1(i32 %AnArg) {
EntryBlock:
%addresult = add i32 1, %AnArg ; [#uses=1]
ret i32 %addresult
}

define i32 @​foo() {
EntryBlock:
%add1 = tail call i32 @​add1(i32 10) ; [#uses=1]
ret i32 %add1
}

Running foo: JIT ran out of memory for function stubs!
Aborted"

The JIT could provide a callback when it runs out of memory, so that the Garbage Collector can be run, that could possibly free up some memory.
This would especially be useful for VMKit.

[llvmbot]

That's crazy talk. :-) I think VMKit ought to provide its own memory manager and detect the low memory situations. I don't think we want to keep the default implementation simple. What do you think?

[llvmbot]

I agree with Evan, the VM should be responsible for freeing the memory, whether it's its own memory, or llvm generated code or stubs. If LLVM runs out of memory, it's the VM's fault.

However, AFAIK there is no support at the moment for freeing stubs in llvm :)

[edwintorok]

mentioned in issue llvm/llvm-bugzilla-archive#3084