2014-03-18 Richard Biener <rguenther@suse.de>

 
	Backport from mainline
	2013-08-27  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/57521
	* tree-if-conv.c (if_convertible_bb_p): Verify that at least
	one edge is non-critical.
	(find_phi_replacement_condition): Make sure to use a non-critical
	edge.  Cleanup and remove old bug workarounds.
	(bb_postdominates_preds): Remove.
	(if_convertible_loop_p_1): Do not compute post-dominators.
	(combine_blocks): Do not free post-dominators.
	(main_tree_if_conversion): Likewise.

	* gcc.dg/torture/pr57521.c: New testcase.

	2013-09-03  Richard Biener  <rguenther@suse.de>

	PR middle-end/57656
	* fold-const.c (negate_expr_p): Fix division case.
	(negate_expr): Likewise.

	* gcc.dg/torture/pr57656.c: New testcase.

	2013-11-19  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/57517
	* tree-predcom.c (combinable_refs_p): Verify the combination
	is always executed when the refs are.

	* gfortran.fortran-torture/compile/pr57517.f90: New testcase.
	* gcc.dg/torture/pr57517.c: Likewise.


git-svn-id: https://gcc.gnu.org/svn/gcc/branches/gcc-4_7-branch@208632 138bc75d-0d04-0410-961f-82ee72b054a4

9 files changed, 199 insertions, 73 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 974814a0dbb..9eadc622bc8 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,30 @@
+2014-03-18  Richard Biener  <rguenther@suse.de>
+ 
+	Backport from mainline
+	2013-08-27  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/57521
+	* tree-if-conv.c (if_convertible_bb_p): Verify that at least
+	one edge is non-critical.
+	(find_phi_replacement_condition): Make sure to use a non-critical
+	edge.  Cleanup and remove old bug workarounds.
+	(bb_postdominates_preds): Remove.
+	(if_convertible_loop_p_1): Do not compute post-dominators.
+	(combine_blocks): Do not free post-dominators.
+	(main_tree_if_conversion): Likewise.
+
+	2013-09-03  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/57656
+	* fold-const.c (negate_expr_p): Fix division case.
+	(negate_expr): Likewise.
+
+	2013-11-19  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/57517
+	* tree-predcom.c (combinable_refs_p): Verify the combination
+	is always executed when the refs are.
+
 2014-03-17  Richard Biener  <rguenther@suse.de>
 
 	Backport from mainline
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 1f864a78ce9..804a05f927a 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -486,11 +486,24 @@ negate_expr_p (tree t)
 	 and actually traps on some architectures.  But if overflow is
 	 undefined, we can negate, because - (INT_MIN / 1) is an
 	 overflow.  */
-      if (INTEGRAL_TYPE_P (TREE_TYPE (t))
-	  && !TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (t)))
-        break;
-      return negate_expr_p (TREE_OPERAND (t, 1))
-             || negate_expr_p (TREE_OPERAND (t, 0));
+      if (INTEGRAL_TYPE_P (TREE_TYPE (t)))
+	{
+	  if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (t)))
+	    break;
+	  /* If overflow is undefined then we have to be careful because
+	     we ask whether it's ok to associate the negate with the
+	     division which is not ok for example for
+	     -((a - b) / c) where (-(a - b)) / c may invoke undefined
+	     overflow because of negating INT_MIN.  So do not use
+	     negate_expr_p here but open-code the two important cases.  */
+	  if (TREE_CODE (TREE_OPERAND (t, 0)) == NEGATE_EXPR
+	      || (TREE_CODE (TREE_OPERAND (t, 0)) == INTEGER_CST
+		  && may_negate_without_overflow_p (TREE_OPERAND (t, 0))))
+	    return true;
+	}
+      else if (negate_expr_p (TREE_OPERAND (t, 0)))
+	return true;
+      return negate_expr_p (TREE_OPERAND (t, 1));
 
