Add conversions between _Float128 and Decimal.

This patch implements conversions between _Float128 and the 3 Decimal floating
types.  It does this by extendending the dfp-bit conversions to add a new
binary floating point type (KF), and doing the conversions in the same manner
as the other binary/decimal conversions.

For conversions from _Float128 to Decimal, this patch uses a function
(__sprintfkf) instead of the sprintf function to convert long double values to
strings.  The __sprintfkf function determines if GLIBC 2.32 or newer is used
and calls the IEEE 128-bit version of sprintf (__sprintfieee128).  If the GLIBC
is earlier than 2.32, the code will convert _Float128 to __ibm128 and then use
the normal sprintf to convert this value.

For conversions from Decimal to _Float128, this patch uses a function
(__strtokf) instead of strtold to convert the strings from the Decimal
conversion to long double.  The __strtokf function determines if GLIBC 2.32 or
newer is used, and if it is, calls the IEEE 128-bit version (__strtoieee128).
If the GLIBC is earlier than 2.32, the code will call strtold and convert the
__ibm128 value to _Float128.

These functions will primarily be used if/when the default PowerPC long double
type is changed to IEEE 128-bit, but they could also be used if the user
explicitly converts _Float128 to/from a Decimal type.

libgcc/
2021-02-22  Michael Meissner  <meissner@linux.ibm.com>

	* config/rs6000/_dd_to_kf.c: New file.
	* config/rs6000/_kf_to_dd.c: New file.
	* config/rs6000/_kf_to_sd.c: New file.
	* config/rs6000/_kf_to_td.c: New file.
	* config/rs6000/_sd_to_kf.c: New file.
	* config/rs6000/_sprintfkf.c: New file.
	* config/rs6000/_sprintfkf.h: New file.
	* config/rs6000/_strtokf.h: New file.
	* config/rs6000/_strtokf.c: New file.
	* config/rs6000/_td_to_kf.c: New file.
	* config/rs6000/quad-float128.h: Add new declarations.
	* config/rs6000/t-float128 (fp128_dec_funcs): New macro.
	(fp128_decstr_funcs): New macro.
	(ibm128_dec_funcs): New macro.
	(fp128_ppc_funcs): Add the new conversions.
	(fp128_dec_objs): Force Decimal <-> __float128 conversions to be
	compiled with -mabi=ieeelongdouble.
	(fp128_decstr_objs): Force __float128 <-> string conversions to be
	compiled with -mabi=ibmlongdouble.
	(ibm128_dec_objs): Force Decimal <-> __float128 conversions to be
	compiled with -mabi=ieeelongdouble.
	(FP128_CFLAGS_DECIMAL): New macro.
	(IBM128_CFLAGS_DECIMAL): New macro.
	* dfp-bit.c (DFP_TO_BFP): Add PowerPC _Float128 support.
	(BFP_TO_DFP): Add PowerPC _Float128 support.
	* dfp-bit.h (BFP_KIND): Add new binary floating point kind for
	IEEE 128-bit floating point.
	(DFP_TO_BFP): Add PowerPC _Float128 support.
	(BFP_TO_DFP): Add PowerPC _Float128 support.
	(BFP_SPRINTF): New macro.

1 files changed, 26 insertions, 0 deletions

diff --git a/libgcc/dfp-bit.h b/libgcc/dfp-bit.h
index 1fa42ee..5e3bfa6 100644
--- a/libgcc/dfp-bit.h
+++ b/libgcc/dfp-bit.h
@@ -241,6 +241,9 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #elif defined (L_sd_to_tf) || defined (L_dd_to_tf) || defined (L_td_to_tf) \
  ||   defined (L_tf_to_sd) || defined (L_tf_to_dd) || defined (L_tf_to_td)
 #define BFP_KIND 4
+#elif defined (L_sd_to_kf) || defined (L_dd_to_kf) || defined (L_td_to_kf) \
+ ||   defined (L_kf_to_sd) || defined (L_kf_to_dd) || defined (L_kf_to_td)
+#define BFP_KIND 5
 #endif
 
