[PATCH 1/2] PowerPC: Allow __ibm128 on older systems.

[Michael Meissner <meissner@linux.ibm.com>]

[PATCH 1/2] PowerPC: Allow __ibm128 on older systems.

In the patch submitted on October 22nd, 2020:
https://gcc.gnu.org/pipermail/gcc-patches/2020-October/556869.html
https://gcc.gnu.org/pipermail/gcc-patches/2020-October/557529.html

Segher suggested that rather than add #ifdef code in libgcc's ibm-ldouble.c to
use __builtin_pack_ibm128 instead of __builtin_pack_longdouble, that I should
instead make __ibm128 available in targets that have 128-bit IBM long double,
but don't support __float128/_Float128.

This patch fixes the compiler to allow __ibm128 on older systems, and it
adjusts the two ibm128 built-in functions to accomidate this change.  The next
patch will be to change libgcc/ibm-ldouble.c to always use the
__builtin_pack_ibm128 function.


I have tested these patches on a little endian power9 server system and there
were no regressions.  I have also tested the paches on a big endian power8
server system and there were no regressions.  On the big endian system, I have
built both compilers with power8 being the default cpu and power5 being the
default cpu.  Can I check this patch into the master branch?

gcc/
2021-01-13  Michael Meissner  <meissner@linux.ibm.com>

	* config/rs6000/rs6000-builtin.def (BU_IBM128_2): Rename
	RS6000_BTM_IBM128 from RS6000_BTM_FLOAT128.
	* config/rs6000/rs6000-call.c (rs6000_invalid_builtin): Update
	error message for __ibm128 built-in functions.
	(rs6000_init_builtins): Create the __ibm128 keyword on older
	systems where long double uses the IBM extended double format,
	even if they don't support IEEE 128-bit floating point.
	* config/rs6000/rs6000.c (rs6000_builtin_mask_calculate): Rename
	RS6000_BTM_IBM128 from RS6000_BTM_FLOAT128.
	(rs6000_builtin_mask_names): Rename RS6000_BTM_IBM128 from
	RS6000_BTM_FLOAT128.
	* config/rs6000/rs6000.h (TARGET_IBM128): New macro.
	(RS6000_BTM_IBM128): Rename from RS6000_BTM_FLOAT128.
	(RS6000_BTM_COMMON): Rename RS6000_BTM_IBM128 from
	RS6000_BTM_FLOAT128.
---
 gcc/config/rs6000/rs6000-builtin.def |  5 ++---
 gcc/config/rs6000/rs6000-call.c      | 14 ++++++++++----
 gcc/config/rs6000/rs6000.c           |  4 ++--
 gcc/config/rs6000/rs6000.h           | 12 +++++++++---
 4 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/gcc/config/rs6000/rs6000-builtin.def b/gcc/config/rs6000/rs6000-builtin.def
index 8aa31ad0a06..1bf76eedadf 100644
--- a/gcc/config/rs6000/rs6000-builtin.def
+++ b/gcc/config/rs6000/rs6000-builtin.def
@@ -728,13 +728,12 @@
 		     | RS6000_BTC_BINARY),				\
 		    CODE_FOR_ ## ICODE)			/* ICODE */
 
-/* 128-bit __ibm128 floating point builtins (use -mfloat128 to indicate that
-   __ibm128 is available).  */
+/* 128-bit __ibm128 floating point builtins.  */
 #define BU_IBM128_2(ENUM, NAME, ATTR, ICODE)				\
   RS6000_BUILTIN_2 (MISC_BUILTIN_ ## ENUM,		/* ENUM */	\
 		    "__builtin_" NAME,			/* NAME */	\
 		    (RS6000_BTM_HARD_FLOAT		/* MASK */	\
-		     | RS6000_BTM_FLOAT128),				\
+		     | RS6000_BTM_IBM128),				\
 		    (RS6000_BTC_ ## ATTR		/* ATTR */	\
 		     | RS6000_BTC_BINARY),				\
 		    CODE_FOR_ ## ICODE)			/* ICODE */
diff --git a/gcc/config/rs6000/rs6000-call.c b/gcc/config/rs6000/rs6000-call.c
index 519313bc0d6..5e58bea7e7a 100644
--- a/gcc/config/rs6000/rs6000-call.c
+++ b/gcc/config/rs6000/rs6000-call.c
@@ -11485,8 +11485,8 @@ rs6000_invalid_builtin (enum rs6000_builtins fncode)
     error ("%qs requires the %qs option", name, "-mhard-float");
   else if ((fnmask & RS6000_BTM_FLOAT128_HW) != 0)
     error ("%qs requires ISA 3.0 IEEE 128-bit floating point", name);
-  else if ((fnmask & RS6000_BTM_FLOAT128) != 0)
-    error ("%qs requires the %qs option", name, "%<-mfloat128%>");
+  else if ((fnmask & RS6000_BTM_IBM128) != 0)
+    error ("%qs requires the IBM 128-bit floating point", name);
   else if ((fnmask & (RS6000_BTM_POPCNTD | RS6000_BTM_POWERPC64))
 	   == (RS6000_BTM_POPCNTD | RS6000_BTM_POWERPC64))
     error ("%qs requires the %qs (or newer), and %qs or %qs options",
@@ -13181,7 +13181,7 @@ rs6000_init_builtins (void)
      For IEEE 128-bit floating point, always create the type __ieee128.  If the
      user used -mfloat128, rs6000-c.c will create a define from __float128 to
      __ieee128.  */
-  if (TARGET_FLOAT128_TYPE)
+  if (TARGET_IBM128)
     {
       if (!TARGET_IEEEQUAD && TARGET_LONG_DOUBLE_128)
 	ibm128_float_type_node = long_double_type_node;
@@ -13195,7 +13195,13 @@ rs6000_init_builtins (void)
 
       lang_hooks.types.register_builtin_type (ibm128_float_type_node,
 					      "__ibm128");
+    }
+
+  else
+    ibm128_float_type_node = long_double_type_node;
 
