------- Comment #4 from daney at gcc dot gnu dot org 2007-06-22 08:38 -------
Looking at the rtl dumps of unwind-dw2.c compiled with -O1 I find:
In unwind-dw2.c.135r.subreg (_Unwind_Resume):
.
.
.
(insn 72 71 73 6 ../../../trunk/libgcc/../gcc/unwind.inc:216 (parallel [
(unspec [
(reg:SI 223)
] 7)
(clobber (scratch:SI))
]) 349 {eh_set_lr_si} (nil))
.
.
.
And in unwind-dw2.c.137r.cse1 (_Unwind_Resume):
.
.
.
DCE: Deleting insn 72
deleting insn with uid = 72.
.
.
.
The insn eh_set_lr_si (see the patch) only clobbers a scratch register, and
since we cannot split it to say we set the return address until after reload, I
don't know how to keep it from being deleted unless we say it is volatile.
I am a bit surprised that the very first thing I tried worked, but after more
thought I cannot come up with anything else.
The patch fixes all c++ and libstdc++ testsuite regressions caused by the
dateflow merge (on mipsel-linux), so I would like to commit it.
Thoughts?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32437