     case NOP_EXPR:
       /* Negate -((double)float) as (double)(-float).  */
@@ -670,16 +683,20 @@ fold_negate_expr (location_t loc, tree t)
 	      return fold_build2_loc (loc, TREE_CODE (t), type,
 				  TREE_OPERAND (t, 0), negate_expr (tem));
 	    }
+	  /* If overflow is undefined then we have to be careful because
+	     we ask whether it's ok to associate the negate with the
+	     division which is not ok for example for
+	     -((a - b) / c) where (-(a - b)) / c may invoke undefined
+	     overflow because of negating INT_MIN.  So do not use
+	     negate_expr_p here but open-code the two important cases.  */
           tem = TREE_OPERAND (t, 0);
-          if (negate_expr_p (tem))
-	    {
-	      if (INTEGRAL_TYPE_P (type)
-		  && (TREE_CODE (tem) != INTEGER_CST
-		      || tree_int_cst_equal (tem, TYPE_MIN_VALUE (type))))
-		fold_overflow_warning (warnmsg, WARN_STRICT_OVERFLOW_MISC);
-	      return fold_build2_loc (loc, TREE_CODE (t), type,
-				  negate_expr (tem), TREE_OPERAND (t, 1));
-	    }
+	  if ((INTEGRAL_TYPE_P (type)
+	       && (TREE_CODE (tem) == NEGATE_EXPR
+		   || (TREE_CODE (tem) == INTEGER_CST
+		       && may_negate_without_overflow_p (tem))))
+	      || !INTEGRAL_TYPE_P (type))
+	    return fold_build2_loc (loc, TREE_CODE (t), type,
+				    negate_expr (tem), TREE_OPERAND (t, 1));
         }
       break;
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 2cd6e12618f..835bd98665d 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,22 @@
+2014-03-18  Richard Biener  <rguenther@suse.de>
+ 
+	Backport from mainline
+	2013-08-27  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/57521
+	* gcc.dg/torture/pr57521.c: New testcase.
+
+	2013-09-03  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/57656
+	* gcc.dg/torture/pr57656.c: New testcase.
+
+	2013-11-19  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/57517
+	* gfortran.fortran-torture/compile/pr57517.f90: New testcase.
+	* gcc.dg/torture/pr57517.c: Likewise.
+
 2014-03-17  Richard Biener  <rguenther@suse.de>
 
 	Backport from mainline
diff --git a/gcc/testsuite/gcc.dg/torture/pr57517.c b/gcc/testsuite/gcc.dg/torture/pr57517.c
new file mode 100644
index 00000000000..2422d8ee64a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr57517.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+
+int x[1024], y[1024], z[1024], w[1024];
+void foo (void)
+{
+  int i;
+  for (i = 1; i < 1024; ++i)
+    {
+      int a = x[i];
+      int b = y[i];
+      int c = x[i-1];
+      int d = y[i-1];
+      if (w[i])
+	z[i] = (a + b) + (c + d);
+    }
+}
diff --git a/gcc/testsuite/gcc.dg/torture/pr57521.c b/gcc/testsuite/gcc.dg/torture/pr57521.c
new file mode 100644
index 00000000000..e7832cb00e8
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr57521.c
@@ -0,0 +1,51 @@
+/* { dg-do run } */
+/* { dg-options "-ftree-loop-if-convert" } */
+
+void abort (void);
+
+int a, b, c, d, o = 1, p;
+short e;
+
+int
+fn1 (int * p1)
+{
+  int f, g, h, j = 0, k = 0, l = 0;
+  unsigned int i;
+  int *m[1] = { &l };
+  for (; b >= 0; b--)
+    {
+      if (*p1)
+	if (j >= 0)
+	  {
+	    int n = 1;
+	    e = 1;
+	    h = a ? a : 1 % n;
+	    g = h > 0 ? 0 : h + 1;
+	    k = c + g;
+	  }
+	else
+	  continue;
+      else
+	{
+
+	  f = d > 0 ? 0 : d + 1;
+	  i = f;
+	  j = 1 + i;
+	}
+      l++;
+    }
+  return k;
+}
+
+int
+main ()
+{
+  for (;; p++)
+    {
+      fn1 (&o);
+      break;
+    }
+  if (e != 1)
+    abort ();
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/torture/pr57656.c b/gcc/testsuite/gcc.dg/torture/pr57656.c
new file mode 100644
index 00000000000..4f3645e4693
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr57656.c
@@ -0,0 +1,13 @@
+/* { dg-do run } */
+/* { dg-options "-fstrict-overflow" } */
+
+int main (void)
+{
+  int a = -1;
+  int b = __INT_MAX__;
+  int c = 2;
+  int t = 1 - ((a - b) / c);  // t = 1 - ( __INT_MIN__ / 2 )
+  if (t != (1 - (-1 - __INT_MAX__) / 2))
+    __builtin_abort();
+  return 0;
+}
diff --git a/gcc/testsuite/gfortran.fortran-torture/compile/pr57517.f90 b/gcc/testsuite/gfortran.fortran-torture/compile/pr57517.f90
new file mode 100644
index 00000000000..f32698aa3a6
--- /dev/null
+++ b/gcc/testsuite/gfortran.fortran-torture/compile/pr57517.f90
@@ -0,0 +1,13 @@
+SUBROUTINE cal_helicity (uh, ph, phb, wavg, ims, ime, its, ite)
+  INTEGER, INTENT( IN ) :: ims, ime, its, ite
+  REAL, DIMENSION( ims:ime), INTENT( IN ) :: ph, phb, wavg
+  REAL, DIMENSION( ims:ime), INTENT( INOUT ) :: uh
+  INTEGER :: i
+  REAL :: zu
+  DO i = its, ite
+    zu =  (ph(i ) + phb(i)) + (ph(i-1) + phb(i-1))
+    IF (wavg(i) .GT. 0) THEN
+      uh(i) = uh(i) + zu 
+    ENDIF
+  END DO
+END SUBROUTINE cal_helicity
diff --git a/gcc/tree-if-conv.c b/gcc/tree-if-conv.c
index 9d09f0f4d26..316b4e2d57d 100644
--- a/gcc/tree-if-conv.c
+++ b/gcc/tree-if-conv.c
@@ -758,20 +758,6 @@ if_convertible_stmt_p (gimple stmt, VEC (data_reference_p, heap) *refs)
   return true;
 }
 
