Re: [PATCH] [PR82155] Fix crash in dwarf2out_abstract_function

[Pierre-Marie de Rodat]

On 11/15/2017 12:16 PM, Richard Biener wrote:

Is it still okay to commit to gcc-7, now?


Yes.


Done. Thank you!

--
Pierre-Marie de Rodat

Re: [PATCH] [PR82155] Fix crash in dwarf2out_abstract_function

[Richard Biener]

On Wed, Nov 15, 2017 at 10:11 AM, Pierre-Marie de Rodat
 wrote:
> Hello Richard,
>
> On 09/25/2017 01:54 PM, Richard Biener wrote:
>>
>> Ok for trunk and gcc-7 branch after a while.
>
> Is it still okay to commit to gcc-7, now?

Yes.

Richard.

> --
> Pierre-Marie de Rodat

Re: [PATCH] [PR82155] Fix crash in dwarf2out_abstract_function

[Pierre-Marie de Rodat]

Hello Richard,

On 09/25/2017 01:54 PM, Richard Biener wrote:

Ok for trunk and gcc-7 branch after a while.

Is it still okay to commit to gcc-7, now?

--
Pierre-Marie de Rodat

Re: [PATCH] [PR82155] Fix crash in dwarf2out_abstract_function

[Pierre-Marie de Rodat]

On 09/25/2017 01:54 PM, Richard Biener wrote:

Ok for trunk and gcc-7 branch after a while.


Thank you, Richard! Committed on trunk as 253147; I’ll wait at least one 
week to revisit the gcc-7 branch commit.


--
Pierre-Marie de Rodat

Re: [PATCH] [PR82155] Fix crash in dwarf2out_abstract_function

[Richard Biener]

On Tue, Sep 12, 2017 at 8:00 AM, Pierre-Marie de Rodat
 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 000..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  struct b { a c; };
> +template  struct e { d *operator->(); };
> +template  class h {
> +public:
> +  typedef e 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>::ag g;;)
> +  g->c.c->l();
> +  }
> +};
> +void fn1() { o(); }
> --
> 2.14.1
>

[PATCH] [PR82155] Fix crash in dwarf2out_abstract_function

[Pierre-Marie de Rodat]

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!

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 000..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  struct b { a c; };
+template  struct e { d *operator->(); };
+template  class h {
+public:
+  typedef e 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>::ag g;;)
+  g->c.c->l();
+  }
+};
+void fn1() { o(); }
-- 
2.14.1