Add gen_(const_)vec_duplicate helpers

This patch adds helper functions for generating constant and
non-constant vector duplicates.  These routines help with SVE because
it is then easier to use:

   (const:M (vec_duplicate:M X))

for a broadcast of X, even if the number of elements in M isn't known
at compile time.  It also makes it easier for general rtx code to treat
constant and non-constant duplicates in the same way.

In the target code, the patch uses gen_vec_duplicate instead of
gen_rtx_VEC_DUPLICATE if handling constants correctly is potentially
useful.  It might be that some or all of the call sites only handle
non-constants in practice, in which case the change is a harmless
no-op (and a saving of a few characters).

Otherwise, the target changes use gen_const_vec_duplicate instead
of gen_rtx_CONST_VECTOR if the constant is obviously a duplicate.
They also include some changes to use CONSTxx_RTX for easy global
constants.

2017-11-01  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* emit-rtl.h (gen_const_vec_duplicate): Declare.
	(gen_vec_duplicate): Likewise.
	* emit-rtl.c (gen_const_vec_duplicate_1): New function, split
	out from...
	(gen_const_vector): ...here.
	(gen_const_vec_duplicate, gen_vec_duplicate): New functions.
	(gen_rtx_CONST_VECTOR): Use gen_const_vec_duplicate for constants
	whose elements are all equal.
	* optabs.c (expand_vector_broadcast): Use gen_const_vec_duplicate.
	* simplify-rtx.c (simplify_const_unary_operation): Likewise.
	(simplify_relational_operation): Likewise.
	* config/aarch64/aarch64.c (aarch64_simd_gen_const_vector_dup):
	Likewise.
	(aarch64_simd_dup_constant): Use gen_vec_duplicate.
	(aarch64_expand_vector_init): Likewise.
	* config/arm/arm.c (neon_vdup_constant): Likewise.
	(neon_expand_vector_init): Likewise.
	(arm_expand_vec_perm): Use gen_const_vec_duplicate.
	(arm_block_set_unaligned_vect): Likewise.
	(arm_block_set_aligned_vect): Likewise.
	* config/arm/neon.md (neon_copysignf<mode>): Likewise.
	* config/i386/i386.c (ix86_expand_vec_perm): Likewise.
	(expand_vec_perm_even_odd_pack): Likewise.
	(ix86_vector_duplicate_value): Use gen_vec_duplicate.
	* config/i386/sse.md (one_cmpl<mode>2): Use CONSTM1_RTX.
	* config/ia64/ia64.c (ia64_expand_vecint_compare): Use
	gen_const_vec_duplicate.
	* config/ia64/vect.md (addv2sf3, subv2sf3): Use CONST1_RTX.
	* config/mips/mips.c (mips_gen_const_int_vector): Use
	gen_const_vec_duplicate.
	(mips_expand_vector_init): Use CONST0_RTX.
	* config/powerpcspe/altivec.md (abs<mode>2, nabs<mode>2): Likewise.
	(define_split): Use gen_const_vec_duplicate.
	* config/rs6000/altivec.md (abs<mode>2, nabs<mode>2): Use CONST0_RTX.
	(define_split): Use gen_const_vec_duplicate.
	* config/s390/vx-builtins.md (vec_genmask<mode>): Likewise.
	(vec_ctd_s64, vec_ctd_u64, vec_ctsl, vec_ctul): Likewise.
	* config/spu/spu.c (spu_const): Likewise.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>

From-SVN: r254292

1 files changed, 48 insertions, 36 deletions

diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
index d91988e..4df550f 100644
--- a/gcc/emit-rtl.c
+++ b/gcc/emit-rtl.c
@@ -5757,32 +5757,60 @@ init_emit (void)
 #endif
 }
 
