On 10/10/13 18:41, Jeff Law wrote: > On 10/10/13 04:00, Andreas Krebbel wrote: >> On 09/10/13 21:46, Jeff Law wrote: >>> On 08/21/13 03:21, Andreas Krebbel wrote: >>>> [RFC] Allow functions calling mcount before prologue to be leaf functions >>>> http://gcc.gnu.org/ml/gcc-patches/2013-04/msg00993.html >>> I don't think this is necessarily correct for all targets. ISTM the >>> ability to consider a function calling mcount as a leaf needs to be a >>> property of the target. >> >> We have already "profile_before_prologue" as a target property. Shouldn't >> this be enough to decide >> upon this? When a function calls mcount before the prologue it shouldn't >> matter whether the function >> is leaf or not. > I don't think so, I think it'd break the PA's 32 bit ABI, maybe the 64 > bit ABI as well. It's the caller's responsibility to build a mini stack > frame if the function makes any calls. If the code in the prologue > expander uses "leafness" to make the decision about whether or not to > allocate the mini frame, then it'd do the wrong thing here. > > I'm just using that as an example, there may be others. Hence my > recommendation this become a target hook with the default off so that > ports can be appropriately audited.
Ok. What I seem to have missed is that "profile_before_prologue" only refers to the profiling code emitted by the FUNCTION_PROFILER macro. Profiling code emitted by PROFILE_HOOK comes after the prologue even if "profile_before_prologue" is true. -Andreas- > > Jeff >
