[Bug c/103031] [12 Regression] Missing static initializer folding with -frounding-math

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103031

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Joseph Myers <jsm28@gcc.gnu.org>:

https://gcc.gnu.org/g:600dcd74b8e614c996b492d97878660faf484094

commit r12-4872-g600dcd74b8e614c996b492d97878660faf484094
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Wed Nov 3 14:58:25 2021 +0000

    c: Fold implicit integer-to-floating conversions in static initializers
with -frounding-math [PR103031]

    Recent fixes to avoid inappropriate folding of some conversions to
    floating-point types with -frounding-math also prevented such folding
    in C static initializers, when folding (in the default rounding mode,
    exceptions discarded) is required for correctness.

    Folding for static initializers is handled via functions in
    fold-const.c calling START_FOLD_INIT and END_FOLD_INIT to adjust flags
    such as flag_rounding_math that should not apply in static initializer
    context, but no such function was being called for the folding of
    these implicit conversions to the type of the object being
    initialized, only for explicit conversions as part of the initializer.

    Arrange for relevant folding (a fold call in convert, in particular)
    to use this special initializer handling (via a new fold_init
    function, in particular).

    Because convert is used by language-independent code but defined in
    each front end, this isn't as simple as just adding a new default
    argument to it.  Instead, I added a new convert_init function; that
    then gets called by c-family code, and C and C++ need convert_init
    implementations (the C++ one does nothing different from convert and
    will never actually get called because the new convert_and_check
    argument will never be true from C++), but other languages don't.

    Bootstrapped with no regressions for x86_64-pc-linux-gnu.

    gcc/
            PR c/103031
            * fold-const.c (fold_init): New function.
            * fold-const.h (fold_init): New prototype.

    gcc/c-family/
            PR c/103031
            * c-common.c (convert_and_check): Add argument init_const.  Call
            convert_init if init_const.
            * c-common.h (convert_and_check): Update prototype.
            (convert_init): New prototype.

    gcc/c/
            PR c/103031
            * c-convert.c (c_convert): New function, based on convert.
            (convert): Make into wrapper of c_convert.
            (convert_init): New function.
            * c-typeck.c (enum impl_conv): Add ic_init_const.
            (convert_for_assignment): Handle ic_init_const like ic_init.  Add
            new argument to convert_and_check call.
            (digest_init): Pass ic_init_const to convert_for_assignment for
            initializers required to be constant.

    gcc/cp/
            PR c/103031
            * cvt.c (convert_init): New function.

    gcc/testsuite/
            PR c/103031
            * gcc.dg/init-rounding-math-1.c: New test.