[gcc r12-5985] Add new constant data structure.

[gcc r12-5985] Add new constant data structure.

[Michael Meissner]

https://gcc.gnu.org/g:c6756b3bc1d2af1c8e86f0ad1711e9b9134520ba

commit r12-5985-gc6756b3bc1d2af1c8e86f0ad1711e9b9134520ba
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Wed Dec 15 00:56:25 2021 -0500

    Add new constant data structure.
    
    This patch provides the data structure and function to convert a
    CONST_INT, CONST_DOUBLE, CONST_VECTOR, or VEC_DUPLICATE of a constant) to
    an array of bytes, half-words, words, and  double words that can be loaded
    into a 128-bit vector register.
    
    The next patches will use this data structure to generate code that
    generates load of the vector/floating point registers using the XXSPLTIDP,
    XXSPLTIW, and LXVKQ instructions that were added in power10.
    
    2021-12-15  Michael Meissner  <meissner@the-meissners.org>
    
    gcc/
    
            * config/rs6000/rs6000-protos.h (VECTOR_128BIT_BITS): New macro.
            (VECTOR_128BIT_BYTES): Likewise.
            (VECTOR_128BIT_HALF_WORDS): Likewise.
            (VECTOR_128BIT_WORDS): Likewise.
            (VECTOR_128BIT_DOUBLE_WORDS): Likewise.
            (vec_const_128bit_type): New structure type.
            (vec_const_128bit_to_bytes): New declaration.
            * config/rs6000/rs6000.c (constant_int_to_128bit_vector): New
            helper function.
            (constant_fp_to_128bit_vector): New helper function.
            (vec_const_128bit_to_bytes): New function.

Diff:
---
 gcc/config/rs6000/rs6000-protos.h |  28 +++++
 gcc/config/rs6000/rs6000.c        | 253 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 281 insertions(+)

diff --git a/gcc/config/rs6000/rs6000-protos.h b/gcc/config/rs6000/rs6000-protos.h
index c01ae005d0b..81345d80952 100644
--- a/gcc/config/rs6000/rs6000-protos.h
+++ b/gcc/config/rs6000/rs6000-protos.h
@@ -222,6 +222,34 @@ address_is_prefixed (rtx addr,
   return (iform == INSN_FORM_PREFIXED_NUMERIC
 	  || iform == INSN_FORM_PCREL_LOCAL);
 }
+
+/* Functions and data structures relating to 128-bit constants that are
+   converted to byte, half-word, word, and double-word values.  All fields are
+   kept in big endian order.  We also convert scalar values to 128-bits if they
+   are going to be loaded into vector registers.  */
+#define VECTOR_128BIT_BITS		128
+#define VECTOR_128BIT_BYTES		(128 / 8)
+#define VECTOR_128BIT_HALF_WORDS	(128 / 16)
+#define VECTOR_128BIT_WORDS		(128 / 32)
+#define VECTOR_128BIT_DOUBLE_WORDS	(128 / 64)
+
+typedef struct {
+  /* Constant as various sized items.  */
+  unsigned HOST_WIDE_INT double_words[VECTOR_128BIT_DOUBLE_WORDS];
+  unsigned int words[VECTOR_128BIT_WORDS];
+  unsigned short half_words[VECTOR_128BIT_HALF_WORDS];
+  unsigned char bytes[VECTOR_128BIT_BYTES];
+
+  unsigned original_size;		/* Constant size before splat.  */
+  bool fp_constant_p;			/* Is the constant floating point?  */
+  bool all_double_words_same;		/* Are the double words all equal?  */
+  bool all_words_same;			/* Are the words all equal?  */
+  bool all_half_words_same;		/* Are the half words all equal?  */
+  bool all_bytes_same;			/* Are the bytes all equal?  */
+} vec_const_128bit_type;
+
+extern bool vec_const_128bit_to_bytes (rtx, machine_mode,
+				       vec_const_128bit_type *);
 #endif /* RTX_CODE */
 
 #ifdef TREE_CODE
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 4481ba57ed7..819314d9fe9 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -28334,6 +28334,259 @@ rs6000_output_addr_vec_elt (FILE *file, int value)
   fprintf (file, "\n");
 }
 
