re PR middle-end/78153 (strlen return value can be assumed to be less than PTRDIFF_MAX)

2016-11-23  Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.org>

	PR middle-end/78153
	* gimple-fold.c (fold_stmt_1): Handle case for GIMPLE_RETURN.
	* tree-vrp.c (extract_range_basic): Handle case for
	CFN_BUILT_IN_STRLEN.

testsuite/
	* gcc.dg/tree-ssa/pr78153-1.c: New test.
	* gcc.dg/tree-ssa/pr78153-2.c: Likewise.

From-SVN: r242786

6 files changed, 61 insertions, 0 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 62e354c..db002f7 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2016-11-23  Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.org>
+
+	PR middle-end/78153
+	* gimple-fold.c (fold_stmt_1): Handle case for GIMPLE_RETURN.
+	* tree-vrp.c (extract_range_basic): Handle case for
+	CFN_BUILT_IN_STRLEN.
+
 2016-11-23  Jeff Law  <law@redhat.com>
 
 	* config/ia64/ia64.c (ia64_emit_insn_before): Fix prototype.
diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c
index aabc8ff..6842301 100644
--- a/gcc/gimple-fold.c
+++ b/gcc/gimple-fold.c
@@ -4406,6 +4406,23 @@ fold_stmt_1 (gimple_stmt_iterator *gsi, bool inplace, tree (*valueize) (tree))
 	}
       break;
 
+    case GIMPLE_RETURN:
+      {
+	greturn *ret_stmt = as_a<greturn *> (stmt);
+	tree ret = gimple_return_retval(ret_stmt);
+
+	if (ret && TREE_CODE (ret) == SSA_NAME && valueize)
+	  {
+	    tree val = valueize (ret);
+	    if (val && val != ret)
+	      {
+		gimple_return_set_retval (ret_stmt, val);
+		changed = true;
+	      }
+	  }
+      }
+      break;
+
     default:;
     }
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 0b5c305..084f366 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2016-11-23  Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.org>
+
+	PR middle-end/78153
+	* gcc.dg/tree-ssa/pr78153-1.c: New test.
+	* gcc.dg/tree-ssa/pr78153-2.c: Likewise.
+
 2016-11-23  James Greenhalgh  <james.greenhalgh@arm.com>
 
 	PR target/63250
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr78153-1.c b/gcc/testsuite/gcc.dg/tree-ssa/pr78153-1.c
new file mode 100644
index 0000000..2530ba0
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr78153-1.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-evrp-slim" } */
+
+void f(const char *s)
+{
+  if (__PTRDIFF_MAX__ <= __builtin_strlen (s))
+    __builtin_abort ();
+}
+
+/* { dg-final { scan-tree-dump-not "__builtin_abort" "evrp" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr78153-2.c b/gcc/testsuite/gcc.dg/tree-ssa/pr78153-2.c
new file mode 100644
index 0000000..de70450
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr78153-2.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-evrp-slim" } */
+
+void f(const char *s)
+{
+  __PTRDIFF_TYPE__ n = __builtin_strlen (s);
+  if (n < 0)
+    __builtin_abort ();
+}
+
+/* { dg-final { scan-tree-dump-not "__builtin_abort" "evrp" } } */
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index 5bd4418..33e0a75 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -4027,6 +4027,16 @@ extract_range_basic (value_range *vr, gimple *stmt)
 			          : vrp_val_max (type), NULL);
 	  }
 	  return;
+	case CFN_BUILT_IN_STRLEN:
+	  {
+	    tree type = TREE_TYPE (gimple_call_lhs (stmt));
+	    tree max = vrp_val_max (ptrdiff_type_node);
+	    wide_int wmax = wi::to_wide (max, TYPE_PRECISION (TREE_TYPE (max)));
+	    tree range_min = build_zero_cst (type); 
+	    tree range_max = wide_int_to_tree (type, wmax - 1);
+	    set_value_range (vr, VR_RANGE, range_min, range_max, NULL);
+	  }
+	  return;
 	default:
 	  break;
 	}