https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91131
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2019-07-10
Ever confirmed|0 |1
Known to fail| |10.0, 8.3.0
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
So your complaint is that
struct Reg_T {
unsigned int a : 3;
unsigned int b : 1;
unsigned int c : 4;
} __attribute__((packed));
volatile struct Reg_T Reg_A;
...
Reg_A = (struct Reg_T){ .a = 0, .b = 0, .c = 0 };
does not yield a single store, correct?
The reason is how we gimplify this:
{
Reg_A.a = 0;
Reg_A.b = 0;
Reg_A.c = 0;
D.2005.a = 0;
D.2005.b = 1;
D.2005.c = 0;
Reg_B = D.2005;
D.2006.a = 7;
D.2006.b = 1;
D.2006.c = 15;
Reg_C = D.2006;
Reg_D = 0;
Reg_E = 255;
D.2007 = 0;
return D.2007;
}
see how for the zero-initializer we emit three volatile accesses.
