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* [gcc(refs/users/meissner/heads/dmf005)] Add saturating subtract built-ins.
@ 2022-12-03  1:30 Michael Meissner
  0 siblings, 0 replies; 3+ messages in thread
From: Michael Meissner @ 2022-12-03  1:30 UTC (permalink / raw)
  To: gcc-cvs

https://gcc.gnu.org/g:a91882c533ccd127187a31793102e63c0b411d47

commit a91882c533ccd127187a31793102e63c0b411d47
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Fri Dec 2 20:29:40 2022 -0500

    Add saturating subtract built-ins.
    
    This patch adds support for a saturating subtract built-in function that may be
    added to a future PowerPC processor.  Note, if it is added, the name of the
    built-in function may change before GCC 13 is released.  If the name changes,
    we will submit a patch changing the name.
    
    I also added support for providing dense math built-in functions, even though
    at present, we have not added any new built-in functions for dense math.  It is
    likely we will want to add new dense math built-in functions as the dense math
    support is fleshed out.
    
    I tested this patch on a little endian power10 system with long double using
    the tradiational IBM double double format.  Assuming the other 6 patches for
    -mcpu=future are checked in (or at least the first patch), can I check this
    patch into the master branch for GCC 13.
    
    2022-12-02   Michael Meissner  <meissner@linux.ibm.com>
    
    gcc/
    
            * config/rs6000/rs6000-builtin.cc (rs6000_invalid_builtin): Add support
            for flagging invalid use of future built-in functions.
            (rs6000_builtin_is_supported): Add support for future built-in
            functions.
            * config/rs6000/rs6000-builtins.def (__builtin_saturate_subtract32): New
            built-in function for -mcpu=future.
            (__builtin_saturate_subtract64): Likewise.
            * config/rs6000/rs6000-gen-builtins.cc (enum bif_stanza): Add stanzas
            for -mcpu=future built-ins.
            (stanza_map): Likewise.
            (enable_string): Likewise.
            (struct attrinfo): Likewise.
            (parse_bif_attrs): Likewise.
            (write_decls): Likewise.
            * config/rs6000/rs6000.md (sat_sub<mode>3): Add saturating subtract
            built-in insn declarations.
            (sat_sub<mode>3_dot): Likewise.
            (sat_sub<mode>3_dot2): Likewise.
            * doc/extend.texi (Future PowerPC built-ins): New section.
    
    gcc/testsuite/
    
            * gcc.target/powerpc/subfus-1.c: New test.
            * gcc.target/powerpc/subfus-2.c: Likewise.
            * lib/target-supports.exp (check_effective_target_powerpc_future_ok):
            New effective target.

Diff:
---
 gcc/config/rs6000/rs6000-builtin.cc         | 17 ++++++++
 gcc/config/rs6000/rs6000-builtins.def       | 11 ++++++
 gcc/config/rs6000/rs6000-gen-builtins.cc    | 35 ++++++++++++++---
 gcc/config/rs6000/rs6000.md                 | 60 +++++++++++++++++++++++++++++
 gcc/doc/extend.texi                         | 24 ++++++++++++
 gcc/testsuite/gcc.target/powerpc/subfus-1.c | 32 +++++++++++++++
 gcc/testsuite/gcc.target/powerpc/subfus-2.c | 32 +++++++++++++++
 gcc/testsuite/lib/target-supports.exp       | 16 +++++++-
 8 files changed, 220 insertions(+), 7 deletions(-)

diff --git a/gcc/config/rs6000/rs6000-builtin.cc b/gcc/config/rs6000/rs6000-builtin.cc
index f4eba184db8..1ac00e4b26c 100644
--- a/gcc/config/rs6000/rs6000-builtin.cc
+++ b/gcc/config/rs6000/rs6000-builtin.cc
@@ -139,6 +139,17 @@ rs6000_invalid_builtin (enum rs6000_gen_builtins fncode)
     case ENB_MMA:
       error ("%qs requires the %qs option", name, "-mmma");
       break;
+    case ENB_FUTURE:
+      error ("%qs requires the %qs option", name, "-mcpu=future");
+      break;
+    case ENB_FUTURE_64:
+      error ("%qs requires the %qs option and either the %qs or %qs option",
+	     name, "-mcpu=future", "-m64", "-mpowerpc64");
+      break;
+    case ENB_DM:
+      error ("%qs requires the %qs or %qs options", name, "-mcpu=future",
+	     "-mdense-math");
+      break;
     default:
     case ENB_ALWAYS:
       gcc_unreachable ();
@@ -194,6 +205,12 @@ rs6000_builtin_is_supported (enum rs6000_gen_builtins fncode)
       return TARGET_HTM;
     case ENB_MMA:
       return TARGET_MMA;
+    case ENB_FUTURE:
+      return TARGET_FUTURE;
+    case ENB_FUTURE_64:
+      return TARGET_FUTURE && TARGET_POWERPC64;
+    case ENB_DM:
+      return TARGET_DENSE_MATH;
     default:
       gcc_unreachable ();
     }
diff --git a/gcc/config/rs6000/rs6000-builtins.def b/gcc/config/rs6000/rs6000-builtins.def
index f76f54793d7..ee141c1d99e 100644
--- a/gcc/config/rs6000/rs6000-builtins.def
+++ b/gcc/config/rs6000/rs6000-builtins.def
@@ -139,6 +139,8 @@
 ;   endian   Needs special handling for endianness
 ;   ibmld    Restrict usage to the case when TFmode is IBM-128
 ;   ibm128   Restrict usage to the case where __ibm128 is supported or if ibmld
+;   future   Restrict usage to future instructions
+;   dm       Restrict usage to dense math
 ;
 ; Each attribute corresponds to extra processing required when
 ; the built-in is expanded.  All such special processing should
@@ -4108,3 +4110,12 @@
 
   void __builtin_vsx_stxvp (v256, unsigned long, const v256 *);
     STXVP nothing {mma,pair}
+
+[future]
+  const signed int __builtin_saturate_subtract32 (signed int, signed int);
+  SAT_SUBSI sat_subsi3 {}
+
+[future-64]
+  const signed long __builtin_saturate_subtract64 (signed long, signed long);
+  SAT_SUBDI sat_subdi3 {}
+
diff --git a/gcc/config/rs6000/rs6000-gen-builtins.cc b/gcc/config/rs6000/rs6000-gen-builtins.cc
index 0bd7a535e5f..f4020141243 100644
--- a/gcc/config/rs6000/rs6000-gen-builtins.cc
+++ b/gcc/config/rs6000/rs6000-gen-builtins.cc
@@ -233,6 +233,9 @@ enum bif_stanza
  BSTZ_P10,
  BSTZ_P10_64,
  BSTZ_MMA,
+ BSTZ_FUTURE,
+ BSTZ_FUTURE_64,
+ BSTZ_DM,
  NUMBIFSTANZAS
 };
 
