https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82242
Alexander Monakov <amonakov at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2017-09-20
CC| |amonakov at gcc dot gnu.org,
| |vmakarov at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #3 from Alexander Monakov <amonakov at gcc dot gnu.org> ---
(Marc, for vectorization -fassociative-math would be required)
I think it's due to handling of possibly-throwing insns in register allocation:
allocno for the accumulator is considered to conflict with all SSE registers,
but the throwing call is outside of the loop, and we don't want spills inside
the loop. Minimal C++ testcase, needs just -O2:
void c();
struct S {~S();};
double f(double *x, int n)
{
S s;
double r = 0;
for (; n; n--)
r += *x++;
c();
return r;
}
I don't understand why throwing calls are more special than normal calls for
IRA, it seems values in call-clobbered registers would need to be spilled
either way...
