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Re: unwind info for epilogues

Ian Lance Taylor wrote:
 This approach seems clearly superior.  I wonder if you can provide some
simple functions for the backends to call to add notes and such.

Possibly. At the moment I can't really think of any, or at least anything more complicated than the existing add_reg_note. I would expect these to become more apparent as ports are converted.

> One could also imagine a more complex function which simply walked the
prologue and did something like what the current dwarf2out.c code does,
except adding reg notes.  That might make it relatively easy to
transition the backends to the new scheme.

This same thought occurred to me. Combine that with tracking the CFA state across basic block boundaries, and markers for the CFA state to be placed at hot/cold section boundaries and we'll fix two outstanding bugs with unwind code.

Now if only someone would rewrite delayed-branch opt to not hork the
CFG, and the aforementioned pass will be easy...


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