From: Uros Bizjak <ubizjak@gmail.com>
To: Hongtao Liu <crazylht@gmail.com>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>, "H. J. Lu" <hjl.tools@gmail.com>
Subject: Re: [PATCH] [PR target/96350]Force ENDBR immediate into memory to avoid fake ENDBR opcode.
Date: Tue, 11 Aug 2020 11:56:04 +0200 [thread overview]
Message-ID: <CAFULd4Y7VZjeZ_9z3LQUzZa_8WKxV76+zO3MbJ2HTvmdaeRYnA@mail.gmail.com> (raw)
In-Reply-To: <CAMZc-bxijnO40pdt6OXejKg89_SuVtM4evFE1F4hvBt81Dwi5Q@mail.gmail.com>
On Tue, Aug 11, 2020 at 11:36 AM Hongtao Liu <crazylht@gmail.com> wrote:
>
> On Tue, Aug 11, 2020 at 4:38 PM Uros Bizjak <ubizjak@gmail.com> wrote:
> >
> > On Tue, Aug 11, 2020 at 5:30 AM Hongtao Liu <crazylht@gmail.com> wrote:
> > >
> > > Hi:
> > > The issue is described in the bugzilla.
> > > Bootstrap is ok, regression test for i386/x86-64 backend is ok.
> > > Ok for trunk?
> > >
> > > ChangeLog
> > > gcc/
> > > PR target/96350
> > > * config/i386/i386.c (ix86_legitimate_constant_p): Return
> > > false for ENDBR immediate.
> > > (ix86_legitimate_address_p): Ditto.
> > > * config/i386/predicated.md
> > > (x86_64_immediate_operand): Exclude ENDBR immediate.
> > > (x86_64_zext_immediate_operand): Ditto.
> > > (x86_64_dwzext_immediate_operand): Ditto.
> > > (ix86_not_endbr_immediate_operand): New predicate.
> > >
> > > gcc/testsuite
> > > * gcc.target/i386/endbr_immediate.c: New test.
> >
> > +;; Return true if VALUE isn't an ENDBR opcode in immediate field.
> > +(define_predicate "ix86_not_endbr_immediate_operand"
> > + (match_test "1")
> >
> > Please reverse the above logic to introduce
> > ix86_endbr_immediate_operand, that returns true for unwanted
> > immediate. Something like:
> >
> > (define_predicate "ix86_endbr_immediate_operand"
> > (match_code "const_int")
> > ...
> >
> > And you will be able to use it like:
> >
> > if (ix86_endbr_immediate_operand (x, VOIDmode)
> > return false;
> >
>
> Changed.
No, it is not.
+ if ((flag_cf_protection & CF_BRANCH)
+ && CONST_INT_P (op))
You don't need to check for const ints here.
And please rewrite the body of the function to something like (untested):
{
unsigned HOST_WIDE_INT val = TARGET_64BIT ? 0xfa1e0ff3 : 0xfb1e0ff3;
if (x == val)
return 1;
if (TARGET_64BIT)
for (; x >= val; x >>= 8)
if (x == val)
return 1;
return 0;
}
so it will at least *look* like some thoughts have been spent on this.
I don't plan to review the code where it is obvious from the first
look that it was thrown together in a hurry. Please get some internal
company signoff first. Ping me in a week for a review.
Uros.
>
> > /* Otherwise we handle everything else in the move patterns. */
> > - return true;
> > + return ix86_not_endbr_immediate_operand (x, VOIDmode);
> > }
> >
> > Please handle this in CASE_CONST_SCALAR_INT: part.
> >
> > + if (disp && !ix86_not_endbr_immediate_operand (disp, VOIDmode))
> > + return false;
> >
> > And this in:
> >
> > /* Validate displacement. */
> > if (disp)
> > {
> >
>
> Changed.
A better place for these new special cases is at the beginning of the
part I referred, not at the end.
Uros.
next prev parent reply other threads:[~2020-08-11 9:56 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-11 3:31 Hongtao Liu
2020-08-11 8:38 ` Uros Bizjak
2020-08-11 9:36 ` Hongtao Liu
2020-08-11 9:56 ` Uros Bizjak [this message]
2020-08-14 4:54 ` Hongtao Liu
2020-08-14 10:03 ` Uros Bizjak
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