[Bug tree-optimization/48625] [trans-mem] Segfault in libitm when compiling with -O2

[patrick.marlier at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48625

--- Comment #3 from Patrick Marlier <patrick.marlier at gmail dot com> 2011-05-03 12:06:13 UTC ---
The problem is that _ITM_beginTransaction shouldn't have caller save
optimization because if the transaction aborts, registers will get random
values. It should be ok for others ITM functions.
I fixed it by adding RETURN_TWICE attribute to BUILT_IN_TM_START as a
workaround but I know it shouldn't be fixed like this. I had a look into gcc
sources but I didn't find the right way to fix it.

By the way, if a user wants to use explicit calls to _ITM_ functions to create
its TM program, _ITM_beginTransaction should have a specific attribute to avoid
caller save optimization. In the same way, the tail call optimization must be
forbidden on _ITM_commitTransaction. How should it be managed?

Patrick Marlier.