Skip to content

[C23] Support the SNAN macros in <float.h> #162858

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 1 commit into
base: main
Choose a base branch
from
+27 −8
Open

[C23] Support the SNAN macros in <float.h> #162858

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
3 changes: 3 additions & 0 deletions clang/docs/ReleaseNotes.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -184,6 +184,9 @@ C2y Feature Support

C23 Feature Support
^^^^^^^^^^^^^^^^^^^
- Added ``FLT_SNAN``, ``DBL_SNAN``, and ``LDBL_SNAN`` to Clang's ``<float.h>``
header in C23 and later modes. This implements
`WG14 N2710 <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2710.htm>`_.

Non-comprehensive list of changes in this release
-------------------------------------------------
Expand Down
9 changes: 9 additions & 0 deletions clang/lib/Headers/float.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -89,6 +89,9 @@
!defined(__STRICT_ANSI__)
# undef INFINITY
# undef NAN
# undef FLT_SNAN
# undef DBL_SNAN
# undef LDBL_SNAN
#endif

/* Characteristics of floating point types, C99 5.2.4.2.2 */
Expand Down Expand Up @@ -160,9 +163,15 @@

#if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L) || \
!defined(__STRICT_ANSI__)
/* C23 5.2.5.3.2p28 */
# define FLT_SNAN (__builtin_nansf(""))
# define DBL_SNAN (__builtin_nans(""))
# define LDBL_SNAN (__builtin_nansl(""))

/* C23 5.2.5.3.3p29-30 */
# define INFINITY (__builtin_inff())
# define NAN (__builtin_nanf(""))

/* C23 5.2.5.3.3p32 */
# define FLT_NORM_MAX __FLT_NORM_MAX__
# define DBL_NORM_MAX __DBL_NORM_MAX__
Expand Down
23 changes: 15 additions & 8 deletions clang/test/C/C2y/n3364.c
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,17 +1,24 @@
// RUN: %clang_cc1 -verify -std=c2y -Wall -pedantic -emit-llvm -o - %s
// RUN: %clang_cc1 -verify -Wall -pedantic -emit-llvm -o - %s
// RUN: %clang_cc1 -verify -std=c2y -ffreestanding -Wall -pedantic -emit-llvm -o - %s
// RUN: %clang_cc1 -verify -ffreestanding -Wall -pedantic -emit-llvm -o - %s
// expected-no-diagnostics

/* WG14 N3364: Yes
* Give consistent wording for SNAN initialization v3
*
* Ensure that initializing from a signaling NAN (optionally with a unary + or
* -) at translation time behaves correctly at runtime.
*
* This also serves as a test for C23's WG14 N2710 which introduces these
* macros into float.h in Clang 22.
*/

#define FLT_SNAN __builtin_nansf("1")
#define DBL_SNAN __builtin_nans("1")
#define LD_SNAN __builtin_nansl("1")
#if __STDC_VERSION__ >= 202311L
#include <float.h>
#else
#define FLT_SNAN __builtin_nansf("")
#define DBL_SNAN __builtin_nans("")
#define LDBL_SNAN __builtin_nansl("")
#endif

float f1 = FLT_SNAN;
float f2 = +FLT_SNAN;
Expand All @@ -27,9 +34,9 @@ double d3 = -DBL_SNAN;
// CHECK: @d2 = {{.*}}global double 0x7FF0000000000001
// CHECK: @d3 = {{.*}}global double 0xFFF0000000000001

long double ld1 = LD_SNAN;
long double ld2 = +LD_SNAN;
long double ld3 = -LD_SNAN;
long double ld1 = LDBL_SNAN;
long double ld2 = +LDBL_SNAN;
long double ld3 = -LDBL_SNAN;
// CHECK: @ld1 = {{.*}}global {{double 0x7FF0000000000001|x86_fp80 0xK7FFF8000000000000001|fp128 0xL00000000000000017FFF000000000000}}
// CHECK: @ld2 = {{.*}}global {{double 0x7FF0000000000001|x86_fp80 0xK7FFF8000000000000001|fp128 0xL00000000000000017FFF000000000000}}
// CHECK: @ld3 = {{.*}}global {{double 0xFFF0000000000001|x86_fp80 0xKFFFF8000000000000001|fp128 0xL0000000000000001FFFF000000000000}}
Loading