> Hello.
>
> As showed in the PR, returning (EAF_NOCLOBBER | EAF_NOESCAPE) for an argument
> that is a function pointer is problematic. Doing such a function call is a
> clobber.
>
> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
>
> Ready to be installed?
> Thanks,
> Martin
>
> PR 101949
>
> gcc/ChangeLog:
>
> * ipa-modref.c (analyze_ssa_name_flags): Do not propagate EAF
> flags arguments for indirect functions.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/lto/pr101949_0.c: New test.
> * gcc.dg/lto/pr101949_1.c: New test.
>
> Co-Authored-By: Richard Biener <[email protected]>
> ---
> gcc/ipa-modref.c | 3 +++
> gcc/testsuite/gcc.dg/lto/pr101949_0.c | 20 ++++++++++++++++++++
> gcc/testsuite/gcc.dg/lto/pr101949_1.c | 4 ++++
> 3 files changed, 27 insertions(+)
> create mode 100644 gcc/testsuite/gcc.dg/lto/pr101949_0.c
> create mode 100644 gcc/testsuite/gcc.dg/lto/pr101949_1.c
>
> diff --git a/gcc/ipa-modref.c b/gcc/ipa-modref.c
> index fafd804d4ba..380ba6926b9 100644
> --- a/gcc/ipa-modref.c
> +++ b/gcc/ipa-modref.c
> @@ -1715,6 +1715,9 @@ analyze_ssa_name_flags (tree name, vec<modref_lattice>
> &lattice, int depth,
> else if (callee && !ipa && recursive_call_p (current_function_decl,
> callee))
> lattice[index].merge (0);
> + /* Ignore indirect calls (PR101949). */
> + else if (callee == NULL_TREE)
> + lattice[index].merge (0);
Thanks for looking into this bug - it is interesting that ipa-pta
requires !EAF_NOCLOBBER when function is called...
I have some work done on teaching ipa-modref (and other propagation
passes) to use ipa-devirt info when the full set of callees is known.
This goes oposite way.
You can drop flags only when callee == NAME and you can just frop
EAF_NOCLOBBER. For example in testcase
struct a {
void (*foo)();
void *bar;
}
void wrap (struct a *a)
{
a->foo ();
}
will prevent us from figuring out that bar can not be modified when you
pass non-ecaping instance of struct a to wrap.
Honza