+\f
+/* Copy an integer constant to the vector constant structure.  */
+
+static void
+constant_int_to_128bit_vector (rtx op,
+			       machine_mode mode,
+			       size_t byte_num,
+			       vec_const_128bit_type *info)
+{
+  unsigned HOST_WIDE_INT uvalue = UINTVAL (op);
+  unsigned bitsize = GET_MODE_BITSIZE (mode);
+
+  for (int shift = bitsize - 8; shift >= 0; shift -= 8)
+    info->bytes[byte_num++] = (uvalue >> shift) & 0xff;
+}
+
+/* Copy a floating point constant to the vector constant structure.  */
+
+static void
+constant_fp_to_128bit_vector (rtx op,
+			      machine_mode mode,
+			      size_t byte_num,
+			      vec_const_128bit_type *info)
+{
+  unsigned bitsize = GET_MODE_BITSIZE (mode);
+  unsigned num_words = bitsize / 32;
+  const REAL_VALUE_TYPE *rtype = CONST_DOUBLE_REAL_VALUE (op);
+  long real_words[VECTOR_128BIT_WORDS];
+
+  /* Make sure we don't overflow the real_words array and that it is
+     filled completely.  */
+  gcc_assert (num_words <= VECTOR_128BIT_WORDS && (bitsize % 32) == 0);
+
+  real_to_target (real_words, rtype, mode);
+
+  /* Iterate over each 32-bit word in the floating point constant.  The
+     real_to_target function puts out words in target endian fashion.  We need
+     to arrange the order so that the bytes are written in big endian order.  */
+  for (unsigned num = 0; num < num_words; num++)
+    {
+      unsigned endian_num = (BYTES_BIG_ENDIAN
+			     ? num
+			     : num_words - 1 - num);
+
+      unsigned uvalue = real_words[endian_num];
+      for (int shift = 32 - 8; shift >= 0; shift -= 8)
+	info->bytes[byte_num++] = (uvalue >> shift) & 0xff;
+    }
+
+  /* Mark that this constant involves floating point.  */
+  info->fp_constant_p = true;
+}
+
+/* Convert a vector constant OP with mode MODE to a vector 128-bit constant
+   structure INFO.
+
+   Break out the constant out to bytes, half words, words, and double words.
+   Return true if we have successfully converted the constant.
+
+   We handle CONST_INT, CONST_DOUBLE, CONST_VECTOR, and VEC_DUPLICATE of
+   constants.  Integer and floating point scalar constants are splatted to fill
+   out the vector.  */
+
+bool
+vec_const_128bit_to_bytes (rtx op,
+			   machine_mode mode,
+			   vec_const_128bit_type *info)
+{
+  /* Initialize the constant structure.  */
+  memset ((void *)info, 0, sizeof (vec_const_128bit_type));
+
+  /* Assume CONST_INTs are DImode.  */
+  if (mode == VOIDmode)
+    mode = CONST_INT_P (op) ? DImode : GET_MODE (op);
+
+  if (mode == VOIDmode)
+    return false;
+
+  unsigned size = GET_MODE_SIZE (mode);
+  bool splat_p = false;
+
+  if (size > VECTOR_128BIT_BYTES)
+    return false;
+
+  /* Set up the bits.  */
+  switch (GET_CODE (op))
+    {
+      /* Integer constants, default to double word.  */
+    case CONST_INT:
+      {
+	constant_int_to_128bit_vector (op, mode, 0, info);
+	splat_p = true;
+	break;
+      }
+
+      /* Floating point constants.  */
+    case CONST_DOUBLE:
+      {
+	/* Fail if the floating point constant is the wrong mode.  */
+	if (GET_MODE (op) != mode)
+	  return false;
+
+	/* SFmode stored as scalars are stored in DFmode format.  */
+	if (mode == SFmode)
+	  {
+	    mode = DFmode;
+	    size = GET_MODE_SIZE (DFmode);
+	  }
+
+	constant_fp_to_128bit_vector (op, mode, 0, info);
+	splat_p = true;
+	break;
+      }
+
+      /* Vector constants, iterate over each element.  On little endian
+	 systems, we have to reverse the element numbers.  */
+    case CONST_VECTOR:
+      {
+	/* Fail if the vector constant is the wrong mode or size.  */
+	if (GET_MODE (op) != mode
+	    || GET_MODE_SIZE (mode) != VECTOR_128BIT_BYTES)
+	  return false;
+
+	machine_mode ele_mode = GET_MODE_INNER (mode);
+	size_t ele_size = GET_MODE_SIZE (ele_mode);
