Re: [PATCH] i386, rs6000, ia64, s390: Fix C++ ICEs with _Float64x or _Float128 [PR107080]

[Jason Merrill <jason@redhat.com>]

On 9/29/22 06:01, Jakub Jelinek wrote:
> Hi!
> 
> The following testcase ICEs on x86 as well as ppc64le (the latter
> with -mabi=ieeelongdouble), because _Float64x there isn't mangled as
> DF64x but e or u9__ieee128 instead.
> Those are the mangling that should be used for the non-standard
> types with the same mode or for long double, but not for _Float64x.
> All the 4 mangle_type targhook implementations start with
> type = TYPE_MAIN_VARIANT (type);
> so I think it is cleanest to handle it the same in all and return NULL
> before the switches on mode or whatever other tests.
> s390 doesn't actually have a bug, but while I was there, having
> type = TYPE_MAIN_VARIANT (type);
> if (TYPE_MAIN_VARIANT (type) == long_double_type_node)
> looked useless to me.
> 
> Tested on x86_64, i686 and powerpc64le, ok for trunk?

OK.

> Note, there is one further problem on aarch64/arm, types with HFmode
> (_Float16 and __fp16) are there mangled as Dh (which is standard
> Itanium mangling:
>                   ::= Dh # IEEE 754r half-precision floating point (16 bits)
>                   ::= DF <number> _ # ISO/IEC TS 18661 binary floating point type _FloatN (N bits)
> so in theory is also ok, but DF16_ is more specific.  Should we just
> change Dh to DF16_ in those backends, or should __fp16 there be distinct
> type from _Float16 where __fp16 would mangle Dh and _Float16 DF16_ ?

You argued for keeping __float128 separate from _Float128, does the same 
argument not apply to this case?

> And there is csky, which mangles __fp16 (but only if type's name is __fp16,
> not _Float16) as __fp16, that looks clearly invalid to me as it isn't
> valid in the mangling grammar.  So perhaps just nuke csky's mangle_type
> and have it mangled as DF16_ by the generic code?

Sounds good.

