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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/108539] Wrong register usage for -m16 -masm=intel
 -march=i386 on asm volatile
Date: Wed, 25 Jan 2023 13:40:42 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108539

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
                 CC|                            |jakub at gcc dot gnu.org
         Resolution|---                         |INVALID

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
That is just misunderstanding of the inline asm syntax, please read the
documentation.
"=3Ddl" doesn't mean that _a output is in %dl register, but either in %edx
register or
in any of the index registers (%eax %ebx %ecx %edx %esi %edi %ebp).
"=3Ddh" means either in %edx register or in nowhere (h isn't a valid constr=
aint).
So, when doing RA _b needs to be put into %edx (the low 8 bits of that aka =
%dl)
and _a into some index register other than %edx.=