show size of stack needed by functions

[Eric Botcazou]

> Of course, the compiler can't dump the callgraph of the whole program.
> But it could dump the list of functions called by every function of a
> translation unit. With annotations which of the calls are inlined. Which
> could then be processed by a script to get the whole callgraph.

We have had something along these lines in our compiler at AdaCore for a few 
years; it's called -fcallgraph-info, it generates a very low-level callgraph 
in VCG format for each compilation unit, and the nodes can be decorated with 
information (typically stack usage indeed).  Then you run a script to "link" 
all the VCG files for a program and you can (try and) compute the worst case 
stack usage for example.  This works reasonably well for embedded stuff.

I'll try and submit something before stage 1 ends if people are interested.

-- 
Eric Botcazou