* Makefile.in (toplev.o): Add value-prof.h dependency.

	(value-prof.o): Add REGS_H dependency.
	* common.opt (fprofile-values, fvpt): New.
	* flags.h (flag_value_profile_transformations): Declare.
	* opts.c (common_handle_option): Handle -fprofile_values and
	-fvpt.
	* profile.c (branch_prob): Don't remove death notes here.
	* timevar.def (TV_VPT): New.
	* value-prof.c: Include regs.h.
	(insn_divmod_values_to_profile, gen_divmod_fixed_value, gen_mod_pow2,
	gen_mod_subtract, divmod_fixed_value_transform,mod_pow2_value_transform,
	mod_subtract_transform, value_profile_transformations): New.
	(insn_values_to_profile): Call insn_divmod_values_to_profile.
	(find_values_to_profile): Add dumps.
	* value-prof.h (value_profile_transformations): Declare.
	* toplev.c: Include value-prof.h.
	(rest_of_handle_value_profile_transformations): New.
	(enum dump_file_index): Add DFI_vpt.
	(dump_file): Add vpt dump.
	(flag_value_profile_transformations): New.
	(lang_independent_options): Add flag_profile_values and
	flag_value_profile_transformations.
	(rest_of_compilation): Call
	rest_of_handle_value_profile_transformations.
	(process_options): Let -fvpt imply -fprofile-values.
	* doc/invoke.texi (-fvpt): Document.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@72685 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 600 insertions, 3 deletions

diff --git a/gcc/value-prof.c b/gcc/value-prof.c
index 5dca281b1df..3924fa76c18 100644
--- a/gcc/value-prof.c
+++ b/gcc/value-prof.c
@@ -32,6 +32,7 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 #include "insn-config.h"
 #include "recog.h"
 #include "optabs.h"
+#include "regs.h"
 
 /* In this file value profile based optimizations will be placed (none are
    here just now, but they are hopefully coming soon).
@@ -49,7 +50,17 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
    -- the expression that is profiled
    -- list of counters starting from the first one.  */
 
+static void insn_divmod_values_to_profile (rtx, unsigned *,
+					   struct histogram_value **);
 static void insn_values_to_profile (rtx, unsigned *, struct histogram_value **);
+static rtx gen_divmod_fixed_value (enum machine_mode, enum rtx_code, rtx, rtx,
+				   rtx, gcov_type);
+static rtx gen_mod_pow2 (enum machine_mode, enum rtx_code, rtx, rtx, rtx);
+static rtx gen_mod_subtract (enum machine_mode, enum rtx_code, rtx, rtx, rtx,
+			     int);
+static bool divmod_fixed_value_transform (rtx insn);
+static bool mod_pow2_value_transform (rtx);
+static bool mod_subtract_transform (rtx);
 
 /* Release the list of VALUES of length N_VALUES for that we want to measure
    histograms.  */
@@ -60,13 +71,106 @@ free_profiled_values (unsigned n_values ATTRIBUTE_UNUSED,
   free (values);
 }
 
