On Fri, Jun 7, 2019 at 11:11 PM Jason Merrill <ja...@redhat.com> wrote:
>
> A tree node that has been poisoned by ggc_free is easily recognizable by the
> TREE_CODE 0xa5a5; let's look for that rather than access some random memory
> off
> the end of the array.
>
> OK for trunk?
OK.
Richard.
> * gdbhooks.py (TreePrinter.to_string): Recognize ggc_free'd memory.
> * tree.c (get_tree_code_name): Likewise.
> * print-tree.c (print_node): Only briefly print a node with an
> invalid code.
> ---
> gcc/print-tree.c | 16 +++++++++-------
> gcc/tree.c | 6 +++++-
> gcc/gdbhooks.py | 3 +++
> gcc/ChangeLog | 7 +++++++
> 4 files changed, 24 insertions(+), 8 deletions(-)
>
> diff --git a/gcc/print-tree.c b/gcc/print-tree.c
> index 81b66a1891b..f69a2c26679 100644
> --- a/gcc/print-tree.c
> +++ b/gcc/print-tree.c
> @@ -233,6 +233,15 @@ print_node (FILE *file, const char *prefix, tree node,
> int indent,
> return;
>
> code = TREE_CODE (node);
> +
> + /* It is unsafe to look at any other fields of a node with ERROR_MARK or
> + invalid code. */
> + if (code == ERROR_MARK || code >= MAX_TREE_CODES)
> + {
> + print_node_brief (file, prefix, node, indent);
> + return;
> + }
> +
> tclass = TREE_CODE_CLASS (code);
>
> /* Don't get too deep in nesting. If the user wants to see deeper,
> @@ -251,13 +260,6 @@ print_node (FILE *file, const char *prefix, tree node,
> int indent,
> return;
> }
>
> - /* It is unsafe to look at any other fields of an ERROR_MARK node. */
> - if (code == ERROR_MARK)
> - {
> - print_node_brief (file, prefix, node, indent);
> - return;
> - }
> -
> /* Allow this function to be called if the table is not there. */
> if (table)
> {
> diff --git a/gcc/tree.c b/gcc/tree.c
> index 43ce44fcee4..4ba0135dfbb 100644
> --- a/gcc/tree.c
> +++ b/gcc/tree.c
> @@ -13444,7 +13444,11 @@ get_tree_code_name (enum tree_code code)
> const char *invalid = "<invalid tree code>";
>
> if (code >= MAX_TREE_CODES)
> - return invalid;
> + {
> + if (code == 0xa5a5)
> + return "ggc_freed";
> + return invalid;
> + }
>
> return tree_code_name[code];
> }
> diff --git a/gcc/gdbhooks.py b/gcc/gdbhooks.py
> index 39f5c4772f9..e08208e1533 100644
> --- a/gcc/gdbhooks.py
> +++ b/gcc/gdbhooks.py
> @@ -222,6 +222,9 @@ class TreePrinter:
> # extern const enum tree_code_class tree_code_type[];
> # #define TREE_CODE_CLASS(CODE) tree_code_type[(int) (CODE)]
>
> + if val_TREE_CODE == 0xa5a5:
> + return '<ggc_freed 0x%x>' % intptr(self.gdbval)
> +
> val_tree_code_type = gdb.parse_and_eval('tree_code_type')
> val_tclass = val_tree_code_type[val_TREE_CODE]
>
> diff --git a/gcc/ChangeLog b/gcc/ChangeLog
> index fa7a5adefb2..8a083599c99 100644
> --- a/gcc/ChangeLog
> +++ b/gcc/ChangeLog
> @@ -1,3 +1,10 @@
> +2019-06-07 Jason Merrill <ja...@redhat.com>
> +
> + * gdbhooks.py (TreePrinter.to_string): Recognize ggc_free'd memory.
> + * tree.c (get_tree_code_name): Likewise.
> + * print-tree.c (print_node): Only briefly print a node with an
> + invalid code.
> +
> 2019-06-07 Jakub Jelinek <ja...@redhat.com>
>
> * Makefile.in (genprogerr): Add condmd.
>
> base-commit: 5f93e2e757ba1dfd0514b3661b6d737ea5492fa9
> --
> 2.20.1
>
