[PATCH 01/50] Add rtl-iter.h

[Richard Sandiford <rdsandiford@googlemail.com>]

This patch adds the new iterators.


gcc/
	* rtl-iter.h: New file.
	* rtlanal.c: Include it.
	(rtx_all_subrtx_bounds, rtx_nonconst_subrtx_bounds): New variables.
	(generic_subrtx_iterator <T>::add_single_to_queue)
	(generic_subrtx_iterator <T>::add_subrtxes_to_queue)
	(generic_subrtx_iterator <T>::free_array): New functions.
	(generic_subrtx_iterator <T>::LOCAL_ELEMS): Define.
	(generic_subrtx_iterator <const_rtx_accessor>)
	(generic_subrtx_iterator <rtx_var_accessor>
	(generic_subrtx_iterator <rtx_ptr_accessor>): Instantiate.
	(setup_reg_subrtx_bounds): New function.
	(init_rtlanal): Call it.

Index: gcc/rtl-iter.h
===================================================================
--- /dev/null	2014-08-02 10:04:40.408500658 +0100
+++ gcc/rtl-iter.h	2014-08-03 11:25:20.308056954 +0100
@@ -0,0 +1,291 @@
+/* RTL iterators
+   Copyright (C) 2014 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+/* This structure describes the subrtxes of an rtx as follows:
+
+   - if the rtx has no subrtxes, START and COUNT are both 0.
+
+   - if all the subrtxes of an rtx are stored in a contiguous block
+     of XEXPs ("e"s), START is the index of the first XEXP and COUNT
+     is the number of them.
+
+   - otherwise START is arbitrary and COUNT is UCHAR_MAX.
+
+   rtx_all_subrtx_bounds applies to all codes.  rtx_nonconst_subrtx_bounds
+   is like rtx_all_subrtx_bounds except that all constant rtxes are treated
+   as having no subrtxes.  */
+struct rtx_subrtx_bound_info {
+  unsigned char start;
+  unsigned char count;
+};
+extern rtx_subrtx_bound_info rtx_all_subrtx_bounds[];
+extern rtx_subrtx_bound_info rtx_nonconst_subrtx_bounds[];
+
+/* Return true if CODE has no subrtxes.  */
+
+static inline bool
+leaf_code_p (enum rtx_code code)
+{
+  return rtx_all_subrtx_bounds[code].count == 0;
+}
+
+/* Used to iterate over subrtxes of an rtx.  T abstracts the type of
+   access.  */
+template <typename T>
+class generic_subrtx_iterator
+{
+  static const size_t LOCAL_ELEMS = 16;
+  typedef typename T::value_type value_type;
+  typedef typename T::rtx_type rtx_type;
+  typedef typename T::rtunion_type rtunion_type;
+
+public:
+  struct array_type
+  {
+    array_type ();
+    ~array_type ();
+    value_type stack[LOCAL_ELEMS];
+    vec <value_type, va_heap, vl_embed> *heap;
+  };
+  generic_subrtx_iterator (array_type &, value_type,
+			   const rtx_subrtx_bound_info *);
+
+  value_type operator * () const;
+  bool at_end () const;
+  void next ();
+  void skip_subrtxes ();
+  void substitute (value_type);
+
+private:
+  /* The bounds to use for iterating over subrtxes.  */
+  const rtx_subrtx_bound_info *m_bounds;
+
+  /* The storage used for the worklist.  */
+  array_type &m_array;
+
+  /* The current rtx.  */
+  value_type m_current;
+
+  /* The base of the current worklist.  */
+  value_type *m_base;
+
+  /* The number of subrtxes in M_BASE.  */
+  size_t m_end;
+
+  /* The following booleans shouldn't end up in registers or memory
+     but just direct control flow.  */
+
+  /* True if the iteration is over.  */
