re PR c++/49039 (LLVM StringRef miscompilation with -O2)

PR tree-optimization/49039
	* tree-vrp.c (extract_range_from_binary_expr): For
	MIN_EXPR <~[a, b], ~[c, d]> and MAX_EXPR <~[a, b], ~[c, d]>
	return ~[MAX_EXPR <a, c>, MIN_EXPR <b, d>].

	* gcc.c-torture/execute/pr49039.c: New test.
	* gcc.dg/tree-ssa/pr49039.c: New test.
	* g++.dg/torture/pr49039.C: New test.

From-SVN: r173876

gcc/ChangeLog

@@ -1,3 +1,10 @@
+2011-05-18  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/49039
+	* tree-vrp.c (extract_range_from_binary_expr): For
+	MIN_EXPR <~[a, b], ~[c, d]> and MAX_EXPR <~[a, b], ~[c, d]>
+	return ~[MAX_EXPR <a, c>, MIN_EXPR <b, d>].
+
 2011-05-18  Tom de Vries  <tom@codesourcery.com>
 
 	PR target/45098

gcc/testsuite/ChangeLog

@@ -1,3 +1,10 @@
+2011-05-18  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/49039
+	* gcc.c-torture/execute/pr49039.c: New test.
+	* gcc.dg/tree-ssa/pr49039.c: New test.
+	* g++.dg/torture/pr49039.C: New test.
+
 2011-05-18  Jason Merrill  <jason@redhat.com>
 
 	* g++.dg/cpp0x/constexpr-incomplete3.C: New.

gcc/testsuite/g++.dg/torture/pr49039.C

@@ -0,0 +1,76 @@
+// PR tree-optimization/49039
+// { dg-do run }
+
+template <class T1, class T2>
+struct pair
+{
+  T1 first;
+  T2 second;
+  pair (const T1 & a, const T2 & b):first (a), second (b) {}
+};
+
+template <class T1, class T2>
+inline pair <T1, T2>
+make_pair (T1 x, T2 y)
+{
+  return pair <T1, T2> (x, y);
+}
+
+typedef __SIZE_TYPE__ size_t;
+struct S
+{
+  const char *Data;
+  size_t Length;
+  static size_t min (size_t a, size_t b) { return a < b ? a : b; }
+  static size_t max (size_t a, size_t b) { return a > b ? a : b; }
+  S () :Data (0), Length (0) { }
+  S (const char *Str) : Data (Str), Length (__builtin_strlen (Str)) {}
+  S (const char *data, size_t length) : Data (data), Length (length) {}
+  bool empty () const { return Length == 0; }
+  size_t size () const { return Length; }
+  S slice (size_t Start, size_t End) const
+  {
+    Start = min (Start, Length);
+    End = min (max (Start, End), Length);
+    return S (Data + Start, End - Start);
+  }
+  pair <S, S> split (char Separator) const
+  {
+    size_t Idx = find (Separator);
+    if (Idx == ~size_t (0))
+      return make_pair (*this, S ());
+    return make_pair (slice (0, Idx), slice (Idx + 1, ~size_t (0)));
+  }
+  size_t find (char C, size_t From = 0) const
+  {
+    for (size_t i = min (From, Length), e = Length; i != e; ++i)
+      if (Data[i] == C)
+	return i;
+    return ~size_t (0);
+  }
+};
+
+void
+Test (const char *arg)
+{
+  S Desc (arg);
+  while (!Desc.empty ())
+    {
+      pair <S, S> Split = Desc.split ('-');
+      S Token = Split.first;
+      Desc = Split.second;
+      if (Token.empty ())
+	continue;
+      Split = Token.split (':');
+      S Specifier = Split.first;
+      if (Specifier.empty ())
+	__builtin_abort ();
+    }
+}
+
+int
+main ()
+{
+  Test ("-");
+  return 0;
+}