-/* Return true when BB post-dominates all its predecessors.  */
-
-static bool
-bb_postdominates_preds (basic_block bb)
-{
-  unsigned i;
-
-  for (i = 0; i < EDGE_COUNT (bb->preds); i++)
-    if (!dominated_by_p (CDI_POST_DOMINATORS, EDGE_PRED (bb, i)->src, bb))
-      return false;
-
-  return true;
-}
-
 /* Return true when BB is if-convertible.  This routine does not check
    basic block's statements and phis.
 
@@ -830,10 +816,23 @@ if_convertible_bb_p (struct loop *loop, basic_block bb, basic_block exit_bb)
 	return false;
       }
 
-  if (EDGE_COUNT (bb->preds) == 2
-      && bb != loop->header
-      && !bb_postdominates_preds (bb))
-    return false;
+  /* At least one incoming edge has to be non-critical as otherwise edge
+     predicates are not equal to basic-block predicates of the edge
+     source.  */
+  if (EDGE_COUNT (bb->preds) > 1
+      && bb != loop->header)
+    {
+      bool found = false;
+      FOR_EACH_EDGE (e, ei, bb->preds)
+	if (EDGE_COUNT (e->src->succs) == 1)
+	  found = true;
+      if (!found)
+	{
+	  if (dump_file && (dump_flags & TDF_DETAILS))
+	    fprintf (dump_file, "only critical predecessors\n");
+	  return false;
+	}
+    }
 
   return true;
 }
@@ -1048,7 +1047,6 @@ if_convertible_loop_p_1 (struct loop *loop,
     return false;
 
   calculate_dominance_info (CDI_DOMINATORS);
-  calculate_dominance_info (CDI_POST_DOMINATORS);
 
   /* Allow statements that can be handled during if-conversion.  */
   ifc_bbs = get_loop_body_in_if_conv_order (loop);
@@ -1184,8 +1182,7 @@ if_convertible_loop_p (struct loop *loop)
    if-conversion.  */
 
 static basic_block
-find_phi_replacement_condition (struct loop *loop,
-				basic_block bb, tree *cond,
+find_phi_replacement_condition (basic_block bb, tree *cond,
 				gimple_stmt_iterator *gsi)
 {
   edge first_edge, second_edge;
@@ -1195,34 +1192,10 @@ find_phi_replacement_condition (struct loop *loop,
   first_edge = EDGE_PRED (bb, 0);
   second_edge = EDGE_PRED (bb, 1);
 
