Hi!

On 2016-08-05T14:16:58-0400, David Malcolm <dmalc...@redhat.com> wrote:
> Committed to trunk as r239175; I'm attaching the final version of the
> patch for reference.

David, you've added here 'gcc/input.h:struct location_hash' (see quoted
below), which will be useful elsewhere, so:

> --- a/gcc/input.c
> +++ b/gcc/input.c

> +/* Internal function.  Canonicalize LOC into a form suitable for
> +   use as a key within the database, stripping away macro expansion,
> +   ad-hoc information, and range information, using the location of
> +   the start of LOC within an ordinary linemap.  */
> +
> +location_t
> +string_concat_db::get_key_loc (location_t loc)
> +{
> +  loc = linemap_resolve_location (line_table, loc, LRK_SPELLING_LOCATION,
> +                               NULL);
> +
> +  loc = get_range_from_loc (line_table, loc).m_start;
> +
> +  return loc;
> +}

OK to push the attached
"Harden 'gcc/input.c:string_concat_db::get_key_loc'"?  (This fell out of
my analysis for development work elsewhere.)

> --- a/gcc/input.h
> +++ b/gcc/input.h

> +struct location_hash : int_hash <location_t, UNKNOWN_LOCATION> { };
> +
> +class GTY(()) string_concat_db
> +{
> +[...]
> +  hash_map <location_hash, string_concat *> *m_table;
> +};

OK to push the attached
"Generalize 'gcc/input.h:struct location_hash'"?


Grüße
 Thomas


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>From 521c94471ae2f044f8cca8025bfa8db2d2936aea Mon Sep 17 00:00:00 2001
From: Thomas Schwinge <tho...@codesourcery.com>
Date: Tue, 31 Aug 2021 23:05:46 +0200
Subject: [PATCH 1/2] Harden 'gcc/input.c:string_concat_db::get_key_loc'

We're using 'UNKNOWN_LOCATION' as a spare value for 'Empty', so should
ascertain that we don't use it as a key additionally.

Follow-up to r239175 (commit 88fa5555a309e5d6c6171b957daaf2f800920869)
"On-demand locations within string-literals".

	gcc/
	* input.c (string_concat_db::get_key_loc): Harden.
---
 gcc/input.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/gcc/input.c b/gcc/input.c
index 4b809862e02..98b8bb64618 100644
--- a/gcc/input.c
+++ b/gcc/input.c
@@ -1483,6 +1483,9 @@ string_concat_db::get_key_loc (location_t loc)
 
   loc = get_range_from_loc (line_table, loc).m_start;
 
+  /* Ascertain that 'loc' is valid as a key in 'm_table'.  */
+  gcc_checking_assert (!RESERVED_LOCATION_P (loc));
+
   return loc;
 }
 
-- 
2.33.0

>From 349a3172f64db93ee98ea39b36489b702b6596ab Mon Sep 17 00:00:00 2001
From: Thomas Schwinge <tho...@codesourcery.com>
Date: Tue, 31 Aug 2021 23:30:25 +0200
Subject: [PATCH 2/2] Generalize 'gcc/input.h:struct location_hash'

This is currently only used here ('gcc/input.h:class string_concat_db'), but is
actually generally useful, so advertize it as such.

Per the rationale given, we may use 'BUILTINS_LOCATION' as spare value for
'Deleted', in addition to the existing use of 'UNKNOWN_LOCATION' as spare value
for 'Empty'.

	gcc/
	* input.h (location_hash): Use 'BUILTINS_LOCATION' as spare value
	for 'Deleted'.  Turn into a '#define'.
---
 gcc/input.h | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/gcc/input.h b/gcc/input.h
index e6881072c5f..46971a2684c 100644
--- a/gcc/input.h
+++ b/gcc/input.h
@@ -36,6 +36,25 @@ extern GTY(()) class line_maps *saved_line_table;
    both UNKNOWN_LOCATION and BUILTINS_LOCATION fit into that.  */
 STATIC_ASSERT (BUILTINS_LOCATION < RESERVED_LOCATION_COUNT);
 
+/* Hasher for 'location_t' values satisfying '!RESERVED_LOCATION_P', thus able
+   to use 'UNKNOWN_LOCATION'/'BUILTINS_LOCATION' as spare values for
+   'Empty'/'Deleted'.  */
+/* If the following is used more than once, 'gengtype' generates duplicate
+   functions (thus: "error: redefinition of 'void gt_ggc_mx(location_hash&)'"
+   etc.):
+
+       struct location_hash
+         : int_hash<location_t, UNKNOWN_LOCATION, BUILTINS_LOCATION> {};
+
+   Likewise for this:
+
+       typedef int_hash<location_t, UNKNOWN_LOCATION, BUILTINS_LOCATION>
+         location_hash;
+
+   Thus, use a plain ol' '#define':
+*/
+#define location_hash int_hash<location_t, UNKNOWN_LOCATION, BUILTINS_LOCATION>
+
 extern bool is_location_from_builtin_token (location_t);
 extern expanded_location expand_location (location_t);
 
@@ -230,8 +249,6 @@ public:
   location_t * GTY ((atomic)) m_locs;
 };
 
-struct location_hash : int_hash <location_t, UNKNOWN_LOCATION> { };
-
 class GTY(()) string_concat_db
 {
  public:
-- 
2.33.0

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