On 08/25/2017 11:31 AM, H.J. Lu wrote:
On Fri, Aug 25, 2017 at 10:15 AM, Martin Sebor <mse...@gmail.com> wrote:
On 08/21/2017 06:21 AM, H.J. Lu wrote:
When warn_if_not_aligned_p is true, a warning will be issued on function
declaration later. There is no need to warn function alignment when
warn_if_not_aligned_p is true.
OK for trunk?
H.J.
--
* c-attribs.c (common_handle_aligned_attribute): Don't warn
function alignment if warn_if_not_aligned_p is true.
---
gcc/c-family/c-attribs.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/gcc/c-family/c-attribs.c b/gcc/c-family/c-attribs.c
index 5f79468407f..78969532543 100644
--- a/gcc/c-family/c-attribs.c
+++ b/gcc/c-family/c-attribs.c
@@ -1754,9 +1754,12 @@ common_handle_aligned_attribute (tree *node, tree
args, int flags,
This formally comes from the c++11 specification but we are
doing it for the GNU attribute syntax as well. */
*no_add_attrs = true;
- else if (TREE_CODE (decl) == FUNCTION_DECL
+ else if (!warn_if_not_aligned_p
+ && TREE_CODE (decl) == FUNCTION_DECL
&& DECL_ALIGN (decl) > (1U << i) * BITS_PER_UNIT)
{
+ /* Don't warn function alignment here if warn_if_not_aligned_p is
+ true. It will be warned later. */
if (DECL_USER_ALIGN (decl))
error ("alignment for %q+D was previously specified as %d "
"and may not be decreased", decl,
Your comment refers to warning but the code here uses error().
That raises two questions for me: a) will the later diagnostic
really be a warning or an error, and if a warning, under what
option will it be issued? and b) why is an error appropriate
here when a warning is appropriate elsewhere (most other
attribute conflicts are at present diagnosed with -Wattributes).
It can be changed to warning.
Okay, that's goo to hear (it validates what I did in the patch
I referenced).
As for your patch, I don't quite see ho the block can ever be
entered. In fact, I had to make changes to the function in
my patch below to let it detect and diagnose the condition
(attempting to reduce the alignment of a function). The
details are in bug 81566. Did I miss something?
Martin
My main motivation for these questions is to understand the
rationale for warning for vs rejecting conflicts so that
a consistent general solution can be implemented for all
attributes (i.e., along the lines of my patch here:
https://gcc.gnu.org/ml/gcc-patches/2017-08/msg01457.html)
Martin