@@ -266,7 +269,10 @@ static stanza_entry stanza_map[NUMBIFSTANZAS] =
     { "htm",		BSTZ_HTM	},
     { "power10",	BSTZ_P10	},
     { "power10-64",	BSTZ_P10_64	},
-    { "mma",		BSTZ_MMA	}
+    { "mma",		BSTZ_MMA	},
+    { "future",		BSTZ_FUTURE	},
+    { "future-64",	BSTZ_FUTURE_64	},
+    { "dm",		BSTZ_DM		},
   };
 
 static const char *enable_string[NUMBIFSTANZAS] =
@@ -291,7 +297,10 @@ static const char *enable_string[NUMBIFSTANZAS] =
     "ENB_HTM",
     "ENB_P10",
     "ENB_P10_64",
-    "ENB_MMA"
+    "ENB_MMA",
+    "ENB_FUTURE",
+    "ENB_FUTURE_64",
+    "ENB_DM",
   };
 
 /* Function modifiers provide special handling for const, pure, and fpmath
@@ -395,6 +404,8 @@ struct attrinfo
   bool isendian;
   bool isibmld;
   bool isibm128;
+  bool isfuture;
+  bool isdm;
 };
 
 /* Fields associated with a function prototype (bif or overload).  */
@@ -1477,7 +1488,8 @@ 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, ibmdld = %d, ibm128 = %d.\n",
+	"lxvrse = %d, lxvrze = %d, endian = %d, ibmdld = %d, ibm128 = %d,",
+	"future = %d, dm = %d.\n",
 	attrptr->isinit, attrptr->isset, attrptr->isextract,
 	attrptr->isnosoft, attrptr->isldvec, attrptr->isstvec,
 	attrptr->isreve, attrptr->ispred, attrptr->ishtm, attrptr->ishtmspr,
@@ -1485,7 +1497,7 @@ parse_bif_attrs (attrinfo *attrptr)
 	attrptr->ismmaint, attrptr->isno32bit, attrptr->is32bit,
 	attrptr->iscpu, attrptr->isldstmask, attrptr->islxvrse,
 	attrptr->islxvrze, attrptr->isendian, attrptr->isibmld,
-	attrptr->isibm128);
+	attrptr->isibm128, attrptr->isfuture, attrptr->isdm);
 #endif
 
   return PC_OK;
@@ -2257,7 +2269,10 @@ write_decls (void)
   fprintf (header_file, "  ENB_HTM,\n");
   fprintf (header_file, "  ENB_P10,\n");
   fprintf (header_file, "  ENB_P10_64,\n");
-  fprintf (header_file, "  ENB_MMA\n");
+  fprintf (header_file, "  ENB_MMA,\n");
+  fprintf (header_file, "  ENB_FUTURE,\n");
+  fprintf (header_file, "  ENB_FUTURE_64,\n");
+  fprintf (header_file, "  ENB_DM\n");
   fprintf (header_file, "};\n\n");
 
   fprintf (header_file, "#define PPC_MAXRESTROPNDS 3\n");
@@ -2301,6 +2316,8 @@ write_decls (void)
   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, "#define bif_ibm128_bit\t\t(0x00800000)\n");
+  fprintf (header_file, "#define bif_future_bit\t\t(0x01000000)\n");
+  fprintf (header_file, "#define bif_dm_bit\t\t(0x02000000)\n");
   fprintf (header_file, "\n");
   fprintf (header_file,
 	   "#define bif_is_init(x)\t\t((x).bifattrs & bif_init_bit)\n");
@@ -2350,6 +2367,10 @@ write_decls (void)
 	   "#define bif_is_ibmld(x)\t((x).bifattrs & bif_ibmld_bit)\n");
   fprintf (header_file,
 	   "#define bif_is_ibm128(x)\t((x).bifattrs & bif_ibm128_bit)\n");
+  fprintf (header_file,
+	   "#define bif_is_future(x)\t((x).bifattrs & bif_future_bit)\n");
+  fprintf (header_file,
+	   "#define bif_is_dm(x)\t((x).bifattrs & bif_dm_bit)\n");
   fprintf (header_file, "\n");
 
   fprintf (header_file,
@@ -2548,6 +2569,10 @@ write_bif_static_init (void)
 	fprintf (init_file, " | bif_ibmld_bit");
       if (bifp->attrs.isibm128)
 	fprintf (init_file, " | bif_ibm128_bit");
+      if (bifp->attrs.isfuture)
+	fprintf (init_file, " | bif_future_bit");
+      if (bifp->attrs.isdm)
+	fprintf (init_file, " | bif_dm_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],
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index 4a5007dc539..e9dfb138603 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -15499,6 +15499,66 @@
 }
   [(set_attr "type" "load")])
 \f
+;; Signed saturation.
+
+;; The subfus instruction is defined as: SUBFUS RT,L,RA,RB.  The extended
+;; mnemonic that we use (subdus and subwus) has the arguments RA and RB
+;; reversed (so it becomes a subtract instead of subtract from).
+
+(define_insn "sat_sub<mode>3"
+  [(set (match_operand:GPR 0 "gpc_reg_operand" "=r")
+	(ss_minus:GPR (match_operand:GPR 1 "gpc_reg_operand" "r")
+		      (match_operand:GPR 2 "gpc_reg_operand" "r")))]
+  "TARGET_FUTURE"
+  "sub<wd>us %0,%1,%2"
+  [(set_attr "type" "add")])
+
+(define_insn_and_split "*sat_sub<mode>3_dot"
+  [(set (match_operand:CC 3 "cc_reg_operand" "=x,?y")
+	(compare:CC (ss_minus:GPR (match_operand:GPR 1 "gpc_reg_operand" "r,r")
+				  (match_operand:GPR 2 "gpc_reg_operand" "r,r"))
+		    (const_int 0)))
+   (clobber (match_scratch:GPR 0 "=r,r"))]
+  "TARGET_FUTURE"
+  "@
+   sub<wd>us. %0,%1,%2
+   #"
+  "&& reload_completed && cc_reg_not_cr0_operand (operands[3], CCmode)"
+  [(set (match_dup 0)
+	(ss_minus:GPR (match_dup 1)
+		      (match_dup 2)))
+   (set (match_dup 3)
+	(compare:CC (match_dup 0)
+		    (const_int 0)))]
+  ""
+  [(set_attr "type" "add")
+   (set_attr "dot" "yes")
+   (set_attr "length" "4,8")])
+
+(define_insn_and_split "*sat_sub<mode>3_dot2"
+  [(set (match_operand:CC 3 "cc_reg_operand" "=x,?y")
+	(compare:CC (ss_minus:GPR (match_operand:GPR 1 "gpc_reg_operand" "r,r")
+				  (match_operand:GPR 2 "gpc_reg_operand" "r,r"))
+		    (const_int 0)))
+   (set (match_operand:GPR 0 "gpc_reg_operand" "=r,r")
+	(ss_minus:GPR (match_dup 1)
+		      (match_dup 2)))]
+  "TARGET_FUTURE"
+  "@
+   sub<wd>us. %0,%1,%2
+   #"
+  "&& reload_completed && cc_reg_not_cr0_operand (operands[3], CCmode)"
+  [(set (match_dup 0)
+	(ss_minus:GPR (match_dup 1)
+		      (match_dup 2)))
+   (set (match_dup 3)
+	(compare:CC (match_dup 0)
+		    (const_int 0)))]
+  ""
+  [(set_attr "type" "add")
+   (set_attr "dot" "yes")
+   (set_attr "length" "4,8")])
+\f
 
