[Bug target/82028] Windows x86_64 should not pass float aggregates in xmm

[Bug target/82028] Windows x86_64 should not pass float aggregates in xmm

[lh_mouse at 126 dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82028

LIU Hao <lh_mouse at 126 dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |lh_mouse at 126 dot com

--- Comment #2 from LIU Hao <lh_mouse at 126 dot com> ---
As per
<https://docs.microsoft.com/en-us/cpp/build/x64-calling-convention?view=msvc-170#parameter-passing>

> Structs and unions of size 8, 16, 32, or 64 bits, and __m64 types, are 
> passed as if they were integers of the same size. Structs or unions of 
> other sizes are passed as a pointer to memory allocated by the caller.

GCC behavior seems incorrect.

[Bug target/82028] Windows x86_64 should not pass float aggregates in xmm

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82028

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
                 CC|                            |10walls at gmail dot com
   Last reconfirmed|                            |2022-01-12

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Thus confirmed.

[Bug target/82028] Windows x86_64 should not pass float aggregates in xmm

[10walls at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82028

--- Comment #4 from jon_y <10walls at gmail dot com> ---
I can't seem to change the bug status to confirmed.

[Bug target/82028] Windows x86_64 should not pass float aggregates in xmm

[nightstrike at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82028

nightstrike <nightstrike at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |nightstrike at gmail dot com

--- Comment #5 from nightstrike <nightstrike at gmail dot com> ---
(In reply to jon_y from comment #4)
> I can't seem to change the bug status to confirmed.

"NEW" is confirmed

[Bug target/82028] Windows x86_64 should not pass float aggregates in xmm

[lh_mouse at 126 dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82028

--- Comment #6 from LIU Hao <lh_mouse at 126 dot com> ---
Looks like this has been fixed?  https://gcc.godbolt.org/z/xP5E76aYz

Despite that however, GCC generates suboptimal code that uses an XMM register
to perform the bitwise AND operation.

[Bug target/82028] Windows x86_64 should not pass float aggregates in xmm

[lh_mouse at 126 dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82028

--- Comment #7 from LIU Hao <lh_mouse at 126 dot com> ---
clang generates 14 bytes:

```
mov rax, 0x7FFFFFFFFFFFFFFF   # 48 B8 FF FF FF FF FF FF FF 7F
and rax, rcx                  # 48 23 C1
ret                           # C3
``

but in principle this function requires only 8 bytes:

```
lea rax, qword ptr [rcx + rcx]    # 48 8D 04 09
shr rax, 1                        # 48 D1 E8
ret                               # C3
``

[Bug target/82028] Windows x86_64 should not pass float aggregates in xmm

[ebotcazou at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82028

Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |DUPLICATE
                 CC|                            |ebotcazou at gcc dot gnu.org

--- Comment #8 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
Fixed in 9.3 and later.

*** This bug has been marked as a duplicate of bug 85667 ***