+/* Find values inside INSN for that we want to measure histograms for
+   division/modulo optimization.  */
+static void
+insn_divmod_values_to_profile (rtx insn, unsigned *n_values,
+			       struct histogram_value **values)
+{
+  rtx set, set_src, op1, op2;
+  enum machine_mode mode;
+
+  if (!INSN_P (insn))
+    return;
+
+  set = single_set (insn);
+  if (!set)
+    return;
+
+  mode = GET_MODE (SET_DEST (set));
+  if (!INTEGRAL_MODE_P (mode))
+    return;
+
+  set_src = SET_SRC (set);
+  switch (GET_CODE (set_src))
+    {
+    case DIV:
+    case MOD:
+    case UDIV:
+    case UMOD:
+      op1 = XEXP (set_src, 0);
+      op2 = XEXP (set_src, 1);
+      if (side_effects_p (op2))
+	return;
+
+      /* Check for a special case where the divisor is power of 2.  */
+      if ((GET_CODE (set_src) == UMOD) && !CONSTANT_P (op2))
+	{
+	  *values = xrealloc (*values,
+			      (*n_values + 1)
+				* sizeof (struct histogram_value));
+	  (*values)[*n_values].value = op2;
+	  (*values)[*n_values].seq = NULL_RTX;
+	  (*values)[*n_values].mode = mode;
+	  (*values)[*n_values].insn = insn;
+	  (*values)[*n_values].type = HIST_TYPE_POW2;
+	  (*values)[*n_values].hdata.pow2.may_be_other = 1;
+	  (*n_values)++;
+	}
+
+      /* Check whether the divisor is not in fact a constant.  */
+      if (!CONSTANT_P (op2))
+	{
+	  *values = xrealloc (*values,
+			      (*n_values + 1)
+				* sizeof (struct histogram_value));
+	  (*values)[*n_values].value = op2;
+	  (*values)[*n_values].mode = mode;
+	  (*values)[*n_values].seq = NULL_RTX;
+	  (*values)[*n_values].insn = insn;
+	  (*values)[*n_values].type = HIST_TYPE_SINGLE_VALUE;
+	  (*n_values)++;
+	}
+
+      /* For mod, check whether it is not often a noop (or replacable by
+	 a few subtractions).  */
+      if (GET_CODE (set_src) == UMOD && !side_effects_p (op1))
+	{
+	  rtx tmp;
+
+	  *values = xrealloc (*values,
+			      (*n_values + 1)
+				* sizeof (struct histogram_value));
+	  start_sequence ();
+	  tmp = simplify_gen_binary (DIV, mode, copy_rtx (op1), copy_rtx (op2));
+	  (*values)[*n_values].value = force_operand (tmp, NULL_RTX);
+	  (*values)[*n_values].seq = get_insns ();
+	  end_sequence ();
+	  (*values)[*n_values].mode = mode;
+	  (*values)[*n_values].insn = insn;
+	  (*values)[*n_values].type = HIST_TYPE_INTERVAL;
+	  (*values)[*n_values].hdata.intvl.int_start = 0;
+	  (*values)[*n_values].hdata.intvl.steps = 2;
+	  (*values)[*n_values].hdata.intvl.may_be_less = 1;
+	  (*values)[*n_values].hdata.intvl.may_be_more = 1;
+	  (*n_values)++;
+	}
+      return;
+
+    default:
+      return;
+    }
+}
+
 /* Find values inside INSN for that we want to measure histograms and adds
    them to list VALUES (increasing the record of its length in N_VALUES).  */
 static void
-insn_values_to_profile (rtx insn ATTRIBUTE_UNUSED,
-			unsigned *n_values ATTRIBUTE_UNUSED,
-			struct histogram_value **values ATTRIBUTE_UNUSED)
+insn_values_to_profile (rtx insn,
+			unsigned *n_values,
+			struct histogram_value **values)
 {
+  if (flag_value_profile_transformations)
+    insn_divmod_values_to_profile (insn, n_values, values);
 }
 
 /* Find list of values for that we want to measure histograms.  */
@@ -86,21 +190,40 @@ find_values_to_profile (unsigned *n_values, struct histogram_value **values)
       switch ((*values)[i].type)
 	{
 	case HIST_TYPE_INTERVAL:
+	  if (rtl_dump_file)
+	    fprintf (rtl_dump_file,
+		     "Interval counter for insn %d, range %d -- %d.\n",
+		     INSN_UID ((*values)[i].insn),
+		     (*values)[i].hdata.intvl.int_start,
+		     ((*values)[i].hdata.intvl.int_start
+		      + (*values)[i].hdata.intvl.steps - 1));
 	  (*values)[i].n_counters = (*values)[i].hdata.intvl.steps +
 		  ((*values)[i].hdata.intvl.may_be_less ? 1 : 0) +
 		  ((*values)[i].hdata.intvl.may_be_more ? 1 : 0);
 	  break;
 
 	case HIST_TYPE_POW2:
+	  if (rtl_dump_file)
+	    fprintf (rtl_dump_file,
+		     "Pow2 counter for insn %d.\n",
+		     INSN_UID ((*values)[i].insn));
 	  (*values)[i].n_counters = GET_MODE_BITSIZE ((*values)[i].mode) +
 		  ((*values)[i].hdata.pow2.may_be_other ? 1 : 0);
 	  break;
 
