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Re: [PATCH] Avoid ICEs with throwing calls with -fprintf-return-value (PR middle-end/78901)
- From: Richard Biener <rguenther at suse dot de>
- To: Jakub Jelinek <jakub at redhat dot com>,Jeff Law <law at redhat dot com>,Martin Sebor <msebor at gmail dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Tue, 03 Jan 2017 07:41:02 +0100
- Subject: Re: [PATCH] Avoid ICEs with throwing calls with -fprintf-return-value (PR middle-end/78901)
- Authentication-results: sourceware.org; auth=none
- References: <20170102195403.GK21933@tucnak>
On January 2, 2017 8:54:03 PM GMT+01:00, Jakub Jelinek <jakub@redhat.com> wrote:
>Hi!
>
>As my earlier patch to adjust cfns.gperf for C99/C11 builtins has been
>committed already, the non-__*_chk builtins (and when using
>__builtin__*_chk
>form even those) should be all noexcept, and when using fortification
>the glibc headers declare those properly throw() and ssp includes just
>use builtins directly. Therefore I think it is just a waste of time to
>add code to handle something that will not really happen in real-world
>code,
>only when somebody declares those incorrectly by hand.
>
>The following patch therefore just punts on stmt_ends_bb_p
>(info.callstmt)
>rather than purging dead edges and scheduling cfg cleanups on
>replacement
>of call with constant if the compiler thinks it might throw, or when
>inserting after the call (also invalid, would need to be inserted on
>fallthrough edge instead).
>
>Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
Richard.
>2017-01-02 Jakub Jelinek <jakub@redhat.com>
>
> PR middle-end/78901
> * gimple-ssa-sprintf.c (try_substitute_return_value): Don't change
> possibly throwing calls.
>
> * g++.dg/opt/pr78901.C: New test.
>
>--- gcc/gimple-ssa-sprintf.c.jj 2017-01-02 12:09:29.000000000 +0100
>+++ gcc/gimple-ssa-sprintf.c 2017-01-02 13:05:08.400755201 +0100
>@@ -2699,9 +2699,15 @@ try_substitute_return_value (gimple_stmt
> the output overflows the destination object (but leave it enabled
> when the function is bounded because then the behavior is well-
> defined). */
>- if (lhs && res.bounded && res.under4k
>+ if (lhs
>+ && res.bounded
>+ && res.under4k
> && (info.bounded || res.number_chars <= info.objsize)
>- && res.number_chars - 1 <= target_int_max ())
>+ && res.number_chars - 1 <= target_int_max ()
>+ /* Not prepared to handle possibly throwing calls here; they
>shouldn't
>+ appear in non-artificial testcases, except when the __*_chk routines
>+ are badly declared. */
>+ && !stmt_ends_bb_p (info.callstmt))
> {
> tree cst = build_int_cst (integer_type_node, res.number_chars - 1);
>
>--- gcc/testsuite/g++.dg/opt/pr78901.C.jj 2017-01-02 13:04:24.271329153
>+0100
>+++ gcc/testsuite/g++.dg/opt/pr78901.C 2017-01-02 13:03:19.000000000
>+0100
>@@ -0,0 +1,18 @@
>+// PR middle-end/78901
>+// { dg-do compile }
>+// { dg-options "-O2 -Wno-stringop-overflow" }
>+
>+extern "C" int __snprintf_chk (char *, __SIZE_TYPE__, int,
>__SIZE_TYPE__, const char *, ...);
>+
>+int
>+foo (char *c)
>+{
>+ try
>+ {
>+ return __snprintf_chk (c, 64, 0, 32, "%s", "abcdefghijklmnopq");
>+ }
>+ catch (...)
>+ {
>+ return -1;
>+ }
>+}
>
> Jakub