procyberian/gcc
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Adjust __builtin_tgmath handling of integer arguments to _FloatN narrowing macros.

Browse source 
When adding __builtin_tgmath to support a better tgmath.h
implementation, I noted that further changes might be needed regarding
the TS 18661 functions that round their results to a narrower type,
because of unresolved issues with how the corresponding type-generic
macros are defined in TS 18661.

The resolution of those issues is still in flux, but the latest
version does indeed require something slightly different from
__builtin_tgmath.  It specifies that integer arguments to type-generic
macros such as f32xadd are treated as _Float64 not double - which was
also present in earlier versions of the resolution - but then it also
specifies different handling for _Float64 arguments and double
arguments, which wasn't in earlier versions.  Specifically, in the
latest version
<http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2213.pdf>, f32xadd
with _Float64 arguments would call f32xaddf64, while f32xadd with
double arguments would call f32xaddf64x.  Since integer arguments are
converted directly to the argument type of the selected function (not
to double / _Float64x unless that ends up as the argument type), this
is a user-visible difference in semantics that means __builtin_tgmath
actually needs to implement treating integer arguments as _Float64 in
this case (the rest of the latest semantics can then be implemented in
the header, with a few inline functions there).

To avoid releasing with the older version of the __builtin_tgmath
semantics that doesn't work with the latest proposed DR#13 resolution,
this patch implements a rule in __builtin_tgmath that maps integer
types to _Float64 (respectively _Complex _Float64 for complex integer
types) where all the specified functions return the same _FloatN or
_FloatNx type.  This does not affect any existing uses of
__builtin_tgmath in glibc's or GCC's tgmath.h since I haven't yet
added any of these type-generic macros to glibc when adding the
corresponding narrowing functions.

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

	* doc/extend.texi (__builtin_tgmath): Document when complex
	integer types are treated as _Complex _Float64.

gcc/c:
	* c-parser.c (c_parser_postfix_expression): For __builtin_tgmath
	where all functions return the same _FloatN or _FloatNx type,
	treat integer types as _Float64 instead of double.

gcc/testsuite:
	* gcc.dg/builtin-tgmath-3.c: New test.

From-SVN: r258751
This commit is contained in:
Joseph Myers 2018-03-21 22:29:37 +00:00 • committed by Joseph Myers
parent f4274af890
commit c5c5822ae5
6 changed files with 89 additions and 5 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

5
gcc/ChangeLog
View file

@ -1,3 +1,8 @@
2018-03-21 Joseph Myers <joseph@codesourcery.com>
* doc/extend.texi (__builtin_tgmath): Document when complex
integer types are treated as _Complex _Float64.
2018-03-21 Tom de Vries <tom@codesourcery.com>
* doc/extend.texi (__builtin_extend_pointer): Remove pasto.

6
gcc/c/ChangeLog
View file

@ -1,3 +1,9 @@
2018-03-21 Joseph Myers <joseph@codesourcery.com>
* c-parser.c (c_parser_postfix_expression): For __builtin_tgmath
where all functions return the same _FloatN or _FloatNx type,
treat integer types as _Float64 instead of double.
2018-03-21 Jakub Jelinek <jakub@redhat.com>
PR c/84999

25
gcc/c/c-parser.c
View file

@ -8530,10 +8530,12 @@ c_parser_postfix_expression (c_parser *parser)
argument is decimal, or if the only alternatives for
type-generic arguments are of decimal types, and are
otherwise treated as double (or _Complex double for
complex integer types). After that adjustment, types
are combined following the usual arithmetic
conversions. If the function only accepts complex
arguments, a complex type is produced. */
complex integer types, or _Float64 or _Complex _Float64
if all the return types are the same _FloatN or
_FloatNx type). After that adjustment, types are
combined following the usual arithmetic conversions.
If the function only accepts complex arguments, a
complex type is produced. */
bool arg_complex = all_complex;
bool arg_binary = all_binary;
bool arg_int_decimal = all_decimal;
@ -8632,6 +8634,19 @@ c_parser_postfix_expression (c_parser *parser)
}
}
}
/* For a macro rounding its result to a narrower type, map
integer types to _Float64 not double if the return type
is a _FloatN or _FloatNx type. */
bool arg_int_float64 = false;
if (parm_kind[0] == tgmath_fixed
&& SCALAR_FLOAT_TYPE_P (parm_first[0])
&& float64_type_node != NULL_TREE)
for (unsigned int j = 0; j < NUM_FLOATN_NX_TYPES; j++)
if (parm_first[0] == FLOATN_TYPE_NODE (j))
{
arg_int_float64 = true;
break;
}
tree arg_real = NULL_TREE;
for (unsigned int j = 1; j <= nargs; j++)
{
@ -8644,6 +8659,8 @@ c_parser_postfix_expression (c_parser *parser)
if (INTEGRAL_TYPE_P (type))
type = (arg_int_decimal
? dfloat64_type_node
: arg_int_float64
? float64_type_node
: double_type_node);
if (arg_real == NULL_TREE)
arg_real = type;

4
gcc/doc/extend.texi
View file

@ -11848,7 +11848,9 @@ corresponding to @var{t} for each function.
The standard rules for @code{<tgmath.h>} macros are used to find a
common type @var{u} from the types of the arguments for parameters
whose types vary between the functions; complex integer types (a GNU
extension) are treated like @code{_Complex double} for this purpose.
extension) are treated like @code{_Complex double} for this purpose
(or @code{_Complex _Float64} if all the function return types are the
same @code{_Float@var{n}} or @code{_Float@var{n}x} type).
If the function return types vary, or are all the same integer type,
the function called is the one for which @var{t} is @var{u}, and it is
an error if there is no such function. If the function return types

4
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,7 @@
2018-03-21 Joseph Myers <joseph@codesourcery.com>
* gcc.dg/builtin-tgmath-3.c: New test.
2018-03-21 Alexandre Oliva <aoliva@redhat.com>
PR c++/71965

50
gcc/testsuite/gcc.dg/builtin-tgmath-3.c Normal file
View file

@ -0,0 +1,50 @@
/* Test __builtin_tgmath: integer arguments mapped to _Float64. */
/* { dg-do run } */
/* { dg-options "" } */
/* { dg-add-options float32 } */
/* { dg-add-options float64 } */
/* { dg-require-effective-target float32_runtime } */
/* { dg-require-effective-target float64_runtime } */
extern void abort (void);
extern void exit (int);
#define CHECK_CALL(C, E, V) \
do \
{ \
if ((C) != (E)) \
abort (); \
extern __typeof (C) V; \
} \
while (0)
extern _Float32 var_f32;
_Float32 t1f (float x) { return x + 1; }
_Float32 t1d (double x) { return x + 2; }
_Float32 t1l (long double x) { return x + 3; }
_Float32 t1f64 (_Float64 x) { return x + 4; }
#define t1v(x) __builtin_tgmath (t1f, t1d, t1l, t1f64, x)
static void
test_1 (void)
{
float f = 1;
double d = 2;
long double ld = 3;
_Float64 f64 = 4;
int i = 5;
CHECK_CALL (t1v (f), 2, var_f32);
CHECK_CALL (t1v (d), 4, var_f32);
CHECK_CALL (t1v (ld), 6, var_f32);
CHECK_CALL (t1v (f64), 8, var_f32);
CHECK_CALL (t1v (i), 9, var_f32);
}
int
main (void)
{
test_1 ();
exit (0);
}