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Re: PATCH: [4.1 Regression]: java compiler generates wrong code onia64
H. J. Lu wrote:
On Sun, Apr 17, 2005 at 11:33:13PM -0400, Andrew Pinski wrote:
On Apr 17, 2005, at 11:31 PM, H. J. Lu wrote:
make_local_function_alias is introduced in
http://gcc.gnu.org/ml/java-patches/2004-q3/msg00618.html
Is there a testcase to show it is really needed? I'd like to run it
on ia32, x86_64 and ia64 to verify its usage.
This was done so that Java code could avoid GOT code.
I am not sure if it makes any differences in GOT on ia32, x86_64 and
ia64. Again, I'd like to see a testcase.
Actually, this was done so that the function pointers in GCJ's method
metadata always point to the actual entry point of a function, and not a
PLT stub. Without this, the PC value returned by _Unwind_GetRegionStart
is, in some circumstances[*], not the same as that in the method's
metadata entry. When this happens, libgcj cannot map stack frames to the
appropriate class and method, which is essential for correct stack
traces and the Java security model.
Bryce
[*] See here for further explanation of the problem:
http://gcc.gnu.org/ml/gcc/2003-12/msg00383.html