[committed] Backport PR87473 fix to GCC 8

Message ID 9f661a32-e49a-c9f1-1250-fc544c8c0858@linux.ibm.com
State New
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  • [committed] Backport PR87473 fix to GCC 8
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Commit Message

Bill Schmidt Oct. 26, 2018, 6:53 p.m.
Committed the backport as follows:

[gcc]

2018-10-26  Bill Schmidt  <wschmidt@linux.ibm.com>

	Backport from mainline
	2018-10-19  Bill Schmidt  <wschmidt@linux.ibm.com>

	PR tree-optimization/87473
	* gimple-ssa-strength-reduction.c (record_phi_increments_1): For
	phi arguments identical to the base expression of the phi
	candidate, record a phi-adjust increment of zero minus the index
	expression of the hidden basis.
	(phi_incr_cost_1): For phi arguments identical to the base
	expression of the phi candidate, the difference to compare against
	the increment is zero minus the index expression of the hidden
	basis, and there is no potential savings from replacing the (phi)
	statement.
	(ncd_with_phi): For phi arguments identical to the base expression
	of the phi candidate, the difference to compare against the
	increment is zero minus the index expression of the hidden basis.
	(all_phi_incrs_profitable_1): For phi arguments identical to the
	base expression of the phi candidate, the increment to be checked
	for profitability is zero minus the index expression of the hidden
	basis.

[gcc/testsuite]

2018-10-26  Bill Schmidt  <wschmidt@linux.ibm.com>

	Backport from mainline
	2018-10-19  Bill Schmidt  <wschmidt@linux.ibm.com>

	PR tree-optimization/87473
	* gcc.c-torture/compile/pr87473.c: New file.

Patch

Index: gcc/gimple-ssa-strength-reduction.c
===================================================================
--- gcc/gimple-ssa-strength-reduction.c	(revision 265534)
+++ gcc/gimple-ssa-strength-reduction.c	(working copy)
@@ -2779,17 +2779,23 @@  record_phi_increments_1 (slsr_cand_t basis, gimple
   for (i = 0; i < gimple_phi_num_args (phi); i++)
     {
       tree arg = gimple_phi_arg_def (phi, i);
+      gimple *arg_def = SSA_NAME_DEF_STMT (arg);
 
-      if (!operand_equal_p (arg, phi_cand->base_expr, 0))
+      if (gimple_code (arg_def) == GIMPLE_PHI)
+	record_phi_increments_1 (basis, arg_def);
+      else
 	{
-	  gimple *arg_def = SSA_NAME_DEF_STMT (arg);
+	  widest_int diff;
 
-	  if (gimple_code (arg_def) == GIMPLE_PHI)
-	    record_phi_increments_1 (basis, arg_def);
+	  if (operand_equal_p (arg, phi_cand->base_expr, 0))
+	    {
+	      diff = -basis->index;
+	      record_increment (phi_cand, diff, PHI_ADJUST);
+	    }
 	  else
 	    {
 	      slsr_cand_t arg_cand = base_cand_from_table (arg);
-	      widest_int diff = arg_cand->index - basis->index;
+	      diff = arg_cand->index - basis->index;
 	      record_increment (arg_cand, diff, PHI_ADJUST);
 	    }
 	}
@@ -2864,29 +2870,43 @@  phi_incr_cost_1 (slsr_cand_t c, const widest_int &
   for (i = 0; i < gimple_phi_num_args (phi); i++)
     {
       tree arg = gimple_phi_arg_def (phi, i);
+      gimple *arg_def = SSA_NAME_DEF_STMT (arg);
 