+  bool m_done;
+
+  /* True if we should skip the subrtxes of M_CURRENT.  */
+  bool m_skip;
+
+  /* True if M_CURRENT has been replaced with a different rtx.  */
+  bool m_substitute;
+
+  static void free_array (array_type &);
+  static size_t add_subrtxes_to_queue (array_type &, value_type *, size_t,
+				       rtx_type);
+  static value_type *add_single_to_queue (array_type &, value_type *, size_t,
+					  value_type);
+};
+
+template <typename T>
+inline generic_subrtx_iterator <T>::array_type::array_type () : heap (0) {}
+
+template <typename T>
+inline generic_subrtx_iterator <T>::array_type::~array_type ()
+{
+  if (__builtin_expect (heap != 0, false))
+    free_array (*this);
+}
+
+/* Iterate over X and its subrtxes, in arbitrary order.  Use ARRAY to
+   store the worklist.  We use an external array in order to avoid
+   capturing the fields of this structure when taking the address of
+   the array.  Use BOUNDS to find the bounds of simple "e"-string codes.  */
+
+template <typename T>
+inline generic_subrtx_iterator <T>::
+generic_subrtx_iterator (array_type &array, value_type x,
+			 const rtx_subrtx_bound_info *bounds)
+  : m_bounds (bounds),
+    m_array (array),
+    m_current (x),
+    m_base (m_array.stack),
+    m_end (0),
+    m_done (false),
+    m_skip (false),
+    m_substitute (false)
+{
+}
+
+/* Return the current subrtx.  */
+
+template <typename T>
+inline typename T::value_type
+generic_subrtx_iterator <T>::operator * () const
+{
+  return m_current;
+}
+
+/* Return true if the iteration has finished.  */
+
+template <typename T>
+inline bool
+generic_subrtx_iterator <T>::at_end () const
+{
+  return m_done;
+}
+
+/* Move on to the next subrtx.  */
+
+template <typename T>
+inline void
+generic_subrtx_iterator <T>::next ()
+{
+  if (m_substitute)
+    {
+      m_substitute = false;
+      m_skip = false;
+      return;
+    }
+  if (!m_skip)
+    {
+      /* Add the subrtxes of M_CURRENT.  */
+      rtx_type x = T::get_rtx (m_current);
+      if (__builtin_expect (x != 0, true))
+	{
+	  enum rtx_code code = GET_CODE (x);
+	  ssize_t count = m_bounds[code].count;
+	  if (count > 0)
+	    {
+	      /* Handle the simple case of a single "e" block that is known
+		 to fit into the current array.  */
+	      if (__builtin_expect (m_end + count <= LOCAL_ELEMS + 1, true))
+		{
+		  /* Set M_CURRENT to the first subrtx and queue the rest.  */
+		  ssize_t start = m_bounds[code].start;
+		  rtunion_type *src = &x->u.fld[start];
+		  if (__builtin_expect (count > 2, false))
+		    m_base[m_end++] = T::get_value (src[2].rt_rtx);
+		  if (count > 1)
+		    m_base[m_end++] = T::get_value (src[1].rt_rtx);
+		  m_current = T::get_value (src[0].rt_rtx);
+		  return;
+		}
+	      /* Handle cases which aren't simple "e" sequences or where
+		 the sequence might overrun M_BASE.  */
+	      count = add_subrtxes_to_queue (m_array, m_base, m_end, x);
+	      if (count > 0)
+		{
+		  m_end += count;
+		  if (m_end > LOCAL_ELEMS)
+		    m_base = m_array.heap->address ();
+		  m_current = m_base[--m_end];
+		  return;
+		}
+	    }
+	}
+    }
+  else
+    m_skip = false;
