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Warn if __bfloat16 or _Float16 are passed or returned. 

2025-10-15  Michael Meissner  <meissner@linux.ibm.com>

gcc/

	* config/rs6000/rs6000-call.cc (init_cumulative_args): Warn if
	__bfloat16 or _Float16 types are returned.
	(rs6000_function_arg): Warn if __bfloat16 or _Float16 types are passed.
This commit is contained in:
Michael Meissner 2025-10-15 18:46:16 -04:00
parent c3e32991c8
commit d111366004
1 changed files with 20 additions and 0 deletions
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20
gcc/config/rs6000/rs6000-call.cc
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@ -686,6 +686,18 @@ init_cumulative_args (CUMULATIVE_ARGS *cum, tree fntype,
" altivec instructions are disabled, use %qs"
" to enable them", "-maltivec");
}
/* Warn that __bfloat16 and _Float16 might be returned differently in the
future. The issue is currently 16-bit floating point is returned in
floating point register #1 in 16-bit format. We may or may not want to
return it as a scalar 64-bit value. */
if (fntype && warn_psabi)
{
machine_mode ret_mode = TYPE_MODE (TREE_TYPE (fntype));
if (ret_mode == BFmode || ret_mode == HFmode)
warning (OPT_Wpsabi, "%s might be returned differently in the future",
ret_mode == BFmode ? "__bfloat16" : "_Float16");
}
}
@ -1643,6 +1655,14 @@ rs6000_function_arg (cumulative_args_t cum_v, const function_arg_info &arg)
return NULL_RTX;
}
/* Warn that _Float16 and __bfloat16 might be passed differently in the
future. The issue is currently 16-bit floating point values are passed in
floating point registers in the native 16-bit format. We may or may not
want to pass the value it as a scalar 64-bit value. */
if (warn_psabi && (mode == BFmode || mode == HFmode))
warning (OPT_Wpsabi, "%s might be passed differently in the future",
mode == BFmode ? "__bfloat16" : "_Float16");
/* Return a marker to indicate whether CR1 needs to set or clear the
bit that V.4 uses to say fp args were passed in registers.
Assume that we don't need the marker for software floating point,