 	case HIST_TYPE_SINGLE_VALUE:
+	  if (rtl_dump_file)
+	    fprintf (rtl_dump_file,
+		     "Single value counter for insn %d.\n",
+		     INSN_UID ((*values)[i].insn));
 	  (*values)[i].n_counters = 3;
 	  break;
 
 	case HIST_TYPE_CONST_DELTA:
+	  if (rtl_dump_file)
+	    fprintf (rtl_dump_file,
+		     "Constant delta counter for insn %d.\n",
+		     INSN_UID ((*values)[i].insn));
 	  (*values)[i].n_counters = 4;
 	  break;
 
@@ -109,3 +232,477 @@ find_values_to_profile (unsigned *n_values, struct histogram_value **values)
 	}
     }
 }
+
+/* Main entry point.  Finds REG_VALUE_PROFILE notes from profiler and uses
+   them to identify and exploit properties of values that are hard to analyze
+   statically.
+
+   We do following transformations:
+
+   1)
+
+   x = a / b;
+
+   where b is almost always a constant N is transformed to
+
+   if (b == N)
+     x = a / N;
+   else
+     x = a / b;
+
+   Analogically with %
+
+   2)
+
+   x = a % b
+
+   where b is almost always a power of 2 and the division is unsigned
+   TODO -- handle signed case as well
+
+   if ((b & (b - 1)) == 0)
+     x = a & (b - 1);
+   else
+     x = x % b;
+
+   Note that when b = 0, no error will occur and x = a; this is correct,
+   as result of such operation is undefined.
+
+   3)
+
+   x = a % b
+
+   where a is almost always less then b and the division is unsigned
+   TODO -- handle signed case as well
+
+   x = a;
+   if (x >= b)
+     x %= b;
+
+   4)
+
+   x = a % b
+
+   where a is almost always less then 2 * b and the division is unsigned
+   TODO -- handle signed case as well
+
+   x = a;
+   if (x >= b)
+     x -= b;
+   if (x >= b)
+     x %= b;
+
+   It would be possible to continue analogically for K * b for other small
+   K's, but it is probably not useful.
+
+   TODO:
+
+   There are other useful cases that could be handled by a similar mechanism,
+   for example:
+   
+   for (i = 0; i < n; i++)
+     ...
+   
+   transform to (for constant N):
+   
+   if (n == N)
+     for (i = 0; i < N; i++)
+       ...
+   else
+     for (i = 0; i < n; i++)
+       ...
+   making unroller happy.  Since this may grow the code significantly,
+   we would have to be very careful here.  */
+
+bool
+value_profile_transformations ()
+{
+  rtx insn, next;
+  int changed = false;
+
+  for (insn = get_insns (); insn; insn = next)
+    {
+      next = NEXT_INSN (insn);
+
+      if (!INSN_P (insn))
+	continue;
+
+      /* Scan for insn carrying a histogram.  */
+      if (!find_reg_note (insn, REG_VALUE_PROFILE, 0))
+	continue;
+
+      /* Ignore cold areas -- we are growing a code.  */
+      if (!maybe_hot_bb_p (BLOCK_FOR_INSN (insn)))
+	continue;
+
+      if (rtl_dump_file)
+	{
+	  fprintf (rtl_dump_file, "Trying transformations on insn %d\n",
+		   INSN_UID (insn));
+	  print_rtl_single (rtl_dump_file, insn);
+	}
+
+      /* Transformations:  */
+      if (flag_value_profile_transformations
+	  && (mod_subtract_transform (insn)
+	      || divmod_fixed_value_transform (insn)
+	      || mod_pow2_value_transform (insn)))
+	changed = true;
+    }
+
+  if (changed)
+    {
+      commit_edge_insertions ();
