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From: "meissner at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/98519] rs6000: @pcrel unsupported on this instruction
 error in pveclib
Date: Tue, 05 Jan 2021 22:07:44 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D98519

--- Comment #15 from Michael Meissner <meissner at gcc dot gnu.org> ---
FWIW, the hook that will need to be modified is rs6000_md_asm_adjust in
rs6000.c.  It appears you are passed the outputs, the inputs, the constrain=
ts,
and the clobbers.  Right now, we just mark the CA register as being clobber=
ed.

The simplest approach is just to prohibit both prefixed and pc-relative
addresses from being passed to the asm.  If a prefixed/pc-relative address =
is
passed as an input/output, we would need to force the address to a base
register, and rewrite the input/output to use that new base register.  That
will allow traditional code to work.

I suspect if we wanted to enable users to actually do prefixed loads/stores=
 in
the asm, we would need a constraint that says this address must be prefixed=
.=20
Possibly another one for pc-relative.  And then the hook would allow the
address without modification.=