Mark Shinwell wrote:
Option (i), which is in all but name the "solution 5" approach [1] proposed last year, means that the "count == 0" case is elevated to the same level of importance as the "count > 0" cases, in line with the use in backtrace (). The problem with this is that on platforms where the soft and hard FPs coincide there is going to be a slight performance degradation, as identified previously, whenever these builtins are used.
I don't have a problem with the proposed patch that implements this. I didn't choose this option earlier because I didn't have a testcase that required it. You have now supplied one (glibc backtrace), so I think it is now reasonable to go forward with this.
The workaround for the performance problem is for backend maintainers to add an appropriate definition for the INITIAL_FRAME_ADDRESS_RTX macro. Perhaps forcing the issue will provide some incentive to people to fix their backends.
-- Jim Wilson, GNU Tools Support, http://www.specifix.com
