[gcc(refs/users/meissner/heads/work100)] Allow __ibm128 even if IEEE 128-bit floating point is not supported.

[gcc(refs/users/meissner/heads/work100)] Allow __ibm128 even if IEEE 128-bit floating point is not supported.

[Michael Meissner]

https://gcc.gnu.org/g:d1c714cf35ee974e3dc02e93fc7f761b29a89660

commit d1c714cf35ee974e3dc02e93fc7f761b29a89660
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Fri Sep 9 14:04:37 2022 -0400

    Allow __ibm128 even if IEEE 128-bit floating point is not supported.
    
    This patch allows the use of the __ibm128 keyword on non-VSX systems.
    Originally, the __ibm128 keyword was only enabled when the IEEE 128-bit
    floating point is enabled.  Sometime back in the GCC 12 development period,
    Segher asked that the __ibm128 keyword be allowed in older systems that don't
    support IEEE 128-bit.  But at the time, stage 1 had closed for GCC 12, so I
    deferred doing this change until GCC 13.  This patch allows __ibm128 to be used
    if either IEEE 128-bit is enabled or long double used the IBM 128-bit format.
    
    2022-09-09   Michael Meissner  <meissner@linux.ibm.com>
    
    gcc/
    
            * config/rs6000/rs6000-builtins.cc (rs6000_init_builtins): Enable using
            the__ibm128 keyword on systems that either use the 128-bit IBM long
            double format for long double or support IEEE 128-bit.
            * config/rs6000/rs6000.cc (rs6000_init_libfuncs): Create IBM 128-bit
            floating point support functions on systems that support the __ibm128
            keyword.
            (rs6000_scalar_mode_supported_p): Likewise.
            * config/rs6000/rs6000.h (TARGET_IBM128): New macro.
            * config/rs6000/rs6000.md (@extenddf<mode>2_fprs): Allow IFmode to be
            converted even if long double is not 128-bits.
            (extenddf<mode>2_vsx): Likewise.
            (extendiftf2):Allow conversion on systems that support the __ibm128
            keyword.
            (extendtfif2): Likewise.
            (trunciftf2): Likewise.
            (trunctfif2): Likewise.

Diff:
---
 gcc/config/rs6000/rs6000-builtin.cc |  2 +-
 gcc/config/rs6000/rs6000.cc         | 13 ++++++++-----
 gcc/config/rs6000/rs6000.h          |  6 ++++++
 gcc/config/rs6000/rs6000.md         |  9 ++++-----
 4 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/gcc/config/rs6000/rs6000-builtin.cc b/gcc/config/rs6000/rs6000-builtin.cc
index 6dfb0db43d6..3cac205ddcd 100644
--- a/gcc/config/rs6000/rs6000-builtin.cc
+++ b/gcc/config/rs6000/rs6000-builtin.cc
@@ -710,7 +710,7 @@ rs6000_init_builtins (void)
      For IEEE 128-bit floating point, always create the type __ieee128.  If the
      user used -mfloat128, rs6000-c.cc will create a define from __float128 to
      __ieee128.  */
-  if (TARGET_LONG_DOUBLE_128 && (!TARGET_IEEEQUAD || TARGET_FLOAT128_TYPE))
+  if (TARGET_IBM128)
     {
       if (!TARGET_IEEEQUAD)
 	ibm128_float_type_node = long_double_type_node;
diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index 6f822434ab0..00fe4c6ab28 100644
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -11112,10 +11112,11 @@ rs6000_init_libfuncs (void)
 {
   /* __float128 support.  */
   if (TARGET_FLOAT128_TYPE)
-    {
-      init_float128_ibm (IFmode);
-      init_float128_ieee (KFmode);
-    }
+    init_float128_ieee (KFmode);
+
+  /* __ibm128 support.  */
+  if (TARGET_IBM128)
+    init_float128_ibm (IFmode);
 