 (include "sync.md")
 (include "vector.md")
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index b1dd39e64b8..a8b50153d9b 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -17783,6 +17783,7 @@ Disable global interrupt.
 * Basic PowerPC Built-in Functions Available on ISA 2.07::
 * Basic PowerPC Built-in Functions Available on ISA 3.0::
 * Basic PowerPC Built-in Functions Available on ISA 3.1::
+* Basic Built-in Functions that may be available on future PowerPCs::
 @end menu
 
 This section describes PowerPC built-in functions that do not require
@@ -18440,6 +18441,29 @@ ISA 3.1 @code{stxvrbx}, @code{stxvrhx}, @code{stxvrwx}, and @code{stxvrdx}
 instructions.
 @findex vec_xst_trunc
 
+@node Basic Built-in Functions that may be available on future PowerPCs
+@subsubsection Potential future PowerPC Built-in Functions
+
+The built-in functions described in this section may be available on
+future PowerPC processors.  At present, these built-ins exist to
+allowing testing of new instructions.  There is no guarantee that
+these instructions will actually be implemented.
+
+The following built-in functions are available on Linux 64-bit systems
+that use a potential future instruction set (@option{-mcpu=future}):
+
+@table @code
+@item int __builtin_saturate_subtract32 (int, int)
+Subtract the second operand from the first operand.  If the value
+would be less than 0, then the result is 0 instead of the negative
+value of the subtraction.
+
+@item long __builtin_saturate_subtract64 (long, long)
+Subtract the second operand from the first operand.  If the value
+would be less than 0, then the result is 0 instead of the negative
+value of the subtraction.
+@end table
+
 @node PowerPC AltiVec/VSX Built-in Functions
 @subsection PowerPC AltiVec/VSX Built-in Functions
 
diff --git a/gcc/testsuite/gcc.target/powerpc/subfus-1.c b/gcc/testsuite/gcc.target/powerpc/subfus-1.c
new file mode 100644
index 00000000000..535e7f8483d
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/subfus-1.c
@@ -0,0 +1,32 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_future_ok } */
+/* { dg-options "-mdejagnu-cpu=future -O2" } */
+
+/* Test whether the saturating subtract built-in generates subwus for 32-bit
+   subtracts.  */
+
+int do_sat_int  (int  a, int  b)
+{
+  return __builtin_saturate_subtract32 (a, b);		/* subwus  */
+}
+
+int do_sat_int_dot  (int  a, int  b, int  *p)
+{
+  int  r = __builtin_saturate_subtract32 (a, b);	/* subwus.  */
+  if (r == 0)
+    *p = 0;
+
+  return r;
+}
+
+void do_sat_int_dot2  (int  a, int  b, int  *p, int *q)
+{
+  if (__builtin_saturate_subtract32 (a, b))		/* subwus.  */
+    *p = 0;
+
+  *q = a + b;
+  return;
+}
+
+/* { dg-final { scan-assembler     {\msubwus\M} } } */
+/* { dg-final { scan-assembler-not {\msubf\M}   } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/subfus-2.c b/gcc/testsuite/gcc.target/powerpc/subfus-2.c
new file mode 100644
index 00000000000..b68e66dd2b0
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/subfus-2.c
@@ -0,0 +1,32 @@
+/* { dg-do compile { target lp64 } } */
+/* { dg-require-effective-target powerpc_future_ok } */
+/* { dg-options "-mdejagnu-cpu=future -O2" } */
+
+/* Test whether the saturating subtract built-in generates subwus for 64-bit
+   subtracts.  */
+
+long do_sat_long  (long  a, long  b)
+{
+  return __builtin_saturate_subtract64 (a, b);		/* subwus  */
+}
+
+long do_sat_long_dot  (long  a, long  b, long  *p)
+{
+  long  r = __builtin_saturate_subtract64 (a, b);	/* subwus.  */
+  if (r == 0)
+    *p = 0;
+
+  return r;
+}
+
+void do_sat_long_dot2  (long  a, long  b, long  *p, long *q)
+{
+  if (__builtin_saturate_subtract64 (a, b))		/* subwus.  */
+    *p = 0;
+
+  *q = a + b;
+  return;
+}
+
+/* { dg-final { scan-assembler     {\msubdus\M} } } */
+/* { dg-final { scan-assembler-not {\msubf\M}   } } */
diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
index 020bc03a3cc..8ddbdf18dc8 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -6548,8 +6548,8 @@ proc check_effective_target_power10_ok { } {
     }
 }
 
-# Return 1 if this is a PowerPC target supporting -mcpu=future or -mdense-math
-# which enables the dense math operations.
+# Return 1 if this is a PowerPC target supporting -mcpu=future which enables
+# the dense math operations.
 proc check_effective_target_powerpc_dense_math_ok { } {
 	return [check_no_compiler_messages_nocache powerpc_dense_math_ok assembly {
 		__vector_quad vq;
@@ -6567,6 +6567,18 @@ proc check_effective_target_powerpc_dense_math_ok { } {
 	} "-mcpu=future"]
 }
 
+# Return 1 if this is a PowerPC target supporting -mcpu=future which enables
+# the saturating subtract instruction.
+proc check_effective_target_powerpc_future_ok { } {
+	return [check_no_compiler_messages powerpc_future_ok object {
+	    #ifndef _ARCH_PWR_FUTURE
+	    #error "not -mcpu=future"
+	    #else
+	    int dummy;
+	    #endif
+	} "-mcpu=future"]
+}
+
 # Return 1 if this is a PowerPC target supporting -mfloat128 via either
 # software emulation on power7/power8 systems or hardware support on power9.

^ permalink raw reply	[flat|nested] 3+ messages in thread

* [gcc(refs/users/meissner/heads/dmf005)] Add saturating subtract built-ins.
@ 2022-12-03  1:41 Michael Meissner
  0 siblings, 0 replies; 3+ messages in thread
From: Michael Meissner @ 2022-12-03  1:41 UTC (permalink / raw)
  To: gcc-cvs

https://gcc.gnu.org/g:0270b358f35c130effde066a158b7c6c5ae0f99f

commit 0270b358f35c130effde066a158b7c6c5ae0f99f
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Fri Dec 2 20:39:55 2022 -0500

    Add saturating subtract built-ins.
    
    This patch adds support for a saturating subtract built-in function that may be
    added to a future PowerPC processor.  Note, if it is added, the name of the
    built-in function may change before GCC 13 is released.  If the name changes,
    we will submit a patch changing the name.
    
    I also added support for providing dense math built-in functions, even though
    at present, we have not added any new built-in functions for dense math.  It is
    likely we will want to add new dense math built-in functions as the dense math
    support is fleshed out.
    
    I tested this patch on a little endian power10 system with long double using
    the tradiational IBM double double format.  Assuming the other 6 patches for
    -mcpu=future are checked in (or at least the first patch), can I check this
    patch into the master branch for GCC 13.
    