+      allocate_reg_info (max_reg_num (), FALSE, FALSE);
+    }
+
+  return changed;
+}
+
+/* Generate code for transformation 1 (with MODE and OPERATION, operands OP1
+   and OP2 whose value is expected to be VALUE and result TARGET).  */
+static rtx
+gen_divmod_fixed_value (enum machine_mode mode, enum rtx_code operation,
+			rtx target, rtx op1, rtx op2, gcov_type value)
+{
+  rtx tmp, tmp1;
+  rtx neq_label = gen_label_rtx ();
+  rtx end_label = gen_label_rtx ();
+  rtx sequence;
+
+  start_sequence ();
+  
+  if (!REG_P (op2))
+    {
+      tmp = gen_reg_rtx (mode);
+      emit_move_insn (tmp, copy_rtx (op2));
+    }
+  else
+    tmp = op2;
+
+  do_compare_rtx_and_jump (tmp, GEN_INT (value), NE, 0, mode, NULL_RTX,
+			   NULL_RTX, neq_label);
+  tmp1 = simplify_gen_binary (operation, mode, copy_rtx (op1), GEN_INT (value));
+  tmp1 = force_operand (tmp1, target);
+  if (tmp1 != target)
+    emit_move_insn (copy_rtx (target), copy_rtx (tmp1));
+
+  emit_jump_insn (gen_jump (end_label));
+  emit_barrier ();
+
+  emit_label (neq_label);
+  tmp1 = simplify_gen_binary (operation, mode, copy_rtx (op1), copy_rtx (tmp));
+  tmp1 = force_operand (tmp1, target);
+  if (tmp1 != target)
+    emit_move_insn (copy_rtx (target), copy_rtx (tmp1));
+  
+  emit_label (end_label);
+
+  sequence = get_insns ();
+  end_sequence ();
+  rebuild_jump_labels (sequence);
+  return sequence;
+}
+
+/* Do transform 1) on INSN if applicable.  */
+static bool
+divmod_fixed_value_transform (rtx insn)
+{
+  rtx set, set_src, set_dest, op1, op2, value, histogram;
+  enum rtx_code code;
+  enum machine_mode mode;
+  gcov_type val, count, all;
+  edge e;
+
+  set = single_set (insn);
+  if (!set)
+    return false;
+
+  set_src = SET_SRC (set);
+  set_dest = SET_DEST (set);
+  code = GET_CODE (set_src);
+  mode = GET_MODE (set_dest);
+  
+  if (code != DIV && code != MOD && code != UDIV && code != UMOD)
+    return false;
+  op1 = XEXP (set_src, false);
+  op2 = XEXP (set_src, 1);
+
+  for (histogram = REG_NOTES (insn);
+       histogram;
+       histogram = XEXP (histogram, 1))
+    if (REG_NOTE_KIND (histogram) == REG_VALUE_PROFILE
+	&& XEXP (XEXP (histogram, 0), 0) == GEN_INT (HIST_TYPE_SINGLE_VALUE))
+      break;
+
+  if (!histogram)
+    return false;
+
+  histogram = XEXP (XEXP (histogram, 0), 1);
+  value = XEXP (histogram, 0);
+  histogram = XEXP (histogram, 1);
+  val = INTVAL (XEXP (histogram, 0));
+  histogram = XEXP (histogram, 1);
+  count = INTVAL (XEXP (histogram, 0));
+  histogram = XEXP (histogram, 1);
+  all = INTVAL (XEXP (histogram, 0));
+
+  /* We requiere that count is at least half of all; this means
+     that for the transformation to fire the value must be constant
+     at least 50% of time (and 75% gives the garantee of usage).  */
+  if (!rtx_equal_p (op2, value) || 2 * count < all)
+    return false;
+
+  if (rtl_dump_file)
+    fprintf (rtl_dump_file, "Div/mod by constant transformation on insn %d\n",
+	     INSN_UID (insn));
+
+  e = split_block (BLOCK_FOR_INSN (insn), PREV_INSN (insn));
+  delete_insn (insn);
+  
+  insert_insn_on_edge (
+	gen_divmod_fixed_value (mode, code, set_dest, op1, op2, val), e);