+  if (TARGET_FLOAT128_TYPE)
+    {
       if (TARGET_IEEEQUAD && TARGET_LONG_DOUBLE_128)
 	ieee128_float_type_node = long_double_type_node;
       else
@@ -13206,7 +13212,7 @@ rs6000_init_builtins (void)
     }
 
   else
-    ieee128_float_type_node = ibm128_float_type_node = long_double_type_node;
+    ieee128_float_type_node = long_double_type_node;
 
   /* Vector pair and vector quad support.  */
   if (TARGET_EXTRA_BUILTINS)
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 282703b9715..d1a817973ba 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -3397,7 +3397,7 @@ rs6000_builtin_mask_calculate (void)
 	  | ((TARGET_LONG_DOUBLE_128
 	      && TARGET_HARD_FLOAT
 	      && !TARGET_IEEEQUAD)	    ? RS6000_BTM_LDBL128   : 0)
-	  | ((TARGET_FLOAT128_TYPE)	    ? RS6000_BTM_FLOAT128  : 0)
+	  | ((TARGET_IBM128)		    ? RS6000_BTM_IBM128    : 0)
 	  | ((TARGET_FLOAT128_HW)	    ? RS6000_BTM_FLOAT128_HW : 0)
 	  | ((TARGET_MMA)		    ? RS6000_BTM_MMA	   : 0)
 	  | ((TARGET_POWER10)               ? RS6000_BTM_P10       : 0));
@@ -23667,7 +23667,7 @@ static struct rs6000_opt_mask const rs6000_builtin_mask_names[] =
   { "hard-float",	 RS6000_BTM_HARD_FLOAT,	false, false },
   { "long-double-128",	 RS6000_BTM_LDBL128,	false, false },
   { "powerpc64",	 RS6000_BTM_POWERPC64,  false, false },
-  { "float128",		 RS6000_BTM_FLOAT128,   false, false },
+  { "ibm128",		 RS6000_BTM_IBM128,     false, false },
   { "float128-hw",	 RS6000_BTM_FLOAT128_HW,false, false },
   { "mma",		 RS6000_BTM_MMA,	false, false },
   { "power10",		 RS6000_BTM_P10,	false, false },
diff --git a/gcc/config/rs6000/rs6000.h b/gcc/config/rs6000/rs6000.h
index 1ff07345a93..a35878ea90c 100644
--- a/gcc/config/rs6000/rs6000.h
+++ b/gcc/config/rs6000/rs6000.h
@@ -509,6 +509,12 @@ extern int rs6000_vector_align[];
 #define TARGET_MINMAX	(TARGET_HARD_FLOAT && TARGET_PPC_GFXOPT		\
 			 && (TARGET_P9_MINMAX || !flag_trapping_math))
 
+/* Whether the '__ibm128' keywork is enabled.  We enable __ibm128 either if the
+   IEEE 128-bit floating point support is enabled or if the long double support
+   uses the 128-bit IBM extended double format.  */
+#define TARGET_IBM128	(TARGET_FLOAT128_TYPE				\
+			 || (!TARGET_IEEEQUAD && TARGET_LONG_DOUBLE_128))
+
 /* In switching from using target_flags to using rs6000_isa_flags, the options
    machinery creates OPTION_MASK_<xxx> instead of MASK_<xxx>.  For now map
    OPTION_MASK_<xxx> back into MASK_<xxx>.  */
@@ -2308,7 +2314,7 @@ extern int frame_pointer_needed;
 #define RS6000_BTC_SAT		RS6000_BTC_MISC	/* saturate sets VSCR.  */
 
 /* Builtin targets.  For now, we reuse the masks for those options that are in
-   target flags, and pick a random bit for ldbl128, which isn't in
+   target flags, and pick a random bit for ldbl128 and ibm128, which aren't in
    target_flags.  */
 #define RS6000_BTM_ALWAYS	0		/* Always enabled.  */
 #define RS6000_BTM_ALTIVEC	MASK_ALTIVEC	/* VMX/altivec vectors.  */
@@ -2330,7 +2336,7 @@ extern int frame_pointer_needed;
 #define RS6000_BTM_LDBL128	MASK_MULTIPLE	/* 128-bit long double.  */
 #define RS6000_BTM_64BIT	MASK_64BIT	/* 64-bit addressing.  */
 #define RS6000_BTM_POWERPC64	MASK_POWERPC64	/* 64-bit registers.  */
-#define RS6000_BTM_FLOAT128	MASK_FLOAT128_KEYWORD /* IEEE 128-bit float.  */
+#define RS6000_BTM_IBM128	MASK_FLOAT128_KEYWORD /* __ibm128 keyword.  */
 #define RS6000_BTM_FLOAT128_HW	MASK_FLOAT128_HW /* IEEE 128-bit float h/w.  */
 #define RS6000_BTM_MMA		MASK_MMA	/* ISA 3.1 MMA.  */
 #define RS6000_BTM_P10		MASK_POWER10
@@ -2354,7 +2360,7 @@ extern int frame_pointer_needed;
 				 | RS6000_BTM_HARD_FLOAT		\
 				 | RS6000_BTM_LDBL128			\
 				 | RS6000_BTM_POWERPC64			\
-				 | RS6000_BTM_FLOAT128			\
+				 | RS6000_BTM_IBM128			\
 				 | RS6000_BTM_FLOAT128_HW		\
 				 | RS6000_BTM_MMA			\
 				 | RS6000_BTM_P10)
-- 
2.22.0


-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797