re PR middle-end/37908 (atomic NAND op generate wrong code; __sync_nand_and_fetch, __sync_fetch_and_nand)

	PR middle-end/37908
	* optabs.c (expand_sync_operation): Properly handle NAND case
	by calculating ~(t1 & val) instead of (~t1 & val).
	* builtins.c (expand_builtin_sync_operation): Warn for changed
	semantics in NAND builtins.
	* c.opt (Wsync-nand): New warning option.  Describe -Wsync-nand.
	
	* doc/invoke.texi (Warning options): Add Wsync-nand.
	* doc/extend.texi (Atomic Builtins) [__sync_fetch_and_nand]: Correct
	__sync_fetch_and_nand builtin operation in the example.  Add a note
	about changed semantics in GCC 4.4.
	[__sync_nand_and_fetch]: Correct __sync_nand_and_fetch builtin
	operation in the example.  Add a note about changed semantics in
	GCC 4.4.

testsuite/ChangeLog:

	PR middle-end/37908
	* gcc.dg/pr37908.c: New test.
	* gcc.dg/ia64-sync-1.c: Correct __sync_fetch_and_nand and
	__sync_nand_and_fetch results.  Add dg-message to look for the warning
	about changed semantics of NAND builtin.
	(init_si, init_di): Change init value for __sync_fetch_and_nand to -1.
	(test_si, test_di): Change expected result of
	__sync_nand_and_fetch to ~7.
	* gcc.dg/ia64-sync-2.c: Correct __sync_fetch_and_nand and
	__sync_nand_and_fetch results.  Add dg-message to look for the warning
	about changed semantics of NAND builtin.
	(init_noret_si, init_noret_di): Change init value for
	__sync_fetch_and_nand to -1.
	(init_noret_si, init_noret_di): Change expected result of
	__sync_nand_and_fetch to ~7.
	* gcc.dg/sync-2.c: Correct __sync_fetch_and_nand and
	__sync_nand_and_fetch results.  Add dg-message to look for the warning
	about changed semantics of NAND builtin.
	(init_qi, init_qi): Change init value for __sync_fetch_and_nand to -1.
	(init_hi, init_hi): Change expected result of
	__sync_nand_and_fetch to ~7.
	* gcc.dg/sync-3.c: Copy from sync-2.c instead of including
	the c source file.
	* gcc.c-torture/compile/sync-1.c: Add dg-message to look for the
	warning about changed semantics of NAND builtin.
	* gcc.c-torture/compile/sync-2.c: Ditto.
	* gcc.c-torture/compile/sync-3.c: Ditto.

From-SVN: r141942

1 files changed, 44 insertions, 0 deletions

diff --git a/gcc/builtins.c b/gcc/builtins.c
index a1bba0d..fd6d0b8 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -5988,6 +5988,50 @@ expand_builtin_sync_operation (enum machine_mode mode, tree exp,
   rtx val, mem;
   enum machine_mode old_mode;
 
+  if (code == NOT && warn_sync_nand)
+    {
+      tree fndecl = get_callee_fndecl (exp);
+      enum built_in_function fcode = DECL_FUNCTION_CODE (fndecl);
+
+      static bool warned_f_a_n, warned_n_a_f;
+
+      switch (fcode)
+	{
+	case BUILT_IN_FETCH_AND_NAND_1:
+	case BUILT_IN_FETCH_AND_NAND_2:
+	case BUILT_IN_FETCH_AND_NAND_4:
+	case BUILT_IN_FETCH_AND_NAND_8:
+	case BUILT_IN_FETCH_AND_NAND_16:
+
+	  if (warned_f_a_n)
+	    break;
+
+	  fndecl = implicit_built_in_decls[BUILT_IN_FETCH_AND_NAND_N];
+	  inform (input_location,
+		  "%qD changed semantics in GCC 4.4", fndecl);
+	  warned_f_a_n = true;
+	  break;
+
+	case BUILT_IN_NAND_AND_FETCH_1:
+	case BUILT_IN_NAND_AND_FETCH_2:
+	case BUILT_IN_NAND_AND_FETCH_4:
+	case BUILT_IN_NAND_AND_FETCH_8:
+	case BUILT_IN_NAND_AND_FETCH_16:
+
+	  if (warned_n_a_f)
+	    break;
+
+	  fndecl = implicit_built_in_decls[BUILT_IN_NAND_AND_FETCH_N];
+	  inform (input_location,
+		  "%qD changed semantics in GCC 4.4", fndecl);
+	  warned_n_a_f = true;
+	  break;
+
+	default:
+	  gcc_unreachable ();
+	}
+    }
+
   /* Expand the operands.  */
   mem = get_builtin_sync_mem (CALL_EXPR_ARG (exp, 0), mode);