    2022-12-02   Michael Meissner  <meissner@linux.ibm.com>
    
    gcc/
    
            * config/rs6000/rs6000-builtin.cc (rs6000_invalid_builtin): Add support
            for flagging invalid use of future built-in functions.
            (rs6000_builtin_is_supported): Add support for future built-in
            functions.
            * config/rs6000/rs6000-builtins.def (__builtin_saturate_subtract32): New
            built-in function for -mcpu=future.
            (__builtin_saturate_subtract64): Likewise.
            * config/rs6000/rs6000-gen-builtins.cc (enum bif_stanza): Add stanzas
            for -mcpu=future built-ins.
            (stanza_map): Likewise.
            (enable_string): Likewise.
            (struct attrinfo): Likewise.
            (parse_bif_attrs): Likewise.
            (write_decls): Likewise.
            * config/rs6000/rs6000.md (sat_sub<mode>3): Add saturating subtract
            built-in insn declarations.
            (sat_sub<mode>3_dot): Likewise.
            (sat_sub<mode>3_dot2): Likewise.
            * doc/extend.texi (Future PowerPC built-ins): New section.
    
    gcc/testsuite/
    
            * gcc.target/powerpc/subfus-1.c: New test.
            * gcc.target/powerpc/subfus-2.c: Likewise.
            * lib/target-supports.exp (check_effective_target_powerpc_future_ok):
            New effective target.

Diff:
---
 gcc/config/rs6000/rs6000-builtin.cc         | 17 ++++++++
 gcc/config/rs6000/rs6000-builtins.def       | 11 ++++++
 gcc/config/rs6000/rs6000-gen-builtins.cc    | 35 ++++++++++++++---
 gcc/config/rs6000/rs6000.md                 | 60 +++++++++++++++++++++++++++++
 gcc/doc/extend.texi                         | 24 ++++++++++++
 gcc/testsuite/gcc.target/powerpc/subfus-1.c | 32 +++++++++++++++
 gcc/testsuite/gcc.target/powerpc/subfus-2.c | 32 +++++++++++++++
 gcc/testsuite/lib/target-supports.exp       | 16 +++++++-
 8 files changed, 220 insertions(+), 7 deletions(-)

diff --git a/gcc/config/rs6000/rs6000-builtin.cc b/gcc/config/rs6000/rs6000-builtin.cc
index f4eba184db8..1ac00e4b26c 100644
--- a/gcc/config/rs6000/rs6000-builtin.cc
+++ b/gcc/config/rs6000/rs6000-builtin.cc
@@ -139,6 +139,17 @@ rs6000_invalid_builtin (enum rs6000_gen_builtins fncode)
     case ENB_MMA:
       error ("%qs requires the %qs option", name, "-mmma");
       break;
+    case ENB_FUTURE:
+      error ("%qs requires the %qs option", name, "-mcpu=future");
+      break;
+    case ENB_FUTURE_64:
+      error ("%qs requires the %qs option and either the %qs or %qs option",
+	     name, "-mcpu=future", "-m64", "-mpowerpc64");
+      break;
+    case ENB_DM:
+      error ("%qs requires the %qs or %qs options", name, "-mcpu=future",
+	     "-mdense-math");
+      break;
     default:
     case ENB_ALWAYS:
       gcc_unreachable ();
@@ -194,6 +205,12 @@ rs6000_builtin_is_supported (enum rs6000_gen_builtins fncode)
       return TARGET_HTM;
     case ENB_MMA:
       return TARGET_MMA;
+    case ENB_FUTURE:
+      return TARGET_FUTURE;
+    case ENB_FUTURE_64:
+      return TARGET_FUTURE && TARGET_POWERPC64;
+    case ENB_DM:
+      return TARGET_DENSE_MATH;
     default:
       gcc_unreachable ();
     }
diff --git a/gcc/config/rs6000/rs6000-builtins.def b/gcc/config/rs6000/rs6000-builtins.def
index f76f54793d7..ee141c1d99e 100644
--- a/gcc/config/rs6000/rs6000-builtins.def
+++ b/gcc/config/rs6000/rs6000-builtins.def
@@ -139,6 +139,8 @@
 ;   endian   Needs special handling for endianness
 ;   ibmld    Restrict usage to the case when TFmode is IBM-128
 ;   ibm128   Restrict usage to the case where __ibm128 is supported or if ibmld
+;   future   Restrict usage to future instructions
+;   dm       Restrict usage to dense math
 ;
 ; Each attribute corresponds to extra processing required when
 ; the built-in is expanded.  All such special processing should
@@ -4108,3 +4110,12 @@
 
   void __builtin_vsx_stxvp (v256, unsigned long, const v256 *);
     STXVP nothing {mma,pair}
+
+[future]
+  const signed int __builtin_saturate_subtract32 (signed int, signed int);
+  SAT_SUBSI sat_subsi3 {}
+
+[future-64]
+  const signed long __builtin_saturate_subtract64 (signed long, signed long);
+  SAT_SUBDI sat_subdi3 {}
+
diff --git a/gcc/config/rs6000/rs6000-gen-builtins.cc b/gcc/config/rs6000/rs6000-gen-builtins.cc
index 0bd7a535e5f..f4020141243 100644
--- a/gcc/config/rs6000/rs6000-gen-builtins.cc
+++ b/gcc/config/rs6000/rs6000-gen-builtins.cc
@@ -233,6 +233,9 @@ enum bif_stanza
  BSTZ_P10,
  BSTZ_P10_64,
  BSTZ_MMA,
+ BSTZ_FUTURE,
+ BSTZ_FUTURE_64,
+ BSTZ_DM,
  NUMBIFSTANZAS
 };
 
@@ -266,7 +269,10 @@ static stanza_entry stanza_map[NUMBIFSTANZAS] =
     { "htm",		BSTZ_HTM	},
     { "power10",	BSTZ_P10	},
     { "power10-64",	BSTZ_P10_64	},
-    { "mma",		BSTZ_MMA	}
+    { "mma",		BSTZ_MMA	},
+    { "future",		BSTZ_FUTURE	},
+    { "future-64",	BSTZ_FUTURE_64	},
+    { "dm",		BSTZ_DM		},
   };
 
 static const char *enable_string[NUMBIFSTANZAS] =
@@ -291,7 +297,10 @@ static const char *enable_string[NUMBIFSTANZAS] =
     "ENB_HTM",
     "ENB_P10",
     "ENB_P10_64",
-    "ENB_MMA"
+    "ENB_MMA",
+    "ENB_FUTURE",
+    "ENB_FUTURE_64",
+    "ENB_DM",
   };
 
 /* Function modifiers provide special handling for const, pure, and fpmath
@@ -395,6 +404,8 @@ struct attrinfo
   bool isendian;
   bool isibmld;
   bool isibm128;
+  bool isfuture;
+  bool isdm;
 };
 
