On Fri, 2 Sep 2011, Arnaud Charlet wrote: > > This fixes the Ada bootstrap failure introduced by alloca folding. > > We now fold alloca (0) to &auto-with-size-zero which confuses us. > > I didn't exactly investigate but what I think happens is that we > > expand that &auto-with-size-zero to NULL instead of > > virtual_stack_dynamic_rtx (see zero-size special-case in > > allocate_dynamic_stack_space) and Ada ends up dereferencing the > > pointer returned from alloca (0) (something to investigate for > > the Ada folks I guess), something which "works" if we just > > return a random stack address. > > Thanks! > > In Ada, it's quite natural to end up with a dynamically sized object of > size 0. For instance, if you declare an array with a dynamic bound: > > Table : Unit_Table (1 .. Last_Unit); > > and Last_Unit happens to be 0 at run-time
But are we expected to read/store from the storage? I'd have expected that alloca (0) returning NULL shouldn't break anything at runtime ... Richard.