+  if (m_end == 0)
+    m_done = true;
+  else
+    m_current = m_base[--m_end];
+}
+
+/* Skip the subrtxes of the current rtx.  */
+
+template <typename T>
+inline void
+generic_subrtx_iterator <T>::skip_subrtxes ()
+{
+  m_skip = true;
+}
+
+/* Ignore the subrtxes of the current rtx and look at X instead.  */
+
+template <typename T>
+inline void
+generic_subrtx_iterator <T>::substitute (value_type x)
+{
+  m_substitute = true;
+  m_current = x;
+}
+
+/* Iterators for const_rtx.  */
+struct const_rtx_accessor
+{
+  typedef const_rtx value_type;
+  typedef const_rtx rtx_type;
+  typedef const rtunion rtunion_type;
+  static rtx_type get_rtx (value_type x) { return x; }
+  static value_type get_value (rtx_type x) { return x; }
+};
+typedef generic_subrtx_iterator <const_rtx_accessor> subrtx_iterator;
+
+/* Iterators for non-constant rtx.  */
+struct rtx_var_accessor
+{
+  typedef rtx value_type;
+  typedef rtx rtx_type;
+  typedef rtunion rtunion_type;
+  static rtx_type get_rtx (value_type x) { return x; }
+  static value_type get_value (rtx_type x) { return x; }
+};
+typedef generic_subrtx_iterator <rtx_var_accessor> subrtx_var_iterator;
+
+/* Iterators for rtx *.  */
+struct rtx_ptr_accessor
+{
+  typedef rtx *value_type;
+  typedef rtx rtx_type;
+  typedef rtunion rtunion_type;
+  static rtx_type get_rtx (value_type ptr) { return *ptr; }
+  static value_type get_value (rtx_type &x) { return &x; }
+};
+typedef generic_subrtx_iterator <rtx_ptr_accessor> subrtx_ptr_iterator;
+
+#define ALL_BOUNDS rtx_all_subrtx_bounds
+#define NONCONST_BOUNDS rtx_nonconst_subrtx_bounds
+
+/* Use ITER to iterate over const_rtx X and its recursive subrtxes,
+   using subrtx_iterator::array ARRAY as the storage for the worklist.
+   ARRAY can be reused for multiple consecutive iterations but shouldn't
+   be shared by two concurrent iterations.  TYPE is ALL if all subrtxes
+   are of interest or NONCONST if it is safe to ignore subrtxes of
+   constants.  */
+#define FOR_EACH_SUBRTX(ITER, ARRAY, X, TYPE) \
+  for (subrtx_iterator ITER (ARRAY, X, TYPE##_BOUNDS); !ITER.at_end (); \
+       ITER.next ())
+
+/* Like FOR_EACH_SUBRTX, but iterate over subrtxes of an rtx X.  */
+#define FOR_EACH_SUBRTX_VAR(ITER, ARRAY, X, TYPE) \
+  for (subrtx_var_iterator ITER (ARRAY, X, TYPE##_BOUNDS); !ITER.at_end (); \
+       ITER.next ())
+
+/* Like FOR_EACH_SUBRTX, but iterate over subrtx pointers of rtx pointer X.
+   For example, if X is &PATTERN (insn) and the pattern is a SET, iterate
+   over &PATTERN (insn), &SET_DEST (PATTERN (insn)), etc.  */
+#define FOR_EACH_SUBRTX_PTR(ITER, ARRAY, X, TYPE) \
+  for (subrtx_ptr_iterator ITER (ARRAY, X, TYPE##_BOUNDS); !ITER.at_end (); \
+       ITER.next ())
Index: gcc/rtlanal.c
===================================================================
--- gcc/rtlanal.c	2014-08-03 11:25:10.713962101 +0100
+++ gcc/rtlanal.c	2014-08-03 11:25:20.309056964 +0100
@@ -37,6 +37,7 @@ Software Foundation; either version 3, o
 #include "tree.h"
 #include "emit-rtl.h"  /* FIXME: Can go away once crtl is moved to rtl.h.  */
 #include "addresses.h"
+#include "rtl-iter.h"
 