 /* Fields associated with a function prototype (bif or overload).  */
@@ -1477,7 +1488,8 @@ 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, ibmdld = %d, ibm128 = %d.\n",
+	"lxvrse = %d, lxvrze = %d, endian = %d, ibmdld = %d, ibm128 = %d,",
+	"future = %d, dm = %d.\n",
 	attrptr->isinit, attrptr->isset, attrptr->isextract,
 	attrptr->isnosoft, attrptr->isldvec, attrptr->isstvec,
 	attrptr->isreve, attrptr->ispred, attrptr->ishtm, attrptr->ishtmspr,
@@ -1485,7 +1497,7 @@ parse_bif_attrs (attrinfo *attrptr)
 	attrptr->ismmaint, attrptr->isno32bit, attrptr->is32bit,
 	attrptr->iscpu, attrptr->isldstmask, attrptr->islxvrse,
 	attrptr->islxvrze, attrptr->isendian, attrptr->isibmld,
-	attrptr->isibm128);
+	attrptr->isibm128, attrptr->isfuture, attrptr->isdm);
 #endif
 
   return PC_OK;
@@ -2257,7 +2269,10 @@ write_decls (void)
   fprintf (header_file, "  ENB_HTM,\n");
   fprintf (header_file, "  ENB_P10,\n");
   fprintf (header_file, "  ENB_P10_64,\n");
-  fprintf (header_file, "  ENB_MMA\n");
+  fprintf (header_file, "  ENB_MMA,\n");
+  fprintf (header_file, "  ENB_FUTURE,\n");
+  fprintf (header_file, "  ENB_FUTURE_64,\n");
+  fprintf (header_file, "  ENB_DM\n");
   fprintf (header_file, "};\n\n");
 
   fprintf (header_file, "#define PPC_MAXRESTROPNDS 3\n");
@@ -2301,6 +2316,8 @@ write_decls (void)
   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, "#define bif_ibm128_bit\t\t(0x00800000)\n");
+  fprintf (header_file, "#define bif_future_bit\t\t(0x01000000)\n");
+  fprintf (header_file, "#define bif_dm_bit\t\t(0x02000000)\n");
   fprintf (header_file, "\n");
   fprintf (header_file,
 	   "#define bif_is_init(x)\t\t((x).bifattrs & bif_init_bit)\n");
@@ -2350,6 +2367,10 @@ write_decls (void)
 	   "#define bif_is_ibmld(x)\t((x).bifattrs & bif_ibmld_bit)\n");
   fprintf (header_file,
 	   "#define bif_is_ibm128(x)\t((x).bifattrs & bif_ibm128_bit)\n");
+  fprintf (header_file,
+	   "#define bif_is_future(x)\t((x).bifattrs & bif_future_bit)\n");
+  fprintf (header_file,
+	   "#define bif_is_dm(x)\t((x).bifattrs & bif_dm_bit)\n");
   fprintf (header_file, "\n");
 
   fprintf (header_file,
@@ -2548,6 +2569,10 @@ write_bif_static_init (void)
 	fprintf (init_file, " | bif_ibmld_bit");
       if (bifp->attrs.isibm128)
 	fprintf (init_file, " | bif_ibm128_bit");
+      if (bifp->attrs.isfuture)
+	fprintf (init_file, " | bif_future_bit");
+      if (bifp->attrs.isdm)
+	fprintf (init_file, " | bif_dm_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],
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index 4a5007dc539..e9dfb138603 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -15499,6 +15499,66 @@
 }
   [(set_attr "type" "load")])
 \f
+;; Signed saturation.
+
+;; The subfus instruction is defined as: SUBFUS RT,L,RA,RB.  The extended
+;; mnemonic that we use (subdus and subwus) has the arguments RA and RB
+;; reversed (so it becomes a subtract instead of subtract from).
+
+(define_insn "sat_sub<mode>3"
+  [(set (match_operand:GPR 0 "gpc_reg_operand" "=r")
+	(ss_minus:GPR (match_operand:GPR 1 "gpc_reg_operand" "r")
+		      (match_operand:GPR 2 "gpc_reg_operand" "r")))]
+  "TARGET_FUTURE"
+  "sub<wd>us %0,%1,%2"
+  [(set_attr "type" "add")])
+
+(define_insn_and_split "*sat_sub<mode>3_dot"
+  [(set (match_operand:CC 3 "cc_reg_operand" "=x,?y")
+	(compare:CC (ss_minus:GPR (match_operand:GPR 1 "gpc_reg_operand" "r,r")
+				  (match_operand:GPR 2 "gpc_reg_operand" "r,r"))
+		    (const_int 0)))
+   (clobber (match_scratch:GPR 0 "=r,r"))]
+  "TARGET_FUTURE"
+  "@
+   sub<wd>us. %0,%1,%2
+   #"
+  "&& reload_completed && cc_reg_not_cr0_operand (operands[3], CCmode)"
+  [(set (match_dup 0)
+	(ss_minus:GPR (match_dup 1)
+		      (match_dup 2)))
+   (set (match_dup 3)
+	(compare:CC (match_dup 0)
+		    (const_int 0)))]
+  ""
+  [(set_attr "type" "add")
+   (set_attr "dot" "yes")
+   (set_attr "length" "4,8")])
+
+(define_insn_and_split "*sat_sub<mode>3_dot2"
+  [(set (match_operand:CC 3 "cc_reg_operand" "=x,?y")
+	(compare:CC (ss_minus:GPR (match_operand:GPR 1 "gpc_reg_operand" "r,r")
+				  (match_operand:GPR 2 "gpc_reg_operand" "r,r"))
+		    (const_int 0)))
+   (set (match_operand:GPR 0 "gpc_reg_operand" "=r,r")
+	(ss_minus:GPR (match_dup 1)
+		      (match_dup 2)))]
+  "TARGET_FUTURE"
+  "@
+   sub<wd>us. %0,%1,%2
+   #"
+  "&& reload_completed && cc_reg_not_cr0_operand (operands[3], CCmode)"
+  [(set (match_dup 0)
+	(ss_minus:GPR (match_dup 1)
+		      (match_dup 2)))
+   (set (match_dup 3)
+	(compare:CC (match_dup 0)
+		    (const_int 0)))]
+  ""
+  [(set_attr "type" "add")
+   (set_attr "dot" "yes")
+   (set_attr "length" "4,8")])
+\f
 
 (include "sync.md")
 (include "vector.md")
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index b1dd39e64b8..a8b50153d9b 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -17783,6 +17783,7 @@ Disable global interrupt.
 * Basic PowerPC Built-in Functions Available on ISA 2.07::
 * Basic PowerPC Built-in Functions Available on ISA 3.0::
 * Basic PowerPC Built-in Functions Available on ISA 3.1::
+* Basic Built-in Functions that may be available on future PowerPCs::
 @end menu
 
 This section describes PowerPC built-in functions that do not require
@@ -18440,6 +18441,29 @@ ISA 3.1 @code{stxvrbx}, @code{stxvrhx}, @code{stxvrwx}, and @code{stxvrdx}
 instructions.
 @findex vec_xst_trunc
 