-      if (!operand_equal_p (arg, phi_cand->base_expr, 0))
+      if (gimple_code (arg_def) == GIMPLE_PHI)
 	{
-	  gimple *arg_def = SSA_NAME_DEF_STMT (arg);
-      
-	  if (gimple_code (arg_def) == GIMPLE_PHI)
+	  int feeding_savings = 0;
+	  tree feeding_var = gimple_phi_result (arg_def);
+	  cost += phi_incr_cost_1 (c, incr, arg_def, &feeding_savings);
+	  if (uses_consumed_by_stmt (feeding_var, phi))
+	    *savings += feeding_savings;
+	}
+      else
+	{
+	  widest_int diff;
+	  slsr_cand_t arg_cand;
+
+	  /* When the PHI argument is just a pass-through to the base
+	     expression of the hidden basis, the difference is zero minus
+	     the index of the basis.  There is no potential savings by
+	     eliminating a statement in this case.  */
+	  if (operand_equal_p (arg, phi_cand->base_expr, 0))
 	    {
-	      int feeding_savings = 0;
-	      tree feeding_var = gimple_phi_result (arg_def);
-	      cost += phi_incr_cost_1 (c, incr, arg_def, &feeding_savings);
-	      if (uses_consumed_by_stmt (feeding_var, phi))
-		*savings += feeding_savings;
+	      arg_cand = (slsr_cand_t)NULL;
+	      diff = -basis->index;
 	    }
 	  else
 	    {
-	      slsr_cand_t arg_cand = base_cand_from_table (arg);
-	      widest_int diff = arg_cand->index - basis->index;
-
-	      if (incr == diff)
+	      arg_cand = base_cand_from_table (arg);
+	      diff = arg_cand->index - basis->index;
+	    }
+	  
+	  if (incr == diff)
+	    {
+	      tree basis_lhs = gimple_assign_lhs (basis->cand_stmt);
+	      cost += add_cost (true, TYPE_MODE (TREE_TYPE (basis_lhs)));
+	      if (arg_cand)
 		{
-		  tree basis_lhs = gimple_assign_lhs (basis->cand_stmt);
 		  tree lhs = gimple_assign_lhs (arg_cand->cand_stmt);
-		  cost += add_cost (true, TYPE_MODE (TREE_TYPE (basis_lhs)));
 		  if (uses_consumed_by_stmt (lhs, phi))
 		    *savings += stmt_cost (arg_cand->cand_stmt, true);
 		}
@@ -3228,23 +3248,26 @@  ncd_with_phi (slsr_cand_t c, const widest_int &inc
   for (i = 0; i < gimple_phi_num_args (phi); i++)
     {
       tree arg = gimple_phi_arg_def (phi, i);
+      gimple *arg_def = SSA_NAME_DEF_STMT (arg);
 
-      if (!operand_equal_p (arg, phi_cand->base_expr, 0))
+      if (gimple_code (arg_def) == GIMPLE_PHI)
+	ncd = ncd_with_phi (c, incr, as_a <gphi *> (arg_def), ncd, where);
+      else 
 	{
-	  gimple *arg_def = SSA_NAME_DEF_STMT (arg);
+	  widest_int diff;
 
-	  if (gimple_code (arg_def) == GIMPLE_PHI)
-	    ncd = ncd_with_phi (c, incr, as_a <gphi *> (arg_def), ncd,
-				where);
-	  else 
+	  if (operand_equal_p (arg, phi_cand->base_expr, 0))
+	    diff = -basis->index;
+	  else
 	    {
 	      slsr_cand_t arg_cand = base_cand_from_table (arg);
-	      widest_int diff = arg_cand->index - basis->index;
-	      basic_block pred = gimple_phi_arg_edge (phi, i)->src;
-
-	      if ((incr == diff) || (!address_arithmetic_p && incr == -diff))
-		ncd = ncd_for_two_cands (ncd, pred, *where, NULL, where);
+	      diff = arg_cand->index - basis->index;
 	    }
+	  
+	  basic_block pred = gimple_phi_arg_edge (phi, i)->src;
+	  
+	  if ((incr == diff) || (!address_arithmetic_p && incr == -diff))
+	    ncd = ncd_for_two_cands (ncd, pred, *where, NULL, where);
 	}
     }
 
@@ -3515,51 +3538,53 @@  all_phi_incrs_profitable_1 (slsr_cand_t c, gphi *p
 	return false;
 
       tree arg = gimple_phi_arg_def (phi, i);
+      gimple *arg_def = SSA_NAME_DEF_STMT (arg);
 
