On Thu, Jul 1, 2021 at 12:16 PM Trevor Saunders <tbsau...@tbsaunde.org> wrote: > > On Wed, Jun 30, 2021 at 11:13:23AM -0400, David Malcolm wrote: > > On Wed, 2021-06-30 at 01:35 -0400, Trevor Saunders wrote: > > > This makes it possible to assert if input_location is used during the > > > lifetime > > > of a scope. This will allow us to find places that currently use it > > > within a > > > function and its callees, or prevent adding uses within the lifetime > > > of a > > > function after all existing uses are removed. > > > > > > bootstrapped and regtested on x86_64-linux-gnu, ok? > > > > > > Trev > > > > [...snip...] > > > > > diff --git a/gcc/diagnostic.c b/gcc/diagnostic.c > > > index d58586f2526..3f68d1d79eb 100644 > > > --- a/gcc/diagnostic.c > > > +++ b/gcc/diagnostic.c > > > @@ -1835,7 +1835,7 @@ internal_error (const char *gmsgid, ...) > > > auto_diagnostic_group d; > > > va_list ap; > > > va_start (ap, gmsgid); > > > - rich_location richloc (line_table, input_location); > > > + rich_location richloc (line_table, UNKNOWN_LOCATION); > > > diagnostic_impl (&richloc, NULL, -1, gmsgid, &ap, DK_ICE); > > > va_end (ap); > > > > > > > I actually make use of this in the analyzer: the analyzer sets > > input_location to stmt->location when analyzing a given stmt - that > > way, if the analyzer ICEs, the ICE is shown at the code construct that > > crashed the analyzer. > > > > This behavior is useful to me, and would be lost with the proposed > > patch. > > I made this change because otherwise if the compiler ICE's while access > to input_location is blocked we end up infinitely recursing complaining > we can't access it while trying to say where the last error was. I was > nervous about the change before, and now I agree we need something > else. > > > Is there a better way of doing what I'm doing? > > > > Is the long-term goal of the patch kit to reduce our reliance on global > > variables? Are we ultimately still going to need a variable for "where > > to show the ICE if gcc crashes"? (perhaps stashing it in the > > diagnostic_context???) > > Yes, the goal is ultimately removal of global state, however I'm not > really ure what the better approach to your problem is, after all even > moving it to the diagnostic context is sort of a global state, and sort > of dupplicates input_location. That said it is somewhat more > constrained, so if it removes usage of input_location perhaps its > worthwhile?
Reduction of global state is of course good - but in particular input_location should be something only used during parsing because it's a quite broken concept otherwise. And fiddling with it tends to be quite fragile... for example see g:7d6f7e92c3b737736a2d8ff97a71af9f230c2f88 for the "fun" you can have with "stale" values in input_location ... IMHO users should have their own "copy", for example the gimplifier instead of mucking with and using input_location could use a similar state in its gimplify_ctx. Richard. > Sorry I'm not yet sure what to propose here. > > Trev > > > > > Hope this is constructive > > Dave > >