[Bug target/106831] New: [13 Regression] mpfr-4.1.0 started failing 2 tests: tget_set_d64 and tget_set_d128

[slyfox at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106831

            Bug ID: 106831
           Summary: [13 Regression] mpfr-4.1.0 started failing 2 tests:
                    tget_set_d64 and tget_set_d128
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: slyfox at gcc dot gnu.org
  Target Milestone: ---

The test failures came up on this week's gcc snapshot updates:

- works: gcc-13.0.0.20220828 -O2
- fails: gcc-13.0.0.20220904 -O2
- works: gcc-13.0.0.20220904 -O0

Against https://ftp.gnu.org/gnu/mpfr/mpfr-4.1.0.tar.xz the following seems to
be enough:

    $ ./configure CC=gcc-13 && make && make check

Did not extract details yet to double-check if it's really a compiler error
(and not an mpfr deficiency). But -O0 / -O2 difference might be a hint.

Two test failures reported:

FAIL: tget_set_d64
==================

Error in check_misc for +0.
  mpfr_get_decimal64() returned:
|1011000110100000000000000000000000000000000000000000000000000000|
  mpfr_set_decimal64() set x to: -0 approx.
    = -0
FAIL tget_set_d64 (exit status: 1)

FAIL: tget_set_d128
===================

Error in check_misc for +0.
  mpfr_get_decimal128() returned: 0.0
  mpfr_set_decimal128() set x to: -0 approx.
    = -0
FAIL tget_set_d128 (exit status: 1)

$ gcc -v
Using built-in specs.
COLLECT_GCC=/<<NIX>>/gcc-13.0.0/bin/gcc
COLLECT_LTO_WRAPPER=/<<NIX>>/gcc-13.0.0/libexec/gcc/x86_64-unknown-linux-gnu/13.0.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with:
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 13.0.0 20220904 (experimental) (GCC)