On Thu, Jul 9, 2015 at 9:31 AM, Steve Ellcey <sell...@imgtec.com> wrote: > On Mon, 2015-06-29 at 11:10 +0100, Richard Henderson wrote: > >> > OK, I think I have this part of the code working on MIPS but >> > crtl->drap_reg is used in the epilogue as well as the prologue even if >> > it is not 'live' in between. If I understand the code correctly the x86 >> > prologue pushes the drap register on to the stack so that the epilogue >> > can pop it off and use it to restore the stack pointer. Is my >> > understanding correct? >> >> Yes. Although that saved copy is also used by unwind info. > > Do you know how and where this saved copy is used by the unwind info? > I don't see any indication that the unwind library knows if a stack has > been dynamically realigned and I don't see where unwind makes use of > this value.
This is a very old patch for DRAP unwind with stack alignment: https://gcc.gnu.org/ml/gcc-patches/2008-07/msg00651.html You can also grep drap_reg in dwarf2out.c. -- H.J.
