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From: "hp at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/114492] New: Invalid use of gcc_assert (notably in
 gcc/config/aarch64/aarch64-ldp-fusion.cc)
Date: Wed, 27 Mar 2024 02:34:31 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114492

            Bug ID: 114492
           Summary: Invalid use of gcc_assert (notably in
                    gcc/config/aarch64/aarch64-ldp-fusion.cc)
           Product: gcc
           Version: 13.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hp at gcc dot gnu.org
                CC: acoplan at gcc dot gnu.org
  Target Milestone: ---
            Target: aarch64

I've noticed invalid uses of gcc_assert in
gcc/config/aarch64/aarch64-ldp-fusion.cc.  Please be advised that the argum=
ent
is *not* evaluated with release checking; I believe most uses can be cured =
by
breaking out the call; i.e. replacing an invalid call:

gcc_assert (function_that_needs_to_be_called_but_most_certainly_returns_tru=
e())

with:

bool x =3D function_that_needs_to_be_called_but_most_certainly_returns_true=
 ();
gcc_assert (x).

(Probably not the only file, just the one I've been looking at, for reasons,
and I thought better enter a bug report, just not going to fix it myself.)

Incidentally, I think "we" ought to add something to gcc that automatically
checks and warns for such invalid use.  There may be a need to implement a
builtin to check that an expression X does not have side-effects, for use b=
oth
within gcc in gcc_assert and user-visible, for implementations of assert; s=
ay
__builtin_pure_p (X).  (The name is ripe to bike-shedding, just choosing a =
mix
of __builtin_constant_p and the "pure" attribute.)=