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authorZack Weinberg <zack@codesourcery.com>2001-11-27 07:42:10 +0000
committerNeil Booth <neil@gcc.gnu.org>2001-11-27 07:42:10 +0000
commit07e96fc688ba9fcc49c0e71ce8a3b484feacac52 (patch)
tree5c35e1a8044ac5dd77b1e3143e71814c99932d3c /gcc/cppfiles.c
parent773105be40493abf39078b62df940476acee344d (diff)
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* cppfiles.c (read_include_file): Add comment.
From-SVN: r47369
Diffstat (limited to 'gcc/cppfiles.c')
-rw-r--r--gcc/cppfiles.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/gcc/cppfiles.c b/gcc/cppfiles.c
index f0d85d9..65bcf62 100644
--- a/gcc/cppfiles.c
+++ b/gcc/cppfiles.c
@@ -382,6 +382,11 @@ read_include_file (pfile, inc)
if (pagesize == -1)
pagesize = getpagesize ();
+ /* Use mmap if the file is big enough to be worth it (controlled
+ by MMAP_THRESHOLD) and if we can safely count on there being
+ at least one readable NUL byte after the end of the file's
+ contents. This is true for all tested operating systems when
+ the file size is not an exact multiple of the page size. */
if (size / pagesize >= MMAP_THRESHOLD
&& (size % pagesize) != 0)
{