+@node Basic Built-in Functions that may be available on future PowerPCs
+@subsubsection Potential future PowerPC Built-in Functions
+
+The built-in functions described in this section may be available on
+future PowerPC processors.  At present, these built-ins exist to
+allowing testing of new instructions.  There is no guarantee that
+these instructions will actually be implemented.
+
+The following built-in functions are available on Linux 64-bit systems
+that use a potential future instruction set (@option{-mcpu=future}):
+
+@table @code
+@item int __builtin_saturate_subtract32 (int, int)
+Subtract the second operand from the first operand.  If the value
+would be less than 0, then the result is 0 instead of the negative
+value of the subtraction.
+
+@item long __builtin_saturate_subtract64 (long, long)
+Subtract the second operand from the first operand.  If the value
+would be less than 0, then the result is 0 instead of the negative
+value of the subtraction.
+@end table
+
 @node PowerPC AltiVec/VSX Built-in Functions
 @subsection PowerPC AltiVec/VSX Built-in Functions
 
diff --git a/gcc/testsuite/gcc.target/powerpc/subfus-1.c b/gcc/testsuite/gcc.target/powerpc/subfus-1.c
new file mode 100644
index 00000000000..535e7f8483d
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/subfus-1.c
@@ -0,0 +1,32 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_future_ok } */
+/* { dg-options "-mdejagnu-cpu=future -O2" } */
+
+/* Test whether the saturating subtract built-in generates subwus for 32-bit
+   subtracts.  */
+
+int do_sat_int  (int  a, int  b)
+{
+  return __builtin_saturate_subtract32 (a, b);		/* subwus  */
+}
+
+int do_sat_int_dot  (int  a, int  b, int  *p)
+{
+  int  r = __builtin_saturate_subtract32 (a, b);	/* subwus.  */
+  if (r == 0)
+    *p = 0;
+
+  return r;
+}
+
+void do_sat_int_dot2  (int  a, int  b, int  *p, int *q)
+{
+  if (__builtin_saturate_subtract32 (a, b))		/* subwus.  */
+    *p = 0;
+
+  *q = a + b;
+  return;
+}
+
+/* { dg-final { scan-assembler     {\msubwus\M} } } */
+/* { dg-final { scan-assembler-not {\msubf\M}   } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/subfus-2.c b/gcc/testsuite/gcc.target/powerpc/subfus-2.c
new file mode 100644
index 00000000000..b68e66dd2b0
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/subfus-2.c
@@ -0,0 +1,32 @@
+/* { dg-do compile { target lp64 } } */
+/* { dg-require-effective-target powerpc_future_ok } */
+/* { dg-options "-mdejagnu-cpu=future -O2" } */
+
+/* Test whether the saturating subtract built-in generates subwus for 64-bit
+   subtracts.  */
+
+long do_sat_long  (long  a, long  b)
+{
+  return __builtin_saturate_subtract64 (a, b);		/* subwus  */
+}
+
+long do_sat_long_dot  (long  a, long  b, long  *p)
+{
+  long  r = __builtin_saturate_subtract64 (a, b);	/* subwus.  */
+  if (r == 0)
+    *p = 0;
+
+  return r;
+}
+
+void do_sat_long_dot2  (long  a, long  b, long  *p, long *q)
+{
+  if (__builtin_saturate_subtract64 (a, b))		/* subwus.  */
+    *p = 0;
+
+  *q = a + b;
+  return;
+}
+
+/* { dg-final { scan-assembler     {\msubdus\M} } } */
+/* { dg-final { scan-assembler-not {\msubf\M}   } } */
diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
index 020bc03a3cc..8ddbdf18dc8 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -6548,8 +6548,8 @@ proc check_effective_target_power10_ok { } {
     }
 }
 
-# Return 1 if this is a PowerPC target supporting -mcpu=future or -mdense-math
-# which enables the dense math operations.
+# Return 1 if this is a PowerPC target supporting -mcpu=future which enables
+# the dense math operations.
 proc check_effective_target_powerpc_dense_math_ok { } {
 	return [check_no_compiler_messages_nocache powerpc_dense_math_ok assembly {
 		__vector_quad vq;
@@ -6567,6 +6567,18 @@ proc check_effective_target_powerpc_dense_math_ok { } {
 	} "-mcpu=future"]
 }
 
+# Return 1 if this is a PowerPC target supporting -mcpu=future which enables
+# the saturating subtract instruction.
+proc check_effective_target_powerpc_future_ok { } {
+	return [check_no_compiler_messages powerpc_future_ok object {
+	    #ifndef _ARCH_PWR_FUTURE
+	    #error "not -mcpu=future"
+	    #else
+	    int dummy;
+	    #endif
+	} "-mcpu=future"]
+}
+
 # Return 1 if this is a PowerPC target supporting -mfloat128 via either
 # software emulation on power7/power8 systems or hardware support on power9.

^ permalink raw reply	[flat|nested] 3+ messages in thread

* [gcc(refs/users/meissner/heads/dmf005)] Add saturating subtract built-ins.
@ 2022-12-03  1:26 Michael Meissner
  0 siblings, 0 replies; 3+ messages in thread
From: Michael Meissner @ 2022-12-03  1:26 UTC (permalink / raw)
  To: gcc-cvs

https://gcc.gnu.org/g:7a2a0a4c9c4298eacc1e4af8c94ac2712637bc01

commit 7a2a0a4c9c4298eacc1e4af8c94ac2712637bc01
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Fri Dec 2 20:24:30 2022 -0500

    Add saturating subtract built-ins.
    
    This patch adds support for a saturating subtract built-in function that may be
    added to a future PowerPC processor.  Note, if it is added, the name of the
    built-in function may change before GCC 13 is released.  If the name changes,
    we will submit a patch changing the name.
    
    I also added support for providing dense math built-in functions, even though
    at present, we have not added any new built-in functions for dense math.  It is
    likely we will want to add new dense math built-in functions as the dense math
    support is fleshed out.
    
    I tested this patch on a little endian power10 system with long double using
    the tradiational IBM double double format.  Assuming the other 6 patches for
    -mcpu=future are checked in (or at least the first patch), can I check this
    patch into the master branch for GCC 13.
    
    2022-12-02   Michael Meissner  <meissner@linux.ibm.com>
    
    gcc/
    
            * config/rs6000/rs6000-builtin.cc (rs6000_invalid_builtin): Add support
            for flagging invalid use of future built-in functions.
            (rs6000_builtin_is_supported): Add support for future built-in
            functions.
            * config/rs6000/rs6000-builtins.def (__builtin_saturate_subtract32): New
            built-in function for -mcpu=future.
            (__builtin_saturate_subtract64): Likewise.
            * config/rs6000/rs6000-gen-builtins.cc (enum bif_stanza): Add stanzas
            for -mcpu=future built-ins.
            (stanza_map): Likewise.
            (enable_string): Likewise.
            (struct attrinfo): Likewise.
            (parse_bif_attrs): Likewise.
            (write_decls): Likewise.
            * config/rs6000/rs6000.md (sat_sub<mode>3): Add saturating subtract
            built-in insn declarations.
            (sat_sub<mode>3_dot): Likewise.
            (sat_sub<mode>3_dot2): Likewise.
            * doc/extend.texi (Future PowerPC built-ins): New section.
    
    gcc/testsuite/
    
            * gcc.target/powerpc/subfus-1.c: New test.
            * gcc.target/powerpc/subfus-2.c: Likewise.
            * lib/target-supports.exp (check_effective_target_powerpc_future_ok):
            New effective target.

