Jeff Law wrote:
> On 11/11/13 07:32, Ulrich Weigand wrote:
> > However, looking more closely, it seems
> > store_unaligned_arguments_into_pseudos
> > is not really useful for PARALLEL arguments in the first place. What this
> > routine does is load arguments into args[i].aligned_regs. But if we have
> > an argument where args[i].reg is a PARALLEL, args[i].aligned_regs will in
> > fact never be used later on at all! Instead, PARALLEL will always be
> > handled directly via emit_group_move (in load_register_parameters), so
> > the code generated by store_unaligned_arguments_into_pseudos for such cases
> > is simply dead anyway.
> Does this work on the PA, particularly the 32bit ABI?
> /* Structures 5 to 8 bytes in size are passed in the general
> registers in the same manner as other non floating-point
> objects. The data is right-justified and zero-extended
> to 64 bits. This is opposite to the normal justification
> used on big endian targets and requires special treatment.
> We now define BLOCK_REG_PADDING to pad these objects.
> Aggregates, complex and vector types are passed in the same
> manner as structures. */
It seems this is exactly one of the cases I mention above, where current
code generates code to load up "aligned registers" which are then never
used again.
I'm not really set up to test PA, but I built a cross to hppa-linux,
and compiled this simple test passing a 5-byte struct:
struct test { char x[5]; };
struct test x;
void func (struct test);
void caller (void)
{
func (x);
}
And indeed with my patch, I'm getting a lot less code at -O0. However,
building with -O2 both with and without my patch, the resulting assembler
files are identical again -- which appears to confirm that this extra
code is in fact dead ...
Bye,
Ulrich
--
Dr. Ulrich Weigand
GNU/Linux compilers and toolchain
[email protected]