 /*  If BFP_KIND is defined, define additional macros:
@@ -291,6 +294,13 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #define BFP_VIA_TYPE long double
 #endif /* LONG_DOUBLE_HAS_TF_MODE */
 
+#elif BFP_KIND == 5
+#define BFP_TYPE _Float128
+#define BFP_FMT "%.36Le"
+#define BFP_VIA_TYPE _Float128
+#define STR_TO_BFP __strtokf
+#include <_strtokf.h>
+
 #endif /* BFP_KIND */
 
 #if WIDTH == 128 || WIDTH_TO == 128
@@ -490,6 +500,9 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #elif BFP_KIND == 4
 #define BFP_TO_DFP	DPD_BID_NAME(__dpd_trunctfsd,__bid_trunctfsd)
 #define DFP_TO_BFP	DPD_BID_NAME(__dpd_extendsdtf,__bid_extendsdtf)
+#elif BFP_KIND == 5
+#define BFP_TO_DFP	DPD_BID_NAME(__dpd_trunckfsd,__bid_trunckfsd)
+#define DFP_TO_BFP	DPD_BID_NAME(__dpd_extendsdkf,__bid_extendsdkf)
 #endif /* BFP_KIND */
 
 #elif WIDTH == 64
@@ -505,6 +518,9 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #elif BFP_KIND == 4
 #define BFP_TO_DFP	DPD_BID_NAME(__dpd_trunctfdd,__bid_trunctfdd)
 #define DFP_TO_BFP	DPD_BID_NAME(__dpd_extendddtf,__bid_extendddtf)
+#elif BFP_KIND == 5
+#define BFP_TO_DFP	DPD_BID_NAME(__dpd_trunckfdd,__bid_trunckfdd)
+#define DFP_TO_BFP	DPD_BID_NAME(__dpd_extendddkf,__bid_extendddkf)
 #endif /* BFP_KIND */
 
 #elif WIDTH == 128
@@ -520,6 +536,9 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #elif BFP_KIND == 4
 #define BFP_TO_DFP	DPD_BID_NAME(__dpd_extendtftd,__bid_extendtftd)
 #define DFP_TO_BFP	DPD_BID_NAME(__dpd_trunctdtf,__bid_trunctdtf)
+#elif BFP_KIND == 5
+#define BFP_TO_DFP	DPD_BID_NAME(__dpd_extendkftd,__bid_extendkftd)
+#define DFP_TO_BFP	DPD_BID_NAME(__dpd_trunctdkf,__bid_trunctdkf)
 #endif /* BFP_KIND */
 
 #endif /* WIDTH */
@@ -609,6 +628,7 @@ extern DFP_C_TYPE INT_TO_DFP (INT_TYPE);
 
 #if defined (L_sd_to_sf) || defined (L_dd_to_sf) || defined (L_td_to_sf) \
  || defined (L_sd_to_df) || defined (L_dd_to_df) || defined (L_td_to_df) \
+ || defined (L_sd_to_kf) || defined (L_dd_to_kf) || defined (L_td_to_kf) \
  || ((defined (L_sd_to_xf) || defined (L_dd_to_xf) || defined (L_td_to_xf)) \
      && LONG_DOUBLE_HAS_XF_MODE) \
  || ((defined (L_sd_to_tf) || defined (L_dd_to_tf) || defined (L_td_to_tf)) \
@@ -623,6 +643,12 @@ extern BFP_TYPE DFP_TO_BFP (DFP_C_TYPE);
  || ((defined (L_tf_to_sd) || defined (L_tf_to_dd) || defined (L_tf_to_td)) \
      && LONG_DOUBLE_HAS_TF_MODE)
 extern DFP_C_TYPE BFP_TO_DFP (BFP_TYPE);
+#define BFP_SPRINTF sprintf
+
+#elif defined (L_kf_to_sd) || defined (L_kf_to_dd) || defined (L_kf_to_td)
+extern DFP_C_TYPE BFP_TO_DFP (BFP_TYPE);
+#include <_sprintfkf.h>
+#define BFP_SPRINTF __sprintfkf
 #endif
 
 #endif /* _DFPBIT_H */