CBE produces calls to __builtin_stack_restore with C compilers that don't support them

[lattner]

Bugzilla Link	1413
Resolution	FIXED
Resolved on	Feb 22, 2010 12:47
Version	2.0
OS	All
CC	@asl

Extended Description

The CBE is unconditionally turning calls to llvm.stacksave into calls to __builtin_stack_restore. It should
only do this if the C compiler supports these. Worst case, it should emit a header that looks like this:

#if !gcc or gcc is too old
#define __builtin_stack_restore(X) 0
#endif

-Chris

[lattner]

assigned to @lattner

[asl]

Can we just emit some inline assembler as an workaround?

[lattner]

in the generated c code? No. I think we should just disable the offending builtins. In 1.9, these
codegen'd to nothing anyway.

-Chris

[tlattner]

Here is the gcc version I was using when I get this error.

[zion]$ gcc --version
gcc (GCC) 3.4.6 20060404 (Red Hat 3.4.6-8)
Copyright (C) 2006 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[asl]

But is it safe?

[lattner]

no, it isn't safe, but it's better that not linking :)

-Chris

[lattner]

Fixed:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20070507/049548.html

[nlewycky]

This won't work in the future. Please see GCC's llvm/llvm-bugzilla-archive#31128 .
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31128

[lattner]

We'll just have to add an upper limit on the gcc version if that patch goes in.

[llvmbot]

mentioned in issue llvm/llvm-bugzilla-archive#1416