Re: [PATCH] [PR target/96350]Force ENDBR immediate into memory to avoid fake ENDBR opcode.

[Uros Bizjak <ubizjak@gmail.com>]

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;

   /* 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)
    {

Uros.

> --
> BR,
> Hongtao