[libcpp,lto,fortran PATCH] Fix linemap_add use and remove unnecessary kludge

[Dodji Seketeli <dodji at redhat dot com>]

Hello,

There are a couple of places in the compiler that need to create line
maps directly by calling linemap_add.

The problem is, sometimes we wrongly do so by passing LC_RENAME as the
reason argument even when creating the first map of a given file.  But
then linemap_add has some code to change that LC_RENAME argument back
into LC_ENTER, as it should have been done initially.

This patch fixes the few calling spots (in pch, lto and fortran) and
turns the then useless fixup kludge in linemap_add into an assert.

I'd like this to be applied to trunk as Jason suggested[1] that
linemap_add drops that kludge while reviewing my macro location tracking
patch set[1].

Bootstrapped with --enable-languages=all,ada --enable-checking and
tested on x86_64-unknown-linux-gnu against trunk.

OK for trunk?

[1]: http://gcc.gnu.org/ml/gcc-patches/2011-08/msg01538.html


libcpp/

	* line-map.c (linemap_add): Assert that reason must not be
	LC_RENAME when called for the first time on a "main input file".

c-family/

	* c-pch.c (c_common_read_pch): Call linemap_add with LC_ENTER as it's
	the first time it's being called on this main TU.

gcc/lto/

	* lto-lang.c (lto_init): Likewise.  Also, avoid calling
	linemap_add twice.

gcc/fortran/

	* scanner.c (load_file): Don't abuse LC_RENAME reason while
	(indirectly) calling linemap_add.
---
 gcc/c-family/c-pch.c  |    2 +-
 gcc/fortran/scanner.c |   24 ++++++++++++++++++++++--
 gcc/lto/lto-lang.c    |    3 +--
 libcpp/line-map.c     |    9 ++++-----
 4 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/gcc/c-family/c-pch.c b/gcc/c-family/c-pch.c
index 3c2fd18..7a289d6 100644
--- a/gcc/c-family/c-pch.c
+++ b/gcc/c-family/c-pch.c
@@ -446,7 +446,7 @@ c_common_read_pch (cpp_reader *pfile, const char *name,
   fclose (f);
 
   line_table->trace_includes = saved_trace_includes;
-  linemap_add (line_table, LC_RENAME, 0, saved_loc.file, saved_loc.line);
+  linemap_add (line_table, LC_ENTER, 0, saved_loc.file, saved_loc.line);
 
   /* Give the front end a chance to take action after a PCH file has
      been loaded.  */
diff --git a/gcc/fortran/scanner.c b/gcc/fortran/scanner.c
index 0c127d4..120d550 100644
--- a/gcc/fortran/scanner.c
+++ b/gcc/fortran/scanner.c
@@ -1887,6 +1887,11 @@ load_file (const char *realfilename, const char *displayedname, bool initial)
   int len, line_len;
   bool first_line;
   const char *filename;
+  /* If realfilename and displayedname are different and non-null then
+     surely realfilename is the preprocessed form of
+     displayedname.  */
+  bool preprocessed_p = (realfilename && displayedname
+			 && strcmp (realfilename, displayedname));
 
   filename = displayedname ? displayedname : realfilename;
 
@@ -1925,9 +1930,24 @@ load_file (const char *realfilename, const char *displayedname, bool initial)
 	}
     }
 
-  /* Load the file.  */
+  /* Load the file.
 
-  f = get_file (filename, initial ? LC_RENAME : LC_ENTER);
+     A "non-initial" file means a file that is being included.  In
+     that case we are creating an LC_ENTER map.
+
+     An "initial" file means a main file; one that is not included.
+     That file has already got at least one (surely more) line map(s)
+     created by gfc_init.  So the subsequent map created in that case
+     must have LC_RENAME reason.
+
+     This latter case is not true for a preprocessed file.  In that
+     case, although the file is "initial", the line maps created by
+     gfc_init was used during the preprocessing of the file.  Now that
+     the preprocessing is over and we are being fed the result of that
+     preprocessing, we need to create a brand new line map for the
+     preprocessed file, so the reason is going to be LC_ENTER.  */
+
+  f = get_file (filename, (initial && !preprocessed_p) ? LC_RENAME : LC_ENTER);
   if (!initial)
     add_file_change (f->filename, f->inclusion_line);
   current_file = f;
diff --git a/gcc/lto/lto-lang.c b/gcc/lto/lto-lang.c
index 83c41e6..d469fb9 100644
--- a/gcc/lto/lto-lang.c
+++ b/gcc/lto/lto-lang.c
@@ -1081,8 +1081,7 @@ lto_init (void)
   flag_generate_lto = flag_wpa;
 
   /* Initialize libcpp line maps for gcc_assert to work.  */
-  linemap_add (line_table, LC_RENAME, 0, NULL, 0);
-  linemap_add (line_table, LC_RENAME, 0, NULL, 0);
+  linemap_add (line_table, LC_ENTER, 0, NULL, 0);
 
   /* Create the basic integer types.  */
   build_common_tree_nodes (flag_signed_char, /*short_double=*/false);
diff --git a/libcpp/line-map.c b/libcpp/line-map.c
index dd3f11c..2a0749a 100644
--- a/libcpp/line-map.c
+++ b/libcpp/line-map.c
@@ -114,11 +114,10 @@ linemap_add (struct line_maps *set, enum lc_reason reason,
   if (reason == LC_RENAME_VERBATIM)
     reason = LC_RENAME;
 
-  /* If we don't keep our line maps consistent, we can easily
-     segfault.  Don't rely on the client to do it for us.  */
-  if (set->depth == 0)
-    reason = LC_ENTER;
-  else if (reason == LC_LEAVE)
+  if (set->depth == 0 && reason == LC_RENAME)
+    abort ();
+
+  if (reason == LC_LEAVE)
     {
       struct line_map *from;
       bool error;
-- 
		Dodji