On Fri, Mar 17, 2023 at 08:09:17PM +0100, Jan Hubicka wrote:
> >
> > I have in the meantime briefly tested following.
> >
> > But if you want to the above way, then at least the testcase could be
> > useful. Though, not sure if the above is all that is needed. Shouldn't
> > set_const_flag_1 upon TREE_READONLY (node->decl) = 0; also adjust
> > TREE_TYPE on the function to
> > tree fntype = TREE_TYPE (node->decl);
> > TREE_TYPE (node->decl)
> > = build_qualified_type (fntype,
> > TYPE_QUALS (fntype) & ~TYPE_QUAL_CONST);
> > too (perhaps guarded on TREE_READONLY (fntype))?
> >
> > 2023-03-16 Jakub Jelinek <ja...@redhat.com>
> >
> > PR tree-optimization/106912
> > gcc/
> > * calls.h (ignore_const_fntype): Declare.
> > * calls.cc (flags_from_decl_or_type): Ignore TYPE_READONLY
> > on types if ignore_const_fntype.
> > * tree-profile.cc: Include calls.h.
> > (tree_profiling): Set ignore_const_fntype if profile_arc_flag
> > or flag_test_coverage.
> > gcc/lto/
> > * lto-lang.cc (lto_post_options): Set ignore_const_fntype if
> > profile_arc_flag or flag_test_coverage and not flag_auto_profile.
> > gcc/testsuite/
> > * gcc.dg/pr106912.c: New test.
> >
> > --- gcc/calls.h.jj 2023-01-02 09:32:51.252868185 +0100
> > +++ gcc/calls.h 2023-03-16 12:23:51.632460586 +0100
> > @@ -134,5 +134,6 @@ extern void maybe_complain_about_tail_ca
> >
> > extern rtx rtx_for_static_chain (const_tree, bool);
> > extern bool cxx17_empty_base_field_p (const_tree);
> > +extern bool ignore_const_fntype;
> >
> > #endif // GCC_CALLS_H
> > --- gcc/calls.cc.jj 2023-02-21 11:44:48.460464845 +0100
> > +++ gcc/calls.cc 2023-03-16 12:27:45.427032110 +0100
> > @@ -800,6 +800,13 @@ is_tm_builtin (const_tree fndecl)
> > return false;
> > }
> >
> > +/* Set if flags_from_decl_or_type should ignore TYPE_READONLY of function
> > + types. This is used when tree-profile.cc instruments const calls,
> > + clears TREE_READONLY on FUNCTION_DECLs which have been instrumented, but
> > + for function types or indirect calls we don't know if the callees have
> > been
> > + instrumented or not. */
> > +bool ignore_const_fntype;
> > +
> > /* Detect flags (function attributes) from the function decl or type node.
> > */
> >
> > int
> > @@ -849,7 +856,7 @@ flags_from_decl_or_type (const_tree exp)
> > }
> > else if (TYPE_P (exp))
> > {
> > - if (TYPE_READONLY (exp))
> > + if (TYPE_READONLY (exp) && !ignore_const_fntype)
>
> I think we want to ignore PURE flag too: if callee modifies counters
> seen by caller, we need to take that into account when optimizing it.
>
> It is not very pretty to have global flag for prifled state, but I can't
> think of scenario where this would break, so perhaps it is good way to
> go?
Note, Richi posted what I think is much cleaner patch in
https://gcc.gnu.org/pipermail/gcc-patches/2023-March/614074.html
Jakub
