[AArch64] Generalise aarch64_simd_valid_immediate for SVE

[Richard Sandiford]

The current aarch64_simd_valid_immediate code predates the move
to the new CONST_VECTOR representation, so for variable-length SVE
it only handles duplicates of single elements, rather than duplicates
of repeating patterns.

This patch removes the restriction.  It means that the validity
of a duplicated constant depends only on the bit pattern, not on
the mode used to represent it.

The patch is needed by a later big-endian fix.

Tested on aarch64_be-elf and aarch64-linux-gnu.  OK to install?

Richard


2018-01-26  Richard Sandiford  <richard.sandif...@linaro.org>

gcc/
        * config/aarch64/aarch64.c (aarch64_simd_valid_immediate): Handle
        all CONST_VECTOR_DUPLICATE_P vectors, not just those with a single
        duplicated element.

Index: gcc/config/aarch64/aarch64.c
===================================================================
--- gcc/config/aarch64/aarch64.c        2018-01-26 13:32:54.240529011 +0000
+++ gcc/config/aarch64/aarch64.c        2018-01-26 13:46:00.955822193 +0000
@@ -13164,10 +13164,11 @@ aarch64_simd_valid_immediate (rtx op, si
     return false;
 
   scalar_mode elt_mode = GET_MODE_INNER (mode);
-  rtx elt = NULL, base, step;
+  rtx base, step;
   unsigned int n_elts;
-  if (const_vec_duplicate_p (op, &elt))
-    n_elts = 1;
+  if (GET_CODE (op) == CONST_VECTOR
+      && CONST_VECTOR_DUPLICATE_P (op))
+    n_elts = CONST_VECTOR_NPATTERNS (op);
   else if ((vec_flags & VEC_SVE_DATA)
           && const_vec_series_p (op, &base, &step))
     {
@@ -13192,14 +13193,17 @@ aarch64_simd_valid_immediate (rtx op, si
            || op == CONSTM1_RTX (mode));
 
   scalar_float_mode elt_float_mode;
-  if (elt
-      && is_a <scalar_float_mode> (elt_mode, &elt_float_mode)
-      && (aarch64_float_const_zero_rtx_p (elt)
-         || aarch64_float_const_representable_p (elt)))
+  if (n_elts == 1
+      && is_a <scalar_float_mode> (elt_mode, &elt_float_mode))
     {
-      if (info)
-       *info = simd_immediate_info (elt_float_mode, elt);
-      return true;
+      rtx elt = CONST_VECTOR_ENCODED_ELT (op, 0);
+      if (aarch64_float_const_zero_rtx_p (elt)
+         || aarch64_float_const_representable_p (elt))
+       {
+         if (info)
+           *info = simd_immediate_info (elt_float_mode, elt);
+         return true;
+       }
     }
 
   unsigned int elt_size = GET_MODE_SIZE (elt_mode);
@@ -13214,11 +13218,11 @@ aarch64_simd_valid_immediate (rtx op, si
   bytes.reserve (n_elts * elt_size);
   for (unsigned int i = 0; i < n_elts; i++)
     {
-      if (!elt || n_elts != 1)
-       /* The vector is provided in gcc endian-neutral fashion.
-          For aarch64_be, it must be laid out in the vector register
-          in reverse order.  */
-       elt = CONST_VECTOR_ELT (op, BYTES_BIG_ENDIAN ? (n_elts - 1 - i) : i);
+      /* The vector is provided in gcc endian-neutral fashion.
+        For aarch64_be Advanced SIMD, it must be laid out in the vector
+        register in reverse order.  */
+      bool swap_p = ((vec_flags & VEC_ADVSIMD) != 0 && BYTES_BIG_ENDIAN);
+      rtx elt = CONST_VECTOR_ELT (op, swap_p ? (n_elts - 1 - i) : i);
 
       if (elt_mode != elt_int_mode)
        elt = gen_lowpart (elt_int_mode, elt);