libgcc: Add support for HF mode (aka _Float16) in libbid

This patch adds support for trunc and extend operations between HF
mode (_Float16) and Decimal Floating Point formats (_Decimal32,
_Decimal64 and _Decimal128).

For simplicity we rely on the implicit conversions inserted by the
compiler between HF and SD/DF/TF modes.  The existing bid*_to_binary*
and binary*_to_bid* functions are non-trivial and at this stage it is
not clear if there is a performance-critical use case involving _Float16
and _Decimal* formats.

The patch also adds two executable tests, to make sure the right
functions are called, available (link phase) and functional.

Tested on aarch64 and x86_64. The number of symbol matches in the
testcases includes the .global XXX to avoid having to match different
call instructions for different targets.

2022-05-04  Christophe Lyon  <christophe.lyon@arm.com>

libgcc/ChangeLog:

	* Makefile.in (D32PBIT_FUNCS): Add _hf_to_sd and _sd_to_hf.
	(D64PBIT_FUNCS): Add _hf_to_dd and _dd_to_hf.
	(D128PBIT_FUNCS): Add _hf_to_td _td_to_hf.

libgcc/config/libbid/ChangeLog:

	* bid_gcc_intrinsics.h (LIBGCC2_HAS_HF_MODE): Define according to
	__LIBGCC_HAS_HF_MODE__.
	(BID_HAS_HF_MODE): Define.
	(HFtype): Define.
	(__bid_extendhfsd): New prototype.
	(__bid_extendhfdd): Likewise.
	(__bid_extendhftd): Likewise.
	(__bid_truncsdhf): Likewise.
	(__bid_truncddhf): Likewise.
	(__bid_trunctdhf): Likewise.
	* _dd_to_hf.c: New file.
	* _hf_to_dd.c: New file.
	* _hf_to_sd.c: New file.
	* _hf_to_td.c: New file.
	* _sd_to_hf.c: New file.
	* _td_to_hf.c: New file.

gcc/testsuite/ChangeLog:

	* gcc.dg/torture/convert-dfp-2.c: New test.
	* gcc.dg/torture/convert-dfp.c: New test.

8 files changed, 256 insertions, 5 deletions

diff --git a/libgcc/Makefile.in b/libgcc/Makefile.in
index 09b3ec8..1fe708a 100644
--- a/libgcc/Makefile.in
+++ b/libgcc/Makefile.in
@@ -677,7 +677,8 @@ D32PBIT_FUNCS = _addsub_sd _div_sd _mul_sd _plus_sd _minus_sd \
 	_si_to_sd _di_to_sd _usi_to_sd _udi_to_sd \
 	_sd_to_sf _sd_to_df _sd_to_xf _sd_to_tf \
 	_sf_to_sd _df_to_sd _xf_to_sd _tf_to_sd \
-	_sd_to_dd _sd_to_td _unord_sd _conv_sd
+	_sd_to_dd _sd_to_td _unord_sd _conv_sd \
+	_hf_to_sd _sd_to_hf
 
 D64PBIT_FUNCS = _addsub_dd _div_dd _mul_dd _plus_dd _minus_dd \
 	_eq_dd _ne_dd _lt_dd _gt_dd _le_dd _ge_dd \
@@ -685,7 +686,8 @@ D64PBIT_FUNCS = _addsub_dd _div_dd _mul_dd _plus_dd _minus_dd \
 	_si_to_dd _di_to_dd _usi_to_dd _udi_to_dd \
 	_dd_to_sf _dd_to_df _dd_to_xf _dd_to_tf \
 	_sf_to_dd _df_to_dd _xf_to_dd _tf_to_dd \
-	_dd_to_sd _dd_to_td _unord_dd _conv_dd
+	_dd_to_sd _dd_to_td _unord_dd _conv_dd \
+	_hf_to_dd _dd_to_hf
 
