re PR tree-optimization/60971 (Wrong code when coercing unsigned char to bool)

	PR tree-optimization/60971
	* tree-tailcall.c (process_assignment): Reject conversions which
	reduce precision.

	* c-c++-common/turtore/pr60971.c: New test.

From-SVN: r209900

4 files changed, 58 insertions, 3 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 42e0182..f22fe1d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2014-04-29  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/60971
+	* tree-tailcall.c (process_assignment): Reject conversions which
+	reduce precision.
+
 2014-04-29  James Greenhalgh  <james.greenhalgh@arm.com>
 
 	* calls.c (initialize_argument_information): Always treat
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index ef61cfe..689f4e8 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2014-04-29  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/60971
+	* c-c++-common/turtore/pr60971.c: New test.
+
 2014-04-29  Alan Lawrence  <alan.lawrence@arm.com>
 
 	* gcc.target/aarch64/simd/simd.exp: New file.
diff --git a/gcc/testsuite/c-c++-common/torture/pr60971.c b/gcc/testsuite/c-c++-common/torture/pr60971.c
new file mode 100644
index 0000000..b7a967d
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/torture/pr60971.c
@@ -0,0 +1,34 @@
+/* PR tree-optimization/60971 */
+/* { dg-do run } */
+
+#ifndef __cplusplus
+#define bool _Bool
+#endif
+
+volatile unsigned char c;
+
+__attribute__((noinline)) unsigned char
+foo (void)
+{
+  return c;
+}
+
+__attribute__((noinline)) bool
+bar (void)
+{
+  return foo () & 1;
+}
+
+int
+main ()
+{
+  c = 0x41;
+  c = bar ();
+  if (c != 1)
+    __builtin_abort ();
+  c = 0x20;
+  c = bar ();
+  if (c != 0)
+    __builtin_abort ();
+  return 0;
+}
diff --git a/gcc/tree-tailcall.c b/gcc/tree-tailcall.c
index 11a2965..9ad25d8 100644
--- a/gcc/tree-tailcall.c
+++ b/gcc/tree-tailcall.c
@@ -285,9 +285,19 @@ process_assignment (gimple stmt, gimple_stmt_iterator call, tree *m,
     {
       /* Reject a tailcall if the type conversion might need
 	 additional code.  */
-      if (gimple_assign_cast_p (stmt)
-	  && TYPE_MODE (TREE_TYPE (dest)) != TYPE_MODE (TREE_TYPE (src_var)))
-	return false;
+      if (gimple_assign_cast_p (stmt))
+	{
+	  if (TYPE_MODE (TREE_TYPE (dest)) != TYPE_MODE (TREE_TYPE (src_var)))
+	    return false;
+
+	  /* Even if the type modes are the same, if the precision of the
+	     type is smaller than mode's precision,
+	     reduce_to_bit_field_precision would generate additional code.  */
+	  if (INTEGRAL_TYPE_P (TREE_TYPE (dest))
+	      && (GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (dest)))
+		  > TYPE_PRECISION (TREE_TYPE (dest))))
+	    return false;
+	}
 
       if (src_var != *ass_var)
 	return false;