So I've done some testing... make_not_regable is NOT being called at
all. When the array is already on the stack, this is no problem, but if
it's in an MM register, then problems start occurring. If I force the
call to make_not_regable, then the bad code disappears. I'm still
learning how it works in this part of the code, especially where the
node location changes.
program m128test;
function Test3(V1, V2: __m128d): __m128d; vectorcall;
begin
Test3[1] := V1[1] + V2[1];
end;
begin
end.
Output:
# Register rsp,rbp allocated
pushq %rbp
.seh_pushreg %rbp
movq %rsp,%rbp
leaq -64(%rsp),%rsp
.seh_stackalloc 64
# Temp -64,16 allocated
.seh_endprologue
# Temp -16,16 allocated
# Temp -32,16 allocated
# Temp -48,16 allocated
# Register xmm0,xmm1 allocated
movdqa %xmm0,-16(%rbp)
# Register xmm0 released
movdqa %xmm1,-32(%rbp)
# Register xmm1 released
# Register mreg32 allocated
movsd -8(%rbp),%mreg32md
addsd -24(%rbp),%mreg32md
# Register mreg32 released
movsd %mreg32md,-40(%rbp)
# Temp -16,16 released
# Temp -32,16 released
# Register xmm0 allocated
movdqa -48(%rbp),%xmm0
# Temp -48,16 released
# Temp -64,16 released
leaq (%rbp),%rsp
popq %rbp
# Register rbp,rsp released
ret
.seh_endproc
# Register xmm0 released
No uninitialised registers are being written (although -48(%rbp) is
uninitialised because I don't write to Test3[0]). Of course I don't
want to force the call to make
On 08/04/2022 20:58, Jonas Maebe via fpc-devel wrote:
On 08/04/2022 20:31, J. Gareth Moreton via fpc-devel wrote:
That might explain a few things. The problem is that under
vectorcall and the System V ABI (the default x86_64 calling
convention for Linux), vector types are supposed to be fully
supported, like an aligned array of 4 Singles should be passed in a
single XMM register.
That's no problem in itself. Normally, make_not_regable will ensure
that such values will be stored in memory on procedure entry and kept
there. Various architectures require that records are also passed in
registers (even if they're larger than 1 register), which also work
fine even though the compiler only supports record regvars occupying
at most one register (or perhaps two, I don't remember).
Jonas
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