[llvm-gcc] Inline function redefinitions error due to 'asm' function rename

[markus-oberhumer]

Bugzilla Link	397
Resolution	FIXED
Resolved on	Feb 22, 2010 12:45
Version	1.0
OS	All
Attachments	Preprocessed source that triggers the error.

Extended Description

This happens on linux/i386:

cc1plus: ../../gcc/llvm-representation.c:237: llvm_value_print_operand:
Assertion `!Fn->ForwardedFunction->ForwardedFunction&&"Cannot double forward!"'
failed.
llvm_bug.cpp:3789: internal compiler error: Aborted
Please submit a full bug report,
with preprocessed source if appropriate.
See URL:http://llvm.cs.uiuc.edu for instructions.

[markus-oberhumer]

assigned to @lattner

[lattner]

Reduced testcase
Here's a mostly reduced testcase

[lattner]

btw, I'm not going to be able to get to this tonight. Probably in the next few
days it will be fixed. Sorry abt that!

[llvmbot]

Hello, I currently encounter the same problem as Markus. It too seems to stem
from the inclusion of file I/O related files. I would greatly appreciate seeing
this problem resolved. If you need my test case too, please let me know. Thank
you very much.

[markus-oberhumer]

Might I ask somebody to look at this bug once again?

It is currently a showstopper for using C++ on linux/i386 for lots of programs,
as the ICE is triggered by just including <sys/stat.h>.

Thanks.

[llvmbot]

I looked at this problem. It is easily reproducible using the reduced testcase.
I believe the problem is the use of asm(...) in the declarations of the
various "stat" functions. At least, when I delete them, it compiles fine.
Since llvm-gcc doesn't support inline assembly, the necessary fix is to hack the
stat.h header file. The original bug report says this comes from linux/i386.
Looking at /usr/include/sys/stat.h on my machine, one potential workaround is to
undefine __REDIRECT before include sys/stat.h This is the macro that uses the
asm statement to redirect to another function name. If it is not defined then
the redirect is done by the pre-processor with a #define.

Worth a try anyway.

[markus-oberhumer]

Please note that the use of asm in this context does not refer to (inline)
assembly, but rather it defines the external (linkage) name of a function/symbol.

[llvmbot]

Just as an update, the reduced test case still triggers the assertion
using today's CVS HEAD llvm-g++.

[llvmbot]

Yes. The changes I made to llvm-expand.c are unrelated and just remove some
compilation warnings that bothered me. I'm not really sure how to fix this
double indirection thing (function defined as asm defined as asm) except using
the workaround I previous posted (undefine __REDIRECT macro)

[lattner]

Hi all,

I'm currently out of town, but I will try to get this one when I get back.
Unfortunately, I don't know if this bug is ours, or if it is in the gcc bits
that we imported. I will find out for sure though when I can.

-Chris

btw, unassignedbugs goes to me, so there is no need to have me on the cc list.
Thanks!

[markus-oberhumer]

More reduced testcase.
I've further reduced the testcase and did more testing:

• it works if you compile it as C source
• it works in C++ if you remove the extern "C"
• it works in C++ if you #define inline to nothing

Also, if you start changing the lstat parameters to someting like int
lstat(int) the ICE goes aways and you get a "warning: LLVM: LinkOnce function
redefined to external!".

Markus

[markus-oberhumer]

Testcase with warning instead of ICE.
For completness, here is the modified testcase that generates "warning: LLVM:
LinkOnce function redefined to external!".

[lattner]

Fixed. Testcase here:
http://mail.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20041122/021380.html

Patch here:
http://mail.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20041122/021381.html

-Chris