Add further _BitInt <-> floating point tests [PR102989]

Add further _BitInt <-> floating point tests [PR102989]

Here are just the testsuite additions from libgcc _BitInt patch review.

On Fri, Sep 01, 2023 at 09:48:22PM +0000, Joseph Myers wrote:
> 1. Test overflowing conversions to integers (including from inf or NaN)
> raise FE_INVALID.  (Note: it's not specified in the standard whether
> inexact conversions to integers raise FE_INEXACT or not, so testing that
> seems less important.)

This is in gcc.dg/bitint-28.c (FE_INVALID) and gcc.dg/bitint-29.c
(FE_INEXACT) for binary and dfp/bitint-8.c new tests.

> 2. Test conversions from integers to floating point raise FE_INEXACT when
> inexact, together with FE_OVERFLOW when overflowing (while exact
> conversions don't raise exceptions).

This is in gcc.dg/bitint-30.c new test.

> 3. Test conversions from integers to floating point respect the rounding
> mode.

This is in gcc.dg/bitint-31.c new test.

> 4. Test converting floating-point values in the range (-1.0, 0.0] to both
> unsigned and signed _BitInt; I didn't see such tests for binary floating
> types, only for decimal types, and the decimal tests didn't include tests
> of negative zero itself as the value converted to _BitInt.

This is done as incremental changes to existing tests.

> 5. Test conversions of noncanonical BID zero to integers (these tests
> would be specific to BID).  See below for a bug in this area.

This is done in dfp/bitint-7.c test.

2023-09-06  Jakub Jelinek  <jakub@redhat.com>

	PR c/102989
	* gcc.dg/torture/bitint-21.c (main): Add tests for -1 for signed only,
	-1 + epsilon, another (-1, 0) range value and -0.
	* gcc.dg/torture/bitint-22.c (main): Likewise.
	* gcc.dg/bitint-28.c: New test.
	* gcc.dg/bitint-29.c: New test.
	* gcc.dg/bitint-30.c: New test.
	* gcc.dg/bitint-31.c: New test.
	* gcc.dg/dfp/bitint-1.c (main): Add tests for -1 for signed only,
	-1 + epsilon and -0.
	* gcc.dg/dfp/bitint-2.c (main): Likewise.
	* gcc.dg/dfp/bitint-3.c (main): Likewise.
	* gcc.dg/dfp/bitint-7.c: New test.
	* gcc.dg/dfp/bitint-8.c: New test.