[PATCH 3/5 ver4] RS6000: Add TI to TD (128-bit DFP) and TD to TI support

[Carl Love <cel@us.ibm.com>]

Will, Segher:

This patch adds support for converting to/from 128-bit integers and
128-bit decimal floating point formats.

The patch has been tested on
    powerpc64-linux instead (Power 8 BE)
    powerpc64-linux instead (Power 9 LE)
    powerpc64-linux instead (Power 10 LE)

Please let me know if the patch is acceptable for mainline.

                   Carl Love
------------------------------------------------

gcc/ChangeLog
dje.gcc@gmail.com, gcc-patches@gcc.gnu.org, Bill Schmidt <wschmidt@linux.vnet.ibm.com>, Peter Bergner <bergner@vnet.ibm.com>,  
2021-04-26  Carl Love  <cel@us.ibm.com>
        * config/rs6000/dfp.md (floattitd2, fixtdti2): New define_insns.
        * config/rs6000/rs6000-call.c (P10V_BUILTIN_VCMPNET_P,
	P10V_BUILTIN_VCMPAET_P): New overloaded definitions.

gcc/testsuite/ChangeLog

2021-04-26  Carl Love  <cel@us.ibm.com>
        * gcc.target/powerpc/int_128bit-runnable.c: Add 128-bit DFP
        conversion tests.
---
 gcc/config/rs6000/dfp.md                      | 14 +++++
 .../gcc.target/powerpc/int_128bit-runnable.c  | 61 +++++++++++++++++++
 2 files changed, 75 insertions(+)

diff --git a/gcc/config/rs6000/dfp.md b/gcc/config/rs6000/dfp.md
index 026be5d48a6..b89d5ecc91d 100644
--- a/gcc/config/rs6000/dfp.md
+++ b/gcc/config/rs6000/dfp.md
@@ -226,6 +226,13 @@
   [(set_attr "type" "dfp")
    (set_attr "size" "128")])
 
+(define_insn "floattitd2"
+  [(set (match_operand:TD 0 "gpc_reg_operand" "=d")
+	(float:TD (match_operand:TI 1 "gpc_reg_operand" "v")))]
+  "TARGET_POWER10"
+  "dcffixqq %0,%1"
+  [(set_attr "type" "dfp")])
+
 ;; Convert a decimal64/128 to a decimal64/128 whose value is an integer.
 ;; This is the first stage of converting it to an integer type.
 
@@ -247,6 +254,13 @@
   "dctfix<q> %0,%1"
   [(set_attr "type" "dfp")
    (set_attr "size" "<bits>")])
+
+(define_insn "fixtdti2"
+  [(set (match_operand:TI 0 "gpc_reg_operand" "=v")
+	(fix:TI (match_operand:TD 1 "gpc_reg_operand" "d")))]
+  "TARGET_POWER10"
+  "dctfixqq %0,%1"
+  [(set_attr "type" "dfp")])
 \f
 ;; Decimal builtin support
 
diff --git a/gcc/testsuite/gcc.target/powerpc/int_128bit-runnable.c b/gcc/testsuite/gcc.target/powerpc/int_128bit-runnable.c
index 042758c8684..625b3869118 100644
--- a/gcc/testsuite/gcc.target/powerpc/int_128bit-runnable.c
+++ b/gcc/testsuite/gcc.target/powerpc/int_128bit-runnable.c
@@ -37,6 +37,7 @@
 #if DEBUG
 #include <stdio.h>
 #include <stdlib.h>
+#include <math.h>
 
 
 void print_i128(__int128_t val)
@@ -58,6 +59,13 @@ int main ()
   __int128_t arg1, result;
   __uint128_t uarg2;
 
+  _Decimal128 arg1_dfp128, result_dfp128, expected_result_dfp128;
+
+  struct conv_t {
+    __uint128_t u128;
+    _Decimal128 d128;
+  } conv, conv2;
+
   vector signed long long int vec_arg1_di, vec_arg2_di;
   vector signed long long int vec_result_di, vec_expected_result_di;
   vector unsigned long long int vec_uarg1_di, vec_uarg2_di, vec_uarg3_di;
@@ -2258,6 +2266,59 @@ int main ()
     abort();
 #endif
   }
+  
+  /* DFP to __int128 and __int128 to DFP conversions */
+  /* Print the DFP value as an unsigned int so we can see the bit patterns.  */
+  conv.u128 = 0x2208000000000000ULL;
+  conv.u128 = (conv.u128 << 64) | 0x4ULL;   //DFP bit pattern for integer 4
+  expected_result_dfp128 = conv.d128;
 
+  arg1 = 4;
+
+  conv.d128 = (_Decimal128) arg1;
+
+  result_dfp128 = (_Decimal128) arg1;
+  if (((conv.u128 >>64) != 0x2208000000000000ULL) &&
+      ((conv.u128 & 0xFFFFFFFFFFFFFFFF) != 0x4ULL)) {
+#if DEBUG
+    printf("ERROR:  convert int128 value ");
+    print_i128 (arg1);
+    conv.d128 = result_dfp128;
+    printf("\nto DFP value 0x%llx %llx (printed as hex bit string) ",
+	   (unsigned long long)((conv.u128) >>64),
+	   (unsigned long long)((conv.u128) & 0xFFFFFFFFFFFFFFFF));
+
+    conv.d128 = expected_result_dfp128;
+    printf("\ndoes not match expected_result = 0x%llx %llx\n\n",
+	   (unsigned long long) (conv.u128>>64),
+	   (unsigned long long) (conv.u128 & 0xFFFFFFFFFFFFFFFF));
+#else
+    abort();
+#endif
+  }
+
+  expected_result = 4;
+
+  conv.u128 = 0x2208000000000000ULL;
+  conv.u128 = (conv.u128 << 64) | 0x4ULL;  // 4 as DFP
+  arg1_dfp128 = conv.d128;
+
+  result = (__int128_t) arg1_dfp128;
+
+  if (result != expected_result) {
+#if DEBUG
+    printf("ERROR:  convert DFP value ");
+    printf("0x%llx %llx (printed as hex bit string) ",
+	   (unsigned long long)(conv.u128>>64),
+	   (unsigned long long)(conv.u128 & 0xFFFFFFFFFFFFFFFF));
+    printf("to __int128 value = ");
+    print_i128 (result);
+    printf("\ndoes not match expected_result = ");
+    print_i128 (expected_result);
+    printf("\n");
+#else
+    abort();
+#endif
+  }
   return 0;
 }
-- 
2.27.0