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Date: Sun, 12 Apr 2015 11:02:00 -0000
From: Gerald Pfeifer
To: Benjamin De Kosnik , gcc-patches@gcc.gnu.org
Subject: Re: [wwwdocs] gcc-4.8/porting_to.html
In-Reply-To: <20130313022916.0728c82e@oakwood>
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References: <20130313022916.0728c82e@oakwood>
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On Wed, 13 Mar 2013, Benjamin De Kosnik wrote:
> Hey! Here is the first pass at the 4.8 porting documentation.
Lovely, thank you, I know this really has proven useful.
And with some unfortunate of delay, some updates from my side:
- Use run-time performance (instead of runtime performance which
Sandra established as the performance of the runtime, I think).
- Code does not use warning options per se.
- Undefined behavior is undefined regardless of how involved
optimizers are.
- Improve markup, fix grammar, break long lines.
- Refer to GNU/Linux.
Applied.
Gerald
Index: porting_to.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-4.8/porting_to.html,v
retrieving revision 1.5
diff -u -r1.5 porting_to.html
--- porting_to.html 11 Jun 2014 18:49:26 -0000 1.5
+++ porting_to.html 12 Apr 2015 00:14:41 -0000
@@ -13,7 +13,7 @@
changes. Some of
these are a result of bug fixing, and some old behaviors have been
intentionally changed in order to support new standards, or relaxed
-in standards-conforming ways to facilitate compilation or runtime
+in standards-conforming ways to facilitate compilation or run-time
performance. Some of these changes are not visible to the naked eye
and will not cause problems when updating from older versions.
@@ -31,9 +31,8 @@
Improvements to the GCC infrastructure allow improvements in
the ability of several existing warnings to spot problematic code. As
-such, new warnings may exist for previously warning-free code that
-uses
--Wmaybe-uninitialized
.
+such, new warnings may exist for previously warning-free code when
+using -Wmaybe-uninitialized
.
Although these warnings will
@@ -49,8 +48,8 @@
More aggressive loop optimizations
Improvements to the GCC infrastructure allow improvements in
-the ability of the optimizers to transform loops. Some loops that previously
-invoked undefined behavior may now be turned into endless loops.
+the ability of the optimizers to transform loops. Some loops that
+invoke undefined behavior may now be turned into endless loops.
For example,
@@ -68,7 +67,8 @@
-When fd is 64 or above, fd * 0x02000001 overflows, which is invalid in C/C++ for signed ints.
+When fd is 64 or above, fd * 0x02000001 overflows, which is invalid for
+signed ints in C/C++.
@@ -119,13 +119,13 @@
^
-
Although these warnings will not result in compilation failure,
-often -Wall
is used in conjunction with
+
Although these warnings will not result in compilation failure per
+se, often -Wall
is used in conjunction with
-Werror
and as a result, new warnings are turned into
new errors.
-To fix, either re-write to use memcpy or dereference the last argument in the
-offending memset call.
+To fix, either re-write to use memcpy
or dereference the
+last argument in the offending memset
call.
As a workaround, use
-Wno-sizeof-pointer-memaccess
.
@@ -134,7 +134,7 @@
Pre-processor pre-includes
-The GCC pre-processor may now pre-includes a file that defines certain
+The GCC pre-processor may now pre-include a file that defines certain
macros for the entirety of the translation unit. This allows
fully conformant implementations of C99/C11 and other standards that
require compiler or compiler + runtime macros that describe
@@ -142,7 +142,7 @@
-On linux, <stdc-predef.h> is pre-included.
+On GNU/Linux, <stdc-predef.h> is pre-included.
@@ -154,8 +154,9 @@
/usr/include/stdc-predef.h:0: error: Syntax error near '3'
-
As a workaround, the stdc-predef.h preinclude can be disabled with
-the use of -ffreestanding
. For non C/C++ code, use the pre-processor flag -P
.
+
As a workaround, the stdc-predef.h pre-include can be disabled with
+the use of -ffreestanding
. For non C/C++ code, use the
+pre-processor flag -P
.
C++ language issues