[gcc r12-5963] rs6000: Some builtins require IBM-128 long double format (PR103623)

[gcc r12-5963] rs6000: Some builtins require IBM-128 long double format (PR103623)

[William Schmidt]

https://gcc.gnu.org/g:74aeb9726756aa79c21028712c26910866e33026

commit r12-5963-g74aeb9726756aa79c21028712c26910866e33026
Author: Bill Schmidt <wschmidt@linux.ibm.com>
Date:   Tue Dec 14 10:09:06 2021 -0600

    rs6000: Some builtins require IBM-128 long double format (PR103623)
    
    2021-12-14  Bill Schmidt  <wschmidt@linux.ibm.com>
    
    gcc/
            PR target/103623
            * config/rs6000/rs6000-builtin-new.def (__builtin_pack_longdouble): Add
            ibmld attribute.
            (__builtin_unpack_longdouble): Likewise.
            * config/rs6000/rs6000-call.c (rs6000_expand_new_builtin): Add special
            handling for ibmld attribute.
            * config/rs6000/rs6000-gen-builtins.c (attrinfo): Add isibmld.
            (parse_bif_attrs): Handle ibmld.
            (write_decls): Likewise.
            (write_bif_static_init): Likewise.

Diff:
---
 gcc/config/rs6000/rs6000-builtin-new.def | 15 +++++++--------
 gcc/config/rs6000/rs6000-call.c          |  7 +++++++
 gcc/config/rs6000/rs6000-gen-builtins.c  | 13 +++++++++++--
 3 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/gcc/config/rs6000/rs6000-builtin-new.def b/gcc/config/rs6000/rs6000-builtin-new.def
index 30556e5c7f2..f7f5d2c32a4 100644
--- a/gcc/config/rs6000/rs6000-builtin-new.def
+++ b/gcc/config/rs6000/rs6000-builtin-new.def
@@ -137,6 +137,7 @@
 ;   lxvrse   Needs special handling for load-rightmost, sign-extended
 ;   lxvrze   Needs special handling for load-rightmost, zero-extended
 ;   endian   Needs special handling for endianness
+;   ibmld    Restrict usage to the case when TFmode is IBM-128
 ;
 ; Each attribute corresponds to extra processing required when
 ; the built-in is expanded.  All such special processing should
@@ -215,13 +216,10 @@
   double __builtin_mffsl ();
     MFFSL rs6000_mffsl {}
 
-; This thing really assumes long double == __ibm128, and I'm told it has
-; been used as such within libgcc.  Given that __builtin_pack_ibm128
-; exists for the same purpose, this should really not be used at all.
-; TODO: Consider adding special handling for this to warn whenever
-; long double is not __ibm128.
+; This is redundant with __builtin_pack_ibm128, as it requires long
+; double to be __ibm128.  Should probably be deprecated.
   const long double __builtin_pack_longdouble (double, double);
-    PACK_TF packtf {}
+    PACK_TF packtf {ibmld}
 
   unsigned long __builtin_ppc_mftb ();
     MFTB rs6000_mftb_di {32bit}
@@ -244,9 +242,10 @@
   const double __builtin_unpack_ibm128 (__ibm128, const int<1>);
     UNPACK_IF unpackif {}
 
-; See above comments for __builtin_pack_longdouble.
+; This is redundant with __builtin_unpack_ibm128, as it requires long
+; double to be __ibm128.  Should probably be deprecated.
   const double __builtin_unpack_longdouble (long double, const int<1>);
-    UNPACK_TF unpacktf {}
+    UNPACK_TF unpacktf {ibmld}
 
 
 ; Builtins that have been around just about forever, but not quite.
diff --git a/gcc/config/rs6000/rs6000-call.c b/gcc/config/rs6000/rs6000-call.c
index d9736eaf21c..3a43a768c5c 100644
--- a/gcc/config/rs6000/rs6000-call.c
+++ b/gcc/config/rs6000/rs6000-call.c
@@ -15741,6 +15741,13 @@ rs6000_expand_new_builtin (tree exp, rtx target,
       return const0_rtx;
     }
 