 /* Forward declarations */
 static void set_of_1 (rtx, const_rtx, void *);
@@ -62,6 +63,9 @@ static unsigned int num_sign_bit_copies1
    -1 if a code has no such operand.  */
 static int non_rtx_starting_operands[NUM_RTX_CODE];
 
+rtx_subrtx_bound_info rtx_all_subrtx_bounds[NUM_RTX_CODE];
+rtx_subrtx_bound_info rtx_nonconst_subrtx_bounds[NUM_RTX_CODE];
+
 /* Truncation narrows the mode from SOURCE mode to DESTINATION mode.
    If TARGET_MODE_REP_EXTENDED (DESTINATION, DESTINATION_REP) is
    SIGN_EXTEND then while narrowing we also have to enforce the
@@ -78,6 +82,93 @@ static unsigned int num_sign_bit_copies1
 static unsigned int
 num_sign_bit_copies_in_rep[MAX_MODE_INT + 1][MAX_MODE_INT + 1];
 \f
+/* Store X into index I of ARRAY.  ARRAY is known to have at least I
+   elements.  Return the new base of ARRAY.  */
+
+template <typename T>
+typename T::value_type *
+generic_subrtx_iterator <T>::add_single_to_queue (array_type &array,
+						  value_type *base,
+						  size_t i, value_type x)
+{
+  if (base == array.stack)
+    {
+      if (i < LOCAL_ELEMS)
+	{
+	  base[i] = x;
+	  return base;
+	}
+      gcc_checking_assert (i == LOCAL_ELEMS);
+      vec_safe_grow (array.heap, i + 1);
+      base = array.heap->address ();
+      memcpy (base, array.stack, sizeof (array.stack));
+      base[LOCAL_ELEMS] = x;
+      return base;
+    }
+  unsigned int length = array.heap->length ();
+  if (length > i)
+    {
+      gcc_checking_assert (base == array.heap->address ());
+      base[i] = x;
+      return base;
+    }
+  else
+    {
+      gcc_checking_assert (i == length);
+      vec_safe_push (array.heap, x);
+      return array.heap->address ();
+    }
+}
+
+/* Add the subrtxes of X to worklist ARRAY, starting at END.  Return the
+   number of elements added to the worklist.  */
+
+template <typename T>
+size_t
+generic_subrtx_iterator <T>::add_subrtxes_to_queue (array_type &array,
+						    value_type *base,
+						    size_t end, rtx_type x)
+{
+  const char *format = GET_RTX_FORMAT (GET_CODE (x));
+  size_t orig_end = end;
+  for (int i = 0; format[i]; ++i)
+    if (format[i] == 'e')
+      {
+	value_type subx = T::get_value (x->u.fld[i].rt_rtx);
+	if (__builtin_expect (end < LOCAL_ELEMS, true))
+	  base[end++] = subx;
+	else
+	  base = add_single_to_queue (array, base, end++, subx);
+      }
+    else if (format[i] == 'E')
+      {
+	int length = GET_NUM_ELEM (x->u.fld[i].rt_rtvec);
+	rtx *vec = x->u.fld[i].rt_rtvec->elem;
+	if (__builtin_expect (end + length <= LOCAL_ELEMS, true))
+	  for (int j = 0; j < length; j++)
+	    base[end++] = T::get_value (vec[j]);
+	else
+	  for (int j = 0; j < length; j++)
+	    base = add_single_to_queue (array, base, end++,
+					T::get_value (vec[j]));
+      }
+  return end - orig_end;
+}
+
+template <typename T>
+void
+generic_subrtx_iterator <T>::free_array (array_type &array)
+{
+  vec_free (array.heap);
+}
+
+template <typename T>
+const size_t generic_subrtx_iterator <T>::LOCAL_ELEMS;
+
+template class generic_subrtx_iterator <const_rtx_accessor>;
+template class generic_subrtx_iterator <rtx_var_accessor>;
+template class generic_subrtx_iterator <rtx_ptr_accessor>;
+
 /* Return 1 if the value of X is unstable
    (would be different at a different point in the program).
    The frame pointer, arg pointer, etc. are considered stable
@@ -5328,8 +5419,42 @@ truncated_to_mode (enum machine_mode mod
   return false;
 }
 \f
+/* Return true if RTX code CODE has a single sequence of zero or more
+   "e" operands and no rtvec operands.  Initialize its rtx_all_subrtx_bounds
+   entry in that case.  */
+
+static bool
+setup_reg_subrtx_bounds (unsigned int code)
+{
+  const char *format = GET_RTX_FORMAT ((enum rtx_code) code);
+  unsigned int i = 0;
+  for (; format[i] != 'e'; ++i)
+    {
+      if (!format[i])
+	/* No subrtxes.  Leave start and count as 0.  */
+	return true;
+      if (format[i] == 'E' || format[i] == 'V')
+	return false;
+    }
+
+  /* Record the sequence of 'e's.  */
+  rtx_all_subrtx_bounds[code].start = i;
+  do
+    ++i;
+  while (format[i] == 'e');
+  rtx_all_subrtx_bounds[code].count = i - rtx_all_subrtx_bounds[code].start;
+  /* rtl-iter.h relies on this.  */
+  gcc_checking_assert (rtx_all_subrtx_bounds[code].count <= 3);
+
+  for (; format[i]; ++i)
+    if (format[i] == 'E' || format[i] == 'V' || format[i] == 'e')
+      return false;
+
+  return true;
+}
+
 /* Initialize non_rtx_starting_operands, which is used to speed up
-   for_each_rtx.  */
+   for_each_rtx, and rtx_all_subrtx_bounds.  */
 void
 init_rtlanal (void)
 {
@@ -5339,6 +5464,10 @@ init_rtlanal (void)
       const char *format = GET_RTX_FORMAT (i);
       const char *first = strpbrk (format, "eEV");
       non_rtx_starting_operands[i] = first ? first - format : -1;
+      if (!setup_reg_subrtx_bounds (i))
+	rtx_all_subrtx_bounds[i].count = UCHAR_MAX;
+      if (GET_RTX_CLASS (i) != RTX_CONST_OBJ)
+	rtx_nonconst_subrtx_bounds[i] = rtx_all_subrtx_bounds[i];
     }
 
   init_num_sign_bit_copies_in_rep ();