Diff:
---
 gcc/config/rs6000/rs6000-builtin.cc      | 17 +++++++++
 gcc/config/rs6000/rs6000-builtins.def    | 11 ++++++
 gcc/config/rs6000/rs6000-gen-builtins.cc | 35 ++++++++++++++++---
 gcc/config/rs6000/rs6000.md              | 60 ++++++++++++++++++++++++++++++++
 gcc/doc/extend.texi                      | 24 +++++++++++++
 gcc/testsuite/lib/target-supports.exp    | 16 +++++++--
 6 files changed, 156 insertions(+), 7 deletions(-)

diff --git a/gcc/config/rs6000/rs6000-builtin.cc b/gcc/config/rs6000/rs6000-builtin.cc
index f4eba184db8..1ac00e4b26c 100644
--- a/gcc/config/rs6000/rs6000-builtin.cc
+++ b/gcc/config/rs6000/rs6000-builtin.cc
@@ -139,6 +139,17 @@ rs6000_invalid_builtin (enum rs6000_gen_builtins fncode)
     case ENB_MMA:
       error ("%qs requires the %qs option", name, "-mmma");
       break;
+    case ENB_FUTURE:
+      error ("%qs requires the %qs option", name, "-mcpu=future");
+      break;
+    case ENB_FUTURE_64:
+      error ("%qs requires the %qs option and either the %qs or %qs option",
+	     name, "-mcpu=future", "-m64", "-mpowerpc64");
+      break;
+    case ENB_DM:
+      error ("%qs requires the %qs or %qs options", name, "-mcpu=future",
+	     "-mdense-math");
+      break;
     default:
     case ENB_ALWAYS:
       gcc_unreachable ();
@@ -194,6 +205,12 @@ rs6000_builtin_is_supported (enum rs6000_gen_builtins fncode)
       return TARGET_HTM;
     case ENB_MMA:
       return TARGET_MMA;
+    case ENB_FUTURE:
+      return TARGET_FUTURE;
+    case ENB_FUTURE_64:
+      return TARGET_FUTURE && TARGET_POWERPC64;
+    case ENB_DM:
+      return TARGET_DENSE_MATH;
     default:
       gcc_unreachable ();
     }
diff --git a/gcc/config/rs6000/rs6000-builtins.def b/gcc/config/rs6000/rs6000-builtins.def
index f76f54793d7..ee141c1d99e 100644
--- a/gcc/config/rs6000/rs6000-builtins.def
+++ b/gcc/config/rs6000/rs6000-builtins.def
@@ -139,6 +139,8 @@
 ;   endian   Needs special handling for endianness
 ;   ibmld    Restrict usage to the case when TFmode is IBM-128
 ;   ibm128   Restrict usage to the case where __ibm128 is supported or if ibmld
+;   future   Restrict usage to future instructions
+;   dm       Restrict usage to dense math
 ;
 ; Each attribute corresponds to extra processing required when
 ; the built-in is expanded.  All such special processing should
@@ -4108,3 +4110,12 @@
 
   void __builtin_vsx_stxvp (v256, unsigned long, const v256 *);
     STXVP nothing {mma,pair}
+
+[future]
+  const signed int __builtin_saturate_subtract32 (signed int, signed int);
+  SAT_SUBSI sat_subsi3 {}
+
+[future-64]
+  const signed long __builtin_saturate_subtract64 (signed long, signed long);
+  SAT_SUBDI sat_subdi3 {}
+
diff --git a/gcc/config/rs6000/rs6000-gen-builtins.cc b/gcc/config/rs6000/rs6000-gen-builtins.cc
index 0bd7a535e5f..f4020141243 100644
--- a/gcc/config/rs6000/rs6000-gen-builtins.cc
+++ b/gcc/config/rs6000/rs6000-gen-builtins.cc
@@ -233,6 +233,9 @@ enum bif_stanza
  BSTZ_P10,
  BSTZ_P10_64,
  BSTZ_MMA,
+ BSTZ_FUTURE,
+ BSTZ_FUTURE_64,
+ BSTZ_DM,
  NUMBIFSTANZAS
 };
 
@@ -266,7 +269,10 @@ static stanza_entry stanza_map[NUMBIFSTANZAS] =
     { "htm",		BSTZ_HTM	},
     { "power10",	BSTZ_P10	},
     { "power10-64",	BSTZ_P10_64	},
-    { "mma",		BSTZ_MMA	}
+    { "mma",		BSTZ_MMA	},
+    { "future",		BSTZ_FUTURE	},
+    { "future-64",	BSTZ_FUTURE_64	},
+    { "dm",		BSTZ_DM		},
   };
 
 static const char *enable_string[NUMBIFSTANZAS] =
@@ -291,7 +297,10 @@ static const char *enable_string[NUMBIFSTANZAS] =
     "ENB_HTM",
     "ENB_P10",
     "ENB_P10_64",
-    "ENB_MMA"
+    "ENB_MMA",
+    "ENB_FUTURE",
+    "ENB_FUTURE_64",
+    "ENB_DM",
   };
 
 /* Function modifiers provide special handling for const, pure, and fpmath
@@ -395,6 +404,8 @@ struct attrinfo
   bool isendian;
   bool isibmld;
   bool isibm128;
+  bool isfuture;
+  bool isdm;
 };
 
 /* Fields associated with a function prototype (bif or overload).  */
@@ -1477,7 +1488,8 @@ 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, ibmdld = %d, ibm128 = %d.\n",
+	"lxvrse = %d, lxvrze = %d, endian = %d, ibmdld = %d, ibm128 = %d,",
+	"future = %d, dm = %d.\n",
 	attrptr->isinit, attrptr->isset, attrptr->isextract,
 	attrptr->isnosoft, attrptr->isldvec, attrptr->isstvec,
 	attrptr->isreve, attrptr->ispred, attrptr->ishtm, attrptr->ishtmspr,
@@ -1485,7 +1497,7 @@ parse_bif_attrs (attrinfo *attrptr)
 	attrptr->ismmaint, attrptr->isno32bit, attrptr->is32bit,
 	attrptr->iscpu, attrptr->isldstmask, attrptr->islxvrse,
 	attrptr->islxvrze, attrptr->isendian, attrptr->isibmld,
-	attrptr->isibm128);
+	attrptr->isibm128, attrptr->isfuture, attrptr->isdm);
 #endif
 
   return PC_OK;
@@ -2257,7 +2269,10 @@ write_decls (void)
   fprintf (header_file, "  ENB_HTM,\n");
   fprintf (header_file, "  ENB_P10,\n");
   fprintf (header_file, "  ENB_P10_64,\n");
-  fprintf (header_file, "  ENB_MMA\n");
+  fprintf (header_file, "  ENB_MMA,\n");
+  fprintf (header_file, "  ENB_FUTURE,\n");
+  fprintf (header_file, "  ENB_FUTURE_64,\n");
+  fprintf (header_file, "  ENB_DM\n");
   fprintf (header_file, "};\n\n");
 