+  if (bif_is_ibmld (*bifaddr) && !FLOAT128_2REG_P (TFmode))
+    {
+      error ("%<%s%> requires %<long double%> to be IBM 128-bit format",
+	     bifaddr->bifname);
+      return const0_rtx;
+    }
+
   if (bif_is_cpu (*bifaddr))
     return new_cpu_expand_builtin (fcode, exp, target);
 
diff --git a/gcc/config/rs6000/rs6000-gen-builtins.c b/gcc/config/rs6000/rs6000-gen-builtins.c
index 34ab70f7609..856770c1659 100644
--- a/gcc/config/rs6000/rs6000-gen-builtins.c
+++ b/gcc/config/rs6000/rs6000-gen-builtins.c
@@ -92,6 +92,7 @@ along with GCC; see the file COPYING3.  If not see
      lxvrse   Needs special handling for load-rightmost, sign-extended
      lxvrze   Needs special handling for load-rightmost, zero-extended
      endian   Needs special handling for endianness
+     ibmld    Restrict usage to the case when TFmode is IBM-128
 
    An example stanza might look like this:
 
@@ -390,6 +391,7 @@ struct attrinfo
   bool islxvrse;
   bool islxvrze;
   bool isendian;
+  bool isibmld;
 };
 
 /* Fields associated with a function prototype (bif or overload).  */
@@ -1435,6 +1437,8 @@ parse_bif_attrs (attrinfo *attrptr)
 	  attrptr->islxvrze = 1;
 	else if (!strcmp (attrname, "endian"))
 	  attrptr->isendian = 1;
+	else if (!strcmp (attrname, "ibmld"))
+	  attrptr->isibmld = 1;
 	else
 	  {
 	    diag (oldpos, "unknown attribute.\n");
@@ -1468,14 +1472,14 @@ parse_bif_attrs (attrinfo *attrptr)
 	"ldvec = %d, stvec = %d, reve = %d, pred = %d, htm = %d, "
 	"htmspr = %d, htmcr = %d, mma = %d, quad = %d, pair = %d, "
 	"mmaint = %d, no32bit = %d, 32bit = %d, cpu = %d, ldstmask = %d, "
-	"lxvrse = %d, lxvrze = %d, endian = %d.\n",
+	"lxvrse = %d, lxvrze = %d, endian = %d, ibmdld= %d.\n",
 	attrptr->isinit, attrptr->isset, attrptr->isextract,
 	attrptr->isnosoft, attrptr->isldvec, attrptr->isstvec,
 	attrptr->isreve, attrptr->ispred, attrptr->ishtm, attrptr->ishtmspr,
 	attrptr->ishtmcr, attrptr->ismma, attrptr->isquad, attrptr->ispair,
 	attrptr->ismmaint, attrptr->isno32bit, attrptr->is32bit,
 	attrptr->iscpu, attrptr->isldstmask, attrptr->islxvrse,
-	attrptr->islxvrze, attrptr->isendian);
+	attrptr->islxvrze, attrptr->isendian, attrptr->isibmld);
 #endif
 
   return PC_OK;
@@ -2289,6 +2293,7 @@ write_decls (void)
   fprintf (header_file, "#define bif_lxvrse_bit\t\t(0x00080000)\n");
   fprintf (header_file, "#define bif_lxvrze_bit\t\t(0x00100000)\n");
   fprintf (header_file, "#define bif_endian_bit\t\t(0x00200000)\n");
+  fprintf (header_file, "#define bif_ibmld_bit\t\t(0x00400000)\n");
   fprintf (header_file, "\n");
   fprintf (header_file,
 	   "#define bif_is_init(x)\t\t((x).bifattrs & bif_init_bit)\n");
@@ -2334,6 +2339,8 @@ write_decls (void)
 	   "#define bif_is_lxvrze(x)\t((x).bifattrs & bif_lxvrze_bit)\n");
   fprintf (header_file,
 	   "#define bif_is_endian(x)\t((x).bifattrs & bif_endian_bit)\n");
+  fprintf (header_file,
+	   "#define bif_is_ibmld(x)\t((x).bifattrs & bif_ibmld_bit)\n");
   fprintf (header_file, "\n");
 
   /* #### Note that the _x is added for now to avoid conflict with
@@ -2568,6 +2575,8 @@ write_bif_static_init (void)
 	fprintf (init_file, " | bif_lxvrze_bit");
       if (bifp->attrs.isendian)
 	fprintf (init_file, " | bif_endian_bit");
+      if (bifp->attrs.isibmld)
+	fprintf (init_file, " | bif_ibmld_bit");
       fprintf (init_file, ",\n");
       fprintf (init_file, "      /* restr_opnd */\t{%d, %d, %d},\n",
 	       bifp->proto.restr_opnd[0], bifp->proto.restr_opnd[1],