-  /* Use condition based on following criteria:
-     1)
-       S1: x = !c ? a : b;
-
-       S2: x = c ? b : a;
-
-       S2 is preferred over S1. Make 'b' first_bb and use its condition.
-
-     2) Do not make loop header first_bb.
-
-     3)
-       S1: x = !(c == d)? a : b;
-
-       S21: t1 = c == d;
-       S22: x = t1 ? b : a;
-
-       S3: x = (c == d) ? b : a;
-
-       S3 is preferred over S1 and S2*, Make 'b' first_bb and use
-       its condition.
-
-     4) If  pred B is dominated by pred A then use pred B's condition.
-        See PR23115.  */
-
-  /* Select condition that is not TRUTH_NOT_EXPR.  */
+  /* Prefer an edge with a not negated predicate.
+     ???  That's a very weak cost model.  */
   tmp_cond = bb_predicate (first_edge->src);
   gcc_assert (tmp_cond);
-
   if (TREE_CODE (tmp_cond) == TRUTH_NOT_EXPR)
     {
       edge tmp_edge;
@@ -1232,11 +1205,9 @@ find_phi_replacement_condition (struct loop *loop,
       second_edge = tmp_edge;
     }
 
-  /* Check if FIRST_BB is loop header or not and make sure that
-     FIRST_BB does not dominate SECOND_BB.  */
-  if (first_edge->src == loop->header
-      || dominated_by_p (CDI_DOMINATORS,
-			 second_edge->src, first_edge->src))
+  /* Check if the edge we take the condition from is not critical.
+     We know that at least one non-critical edge exists.  */
+  if (EDGE_COUNT (first_edge->src->succs) > 1)
     {
       *cond = bb_predicate (second_edge->src);
 
@@ -1311,9 +1282,6 @@ predicate_scalar_phi (gimple phi, tree cond,
 	  arg_1 = gimple_phi_arg_def (phi, 1);
 	}
 
-      gcc_checking_assert (bb == bb->loop_father->header
-			   || bb_postdominates_preds (bb));
-
       /* Build new RHS using selected condition and arguments.  */
       rhs = build3 (COND_EXPR, TREE_TYPE (res),
 		    unshare_expr (cond), arg_0, arg_1);
@@ -1359,7 +1327,7 @@ predicate_all_scalar_phis (struct loop *loop)
       /* BB has two predecessors.  Using predecessor's aux field, set
 	 appropriate condition for the PHI node replacement.  */
       gsi = gsi_after_labels (bb);
-      true_bb = find_phi_replacement_condition (loop, bb, &cond, &gsi);
+      true_bb = find_phi_replacement_condition (bb, &cond, &gsi);
 
       while (!gsi_end_p (phi_gsi))
 	{
@@ -1791,8 +1759,6 @@ main_tree_if_conversion (void)
   if (changed && flag_tree_loop_if_convert_stores)
     todo |= TODO_update_ssa_only_virtuals;
 
-  free_dominance_info (CDI_POST_DOMINATORS);
-
   return todo;
 }
 
diff --git a/gcc/tree-predcom.c b/gcc/tree-predcom.c
index 1566902e3d7..61a1c741d1c 100644
--- a/gcc/tree-predcom.c
+++ b/gcc/tree-predcom.c
@@ -2117,7 +2117,11 @@ combinable_refs_p (dref r1, dref r2,
 
   stmt = find_common_use_stmt (&name1, &name2);
 
-  if (!stmt)
+  if (!stmt
+      /* A simple post-dominance check - make sure the combination
+         is executed under the same condition as the references.  */
+      || (gimple_bb (stmt) != gimple_bb (r1->stmt)
+	  && gimple_bb (stmt) != gimple_bb (r2->stmt)))
     return false;
 
   acode = gimple_assign_rhs_code (stmt);