[4.9] Fix bogus warnings about array-bounds.

2015-01-28  Ilya Enkovich  <ilya.enkovich@intel.com>

	PR tree-optimization/64277
	* tree-ssa-loop-niter.c (record_nonwrapping_iv): Use base
	range info when possible to refine estimation.

2015-01-27  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/56273
	PR tree-optimization/59124
	PR tree-optimization/64277
	* tree-vrp.c (vrp_finalize): Emit array-bound warnings only
	from the first VRP pass.

	* g++.dg/warn/Warray-bounds-6.C: New testcase.
	* gcc.dg/Warray-bounds-12.c: Likewise.
	* gcc.dg/Warray-bounds-13.c: Likewise.

Change-Id: I175b420a4c8150ecf986d477e4c51cbbff276c82
Signed-off-by: Alexander Ivchenko <alexander.ivchenko@intel.com>

6 files changed, 110 insertions, 2 deletions

diff --git a/gcc-4.9/gcc/testsuite/g++.dg/warn/Warray-bounds-6.C b/gcc-4.9/gcc/testsuite/g++.dg/warn/Warray-bounds-6.C
new file mode 100644
index 000000000..f2e5f2f59
--- /dev/null
+++ b/gcc-4.9/gcc/testsuite/g++.dg/warn/Warray-bounds-6.C
@@ -0,0 +1,26 @@
+// { dg-do compile }
+// { dg-options "-O3 -Warray-bounds" }
+
+struct type {
+    bool a, b;
+    bool get_b() { return b; }
+};
+
+type stuff[9u];
+
+void bar();
+
+void foo()
+{
+  for(unsigned i = 0u; i < 9u; i++)
+    {
+      if(!stuff[i].a)
+	continue;
+
+      bar();
+
+      for(unsigned j = i + 1u; j < 9u; j++)
+	if(stuff[j].a && stuff[j].get_b()) // { dg-bogus "above array bounds" }
+	  return;
+    }
+}
diff --git a/gcc-4.9/gcc/testsuite/gcc.dg/Warray-bounds-12.c b/gcc-4.9/gcc/testsuite/gcc.dg/Warray-bounds-12.c
new file mode 100644
index 000000000..ef26c6596
--- /dev/null
+++ b/gcc-4.9/gcc/testsuite/gcc.dg/Warray-bounds-12.c
@@ -0,0 +1,26 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -Warray-bounds" } */
+/* { dg-additional-options "-mssse3" { target x86_64-*-* i?86-*-* } } */
+
+void foo(short a[], short m)
+{
+  int i, j;
+  int f1[10];
+  short nc;
+
+  nc = m + 1;
+  if (nc > 3)
+    {
+      for (i = 0; i <= nc; i++)
+	{
+	  f1[i] = f1[i] + 1;
+	}
+    }
+
+  for (i = 0, j = m; i < nc; i++, j--)
+    {
+      a[i] = f1[i]; /* { dg-bogus "above array bounds" } */
+      a[j] = i;
+    }
+  return;
+}
diff --git a/gcc-4.9/gcc/testsuite/gcc.dg/Warray-bounds-13.c b/gcc-4.9/gcc/testsuite/gcc.dg/Warray-bounds-13.c
new file mode 100644
index 000000000..7b40a8388
--- /dev/null
+++ b/gcc-4.9/gcc/testsuite/gcc.dg/Warray-bounds-13.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -Warray-bounds" } */
+
+extern char *bar[17];
+
+int foo(int argc, char **argv)
+{
+  int i;
+  int n = 0;
+
+  for (i = 0; i < argc; i++)
+    n++;
+
+  for (i = 0; i < argc; i++)
+    argv[i] = bar[i + n]; /* { dg-bogus "above array bounds" } */
+
+  return 0;
+}
diff --git a/gcc-4.9/gcc/testsuite/gcc.dg/pr64277.c b/gcc-4.9/gcc/testsuite/gcc.dg/pr64277.c
new file mode 100644
index 000000000..c6ef33119
--- /dev/null
+++ b/gcc-4.9/gcc/testsuite/gcc.dg/pr64277.c
@@ -0,0 +1,23 @@
+/* PR tree-optimization/64277 */
+/* { dg-do compile } */
+/* { dg-options "-O3 -Wall -Werror -fdump-tree-cunroll-details" } */
+/* { dg-final { scan-tree-dump "loop with 5 iterations completely unrolled" "cunroll" } } */
+/* { dg-final { scan-tree-dump "loop with 6 iterations completely unrolled" "cunroll" } } */
+/* { dg-final { cleanup-tree-dump "cunroll" } } */
+
+int f1[10];
+void test1 (short a[], short m, unsigned short l)
+{
+  int i = l;
+  for (i = i + 5; i < m; i++)
+    f1[i] = a[i]++;
+}
+
+void test2 (short a[], short m, short l)
+{
+  int i;
+  if (m > 5)
+    m = 5;
+  for (i = m; i > l; i--)
+    f1[i] = a[i]++;
+}
diff --git a/gcc-4.9/gcc/tree-ssa-loop-niter.c b/gcc-4.9/gcc/tree-ssa-loop-niter.c
index 7628363cc..62175f344 100644
--- a/gcc-4.9/gcc/tree-ssa-loop-niter.c
+++ b/gcc-4.9/gcc/tree-ssa-loop-niter.c
@@ -2724,6 +2724,7 @@ record_nonwrapping_iv (struct loop *loop, tree base, tree step, gimple stmt,
   tree niter_bound, extreme, delta;
   tree type = TREE_TYPE (base), unsigned_type;
   double_int max;
+  tree orig_base = base;
 