 D128PBIT_FUNCS = _addsub_td _div_td _mul_td _plus_td _minus_td \
 	_eq_td _ne_td _lt_td _gt_td _le_td _ge_td \
@@ -693,7 +695,8 @@ D128PBIT_FUNCS = _addsub_td _div_td _mul_td _plus_td _minus_td \
 	_si_to_td _di_to_td _usi_to_td _udi_to_td \
 	_td_to_sf _td_to_df _td_to_xf _td_to_tf \
 	_sf_to_td _df_to_td _xf_to_td _tf_to_td \
-	_td_to_sd _td_to_dd _unord_td _conv_td
+	_td_to_sd _td_to_dd _unord_td _conv_td \
+	_hf_to_td _td_to_hf
 
 ifeq ($(enable_decimal_float),bid)
 ifneq ($(D32PBIT),)
diff --git a/libgcc/config/libbid/_dd_to_hf.c b/libgcc/config/libbid/_dd_to_hf.c
new file mode 100644
index 0000000..5e58288
--- /dev/null
+++ b/libgcc/config/libbid/_dd_to_hf.c
@@ -0,0 +1,38 @@
+/* Copyright (C) 2022 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+<http://www.gnu.org/licenses/>.  */
+
+#include "bid_conf.h"
+#include "bid_functions.h"
+#include "bid_gcc_intrinsics.h"
+
+#if LIBGCC2_HAS_HF_MODE || BID_HAS_HF_MODE
+HFtype
+__bid_truncddhf (_Decimal64 x) {
+  HFtype res;
+  union decimal64 ux;
+
+  ux.d = x;
+  res = __bid64_to_binary32 (ux.i);
+  return (res);
+}
+#endif
diff --git a/libgcc/config/libbid/_hf_to_dd.c b/libgcc/config/libbid/_hf_to_dd.c
new file mode 100644
index 0000000..f85100e
--- /dev/null
+++ b/libgcc/config/libbid/_hf_to_dd.c
@@ -0,0 +1,36 @@
+/* Copyright (C) 2022 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+<http://www.gnu.org/licenses/>.  */
+
+#include "bid_conf.h"
+#include "bid_functions.h"
+#include "bid_gcc_intrinsics.h"
+
+#if LIBGCC2_HAS_HF_MODE || BID_HAS_HF_MODE
+_Decimal64
+__bid_extendhfdd (HFtype x) {
+  union decimal64 res;
+  SFtype xsf = x;
+  res.i = __binary32_to_bid64 (xsf);
+  return (res.d);
+}
+#endif
diff --git a/libgcc/config/libbid/_hf_to_sd.c b/libgcc/config/libbid/_hf_to_sd.c
new file mode 100644
index 0000000..285b80c
--- /dev/null
+++ b/libgcc/config/libbid/_hf_to_sd.c
@@ -0,0 +1,36 @@
+/* Copyright (C) 2022 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+<http://www.gnu.org/licenses/>.  */
+
+#include "bid_conf.h"
+#include "bid_functions.h"
+#include "bid_gcc_intrinsics.h"
+
+#if LIBGCC2_HAS_HF_MODE || BID_HAS_HF_MODE
+_Decimal32
+__bid_extendhfsd (HFtype x) {
+  union decimal32 res;
+  SFtype xsf = x;
+  res.i = __binary32_to_bid32 (xsf);
+  return (res.d);
+}
+#endif
diff --git a/libgcc/config/libbid/_hf_to_td.c b/libgcc/config/libbid/_hf_to_td.c
new file mode 100644
index 0000000..99b661e
--- /dev/null
+++ b/libgcc/config/libbid/_hf_to_td.c
@@ -0,0 +1,36 @@
+/* Copyright (C) 2022 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+<http://www.gnu.org/licenses/>.  */
+
+#include "bid_conf.h"
+#include "bid_functions.h"
+#include "bid_gcc_intrinsics.h"
+
+#if LIBGCC2_HAS_HF_MODE || BID_HAS_HF_MODE
+_Decimal128
+__bid_extendhftd (HFtype x) {
+  union decimal128 res;
+  SFtype xsf = x;
+  res.i = __binary32_to_bid128 (xsf);
+  return (res.d);
+}
+#endif
diff --git a/libgcc/config/libbid/_sd_to_hf.c b/libgcc/config/libbid/_sd_to_hf.c
new file mode 100644
index 0000000..e4e3125
--- /dev/null
+++ b/libgcc/config/libbid/_sd_to_hf.c
@@ -0,0 +1,38 @@
+/* Copyright (C) 2022 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+<http://www.gnu.org/licenses/>.  */
+
+#include "bid_conf.h"
+#include "bid_functions.h"
+#include "bid_gcc_intrinsics.h"
+
+#if LIBGCC2_HAS_HF_MODE || BID_HAS_HF_MODE
+HFtype
+__bid_truncsdhf (_Decimal32 x) {
+  HFtype res;
+  union decimal32 ux;
+
+  ux.d = x;
+  res = __bid32_to_binary32 (ux.i);
+  return (res);
+}
+#endif
diff --git a/libgcc/config/libbid/_td_to_hf.c b/libgcc/config/libbid/_td_to_hf.c
new file mode 100644
index 0000000..c4ebe58
--- /dev/null
+++ b/libgcc/config/libbid/_td_to_hf.c
@@ -0,0 +1,38 @@
+/* Copyright (C) 2022 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+<http://www.gnu.org/licenses/>.  */
+
+#include "bid_conf.h"
+#include "bid_functions.h"
+#include "bid_gcc_intrinsics.h"
+
+#if LIBGCC2_HAS_HF_MODE || BID_HAS_HF_MODE
+HFtype
+__bid_trunctdhf (_Decimal128 x) {
+  HFtype res;
+  union decimal128 ux;
+
+  ux.d = x;
+  res = __bid128_to_binary32 (ux.i);
+  return (res);
+}
+#endif
diff --git a/libgcc/config/libbid/bid_gcc_intrinsics.h b/libgcc/config/libbid/bid_gcc_intrinsics.h
index b0a23de..15c0507 100644
--- a/libgcc/config/libbid/bid_gcc_intrinsics.h
+++ b/libgcc/config/libbid/bid_gcc_intrinsics.h
@@ -31,6 +31,12 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #include "tm.h"
 #include "libgcc_tm.h"
 
