Re: Document __builtin_*_overflow
Hi Jakub, On Wednesday 2014-11-12 14:13, Jakub Jelinek wrote: This patch mentions __builtin_*_overflow in gcc-5/changes.html. Ok for CVS? I've fallen a bit behind with GCC patches, sorry. What do you think about this follow-up patch on top of yours? Gerald Index: changes.html === RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-5/changes.html,v retrieving revision 1.41 diff -u -r1.41 changes.html --- changes.html23 Nov 2014 14:42:28 - 1.41 +++ changes.html25 Nov 2014 18:49:02 - @@ -157,14 +157,14 @@ These builtins have two integral arguments (which don't need to have the same type), the arguments are extended to infinite precision signed type, code+/code, code-/code or code*/code - is performed on those and the result is stored into some integer - variable pointed by the last argument. If the stored value is equal - to the infinite precision result, the built-in functions return + is performed on those, and the result is stored in an integer + variable pointed to by the last argument. If the stored value is + equal to the infinite precision result, the built-in functions return codefalse/code, otherwise codetrue/code. The type of the integer variable that will hold the result can be different from - the types of arguments. The following snippet demonstrates how - this can be used in computing the size for the codecalloc/code - function: + the types of the first two arguments. The following snippet + demonstrates how this can be used in computing the size for the + codecalloc/code function: blockquotepre void * calloc (size_t x, size_t y) @@ -177,8 +177,8 @@ return ret; } /pre/blockquote - On e.g. i?86 or x86-64 the above will result in codemul/code - instruction followed by jump on overflow. + On e.g. i?86 or x86-64 the above will result in a codemul/code + instruction followed by a jump on overflow. /li liThe option code-fextended-identifiers/code is now enabled by default for C++, and for C99 and later C versions. Various Gerald
Re: Document __builtin_*_overflow
On Tue, Nov 25, 2014 at 07:50:02PM +0100, Gerald Pfeifer wrote: Hi Jakub, On Wednesday 2014-11-12 14:13, Jakub Jelinek wrote: This patch mentions __builtin_*_overflow in gcc-5/changes.html. Ok for CVS? I've fallen a bit behind with GCC patches, sorry. What do you think about this follow-up patch on top of yours? LGTM, thanks. --- changes.html 23 Nov 2014 14:42:28 - 1.41 +++ changes.html 25 Nov 2014 18:49:02 - @@ -157,14 +157,14 @@ These builtins have two integral arguments (which don't need to have the same type), the arguments are extended to infinite precision signed type, code+/code, code-/code or code*/code - is performed on those and the result is stored into some integer - variable pointed by the last argument. If the stored value is equal - to the infinite precision result, the built-in functions return + is performed on those, and the result is stored in an integer + variable pointed to by the last argument. If the stored value is + equal to the infinite precision result, the built-in functions return codefalse/code, otherwise codetrue/code. The type of the integer variable that will hold the result can be different from - the types of arguments. The following snippet demonstrates how - this can be used in computing the size for the codecalloc/code - function: + the types of the first two arguments. The following snippet + demonstrates how this can be used in computing the size for the + codecalloc/code function: blockquotepre void * calloc (size_t x, size_t y) @@ -177,8 +177,8 @@ return ret; } /pre/blockquote - On e.g. i?86 or x86-64 the above will result in codemul/code - instruction followed by jump on overflow. + On e.g. i?86 or x86-64 the above will result in a codemul/code + instruction followed by a jump on overflow. /li liThe option code-fextended-identifiers/code is now enabled by default for C++, and for C99 and later C versions. Various Gerald Jakub
Document __builtin_*_overflow
Hi!
This patch mentions __builtin_*_overflow in gcc-5/changes.html.
Ok for CVS?
--- gcc-5/changes.html 27 Oct 2014 18:05:26 - 1.20
+++ gcc-5/changes.html 12 Nov 2014 13:09:01 -
@@ -84,7 +84,36 @@
of the standard directive code#include/code
and the extension code#include_next/code respectively.