-      if (!operand_equal_p (arg, phi_cand->base_expr, 0))
+      if (gimple_code (arg_def) == GIMPLE_PHI)
 	{
-	  gimple *arg_def = SSA_NAME_DEF_STMT (arg);
+	  if (!all_phi_incrs_profitable_1 (c, as_a <gphi *> (arg_def), spread)
+	      || *spread > MAX_SPREAD)
+	    return false;
+	}
+      else
+	{
+	  int j;
+	  widest_int increment;
 
-	  if (gimple_code (arg_def) == GIMPLE_PHI)
-	    {
-	      if (!all_phi_incrs_profitable_1 (c, as_a <gphi *> (arg_def),
-					       spread)
-		  || *spread > MAX_SPREAD)
-		return false;
-	    }
+	  if (operand_equal_p (arg, phi_cand->base_expr, 0))
+	    increment = -basis->index;
 	  else
 	    {
-	      int j;
 	      slsr_cand_t arg_cand = base_cand_from_table (arg);
-	      widest_int increment = arg_cand->index - basis->index;
+	      increment = arg_cand->index - basis->index;
+	    }
 
-	      if (!address_arithmetic_p && wi::neg_p (increment))
-		increment = -increment;
+	  if (!address_arithmetic_p && wi::neg_p (increment))
+	    increment = -increment;
 
-	      j = incr_vec_index (increment);
+	  j = incr_vec_index (increment);
 
-	      if (dump_file && (dump_flags & TDF_DETAILS))
-		{
-		  fprintf (dump_file, "  Conditional candidate %d, phi: ",
-			   c->cand_num);
-		  print_gimple_stmt (dump_file, phi, 0);
-		  fputs ("    increment: ", dump_file);
-		  print_decs (increment, dump_file);
-		  if (j < 0)
-		    fprintf (dump_file,
-			     "\n  Not replaced; incr_vec overflow.\n");
-		  else {
-		    fprintf (dump_file, "\n    cost: %d\n", incr_vec[j].cost);
-		    if (profitable_increment_p (j))
-		      fputs ("  Replacing...\n", dump_file);
-		    else
-		      fputs ("  Not replaced.\n", dump_file);
-		  }
-		}
+	  if (dump_file && (dump_flags & TDF_DETAILS))
+	    {
+	      fprintf (dump_file, "  Conditional candidate %d, phi: ",
+		       c->cand_num);
+	      print_gimple_stmt (dump_file, phi, 0);
+	      fputs ("    increment: ", dump_file);
+	      print_decs (increment, dump_file);
+	      if (j < 0)
+		fprintf (dump_file,
+			 "\n  Not replaced; incr_vec overflow.\n");
+	      else {
+		fprintf (dump_file, "\n    cost: %d\n", incr_vec[j].cost);
+		if (profitable_increment_p (j))
+		  fputs ("  Replacing...\n", dump_file);
+		else
+		  fputs ("  Not replaced.\n", dump_file);
+	      }
+	    }
 
-	      if (j < 0 || !profitable_increment_p (j))
-		return false;
-	    }
+	  if (j < 0 || !profitable_increment_p (j))
+	    return false;
 	}
     }
 
Index: gcc/testsuite/gcc.c-torture/compile/pr87473.c
===================================================================
--- gcc/testsuite/gcc.c-torture/compile/pr87473.c	(nonexistent)
+++ gcc/testsuite/gcc.c-torture/compile/pr87473.c	(working copy)
@@ -0,0 +1,19 @@ 
+/* PR87473: SLSR ICE on hidden basis with |increment| > 1.  */
+/* { dg-additional-options "-fno-tree-ch" } */
+
+void
+t6 (int qz, int wh)
+{
+  int jl = wh;
+
+  while (1.0 / 0 < 1)
+    {
+      qz = wh * (wh + 2);
+
+      while (wh < 1)
+        jl = 0;
+    }
+
+  while (qz < 1)
+    qz = jl * wh;
+}