+	size_t nunits = GET_MODE_NUNITS (mode);
+
+	for (size_t num = 0; num < nunits; num++)
+	  {
+	    rtx ele = CONST_VECTOR_ELT (op, num);
+	    size_t byte_num = (BYTES_BIG_ENDIAN
+			       ? num
+			       : nunits - 1 - num) * ele_size;
+
+	    if (CONST_INT_P (ele))
+	      constant_int_to_128bit_vector (ele, ele_mode, byte_num, info);
+	    else if (CONST_DOUBLE_P (ele))
+	      constant_fp_to_128bit_vector (ele, ele_mode, byte_num, info);
+	    else
+	      return false;
+	  }
+
+	break;
+      }
+
+	/* Treat VEC_DUPLICATE of a constant just like a vector constant.
+	   Since we are duplicating the element, we don't have to worry about
+	   endian issues.  */
+    case VEC_DUPLICATE:
+      {
+	/* Fail if the vector duplicate is the wrong mode or size.  */
+	if (GET_MODE (op) != mode
+	    || GET_MODE_SIZE (mode) != VECTOR_128BIT_BYTES)
+	  return false;
+
+	machine_mode ele_mode = GET_MODE_INNER (mode);
+	size_t ele_size = GET_MODE_SIZE (ele_mode);
+	rtx ele = XEXP (op, 0);
+	size_t nunits = GET_MODE_NUNITS (mode);
+
+	if (!CONST_INT_P (ele) && !CONST_DOUBLE_P (ele))
+	  return false;
+
+	for (size_t num = 0; num < nunits; num++)
+	  {
+	    size_t byte_num = num * ele_size;
+
+	    if (CONST_INT_P (ele))
+	      constant_int_to_128bit_vector (ele, ele_mode, byte_num, info);
+	    else
+	      constant_fp_to_128bit_vector (ele, ele_mode, byte_num, info);
+	  }
+
+	break;
+      }
+
+      /* Any thing else, just return failure.  */
+    default:
+      return false;
+    }
+
+  /* Splat the constant to fill 128 bits if desired.  */
+  if (splat_p && size < VECTOR_128BIT_BYTES)
+    {
+      if ((VECTOR_128BIT_BYTES % size) != 0)
+	return false;
+
+      for (size_t offset = size;
+	   offset < VECTOR_128BIT_BYTES;
+	   offset += size)
+	memcpy ((void *) &info->bytes[offset],
+		(void *) &info->bytes[0],
+		size);
+    }
+
+  /* Remember original size.  */
+  info->original_size = size;
+
+  /* Determine if the bytes are all the same.  */
+  unsigned char first_byte = info->bytes[0];
+  info->all_bytes_same = true;
+  for (size_t i = 1; i < VECTOR_128BIT_BYTES; i++)
+    if (first_byte != info->bytes[i])
+      {
+	info->all_bytes_same = false;
+	break;
+      }
+
+  /* Pack half words together & determine if all of the half words are the
+     same.  */
+  for (size_t i = 0; i < VECTOR_128BIT_HALF_WORDS; i++)
+    info->half_words[i] = ((info->bytes[i * 2] << 8)
+			   | info->bytes[(i * 2) + 1]);
+
+  unsigned short first_hword = info->half_words[0];
+  info->all_half_words_same = true;
+  for (size_t i = 1; i < VECTOR_128BIT_HALF_WORDS; i++)
+    if (first_hword != info->half_words[i])
+      {
+	info->all_half_words_same = false;
+	break;
+      }
+
+  /* Pack words together & determine if all of the words are the same.  */
+  for (size_t i = 0; i < VECTOR_128BIT_WORDS; i++)
+    info->words[i] = ((info->bytes[i * 4] << 24)
+		      | (info->bytes[(i * 4) + 1] << 16)
+		      | (info->bytes[(i * 4) + 2] << 8)
+		      | info->bytes[(i * 4) + 3]);
+
+  info->all_words_same
+    = (info->words[0] == info->words[1]
+       && info->words[0] == info->words[1]
+       && info->words[0] == info->words[2]
+       && info->words[0] == info->words[3]);
+
+  /* Pack double words together & determine if all of the double words are the
+     same.  */
+  for (size_t i = 0; i < VECTOR_128BIT_DOUBLE_WORDS; i++)
+    {
+      unsigned HOST_WIDE_INT d_word = 0;
+      for (size_t j = 0; j < 8; j++)
+	d_word = (d_word << 8) | info->bytes[(i * 8) + j];
+
+      info->double_words[i] = d_word;
+    }
+
+  info->all_double_words_same
+    = (info->double_words[0] == info->double_words[1]);
+
+  return true;
+}
+
 struct gcc_target targetm = TARGET_INITIALIZER;
 
 #include "gt-rs6000.h"