-/* Generate a vector constant for mode MODE and constant value CONSTANT.  */
+/* Like gen_const_vec_duplicate, but ignore const_tiny_rtx.  */
 
 static rtx
-gen_const_vector (machine_mode mode, int constant)
+gen_const_vec_duplicate_1 (machine_mode mode, rtx el)
 {
-  rtx tem;
-  rtvec v;
-  int units, i;
-  machine_mode inner;
+  int nunits = GET_MODE_NUNITS (mode);
+  rtvec v = rtvec_alloc (nunits);
+  for (int i = 0; i < nunits; ++i)
+    RTVEC_ELT (v, i) = el;
+  return gen_rtx_raw_CONST_VECTOR (mode, v);
+}
 
-  units = GET_MODE_NUNITS (mode);
-  inner = GET_MODE_INNER (mode);
+/* Generate a vector constant of mode MODE in which every element has
+   value ELT.  */
 
-  gcc_assert (!DECIMAL_FLOAT_MODE_P (inner));
+rtx
+gen_const_vec_duplicate (machine_mode mode, rtx elt)
+{
+  scalar_mode inner_mode = GET_MODE_INNER (mode);
+  if (elt == CONST0_RTX (inner_mode))
+    return CONST0_RTX (mode);
+  else if (elt == CONST1_RTX (inner_mode))
+    return CONST1_RTX (mode);
+  else if (elt == CONSTM1_RTX (inner_mode))
+    return CONSTM1_RTX (mode);
+
+  return gen_const_vec_duplicate_1 (mode, elt);
+}
+
+/* Return a vector rtx of mode MODE in which every element has value X.
+   The result will be a constant if X is constant.  */
+
+rtx
+gen_vec_duplicate (machine_mode mode, rtx x)
+{
+  if (CONSTANT_P (x))
+    return gen_const_vec_duplicate (mode, x);
+  return gen_rtx_VEC_DUPLICATE (mode, x);
+}
 
-  v = rtvec_alloc (units);
+/* Generate a new vector constant for mode MODE and constant value
+   CONSTANT.  */
 
-  /* We need to call this function after we set the scalar const_tiny_rtx
-     entries.  */
-  gcc_assert (const_tiny_rtx[constant][(int) inner]);
+static rtx
+gen_const_vector (machine_mode mode, int constant)
+{
+  machine_mode inner = GET_MODE_INNER (mode);
 
-  for (i = 0; i < units; ++i)
-    RTVEC_ELT (v, i) = const_tiny_rtx[constant][(int) inner];
+  gcc_assert (!DECIMAL_FLOAT_MODE_P (inner));
+
+  rtx el = const_tiny_rtx[constant][(int) inner];
+  gcc_assert (el);
 
-  tem = gen_rtx_raw_CONST_VECTOR (mode, v);
-  return tem;
+  return gen_const_vec_duplicate_1 (mode, el);
 }
 
 /* Generate a vector like gen_rtx_raw_CONST_VEC, but use the zero vector when
@@ -5790,28 +5818,12 @@ gen_const_vector (machine_mode mode, int constant)
 rtx
 gen_rtx_CONST_VECTOR (machine_mode mode, rtvec v)
 {
-  machine_mode inner = GET_MODE_INNER (mode);
-  int nunits = GET_MODE_NUNITS (mode);
-  rtx x;
-  int i;
-
-  /* Check to see if all of the elements have the same value.  */
-  x = RTVEC_ELT (v, nunits - 1);
-  for (i = nunits - 2; i >= 0; i--)
-    if (RTVEC_ELT (v, i) != x)
-      break;
+  gcc_assert (GET_MODE_NUNITS (mode) == GET_NUM_ELEM (v));
 
   /* If the values are all the same, check to see if we can use one of the
      standard constant vectors.  */
-  if (i == -1)
-    {
-      if (x == CONST0_RTX (inner))
-	return CONST0_RTX (mode);
-      else if (x == CONST1_RTX (inner))
-	return CONST1_RTX (mode);
-      else if (x == CONSTM1_RTX (inner))
-	return CONSTM1_RTX (mode);
-    }
+  if (rtvec_all_equal_p (v))
+    return gen_const_vec_duplicate (mode, RTVEC_ELT (v, 0));
 
   return gen_rtx_raw_CONST_VECTOR (mode, v);
 }