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Generalise VEC_DUPLICATE folding for variable-length vectors

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This patch uses the constant vector encoding scheme to handle
more cases of a VEC_DUPLICATE of another vector.  Duplicating
any fixed-length vector is fine, and duplicating a variable-length
vector is OK as long as that vector is also a duplicate of a
fixed-length sequence.

Other cases fell through to:

  if (VECTOR_MODE_P (mode) && GET_CODE (op) == CONST_VECTOR)

which was only expecting to deal with elementwise operations.

2019-07-29  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* simplify-rtx.c (simplify_const_unary_operation): Fold a
	VEC_DUPLICATE of a fixed-length vector even if the result
	is variable-length.  Likewise fold a duplicate of a
	variable-length vector if the variable-length vector is
	itself a duplicate of a fixed-length sequence.
	(test_vector_ops_duplicate): Test more cases.

From-SVN: r273868
This commit is contained in:
Richard Sandiford 2019-07-29 08:42:19 +00:00 • committed by Richard Sandiford
parent 4ce6ab6889
commit 708cc6132b
2 changed files with 34 additions and 12 deletions
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9
gcc/ChangeLog
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@ -1,3 +1,12 @@
2019-07-29 Richard Sandiford <richard.sandiford@arm.com>
* simplify-rtx.c (simplify_const_unary_operation): Fold a
VEC_DUPLICATE of a fixed-length vector even if the result
is variable-length. Likewise fold a duplicate of a
variable-length vector if the variable-length vector is
itself a duplicate of a fixed-length sequence.
(test_vector_ops_duplicate): Test more cases.
2019-07-29 Richard Sandiford <richard.sandiford@arm.com>
* vector-builder.h (vector_builder): Add a shape template parameter.

37
gcc/simplify-rtx.c
View file

@ -1736,23 +1736,24 @@ simplify_const_unary_operation (enum rtx_code code, machine_mode mode,
}
if (CONST_SCALAR_INT_P (op) || CONST_DOUBLE_AS_FLOAT_P (op))
return gen_const_vec_duplicate (mode, op);
unsigned int n_elts;
if (GET_CODE (op) == CONST_VECTOR
&& GET_MODE_NUNITS (mode).is_constant (&n_elts))
&& (CONST_VECTOR_DUPLICATE_P (op)
|| CONST_VECTOR_NUNITS (op).is_constant ()))
{
/* This must be constant if we're duplicating it to a constant
number of elements. */
unsigned int in_n_elts = CONST_VECTOR_NUNITS (op).to_constant ();
gcc_assert (in_n_elts < n_elts);
gcc_assert ((n_elts % in_n_elts) == 0);
rtvec v = rtvec_alloc (n_elts);
for (unsigned i = 0; i < n_elts; i++)
RTVEC_ELT (v, i) = CONST_VECTOR_ELT (op, i % in_n_elts);
return gen_rtx_CONST_VECTOR (mode, v);
unsigned int npatterns = (CONST_VECTOR_DUPLICATE_P (op)
? CONST_VECTOR_NPATTERNS (op)
: CONST_VECTOR_NUNITS (op).to_constant ());
gcc_assert (multiple_p (GET_MODE_NUNITS (mode), npatterns));
rtx_vector_builder builder (mode, npatterns, 1);
for (unsigned i = 0; i < npatterns; i++)
builder.quick_push (CONST_VECTOR_ELT (op, i));
return builder.build ();
}
}
if (VECTOR_MODE_P (mode) && GET_CODE (op) == CONST_VECTOR)
if (VECTOR_MODE_P (mode)
&& GET_CODE (op) == CONST_VECTOR
&& known_eq (GET_MODE_NUNITS (mode), CONST_VECTOR_NUNITS (op)))
{
gcc_assert (GET_MODE (op) == op_mode);
@ -6977,6 +6978,18 @@ test_vector_ops_duplicate (machine_mode mode, rtx scalar_reg)
&& mode_for_vector (inner_mode, 2).exists (&narrower_mode)
&& VECTOR_MODE_P (narrower_mode))
{
/* Test VEC_DUPLICATE of a vector. */
rtx_vector_builder nbuilder (narrower_mode, 2, 1);
nbuilder.quick_push (const0_rtx);
nbuilder.quick_push (const1_rtx);
rtx_vector_builder builder (mode, 2, 1);
builder.quick_push (const0_rtx);
builder.quick_push (const1_rtx);
ASSERT_RTX_EQ (builder.build (),
simplify_unary_operation (VEC_DUPLICATE, mode,
nbuilder.build (),
narrower_mode));
/* Test VEC_SELECT of a vector. */
rtx vec_par
= gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, const1_rtx, const0_rtx));