> 2022-09-29  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR c++/107080
> 	* config/i386/i386.cc (ix86_mangle_type): Always return NULL
> 	for float128_type_node or float64x_type_node, don't check
> 	float128t_type_node later on.
> 	* config/ia64/ia64.cc (ia64_mangle_type): Always return NULL
> 	for float128_type_node or float64x_type_node.
> 	* config/rs6000/rs6000.cc (rs6000_mangle_type): Likewise.
> 	Don't check float128_type_node later on.
> 	* config/s390/s390.cc (s390_mangle_type): Don't use
> 	TYPE_MAIN_VARIANT on type which was set to TYPE_MAIN_VARIANT
> 	a few lines earlier.
> 
> 	* g++.dg/cpp23/ext-floating11.C: New test.
> 
> --- gcc/config/i386/i386.cc.jj	2022-09-29 09:13:25.713718513 +0200
> +++ gcc/config/i386/i386.cc	2022-09-29 11:29:20.828358152 +0200
> @@ -22725,6 +22725,9 @@ ix86_mangle_type (const_tree type)
>         && TREE_CODE (type) != INTEGER_TYPE && TREE_CODE (type) != REAL_TYPE)
>       return NULL;
>   
> +  if (type == float128_type_node || type == float64x_type_node)
> +    return NULL;
> +
>     switch (TYPE_MODE (type))
>       {
>       case E_BFmode:
> @@ -22735,10 +22738,7 @@ ix86_mangle_type (const_tree type)
>         return "DF16_";
>       case E_TFmode:
>         /* __float128 is "g".  */
> -      if (type == float128t_type_node)
> -	return "g";
> -      /* _Float128 should mangle as "DF128_" done in generic code.  */
> -      return NULL;
> +      return "g";
>       case E_XFmode:
>         /* "long double" or __float80 is "e".  */
>         return "e";
> --- gcc/config/ia64/ia64.cc.jj	2022-09-27 08:03:26.977984661 +0200
> +++ gcc/config/ia64/ia64.cc	2022-09-29 11:29:44.071037677 +0200
> @@ -11225,6 +11225,9 @@ ia64_mangle_type (const_tree type)
>         && TREE_CODE (type) != INTEGER_TYPE && TREE_CODE (type) != REAL_TYPE)
>       return NULL;
>   
> +  if (type == float128_type_node || type == float64x_type_node)
> +    return NULL;
> +
>     /* On HP-UX, "long double" is mangled as "e" so __float128 is
>        mangled as "e".  */
>     if (!TARGET_HPUX && TYPE_MODE (type) == TFmode)
> --- gcc/config/rs6000/rs6000.cc.jj	2022-09-27 08:03:26.999984363 +0200
> +++ gcc/config/rs6000/rs6000.cc	2022-09-29 11:26:10.290985331 +0200
> @@ -20270,13 +20270,12 @@ rs6000_mangle_type (const_tree type)
>     if (type == bool_int_type_node) return "U6__booli";
>     if (type == bool_long_long_type_node) return "U6__boolx";
>   
> +  if (type == float128_type_node || type == float64x_type_node)
> +    return NULL;
> +
>     if (SCALAR_FLOAT_TYPE_P (type) && FLOAT128_IBM_P (TYPE_MODE (type)))
>       return "g";
> -  if (SCALAR_FLOAT_TYPE_P (type)
> -      && FLOAT128_IEEE_P (TYPE_MODE (type))
> -      /* _Float128 should mangle as DF128_ (done in generic code)
> -	 rather than u9__ieee128 (used for __ieee128 and __float128).  */
> -      && type != float128_type_node)
> +  if (SCALAR_FLOAT_TYPE_P (type) && FLOAT128_IEEE_P (TYPE_MODE (type)))
>       return "u9__ieee128";
>   
>     if (type == vector_pair_type_node)
> --- gcc/config/s390/s390.cc.jj	2022-09-26 18:47:26.950349802 +0200
> +++ gcc/config/s390/s390.cc	2022-09-29 11:26:51.180421534 +0200
> @@ -7642,8 +7642,7 @@ s390_mangle_type (const_tree type)
>     if (type == s390_builtin_types[BT_BV4SI]) return "U6__booli";
>     if (type == s390_builtin_types[BT_BV2DI]) return "U6__booll";
>   
> -  if (TYPE_MAIN_VARIANT (type) == long_double_type_node
> -      && TARGET_LONG_DOUBLE_128)
> +  if (type == long_double_type_node && TARGET_LONG_DOUBLE_128)
>       return "g";
>   
>     /* For all other types, use normal C++ mangling.  */
> --- gcc/testsuite/g++.dg/cpp23/ext-floating11.C.jj	2022-09-29 11:33:46.331697320 +0200
> +++ gcc/testsuite/g++.dg/cpp23/ext-floating11.C	2022-09-29 11:40:30.610123406 +0200
> @@ -0,0 +1,79 @@
> +// P1467R9 - Extended floating-point types and standard names.
> +// { dg-do compile { target c++23 } }
> +// { dg-options "" }
> +
> +#include "ext-floating.h"
> +
> +#ifdef __STRICT_ANSI__
> +#undef __SIZEOF_FLOAT128__
> +#endif
> +
> +extern "C" void abort ();
> +
> +using namespace std;
> +
> +template <typename T, typename U>
> +int
> +foo (T x, U y) noexcept
> +{
> +  return 3;
> +}
> +
> +int
> +main ()
> +{
> +  if (foo (0.0f, 0.0f) != 3)
> +    abort ();
> +  if (foo (0.0, 0.0) != 3)
> +    abort ();
> +  if (foo (0.0L, 0.0L) != 3)
> +    abort ();
> +#ifdef __STDCPP_FLOAT16_T__
> +  if (foo (0.0f16, 0.0f16) != 3)
> +    abort ();
> +  if (foo (0.0f, 0.0f16) != 3)
> +    abort ();
> +#endif
> +#ifdef __STDCPP_FLOAT32_T__
> +  if (foo (0.0f32, 0.0f32) != 3)
> +    abort ();
> +  if (foo (0.0f, 0.0f32) != 3)
> +    abort ();
> +#endif
> +#ifdef __STDCPP_FLOAT64_T__
> +  if (foo (0.0f64, 0.0f64) != 3)
> +    abort ();
> +  if (foo (0.0, 0.0f64) != 3)
> +    abort ();
> +#endif
> +#ifdef __STDCPP_FLOAT128_T__
> +  if (foo (0.0f128, 0.0f128) != 3)
> +    abort ();
> +  if (foo (0.0L, 0.0f128) != 3)
> +    abort ();
> +#endif
> +#ifdef __STDCPP_BFLOAT16_T__
> +  if (foo (0.0bf16, 0.0bf16) != 3)
> +    abort ();
> +  if (foo (0.0f, 0.0bf16) != 3)
> +    abort ();
> +#endif
> +#ifdef __FLT32X_MANT_DIG__
> +  if (foo (0.0f32x, 0.0f32x) != 3)
> +    abort ();
> +  if (foo (0.0, 0.0f32x) != 3)
> +    abort ();
> +#endif
> +#ifdef __FLT64X_MANT_DIG__
> +  if (foo (0.0f64x, 0.0f64x) != 3)
> +    abort ();
> +  if (foo (0.0L, 0.0f64x) != 3)
> +    abort ();
> +#endif
> +#ifdef __FLT128X_MANT_DIG__
> +  if (foo (0.0f128x, 0.0f128x) != 3)
> +    abort ();
> +  if (foo (0.0L, 0.0f128x) != 3)
> +    abort ();
> +#endif
> +}
> 
> 	Jakub
>