re PR tree-optimization/78720 (Illegal instruction in generated code)

	PR tree-optimization/78720
	* match.pd (A < 0 ? C : 0): Only optimize for signed A.  If shift
	is negative, sign extend to @1's type and than AND with C.

	* gcc.c-torture/execute/pr78720.c: New test.

Co-Authored-By: Marc Glisse <marc.glisse@inria.fr>

From-SVN: r243516

gcc/ChangeLog

 2016-12-10  Jakub Jelinek  <jakub@redhat.com>
+	    Marc Glisse  <marc.glisse@inria.fr>
+
+	PR tree-optimization/78720
+	* match.pd (A < 0 ? C : 0): Only optimize for signed A.  If shift
+	is negative, sign extend to @1's type and than AND with C.
+
+2016-12-10  Jakub Jelinek  <jakub@redhat.com>
 
 	PR fortran/78758
 	* tree-object-size.c (compute_object_offset) <case ARRAY_REF>: Handle

gcc/match.pd

@@ -2768,17 +2768,22 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
     (ncmp (convert:stype @0) { build_zero_cst (stype); })))))
 
 /* If we have A < 0 ? C : 0 where C is a power of 2, convert
-   this into a right shift followed by ANDing with C.  */
+   this into a right shift or sign extension followed by ANDing with C.  */
 (simplify
  (cond
   (lt @0 integer_zerop)
   integer_pow2p@1 integer_zerop)
- (with {
+ (if (!TYPE_UNSIGNED (TREE_TYPE (@0)))
+  (with {
     int shift = element_precision (@0) - wi::exact_log2 (@1) - 1;
-  }
-  (bit_and
-   (convert (rshift @0 { build_int_cst (integer_type_node, shift); }))
-   @1)))
+   }
+   (if (shift >= 0)
+    (bit_and
+     (convert (rshift @0 { build_int_cst (integer_type_node, shift); }))
+     @1)
+    /* Otherwise ctype must be wider than TREE_TYPE (@0) and pure
+       sign extension followed by AND with C will achieve the effect.  */
+    (bit_and (convert @0) @1)))))
 
 /* When the addresses are not directly of decls compare base and offset.
    This implements some remaining parts of fold_comparison address

gcc/testsuite/ChangeLog

 2016-12-10  Jakub Jelinek  <jakub@redhat.com>
 
+	PR tree-optimization/78720
+	* gcc.c-torture/execute/pr78720.c: New test.
+
 	PR fortran/78758
 	* gfortran.dg/pr78758.f90: New test.
 	* gfortran.dg/pr38868.f: Remove again bogus warning.

gcc/testsuite/gcc.c-torture/execute/pr78720.c

+/* PR tree-optimization/78720 */
+
+__attribute__((noinline, noclone)) long int
+foo (signed char x)
+{
+  return x < 0 ? 0x80000L : 0L;
+}
+
+__attribute__((noinline, noclone)) long int
+bar (signed char x)
+{
+  return x < 0 ? 0x80L : 0L;
+}
+
+__attribute__((noinline, noclone)) long int
+baz (signed char x)
+{
+  return x < 0 ? 0x20L : 0L;
+}
+
+int
+main ()
+{
+  if (foo (-1) != 0x80000L || bar (-1) != 0x80L || baz (-1) != 0x20L
+      || foo (0) != 0L || bar (0) != 0L || baz (0) != 0L
+      || foo (31) != 0L || bar (31) != 0L || baz (31) != 0L)
+    __builtin_abort ();
+  return 0;
+}