[Bug tree-optimization/111015] [11/12/13/14 Regression] __int128 bitfields optimized incorrectly to the 64 bit operations

["mikpelinux at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111015

Mikael Pettersson <mikpelinux at gmail dot com> changed:

           What    |Removed                     |Added
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                 CC|                            |mikpelinux at gmail dot com

--- Comment #3 from Mikael Pettersson <mikpelinux at gmail dot com> ---
10.5.0 is good, 11.4.0 and above are affected, started with (or was exposed
by):

commit ed01d707f8594827de95304371d5b62752410842
Author: Eric Botcazou <ebotcazou@gcc.gnu.org>
Date:   Mon May 25 22:13:11 2020 +0200

    Fix internal error on store to FP component at -O2

    This is about a GIMPLE verification failure at -O2 or above because
    the GIMPLE store merging pass generates a NOP_EXPR between a FP type
    and an integral type.  This happens when the bit-field insertion path
    is taken for a FP field, which can happen in Ada for bit-packed record
    types.

    It is fixed by generating an intermediate VIEW_CONVERT_EXPR.  The patch
    also tames a little the bit-field insertion path because, for bit-packed
    record  types in Ada, you can end up with large bit-field regions, which
    results in a lot of mask-and-shifts instructions.

    gcc/ChangeLog
            * gimple-ssa-store-merging.c
(merged_store_group::can_be_merged_into):
            Only turn MEM_REFs into bit-field stores for small bit-field
regions
            (imm_store_chain_info::output_merged_store): Be prepared for
sources
            with non-integral type in the bit-field insertion case.
            (pass_store_merging::process_store): Use MAX_BITSIZE_MODE_ANY_INT
as
            the largest size for the bit-field case.

    gcc/testsuite/ChangeLog
            * gnat.dg/opt84.adb: New test.

 gcc/ChangeLog                   |  9 +++++
 gcc/gimple-ssa-store-merging.c  | 20 ++++++++---
 gcc/testsuite/ChangeLog         |  4 +++
 gcc/testsuite/gnat.dg/opt84.adb | 74 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 103 insertions(+), 4 deletions(-)
 create mode 100644 gcc/testsuite/gnat.dg/opt84.adb