+
+  return true;
+}
+
+/* Generate code for transformation 2 (with MODE and OPERATION, operands OP1
+   and OP2 and result TARGET).  */
+static rtx
+gen_mod_pow2 (enum machine_mode mode, enum rtx_code operation, rtx target,
+	      rtx op1, rtx op2)
+{
+  rtx tmp, tmp1, tmp2, tmp3;
+  rtx neq_label = gen_label_rtx ();
+  rtx end_label = gen_label_rtx ();
+  rtx sequence;
+
+  start_sequence ();
+  
+  if (!REG_P (op2))
+    {
+      tmp = gen_reg_rtx (mode);
+      emit_move_insn (tmp, copy_rtx (op2));
+    }
+  else
+    tmp = op2;
+
+  tmp1 = expand_simple_binop (mode, PLUS, tmp, constm1_rtx, NULL_RTX,
+			      0, OPTAB_WIDEN);
+  tmp2 = expand_simple_binop (mode, AND, tmp, tmp1, NULL_RTX,
+			      0, OPTAB_WIDEN);
+  do_compare_rtx_and_jump (tmp2, const0_rtx, NE, 0, mode, NULL_RTX,
+			   NULL_RTX, neq_label);
+  tmp3 = expand_simple_binop (mode, AND, op1, tmp1, target,
+			      0, OPTAB_WIDEN);
+  if (tmp3 != target)
+    emit_move_insn (copy_rtx (target), tmp3);
+  emit_jump_insn (gen_jump (end_label));
+  emit_barrier ();
+
+  emit_label (neq_label);
+  tmp1 = simplify_gen_binary (operation, mode, copy_rtx (op1), copy_rtx (tmp));
+  tmp1 = force_operand (tmp1, target);
+  if (tmp1 != target)
+    emit_move_insn (target, tmp1);
+  
+  emit_label (end_label);
+
+  sequence = get_insns ();
+  end_sequence ();
+  rebuild_jump_labels (sequence);
+  return sequence;
+}
+
+/* Do transform 2) on INSN if applicable.  */
+static bool
+mod_pow2_value_transform (rtx insn)
+{
+  rtx set, set_src, set_dest, op1, op2, value, histogram;
+  enum rtx_code code;
+  enum machine_mode mode;
+  gcov_type wrong_values, count;
+  edge e;
+  int i;
+
+  set = single_set (insn);
+  if (!set)
+    return false;
+
+  set_src = SET_SRC (set);
+  set_dest = SET_DEST (set);
+  code = GET_CODE (set_src);
+  mode = GET_MODE (set_dest);
+  
+  if (code != UMOD)
+    return false;
+  op1 = XEXP (set_src, 0);
+  op2 = XEXP (set_src, 1);
+
+  for (histogram = REG_NOTES (insn);
+       histogram;
+       histogram = XEXP (histogram, 1))
+    if (REG_NOTE_KIND (histogram) == REG_VALUE_PROFILE
+	&& XEXP (XEXP (histogram, 0), 0) == GEN_INT (HIST_TYPE_POW2))
+      break;
+
+  if (!histogram)
+    return false;
+
+  histogram = XEXP (XEXP (histogram, 0), 1);
+  value = XEXP (histogram, 0);
+  histogram = XEXP (histogram, 1);
+  wrong_values =INTVAL (XEXP (histogram, 0));
+  histogram = XEXP (histogram, 1);
+
+  count = 0;
+  for (i = 0; i < GET_MODE_BITSIZE (mode); i++)
+    {
+      count += INTVAL (XEXP (histogram, 0));
+      histogram = XEXP (histogram, 1);
+    }
+
+  if (!rtx_equal_p (op2, value))
+    return false;
+
+  /* We require that we hit a power of two at least half of all evaluations.  */
+  if (count < wrong_values)
+    return false;
+
+  if (rtl_dump_file)
+    fprintf (rtl_dump_file, "Mod power of 2 transformation on insn %d\n",
+	     INSN_UID (insn));
+
+  e = split_block (BLOCK_FOR_INSN (insn), PREV_INSN (insn));
+  delete_insn (insn);
+  
+  insert_insn_on_edge (
+	gen_mod_pow2 (mode, code, set_dest, op1, op2), e);
+
+  return true;
+}
+
