[RS6000] PR90545, gcc.target/powerpc/fold-vec-splats-floatdouble.c fails

[Alan Modra]

Bootstrapped powerpc64le-linux power8 and power9, OK to apply?

I figure a tweak to register_move_cost is better than sprinkling ?s
in instruction alternatives.

        PR 90545
        * config/rs6000/rs6000.c (rs6000_register_move_cost): Increase
        power9 direct move cost.
        * testsuite/gcc.target/powerpc/fold-vec-splats-floatdouble.c:
        Correct comments and rename functions to suit parameters.

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index d27871ab907..d0e37d98ed5 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -34678,8 +34678,14 @@ rs6000_register_move_cost (machine_mode mode,
        {
          if (TARGET_DIRECT_MOVE)
            {
+             /* Keep the cost for direct moves above that for within
+                a register class even if the actual processor cost is
+                comparable.  We do this because a direct move insn
+                can't be a nop, whereas with ideal register
+                allocation a move within the same class might turn
+                out to be a nop.  */
              if (rs6000_tune == PROCESSOR_POWER9)
-               ret = 2 * hard_regno_nregs (FIRST_GPR_REGNO, mode);
+               ret = 3 * hard_regno_nregs (FIRST_GPR_REGNO, mode);
              else
                ret = 4 * hard_regno_nregs (FIRST_GPR_REGNO, mode);
              /* SFmode requires a conversion when moving between gprs
diff --git a/gcc/testsuite/gcc.target/powerpc/fold-vec-splats-floatdouble.c 
b/gcc/testsuite/gcc.target/powerpc/fold-vec-splats-floatdouble.c
index c4544f1a452..3c7cc7c9a67 100644
--- a/gcc/testsuite/gcc.target/powerpc/fold-vec-splats-floatdouble.c
+++ b/gcc/testsuite/gcc.target/powerpc/fold-vec-splats-floatdouble.c
@@ -8,20 +8,20 @@
 #include <altivec.h>
 
 vector float
-test1d (float x)
+test1f (float x)
 {
   return vec_splats (x);
 }
 
 vector double
-test1f (double x)
+test1d (double x)
 {
   return vec_splats (x);
 }
 
-// float test generates the permute instruction.
+// double test generates the permute instruction.
 /* { dg-final { scan-assembler-times "xxpermdi" 1 } } */
 
-// double test generates a convert (double to single non-signalling) followed 
by a splat.
+// float test generates a convert (double to single non-signalling) followed 
by a splat.
 /* { dg-final { scan-assembler-times {\mxscvdpspn?\M} 1 } } */
 /* { dg-final { scan-assembler-times {\mvspltw\M|\mxxspltw\M} 1 } } */

-- 
Alan Modra
Australia Development Lab, IBM