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| -rw-r--r-- | gcc/doc/extend.texi | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index adba057..68d7760 100644 --- a/gcc/doc/extend.texi +++ b/gcc/doc/extend.texi @@ -12796,7 +12796,9 @@ __atomic_store_n(&lockvar, 0, __ATOMIC_RELEASE|__ATOMIC_HLE_RELEASE); @end smallexample @node Object Size Checking -@section Object Size Checking Built-in Functions +@section Object Size Checking + +@subsection Object Size Checking Built-in Functions @findex __builtin_object_size @findex __builtin_dynamic_object_size @findex __builtin___memcpy_chk @@ -12878,11 +12880,17 @@ which objects @var{ptr} points to at compile time are the same as in the case of @code{__builtin_object_size}. @end deftypefn -There are built-in functions added for many common string operation -functions, e.g., for @code{memcpy} @code{__builtin___memcpy_chk} -built-in is provided. This built-in has an additional last argument, -which is the number of bytes remaining in the object the @var{dest} -argument points to or @code{(size_t) -1} if the size is not known. +@subsection Object Size Checking and Source Fortification + +Hardening of function calls using the @code{_FORTIFY_SOURCE} macro is +one of the key uses of the object size checking built-in functions. To +make implementation of these features more convenient and improve +optimization and diagnostics, there are built-in functions added for +many common string operation functions, e.g., for @code{memcpy} +@code{__builtin___memcpy_chk} built-in is provided. This built-in has +an additional last argument, which is the number of bytes remaining in +the object the @var{dest} argument points to or @code{(size_t) -1} if +the size is not known. The built-in functions are optimized into the normal string functions like @code{memcpy} if the last argument is @code{(size_t) -1} or if |