/li
-
+liA new set of built-in functions for arithmetics with overflow checking
+ has been added: code__builtin_add_overflow/code,
+ code__builtin_sub_overflow/code and
code__builtin_mul_overflow/code
+ and for compatibility with clang also other variants.
+ These builtins have two integral arguments (which don't need to have
+ the same type), the arguments are extended to infinite precision
+ signed type, code+/code, code-/code or code*/code
+ is performed on those and the result is stored into some integer
+ variable pointed by the last argument. If the stored value is equal
+ to the infinite precision result, the built-in functions return
+ codefalse/code, otherwise codetrue/code. The type of
+ the integer variable that will hold the result can be different from
+ the types of arguments. The following snippet demonstrates how
+ this can be used in computing the size for the codecalloc/code
+ function:
+blockquotepre
+void *
+calloc (size_t x, size_t y)
+{
+ size_t sz;
+ if (__builtin_mul_overflow (x, y, amp;sz)
+return NULL;
+ void *ret = malloc (sz);
+ if (ret) memset (res, 0, sz);
+ return ret;
+}
+/pre/blockquote
+ On e.g. i?86 or x86-64 the above will result in codemul/code
+ instruction followed by jump on overflow.
+/li
/ul
h3 id=cC/h3
Jakub
Re: Document __builtin_*_overflow
On Wed, Nov 12, 2014 at 2:13 PM, Jakub Jelinek ja...@redhat.com wrote:
Hi!
This patch mentions __builtin_*_overflow in gcc-5/changes.html.
Ok for CVS?
Ok.
Thanks,
Richard.
--- gcc-5/changes.html 27 Oct 2014 18:05:26 - 1.20
+++ gcc-5/changes.html 12 Nov 2014 13:09:01 -
@@ -84,7 +84,36 @@
of the standard directive code#include/code
and the extension code#include_next/code respectively.
/li
-
+liA new set of built-in functions for arithmetics with overflow
checking
+ has been added: code__builtin_add_overflow/code,
+ code__builtin_sub_overflow/code and
code__builtin_mul_overflow/code
+ and for compatibility with clang also other variants.
+ These builtins have two integral arguments (which don't need to have
+ the same type), the arguments are extended to infinite precision
+ signed type, code+/code, code-/code or code*/code
+ is performed on those and the result is stored into some integer
+ variable pointed by the last argument. If the stored value is equal
+ to the infinite precision result, the built-in functions return
+ codefalse/code, otherwise codetrue/code. The type of
+ the integer variable that will hold the result can be different from
+ the types of arguments. The following snippet demonstrates how
+ this can be used in computing the size for the codecalloc/code
+ function:
+blockquotepre
+void *
+calloc (size_t x, size_t y)
+{
+ size_t sz;
+ if (__builtin_mul_overflow (x, y, amp;sz)
+return NULL;
+ void *ret = malloc (sz);
+ if (ret) memset (res, 0, sz);
+ return ret;
+}
+/pre/blockquote
+ On e.g. i?86 or x86-64 the above will result in codemul/code
+ instruction followed by jump on overflow.
+/li
/ul
h3 id=cC/h3
Jakub
Re: Document __builtin_*_overflow
On 12 Nov 2014, at 14:13, Jakub Jelinek ja...@redhat.com wrote: + size_t sz; + if (__builtin_mul_overflow (x, y, amp;sz) Missing right parenthesis ?
Re: Document __builtin_*_overflow
On Wed, Nov 12, 2014 at 03:39:25PM +0100, Tristan Gingold wrote: On 12 Nov 2014, at 14:13, Jakub Jelinek ja...@redhat.com wrote: + size_t sz; + if (__builtin_mul_overflow (x, y, amp;sz) Missing right parenthesis ? Thanks, fixed. Jakub
