PPC doesn't support non-lazy JIT compilation

[Quuxplusone]

Bugzilla Link	PR4816
Status	NEW
Importance	P normal
Reported by	Török Edwin (edwin+bugs@etorok.eu)
Reported on	2009-08-28 11:36:48 -0700
Last modified on	2011-03-18 06:37:43 -0700
Version	unspecified
Hardware	PC Linux
CC	annulen@yandex.ru, jyasskin@google.com, llvm-bugs@lists.llvm.org
Fixed by commit(s)
Attachments	x.bc (492 bytes, application/octet-stream) jitemitter-place-stubs.patch (36065 bytes, text/plain)
Blocks
Blocked by
See also

Created attachment 3386
x.bc

Disabling lazy compilation fails on PPC:

Release/bin/lli -disable-lazy-compilation  ~/x.bc
Assertion failed: (0 && "This target doesn't implement
emitFunctionStubAtAddr!"), function emitFunctionStubAtAddr, file
/Users/acab/clamav-
devel/libclamav/llvm/llvm/include/llvm/Target/TargetJITInfo.h, line 65.
0   lli               0x0065d50c llvm::sys::RWMutexImpl::writer_release() + 476
1   lli               0x0065dddc llvm::sys::RemoveFileOnSignal(llvm::sys::Path
const&, std::string*) + 1244
2   libSystem.B.dylib 0x92f639fc _sigtramp + 68
Stack dump:
0.      Program arguments: Release/bin/lli -disable-lazy-compilation
/Users/acab/x.bc
Abort trap

It seems that X86 is the only target that implements that method.

In this case it is simply a matter of ordering the functions bottom-up
according to the callgraph, and then non-lazy compilation should succeeed on
the Mac too in this case, BUT it would fail for mutually recursive functions.

Is there a workaround that doesn't need emitFunctinStubAtAddr, or should I just
always use lazy compilation on Mac/PPC? (rather anything non-X86?)

[Quuxplusone]

Attached x.bc (492 bytes, application/octet-stream): x.bc

[Quuxplusone]

I'm pretty sure you're correct that the eager JIT only exists on x86. It doesn't look that hard to implement emitFunctionStubAtAddr given emitFunctionStub (with some thought, maybe we can unify them), but I don't have a PPC or ARM to test on, so I'm a bit reluctant to try it myself. Would you be interested in taking a shot at the implementation? If not, I may be able to find a machine to test on or use the buildbots as guinea pigs.

[Quuxplusone]

(In reply to comment #1)
> I'm pretty sure you're correct that the eager JIT only exists on x86. It
> doesn't look that hard to implement emitFunctionStubAtAddr given
> emitFunctionStub (with some thought, maybe we can unify them), but I don't
have
> a PPC or ARM to test on, so I'm a bit reluctant to try it myself. Would you be
> interested in taking a shot at the implementation?

For PPC and ARM there are some Linux machines on the compile farm.
They are about 7-13 times slower than my x86-64 box though, so it may take some
time to compile LLVM initially.

>If not, I may be able to
> find a machine to test on or use the buildbots as guinea pigs.
>

I may have some time for this late next week.

[Quuxplusone]

I may wind up fixing this as part of the redesign for PR5201, so don't waste time working on it yet.

[Quuxplusone]

Attached jitemitter-place-stubs.patch (36065 bytes, text/plain): Possible fix