   fprintf (header_file, "#define PPC_MAXRESTROPNDS 3\n");
@@ -2301,6 +2316,8 @@ write_decls (void)
   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, "#define bif_ibm128_bit\t\t(0x00800000)\n");
+  fprintf (header_file, "#define bif_future_bit\t\t(0x01000000)\n");
+  fprintf (header_file, "#define bif_dm_bit\t\t(0x02000000)\n");
   fprintf (header_file, "\n");
   fprintf (header_file,
 	   "#define bif_is_init(x)\t\t((x).bifattrs & bif_init_bit)\n");
@@ -2350,6 +2367,10 @@ write_decls (void)
 	   "#define bif_is_ibmld(x)\t((x).bifattrs & bif_ibmld_bit)\n");
   fprintf (header_file,
 	   "#define bif_is_ibm128(x)\t((x).bifattrs & bif_ibm128_bit)\n");
+  fprintf (header_file,
+	   "#define bif_is_future(x)\t((x).bifattrs & bif_future_bit)\n");
+  fprintf (header_file,
+	   "#define bif_is_dm(x)\t((x).bifattrs & bif_dm_bit)\n");
   fprintf (header_file, "\n");
 
   fprintf (header_file,
@@ -2548,6 +2569,10 @@ write_bif_static_init (void)
 	fprintf (init_file, " | bif_ibmld_bit");
       if (bifp->attrs.isibm128)
 	fprintf (init_file, " | bif_ibm128_bit");
+      if (bifp->attrs.isfuture)
+	fprintf (init_file, " | bif_future_bit");
+      if (bifp->attrs.isdm)
+	fprintf (init_file, " | bif_dm_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],
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index 4a5007dc539..e9dfb138603 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -15499,6 +15499,66 @@
 }
   [(set_attr "type" "load")])
 \f
+;; Signed saturation.
+
+;; The subfus instruction is defined as: SUBFUS RT,L,RA,RB.  The extended
+;; mnemonic that we use (subdus and subwus) has the arguments RA and RB
+;; reversed (so it becomes a subtract instead of subtract from).
+
+(define_insn "sat_sub<mode>3"
+  [(set (match_operand:GPR 0 "gpc_reg_operand" "=r")
+	(ss_minus:GPR (match_operand:GPR 1 "gpc_reg_operand" "r")
+		      (match_operand:GPR 2 "gpc_reg_operand" "r")))]
+  "TARGET_FUTURE"
+  "sub<wd>us %0,%1,%2"
+  [(set_attr "type" "add")])
+
+(define_insn_and_split "*sat_sub<mode>3_dot"
+  [(set (match_operand:CC 3 "cc_reg_operand" "=x,?y")
+	(compare:CC (ss_minus:GPR (match_operand:GPR 1 "gpc_reg_operand" "r,r")
+				  (match_operand:GPR 2 "gpc_reg_operand" "r,r"))
+		    (const_int 0)))
+   (clobber (match_scratch:GPR 0 "=r,r"))]
+  "TARGET_FUTURE"
+  "@
+   sub<wd>us. %0,%1,%2
+   #"
+  "&& reload_completed && cc_reg_not_cr0_operand (operands[3], CCmode)"
+  [(set (match_dup 0)
+	(ss_minus:GPR (match_dup 1)
+		      (match_dup 2)))
+   (set (match_dup 3)
+	(compare:CC (match_dup 0)
+		    (const_int 0)))]
+  ""
+  [(set_attr "type" "add")
+   (set_attr "dot" "yes")
+   (set_attr "length" "4,8")])
+
+(define_insn_and_split "*sat_sub<mode>3_dot2"
+  [(set (match_operand:CC 3 "cc_reg_operand" "=x,?y")
+	(compare:CC (ss_minus:GPR (match_operand:GPR 1 "gpc_reg_operand" "r,r")
+				  (match_operand:GPR 2 "gpc_reg_operand" "r,r"))
+		    (const_int 0)))
+   (set (match_operand:GPR 0 "gpc_reg_operand" "=r,r")
+	(ss_minus:GPR (match_dup 1)
+		      (match_dup 2)))]
+  "TARGET_FUTURE"
+  "@
+   sub<wd>us. %0,%1,%2
+   #"
+  "&& reload_completed && cc_reg_not_cr0_operand (operands[3], CCmode)"
+  [(set (match_dup 0)
+	(ss_minus:GPR (match_dup 1)
+		      (match_dup 2)))
+   (set (match_dup 3)
+	(compare:CC (match_dup 0)
+		    (const_int 0)))]
+  ""
+  [(set_attr "type" "add")
+   (set_attr "dot" "yes")
+   (set_attr "length" "4,8")])
+\f
 
 (include "sync.md")
 (include "vector.md")
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index b1dd39e64b8..a8b50153d9b 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -17783,6 +17783,7 @@ Disable global interrupt.
 * Basic PowerPC Built-in Functions Available on ISA 2.07::
 * Basic PowerPC Built-in Functions Available on ISA 3.0::
 * Basic PowerPC Built-in Functions Available on ISA 3.1::
+* Basic Built-in Functions that may be available on future PowerPCs::
 @end menu
 
 This section describes PowerPC built-in functions that do not require
@@ -18440,6 +18441,29 @@ ISA 3.1 @code{stxvrbx}, @code{stxvrhx}, @code{stxvrwx}, and @code{stxvrdx}
 instructions.
 @findex vec_xst_trunc
 
+@node Basic Built-in Functions that may be available on future PowerPCs
+@subsubsection Potential future PowerPC Built-in Functions
+
+The built-in functions described in this section may be available on
+future PowerPC processors.  At present, these built-ins exist to
+allowing testing of new instructions.  There is no guarantee that
+these instructions will actually be implemented.
+
+The following built-in functions are available on Linux 64-bit systems
+that use a potential future instruction set (@option{-mcpu=future}):
+
+@table @code
+@item int __builtin_saturate_subtract32 (int, int)
+Subtract the second operand from the first operand.  If the value
+would be less than 0, then the result is 0 instead of the negative
+value of the subtraction.
+
+@item long __builtin_saturate_subtract64 (long, long)
+Subtract the second operand from the first operand.  If the value
+would be less than 0, then the result is 0 instead of the negative
+value of the subtraction.
+@end table
+
 @node PowerPC AltiVec/VSX Built-in Functions
 @subsection PowerPC AltiVec/VSX Built-in Functions
 
diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
index 020bc03a3cc..8ddbdf18dc8 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -6548,8 +6548,8 @@ proc check_effective_target_power10_ok { } {
     }
 }
 
-# Return 1 if this is a PowerPC target supporting -mcpu=future or -mdense-math
-# which enables the dense math operations.
+# Return 1 if this is a PowerPC target supporting -mcpu=future which enables
+# the dense math operations.
 proc check_effective_target_powerpc_dense_math_ok { } {
 	return [check_no_compiler_messages_nocache powerpc_dense_math_ok assembly {
 		__vector_quad vq;
@@ -6567,6 +6567,18 @@ proc check_effective_target_powerpc_dense_math_ok { } {
 	} "-mcpu=future"]
 }
 
+# Return 1 if this is a PowerPC target supporting -mcpu=future which enables
+# the saturating subtract instruction.
+proc check_effective_target_powerpc_future_ok { } {
+	return [check_no_compiler_messages powerpc_future_ok object {
+	    #ifndef _ARCH_PWR_FUTURE
+	    #error "not -mcpu=future"
+	    #else
+	    int dummy;
+	    #endif
+	} "-mcpu=future"]
+}
+
 # Return 1 if this is a PowerPC target supporting -mfloat128 via either
 # software emulation on power7/power8 systems or hardware support on power9.

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