+#ifdef __LIBGCC_HAS_HF_MODE__
+#define LIBGCC2_HAS_HF_MODE 1
+#else
+#define LIBGCC2_HAS_HF_MODE 0
+#endif
+
 #ifdef __LIBGCC_HAS_XF_MODE__
 #define LIBGCC2_HAS_XF_MODE 1
 #else
@@ -43,6 +49,10 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #define LIBGCC2_HAS_TF_MODE 0
 #endif
 
+#ifndef BID_HAS_HF_MODE
+#define BID_HAS_HF_MODE LIBGCC2_HAS_HF_MODE
+#endif
+
 #ifndef BID_HAS_XF_MODE
 #define BID_HAS_XF_MODE LIBGCC2_HAS_XF_MODE
 #endif
@@ -53,6 +63,9 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 
 /* Some handy typedefs.  */
 
+#if LIBGCC2_HAS_HF_MODE
+typedef float HFtype __attribute__ ((mode (HF)));
+#endif /* LIBGCC2_HAS_HF_MODE */
 typedef float SFtype __attribute__ ((mode (SF)));
 typedef float DFtype __attribute__ ((mode (DF)));
 #if LIBGCC2_HAS_XF_MODE
@@ -98,6 +111,12 @@ typedef __attribute__ ((aligned(16))) struct
 #endif
 #endif
 
+#if BID_HAS_HF_MODE
+#ifndef HFtype
+#define HFtype _Float16
+#endif
+#endif
+
 #ifndef SFtype
 #define SFtype float
 #endif
@@ -110,8 +129,7 @@ typedef __attribute__ ((aligned(16))) struct
 #ifndef XFtype
 #define XFtype long double
 #endif
-
-#endif   /* IN_LIBGCC2 */
+#endif
 
 #if BID_HAS_TF_MODE
 #ifndef TFtype
@@ -249,6 +267,14 @@ extern _Decimal128 __bid_extendxftd (XFtype);
 extern int isinfd32 (_Decimal32);
 extern int isinfd64 (_Decimal64);
 extern int isinfd128 (_Decimal128);
+#if BID_HAS_HF_MODE
+extern _Decimal32 __bid_extendhfsd (HFtype);
+extern _Decimal64 __bid_extendhfdd (HFtype);
+extern _Decimal128 __bid_extendhftd (HFtype);
+extern HFtype __bid_truncsdhf (_Decimal32);
+extern HFtype __bid_truncddhf (_Decimal64);
+extern HFtype __bid_trunctdhf (_Decimal128);
+#endif
 #endif  /* BID_HAS_GCC_DECIMAL_INTRINSICS */
 
 extern void __dfp_set_round (int);