   /* AIX/Darwin/64-bit Linux quad floating point routines.  */
   if (TARGET_LONG_DOUBLE_128)
@@ -23757,7 +23758,9 @@ rs6000_scalar_mode_supported_p (scalar_mode mode)
 
   if (DECIMAL_FLOAT_MODE_P (mode))
     return default_decimal_float_supported_p ();
-  else if (TARGET_FLOAT128_TYPE && (mode == KFmode || mode == IFmode))
+  else if (TARGET_FLOAT128_TYPE && mode == KFmode)
+    return true;
+  else if (TARGET_IBM128 && mode == IFmode)
     return true;
   else
     return default_scalar_mode_supported_p (mode);
diff --git a/gcc/config/rs6000/rs6000.h b/gcc/config/rs6000/rs6000.h
index eb7b2158497..ee14aa974c1 100644
--- a/gcc/config/rs6000/rs6000.h
+++ b/gcc/config/rs6000/rs6000.h
@@ -564,6 +564,12 @@ extern int rs6000_vector_align[];
 					 && TARGET_P8_VECTOR		\
 					 && TARGET_POWERPC64)
 
+/* Whether the __ibm128 keyword is allowed.  Any system that supports _Float128
+   is assumed to be capable of supporting __ibm128.  Similarly if the long
+   double size is 128 bits, we assume __ibm128 is supported.  We don't want to
+   support it on a system without existing 128-bit long doubles.  */
+#define TARGET_IBM128	(TARGET_FLOAT128_TYPE || TARGET_LONG_DOUBLE_128)
+
 /* Inlining allows targets to define the meanings of bits in target_info
    field of ipa_fn_summary by itself, the used bits for rs6000 are listed
    below.  */
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index 838d38616b7..e86ddcf95a2 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -8622,8 +8622,7 @@
 	(float_extend:IBM128
 	 (match_operand:DF 1 "nonimmediate_operand" "d,m,d")))
    (use (match_operand:DF 2 "nonimmediate_operand" "m,m,d"))]
-  "!TARGET_VSX && TARGET_HARD_FLOAT
-   && TARGET_LONG_DOUBLE_128 && FLOAT128_IBM_P (<MODE>mode)"
+  "!TARGET_VSX && TARGET_HARD_FLOAT && FLOAT128_IBM_P (<MODE>mode)"
   "#"
   "&& reload_completed"
   [(set (match_dup 3) (match_dup 1))
@@ -8640,7 +8639,7 @@
   [(set (match_operand:IBM128 0 "gpc_reg_operand" "=d,d")
 	(float_extend:IBM128
 	 (match_operand:DF 1 "nonimmediate_operand" "wa,m")))]
-  "TARGET_LONG_DOUBLE_128 && TARGET_VSX && FLOAT128_IBM_P (<MODE>mode)"
+  "TARGET_VSX && FLOAT128_IBM_P (<MODE>mode)"
   "#"
   "&& reload_completed"
   [(set (match_dup 2) (match_dup 1))
@@ -9126,7 +9125,7 @@
 (define_insn_and_split "extendtfif2"
   [(set (match_operand:IF 0 "gpc_reg_operand" "=wa,wa,r,r")
 	(float_extend:IF (match_operand:TF 1 "gpc_reg_operand" "0,wa,0,r")))]
-  "TARGET_HARD_FLOAT && FLOAT128_IBM_P (TFmode)"
+  "TARGET_HARD_FLOAT && TARGET_IBM128 && FLOAT128_IBM_P (TFmode)"
   "#"
   "&& reload_completed"
   [(set (match_dup 0)
@@ -9140,7 +9139,7 @@
 (define_insn_and_split "extendiftf2"
   [(set (match_operand:TF 0 "gpc_reg_operand" "=wa,wa,r,r")
 	(float_extend:TF (match_operand:IF 1 "gpc_reg_operand" "0,wa,0,r")))]
-  "TARGET_HARD_FLOAT && FLOAT128_IBM_P (TFmode)"
+  "TARGET_HARD_FLOAT && TARGET_IBM128 && FLOAT128_IBM_P (TFmode)"
   "#"
   "&& reload_completed"
   [(set (match_dup 0)