gcc/testsuite/gcc.c-torture/execute/pr49039.c

@@ -0,0 +1,26 @@
+/* PR tree-optimization/49039 */
+extern void abort (void);
+int cnt;
+
+__attribute__((noinline, noclone)) void
+foo (unsigned int x, unsigned int y)
+{
+  unsigned int minv, maxv;
+  if (x == 1 || y == -2U)
+    return;
+  minv = x < y ? x : y;
+  maxv = x > y ? x : y;
+  if (minv == 1)
+    ++cnt;
+  if (maxv == -2U)
+    ++cnt;
+}
+
+int
+main ()
+{
+  foo (-2U, 1);
+  if (cnt != 2)
+    abort ();
+  return 0;
+}

gcc/testsuite/gcc.dg/tree-ssa/pr49039.c

@@ -0,0 +1,31 @@
+/* PR tree-optimization/49039 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-vrp1" } */
+
+extern void bar (void);
+
+void
+foo (unsigned int x, unsigned int y)
+{
+  unsigned int minv, maxv;
+  if (x >= 3 && x <= 6)
+    return;
+  if (y >= 5 && y <= 8)
+    return;
+  minv = x < y ? x : y;
+  maxv = x > y ? x : y;
+  if (minv == 5)
+    bar ();
+  if (minv == 6)
+    bar ();
+  if (maxv == 5)
+    bar ();
+  if (maxv == 6)
+    bar ();
+}
+
+/* { dg-final { scan-tree-dump "Folding predicate minv_\[0-9\]* == 5 to 0" "vrp1" } } */
+/* { dg-final { scan-tree-dump "Folding predicate minv_\[0-9\]* == 6 to 0" "vrp1" } } */
+/* { dg-final { scan-tree-dump "Folding predicate maxv_\[0-9\]* == 5 to 0" "vrp1" } } */
+/* { dg-final { scan-tree-dump "Folding predicate maxv_\[0-9\]* == 6 to 0" "vrp1" } } */
+/* { dg-final { cleanup-tree-dump "vrp1" } } */

gcc/tree-vrp.c

@@ -1,5 +1,5 @@
 /* Support routines for Value Range Propagation (VRP).
-   Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010
+   Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011
    Free Software Foundation, Inc.
    Contributed by Diego Novillo <dnovillo@redhat.com>.
 
@@ -2358,17 +2358,27 @@ extract_range_from_binary_expr (value_range_t *vr,
 	 op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0].
 	 Note that we are guaranteed to have vr0.type == vr1.type at
 	 this point.  */
-      if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE)
+      if (vr0.type == VR_ANTI_RANGE)
 	{
-	  set_value_range_to_varying (vr);
-	  return;
+	  if (code == PLUS_EXPR)
+	    {
+	      set_value_range_to_varying (vr);
+	      return;
+	    }
+	  /* For MIN_EXPR and MAX_EXPR with two VR_ANTI_RANGEs,
+	     the resulting VR_ANTI_RANGE is the same - intersection
+	     of the two ranges.  */
+	  min = vrp_int_const_binop (MAX_EXPR, vr0.min, vr1.min);
+	  max = vrp_int_const_binop (MIN_EXPR, vr0.max, vr1.max);
+	}
+      else
+	{
+	  /* For operations that make the resulting range directly
+	     proportional to the original ranges, apply the operation to
+	     the same end of each range.  */
+	  min = vrp_int_const_binop (code, vr0.min, vr1.min);
+	  max = vrp_int_const_binop (code, vr0.max, vr1.max);
 	}
-
-      /* For operations that make the resulting range directly
-	 proportional to the original ranges, apply the operation to
-	 the same end of each range.  */
-      min = vrp_int_const_binop (code, vr0.min, vr1.min);
-      max = vrp_int_const_binop (code, vr0.max, vr1.max);
 
       /* If both additions overflowed the range kind is still correct.
 	 This happens regularly with subtracting something in unsigned