> On Thu, Apr 7, 2022 at 1:20 PM Jan Hubicka via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
> >
> > Hi,
> > this patch fixes ipa-modref propagation of pure/const functions. When we
> > inline
> > function, the modref summary is updated to represent the function after
> > inlining and there we need to propagate nondeterministic and side-effects
> > flag.
> >
> > Bootstrapped/regtested x86_64-linux, will commit it shortly.
>
> I noticed we have ->writes_errno in the summary which we do not handle
> in this function either? That's also missing on the GCC 11 branch
writes_errno should be safe: it only can be set if function calls
something that has writes_errno in fnspec and that is propagated at IPA
time. Similarly with calls_interposable.
> (where I just picked r12-2851-g9851a1631f2915 and
> r12-5538-ga70faf6e4df748, both still in testing).
Thanks! I will look into gcc 11 backports as well after fixing the P1s.
Honza
>
> Richard.
>
> > Honza
> >
> > gcc/ChangeLog:
> >
> > 2022-04-07 Jan Hubicka <hubi...@ucw.cz>
> >
> > PR ipa/105160
> > * ipa-modref.cc (ipa_merge_modref_summary_after_inlining):
> >
> > gcc/testsuite/ChangeLog:
> >
> > 2022-04-07 Jan Hubicka <hubi...@ucw.cz>
> >
> > PR ipa/105160
> > * gcc.dg/ipa/pr105160.c: New test.
> >
> > diff --git a/gcc/ipa-modref.cc b/gcc/ipa-modref.cc
> > index acfd7d80ff8..556816ab429 100644
> > --- a/gcc/ipa-modref.cc
> > +++ b/gcc/ipa-modref.cc
> > @@ -5281,6 +5281,29 @@ ipa_merge_modref_summary_after_inlining (cgraph_edge
> > *edge)
> > if (!ignore_stores)
> > to_info_lto->stores->collapse ();
> > }
> > + /* Merge side effects and non-determinism.
> > + PURE/CONST flags makes functions deterministic and if there is
> > + no LOOPING_CONST_OR_PURE they also have no side effects. */
> > + if (!(flags & (ECF_CONST | ECF_NOVOPS | ECF_PURE))
> > + || (flags & ECF_LOOPING_CONST_OR_PURE))
> > + {
> > + if (to_info)
> > + {
> > + if (!callee_info || callee_info->side_effects)
> > + to_info->side_effects = true;
> > + if ((!callee_info || callee_info->nondeterministic)
> > + && !ignore_nondeterminism_p (edge->caller->decl, flags))
> > + to_info->nondeterministic = true;
> > + }
> > + if (to_info_lto)
> > + {
> > + if (!callee_info_lto || callee_info_lto->side_effects)
> > + to_info_lto->side_effects = true;
> > + if ((!callee_info_lto || callee_info_lto->nondeterministic)
> > + && !ignore_nondeterminism_p (edge->caller->decl, flags))
> > + to_info_lto->nondeterministic = true;
> > + }
> > + }
> > if (callee_info || callee_info_lto)
> > {
> > auto_vec <modref_parm_map, 32> parm_map;
> > diff --git a/gcc/testsuite/gcc.dg/ipa/pr105160.c
> > b/gcc/testsuite/gcc.dg/ipa/pr105160.c
> > new file mode 100644
> > index 00000000000..ea80545b102
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.dg/ipa/pr105160.c
> > @@ -0,0 +1,77 @@
> > +/* { dg-do compile } */
> > +/* { dg-options "-O -fdump-ipa-modref" } */
> > +#define sysreg_read(regname) \
> > +({ \
> > + unsigned long __sr_val; \
> > + asm volatile(""); \
> > + \
> > + __sr_val; \
> > +})
> > +
> > +#define sysreg_write(regname, __sw_val) \
> > +do { \
> > + asm volatile(""); \
> > +} while (0)
> > +
> > +#define isb() \
> > +do { \
> > + asm volatile( \
> > + "isb" \
> > + : \
> > + : \
> > + : "memory"); \
> > +} while (0)
> > +
> > +static unsigned long sctlr_read(void)
> > +{
> > + return sysreg_read(sctlr_el1);
> > +}
> > +
> > +static void sctlr_write(unsigned long val)
> > +{
> > + sysreg_write(sctlr_el1, val);
> > +}
> > +
> > +static void sctlr_rmw(void)
> > +{
> > + unsigned long val;
> > +
> > + val = sctlr_read();
> > + val |= 1UL << 7;
> > + sctlr_write(val);
> > +}
> > +
> > +void sctlr_read_multiple(void)
> > +{
> > + sctlr_read();
> > + sctlr_read();
> > + sctlr_read();
> > + sctlr_read();
> > +}
> > +
> > +void sctlr_write_multiple(void)
> > +{
> > + sctlr_write(0);
> > + sctlr_write(0);
> > + sctlr_write(0);
> > + sctlr_write(0);
> > + sctlr_write(0);
> > +}
> > +
> > +void sctlr_rmw_multiple(void)
> > +{
> > + sctlr_rmw();
> > + sctlr_rmw();
> > + sctlr_rmw();
> > + sctlr_rmw();
> > +}
> > +
> > +void function(void)
> > +{
> > + sctlr_read_multiple();
> > + sctlr_write_multiple();
> > + sctlr_rmw_multiple();
> > +
> > + isb();
> > +}
> > +/* { dg-final { scan-ipa-dump-not "Function found to be const" "modref" }
> > } */