   if (TREE_CODE (step) != INTEGER_CST || integer_zerop (step))
     return;
@@ -2747,7 +2748,14 @@ record_nonwrapping_iv (struct loop *loop, tree base, tree step, gimple stmt,
 
   if (tree_int_cst_sign_bit (step))
     {
+      double_int min, max;
       extreme = fold_convert (unsigned_type, low);
+      if (TREE_CODE (orig_base) == SSA_NAME
+	  && TREE_CODE (high) == INTEGER_CST
+	  && INTEGRAL_TYPE_P (TREE_TYPE (orig_base))
+	  && get_range_info (orig_base, &min, &max) == VR_RANGE
+	  && max.slt (TREE_INT_CST (high)))
+	base = double_int_to_tree (unsigned_type, max);
       if (TREE_CODE (base) != INTEGER_CST)
 	base = fold_convert (unsigned_type, high);
       delta = fold_build2 (MINUS_EXPR, unsigned_type, base, extreme);
@@ -2755,8 +2763,15 @@ record_nonwrapping_iv (struct loop *loop, tree base, tree step, gimple stmt,
     }
   else
     {
+      double_int min, max;
       extreme = fold_convert (unsigned_type, high);
-      if (TREE_CODE (base) != INTEGER_CST)
+      if (TREE_CODE (orig_base) == SSA_NAME
+	  && TREE_CODE (low) == INTEGER_CST
+	  && INTEGRAL_TYPE_P (TREE_TYPE (orig_base))
+	  && get_range_info (orig_base, &min, &max) == VR_RANGE
+	  && min.sgt (TREE_INT_CST (low)))
+	base = double_int_to_tree (unsigned_type, min);
+      else if (TREE_CODE (base) != INTEGER_CST)
 	base = fold_convert (unsigned_type, low);
       delta = fold_build2 (MINUS_EXPR, unsigned_type, extreme, base);
     }
diff --git a/gcc-4.9/gcc/tree-vrp.c b/gcc-4.9/gcc/tree-vrp.c
index 2c80135f9..b31194410 100644
--- a/gcc-4.9/gcc/tree-vrp.c
+++ b/gcc-4.9/gcc/tree-vrp.c
@@ -9728,7 +9728,7 @@ vrp_finalize (void)
   substitute_and_fold (op_with_constant_singleton_value_range,
 		       vrp_fold_stmt, false);
 
-  if (warn_array_bounds)
+  if (warn_array_bounds && first_pass_instance)
     check_all_array_refs ();
 
   /* We must identify jump threading opportunities before we release