[gcc(refs/users/meissner/heads/work071)] Add LXVKQ support.

[Michael Meissner <meissner@gcc.gnu.org>]

https://gcc.gnu.org/g:f77237f641d422a76607b1006d45dde09d9b5a4f

commit f77237f641d422a76607b1006d45dde09d9b5a4f
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Thu Oct 14 12:50:46 2021 -0400

    Add LXVKQ support.
    
    This patch adds support to generate the LXVKQ instruction to load specific
    IEEE-128 floating point constants.
    
    Compared to the last time I submitted this patch, I modified it so that it
    uses the bit pattern of the vector to see if it can generate the LXVKQ
    instruction.  This means on a little endian Power<xxx> system, the
    following code will generate a LXVKQ 34,16 instruction:
    
        vector long long foo (void)
        {
          return (vector long long) { 0x0000000000000000, 0x8000000000000000 };
        }
    
    because that vector pattern is the same bit pattern as -0.0F128.
    
    2021-10-14  Michael Meissner  <meissner@the-meissners.org>
    
    gcc/testsuite/
    
            * gcc.target/powerpc/float128-constant.c: New test.

Diff:
---
 .../gcc.target/powerpc/float128-constant.c         | 160 +++++++++++++++++++++
 1 file changed, 160 insertions(+)

diff --git a/gcc/testsuite/gcc.target/powerpc/float128-constant.c b/gcc/testsuite/gcc.target/powerpc/float128-constant.c
new file mode 100644
index 00000000000..f6becac1075
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/float128-constant.c
@@ -0,0 +1,160 @@
+/* { dg-require-effective-target ppc_float128_hw } */
+/* { dg-require-effective-target power10_ok } */
+/* { dg-options "-mdejagnu-cpu=power10 -mlxvkq -O2" } */
+
+/* Test whether the LXVKQ instruction is generated to load special IEEE 128-bit
+   constants.  */
+
+_Float128
+return_0 (void)
+{
+  return 0.0f128;			/* XXSPLTIB 34,0.  */
+}
+
+_Float128
+return_1 (void)
+{
+  return 1.0f128;			/* LXVKQ 34,1.  */
+}
+
+_Float128
+return_2 (void)
+{
+  return 2.0f128;			/* LXVKQ 34,2.  */
+}
+
+_Float128
+return_3 (void)
+{
+  return 3.0f128;			/* LXVKQ 34,3.  */
+}
+
+_Float128
+return_4 (void)
+{
+  return 4.0f128;			/* LXVKQ 34,4.  */
+}
+
+_Float128
+return_5 (void)
+{
+  return 5.0f128;			/* LXVKQ 34,5.  */
+}
+
+_Float128
+return_6 (void)
+{
+  return 6.0f128;			/* LXVKQ 34,6.  */
+}
+
+_Float128
+return_7 (void)
+{
+  return 7.0f128;			/* LXVKQ 34,7.  */
+}
+
+_Float128
+return_m0 (void)
+{
+  return -0.0f128;			/* LXVKQ 34,16.  */
+}
+
+_Float128
+return_m1 (void)
+{
+  return -1.0f128;			/* LXVKQ 34,17.  */
+}
+
+_Float128
+return_m2 (void)
+{
+  return -2.0f128;			/* LXVKQ 34,18.  */
+}
+
+_Float128
+return_m3 (void)
+{
+  return -3.0f128;			/* LXVKQ 34,19.  */
+}
+
+_Float128
+return_m4 (void)
+{
+  return -4.0f128;			/* LXVKQ 34,20.  */
+}
+
+_Float128
+return_m5 (void)
+{
+  return -5.0f128;			/* LXVKQ 34,21.  */
+}
+
+_Float128
+return_m6 (void)
+{
+  return -6.0f128;			/* LXVKQ 34,22.  */
+}
+
+_Float128
+return_m7 (void)
+{
+  return -7.0f128;			/* LXVKQ 34,23.  */
+}
+
+_Float128
+return_inf (void)
+{
+  return __builtin_inff128 ();		/* LXVKQ 34,8.  */
+}
+
+_Float128
+return_minf (void)
+{
+  return - __builtin_inff128 ();	/* LXVKQ 34,24.  */
+}
+
+_Float128
+return_nan (void)
+{
+  return __builtin_nanf128 ("");	/* LXVKQ 34,9.  */
+}
+
+/* Note, the following NaNs should not generate a LXVKQ instruction.  */
+_Float128
+return_mnan (void)
+{
+  return - __builtin_nanf128 ("");	/* PLXV 34,... */
+}
+
+_Float128
+return_nan2 (void)
+{
+  return __builtin_nanf128 ("1");	/* PLXV 34,... */
+}
+
+_Float128
+return_nans (void)
+{
+  return __builtin_nansf128 ("");	/* PLXV 34,... */
+}
+
+vector long long
+return_longlong_neg_0 (void)
+{
+  /* This vector is the same pattern as -0.0F128.  */
+#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#define FIRST	0x8000000000000000
+#define SECOND	0x0000000000000000
+
+#else
+#define FIRST	0x0000000000000000
+#define SECOND	0x8000000000000000
+#endif
+
+  return (vector long long) { FIRST, SECOND };	/* LXVKQ 34,16.  */
+}
+
+/* { dg-final { scan-assembler-times {\mlxvkq\M}    19 } } */
+/* { dg-final { scan-assembler-times {\mplxv\M}      3 } } */
+/* { dg-final { scan-assembler-times {\mxxspltib\M}  1 } } */
+