[Bug target/89222] [7/8 regression] ARM thumb-2 misoptimisation of func ptr call with -O2 or -Os

[wilco at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89222

--- Comment #10 from Wilco <wilco at gcc dot gnu.org> ---
Author: wilco
Date: Tue Jul 16 12:37:14 2019
New Revision: 273526

URL: https://gcc.gnu.org/viewcvs?rev=273526&root=gcc&view=rev
Log:
[ARM] Fix PR89222

The GCC optimizer can generate symbols with non-zero offset from simple
if-statements. Bit zero is used for the Arm/Thumb state bit, so relocations
with offsets fail if it changes bit zero and the relocation forces bit zero
to true.  The fix is to disable offsets on function pointer symbols.  

    gcc/
        PR target/89222
        * config/arm/arm.md (movsi): Use targetm.cannot_force_const_mem
        to decide when to split off a non-zero offset from a symbol.
        * config/arm/arm.c (arm_cannot_force_const_mem): Disallow offsets
        in function symbols.

    testsuite/
        PR target/89222
        * gcc.target/arm/pr89222.c: Add new test.

Added:
    branches/gcc-8-branch/gcc/testsuite/gcc.target/arm/pr89222.c
Modified:
    branches/gcc-8-branch/gcc/ChangeLog
    branches/gcc-8-branch/gcc/config/arm/arm.c
    branches/gcc-8-branch/gcc/config/arm/arm.md
    branches/gcc-8-branch/gcc/testsuite/ChangeLog