+/* Generate code for transformations 3 and 4 (with MODE and OPERATION,
+   operands OP1 and OP2, result TARGET and at most SUB subtractions).  */
+static rtx
+gen_mod_subtract (enum machine_mode mode, enum rtx_code operation,
+		  rtx target, rtx op1, rtx op2, int sub)
+{
+  rtx tmp, tmp1;
+  rtx end_label = gen_label_rtx ();
+  rtx sequence;
+  int i;
+
+  start_sequence ();
+  
+  if (!REG_P (op2))
+    {
+      tmp = gen_reg_rtx (mode);
+      emit_move_insn (tmp, copy_rtx (op2));
+    }
+  else
+    tmp = op2;
+
+  emit_move_insn (target, copy_rtx (op1));
+  do_compare_rtx_and_jump (target, tmp, LTU, 0, mode, NULL_RTX,
+			   NULL_RTX, end_label);
+  
+
+  for (i = 0; i < sub; i++)
+    {
+      tmp1 = expand_simple_binop (mode, MINUS, target, tmp, target,
+	    			  0, OPTAB_WIDEN);
+      if (tmp1 != target)
+	emit_move_insn (target, tmp1);
+      do_compare_rtx_and_jump (target, tmp, LTU, 0, mode, NULL_RTX,
+    			       NULL_RTX, end_label);
+    }
+
+  tmp1 = simplify_gen_binary (operation, mode, copy_rtx (target), copy_rtx (tmp));
+  tmp1 = force_operand (tmp1, target);
+  if (tmp1 != target)
+    emit_move_insn (target, tmp1);
+  
+  emit_label (end_label);
+
+  sequence = get_insns ();
+  end_sequence ();
+  rebuild_jump_labels (sequence);
+  return sequence;
+}
+
+/* Do transforms 3) and 4) on INSN if applicable.  */
+static bool
+mod_subtract_transform (rtx insn)
+{
+  rtx set, set_src, set_dest, op1, op2, value, histogram;
+  enum rtx_code code;
+  enum machine_mode mode;
+  gcov_type wrong_values, counts[2], count, all;
+  edge e;
+  int i;
+
+  set = single_set (insn);
+  if (!set)
+    return false;
+
+  set_src = SET_SRC (set);
+  set_dest = SET_DEST (set);
+  code = GET_CODE (set_src);
+  mode = GET_MODE (set_dest);
+  
+  if (code != UMOD)
+    return false;
+  op1 = XEXP (set_src, 0);
+  op2 = XEXP (set_src, 1);
+
+  for (histogram = REG_NOTES (insn);
+       histogram;
+       histogram = XEXP (histogram, 1))
+    if (REG_NOTE_KIND (histogram) == REG_VALUE_PROFILE
+	&& XEXP (XEXP (histogram, 0), 0) == GEN_INT (HIST_TYPE_INTERVAL))
+      break;
+
+  if (!histogram)
+    return false;
+
+  histogram = XEXP (XEXP (histogram, 0), 1);
+  value = XEXP (histogram, 0);
+  histogram = XEXP (histogram, 1);
+
+  all = 0;
+  for (i = 0; i < 2; i++)
+    {
+      counts[i] = INTVAL (XEXP (histogram, 0));
+      all += counts[i];
+      histogram = XEXP (histogram, 1);
+    }
+  wrong_values = INTVAL (XEXP (histogram, 0));
+  histogram = XEXP (histogram, 1);
+  wrong_values += INTVAL (XEXP (histogram, 0));
+  all += wrong_values;
+
+  /* We require that we use just subtractions in at least 50% of all
+     evaluations.  */
+  count = 0;
+  for (i = 0; i < 2; i++)
+    {
+      count += counts[i];
+      if (count * 2 >= all)
+	break;
+    }
+  
+  if (i == 2)
+    return false;
+
+  if (rtl_dump_file)
+    fprintf (rtl_dump_file, "Mod subtract transformation on insn %d\n",
+	     INSN_UID (insn));
+
+  e = split_block (BLOCK_FOR_INSN (insn), PREV_INSN (insn));
+  delete_insn (insn);
+  
+  insert_insn_on_edge (
+	gen_mod_subtract (mode, code, set_dest, op1, op2, i), e);
+
+  return true;
+}