Hi,
I have a question about the semantics of the tls_model attribute in GCC.
For code such as this:
static __thread int __attribute((tls_model("global-dynamic"))) x;
int *f() { return &x; }
GCC will generate code using the global-dynamic model, also when
compiled without -fpic.
It does this even though it would be safe to use the faster local-exec
model, and the static linker will probably change the code to
local-exec anyway.
Is there a reason for this? The tls_model attribute was added in [1]
by Jakub, and it looks like that patch did go out of its way also to
support e.g. global-dynamic in non-pic code.
The reason I'm asking is that I'm adding support for this attribute in
LLVM, and we're discussing [2] what the semantics should be.
Thanks,
Hans
[1]. http://gcc.gnu.org/ml/gcc-patches/2002-09/msg00668.html
[2]. http://lists.cs.uiuc.edu/pipermail/llvmdev/2012-June/050597.html
