https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82914
Bug ID: 82914
Summary: 'struct __attribute__ ((aligned (N))) s' ignores
'aligned' attribute
Product: gcc
Version: 7.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: eggert at gnu dot org
Target Milestone: ---
I'm reporting a GCC problem that caused Emacs to SIGSEGV as described here:
https://bugs.gnu.org/29183
I tracked the problem down to an '__attribute__ ((aligned (8)))' that GCC
silently ignored. To reproduce the problem, consider the following program:
struct s { char mem; };
__attribute__ ((aligned (8))) struct s a;
struct __attribute__ ((aligned (8))) s b;
struct s __attribute__ ((aligned (8))) c;
struct s d __attribute__ ((aligned (8)));
Compile this with 'gcc -S' on x86-64, and you get:
.comm a,1,8
.comm b,1,1
.comm c,1,8
.comm d,1,8
Although the variables a, c, and d are properly aligned, the variable b is not:
the 'aligned' attribute is silently ignored for b.
I reproduced this problem with GCC 7.2.1 20170915 (Red Hat 7.2.1-2), running on
Fedora 26 x86-64.
