Hi,
This patch documents __builtin_setjmp and __builtin_longjmp. OK to
install?
Thanks.
H.J.
---
2013-11-10 H.J. Lu <hongjiu...@intel.com>
PR other/59039
* doc/extend.texi: Document __builtin_setjmp and
__builtin_longjmp.
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 0d72819..44b7c59 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -27,6 +27,7 @@ extensions, accepted by GCC in C90 mode and in C++.
* Local Labels:: Labels local to a block.
* Labels as Values:: Getting pointers to labels, and computed gotos.
* Nested Functions:: As in Algol and Pascal, lexical scoping of functions.
+* Nonlocal Gotos:: Nonlocal gotos
* Constructing Calls:: Dispatching a call to another function.
* Typeof:: @code{typeof}: referring to the type of an expression.
* Conditionals:: Omitting the middle operand of a @samp{?:} expression.
@@ -518,6 +519,36 @@ bar (int *array, int offset, int size)
@}
@end smallexample
+@node Nonlocal Gotos
+@section Nonlocal Gotos
+@cindex nonlocal gotos
+
+GCC provides builtin functions @code{__builtin_setjmp} and
+@code{__builtin_longjmp} which operate similarly to the C library
+functions of the same name, but are more efficient.
+
+@deftypefn {Built-in Function} {int} __builtin_setjmp (intptr_t *@var{buf})
+This function saves the current stack context in @code{setjmp} buffer,
+@var{buf}. @code{__builtin_setjmp} returns 0 when returning directly,
+and @var{1} when returning from @code{__builtin_longjmp} using the same
+@code{setjmp} buffer.
+@end deftypefn
+
+@deftypefn {Built-in Function} {void} __builtin_longjmp (intptr_t *@var{buf},
int @var{val})
+This function restores the stack context in @code{setjmp} buffer,
+@var{buf}, saved by the last call of @code{__builtin_setjmp}. After
+@code{__builtin_longjmp} is finished, program resumes execution as
+if the last @code{__builtin_setjmp} just returns the value @var{val},
+which must be @var{1}.
+@end deftypefn
+
+The @code{setjmp} buffer is an array of five @code{intptr_t}. The buffer
+will generally contain the frame address, the resume address and the stack
+address. The other elements may be used in a machine-specific way.
+
+@code{__builtin_setjmp} and @code{__builtin_longjmp} may not be used
+in the same function with the same @code{setjmp} buffer.
+
@node Constructing Calls
@section Constructing Function Calls
@cindex constructing calls
