re PR tree-optimization/78496 (Missed opportunities for jump threading)

	PR tree-optimization/78496
	* tree-vrp.c (simplify_assert_expr_using_ranges): New function.
	(simplify_stmt_using_ranges): Call it.
	(vrp_dom_walker::before_dom_children): Extract equivalences
	from an ASSERT_EXPR with an equality comparison against a
	constant.

	PR tree-optimization/78496
	* gcc.dg/tree-ssa/ssa-thread-16.c: New test.
	* gcc.dg/tree-ssa/ssa-thread-17.c: New test.

From-SVN: r247721

3 files changed, 80 insertions, 0 deletions

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index fca5b87..42782a6 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2017-05-06  Jeff Law  <law@redhat.com>
+
+	PR tree-optimization/78496
+	* gcc.dg/tree-ssa/ssa-thread-16.c: New test.
+	* gcc.dg/tree-ssa/ssa-thread-17.c: New test.
+
 2017-05-06  Richard Sandiford  <richard.sandiford@linaro.org>
 
 	* gcc.target/aarch64/spill_1.c: New test.
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-16.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-16.c
new file mode 100644
index 0000000..78c349c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-16.c
@@ -0,0 +1,38 @@
+/* { dg-do compile } */ 
+/* { dg-options "-O2 -fdump-tree-vrp1-details" } */
+
+/* We should thread the if (exp == 2) conditional on the
+   the path from inside the if (x) THEN arm.  It is the only
+   jump threading opportunity in this code.  */
+   
+/* { dg-final { scan-tree-dump-times "Threaded" 1 "vrp1" } } */
+
+
+extern void abort (void) __attribute__ ((__nothrow__, __leaf__))
+  __attribute__ ((__noreturn__));
+
+int x;
+
+
+int code;
+void
+do_jump (int exp)
+{
+  switch (code)
+    {
+    case 4:
+      if ((exp) == 1)
+	goto normal;
+      if (x)
+	{
+	  if (exp != 0)
+	    abort ();
+	}
+      if ((exp) == 2)
+	goto normal;
+    case 3:
+	abort ();
+    }
+  normal:
+      ;
+}
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-17.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-17.c
new file mode 100644
index 0000000..692658f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-17.c
@@ -0,0 +1,36 @@
+/* { dg-do compile } */ 
+/* { dg-options "-O2 -fdump-tree-vrp1-details" } */
+
+/* We should simplify one ASSERT_EXPR from a relational
+   into an equality test.  */
+/* { dg-final { scan-tree-dump-times "Folded into:\[^\r\n\]*ASSERT_EXPR\*\[^\r\n\]* == 1" 1 "vrp1" } } */
+
+/* And simplification of the ASSERT_EXPR leads to a jump threading opportunity.  */
+/* { dg-final { scan-tree-dump-times "Threaded" 1 "vrp1" } } */
+
+extern void abort (void) __attribute__ ((__nothrow__, __leaf__))
+  __attribute__ ((__noreturn__));
+
+union gimple_statement_d;
+typedef union gimple_statement_d *gimple;
+
+
+
+union gimple_statement_d
+{
+  unsigned num_ops;
+};
+
+void
+gimple_assign_set_rhs_with_ops_1 (int code, gimple stmt, unsigned new_rhs_ops)
+{
+
+  stmt->num_ops = new_rhs_ops + 1;
+  if (stmt->num_ops <= 1)
+    abort ();
+  if (new_rhs_ops > 1)
+    if (stmt->num_ops <= 2)
+      abort ();
+  if (new_rhs_ops > 2)
+      abort ();
+}