On Tue, Sep 12, 2017 at 8:00 AM, Pierre-Marie de Rodat
<dero...@adacore.com> wrote:
> Hello,
>
> This patch is an attempt to fix the crash reported in PR82155.
>
> When generating a C++ class method for a class that is itself nested in
> a class method, dwarf2out_early_global_decl currently leaves the
> existing context DIE as it is if it already exists. However, it is
> possible that this call happens at a point where this context DIE is
> just a declaration that is itself not located in its own context.
>
> From there, if dwarf2out_early_global_decl is not called on any of the
> FUNCTION_DECL in the context chain, DIEs will be left badly scoped and
> some (such as the nested method) will be removed by the type pruning
> machinery. As a consequence, dwarf2out_abstract_function will will
> crash when called on the corresponding DECL because it asserts that the
> DECL has a DIE.
>
> This patch fixes this crash making dwarf2out_early_global_decl process
> context DIEs the same way we process abstract origins for FUNCTION_DECL:
> if the corresponding DIE exists but is only a declaration, call
> dwarf2out_decl anyway on it so that it is turned into a more complete
> DIE and so that it is relocated in the proper context.
>
> Bootstrapped and regtested on x86_64-linux. The crash this addresses is
> present both on trunk and on the gcc-7 branch: I suggest we commit this
> patch on both branches. Ok to commit? Thank you in advance!
Ok for trunk and gcc-7 branch after a while.
Thanks,
Richard.
> gcc/
>
> PR debug/82155
> * dwarf2out.c (dwarf2out_early_global_decl): Call dwarf2out_decl
> on the FUNCTION_DECL function context if it has a DIE that is a
> declaration.
>
> gcc/testsuite/
>
> * g++.dg/pr82155.C: New testcase.
> ---
> gcc/dwarf2out.c | 10 ++++++++--
> gcc/testsuite/g++.dg/pr82155.C | 36 ++++++++++++++++++++++++++++++++++++
> 2 files changed, 44 insertions(+), 2 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/pr82155.C
>
> diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
> index 00d6d951ba3..4cfc9c186af 100644
> --- a/gcc/dwarf2out.c
> +++ b/gcc/dwarf2out.c
> @@ -25500,10 +25500,16 @@ dwarf2out_early_global_decl (tree decl)
> so that all nested DIEs are generated at the proper scope in the
> first shot. */
> tree context = decl_function_context (decl);
> - if (context != NULL && lookup_decl_die (context) == NULL)
> + if (context != NULL)
> {
> + dw_die_ref context_die = lookup_decl_die (context);
> current_function_decl = context;
> - dwarf2out_decl (context);
> +
> + /* Avoid emitting DIEs multiple times, but still process CONTEXT
> + enough so that it lands in its own context. This avoids type
> + pruning issues later on. */
> + if (context_die == NULL || is_declaration_die (context_die))
> + dwarf2out_decl (context);
> }
>
> /* Emit an abstract origin of a function first. This happens
> diff --git a/gcc/testsuite/g++.dg/pr82155.C b/gcc/testsuite/g++.dg/pr82155.C
> new file mode 100644
> index 00000000000..75d9b615f39
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/pr82155.C
> @@ -0,0 +1,36 @@
> +/* { dg-do compile { target c++11 } } */
> +/* { dg-options "-g -O2" } */
> +
> +template <typename a> struct b { a c; };
> +template <typename d> struct e { d *operator->(); };
> +template <typename d> class h {
> +public:
> + typedef e<d> ag;
> +};
> +class i {
> +protected:
> + i(int);
> +};
> +class j {
> + virtual void k(int) = 0;
> +
> +public:
> + int f;
> + void l() { k(f); }
> +};
> +struct m : i {
> + int cn;
> + m() : i(cn) {
> + struct n : j {
> + n() {}
> + void k(int) {}
> + };
> + }
> +};
> +struct o {
> + o() {
> + for (h<b<b<j *>>>::ag g;;)
> + g->c.c->l();
> + }
> +};
> +void fn1() { o(); }
> --
> 2.14.1
>
