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From: "bergner at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/114759] New: Power: multiple issues with -mrop-protect
Date: Wed, 17 Apr 2024 21:18:07 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: target
X-Bugzilla-Version: 14.0
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X-Bugzilla-Severity: normal
X-Bugzilla-Who: bergner at gcc dot gnu.org
X-Bugzilla-Status: UNCONFIRMED
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X-Bugzilla-Priority: P3
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114759

            Bug ID: 114759
           Summary: Power: multiple issues with -mrop-protect
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: bergner at gcc dot gnu.org
  Target Milestone: ---

There are multiple issues with the -mrop-protect option which are all
inter-related.

1. We always define the __ROP_PROTECT__ predefined macro when using
-mrop-protect, even when we've silently disabled ROP protection because of a
too old -mcpu=3DCPU value.  We should only emit __ROP_PROTECT__ when it's l=
egal
to emit the ROP insns.

2. We always disable shrink-wrapping when -mrop-protect is used, even when
we've silently disabled ROP protection because of a too old -mcpu=3DCPU val=
ue.=20
We should not disable shrink-wrapping if we've disabled ROP protection.

3. We silently disable ROP protection for everything other than -mcpu=3Dpow=
er10.=20
The binutils assembler accepts the ROP insns back to Power8, so we should e=
mit
them for Power8 and later.

4. We give an error when -mrop-protect is used with any -mabi=3DABI value n=
ot
equal to ELFv2, whereas a too old -mcpu=3DCPU value only causes us to silen=
tly
disable ROP protection.  I think both scenarios should behave similarly, so
either we silently disable ROP protection for both or we give an error for
both.

This is not a regression.  I consider 1. to be a correctness/wrong code bug=
.=