On Thu, 2021-07-01 at 11:40 -0400, David Malcolm wrote: > On Thu, 2021-07-01 at 14:53 +0200, Richard Biener wrote: > > 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 > > ... > > Yeah. Another example, from the analyzer, is > g:2fbea4190e76a59c4880727cf84706fe083c00ae (PR 93349) > > > > 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. > > Some ideas (not necessarily good ones): > > (a) the diagnostic_context could have an ice_location field, and use > that in internal_error (and maybe an RAII class for setting/clearing > it). > > (b) move input_location to diagnostic_context, and add: > #define input_location (global_dc->x_input_location) > or: > #define input_location (global_dc->x_default_location) > which add an indirection everywhere. I don't love these ideas, in > that > we already overuse the preprocessor IMHO. > > Trevor: BTW, if you're looking for global state to eliminate, it > might > be nice to move the globals in input.c for caching source lines > (fcache_tab etc) into a new source_cache class, and have the > diagnostic_context own it via a new "source_cache *" field.
Actually, I just found an old working copy on my drive that does most of this; I'll try cleaning it up for gcc 12 and see if I can get it to bootstrap. Dave
