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.



git-svn-id: https://gcc.gnu.org/svn/gcc/trunk@141942 138bc75d-0d04-0410-961f-82ee72b054a4

2 files changed, 16 insertions, 3 deletions

diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index e03eaf9faad..43e91afe8b4 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -5774,9 +5774,12 @@ returns the value that had previously been in memory.  That is,
 
 @smallexample
 @{ tmp = *ptr; *ptr @var{op}= value; return tmp; @}
-@{ tmp = *ptr; *ptr = ~tmp & value; return tmp; @}   // nand
+@{ tmp = *ptr; *ptr = ~(tmp & value); return tmp; @}   // nand
 @end smallexample
 
+@emph{Note:} GCC 4.4 and later implement @code{__sync_fetch_and_nand}
+builtin as @code{*ptr = ~(tmp & value)} instead of @code{*ptr = ~tmp & value}.
+
 @item @var{type} __sync_add_and_fetch (@var{type} *ptr, @var{type} value, ...)
 @itemx @var{type} __sync_sub_and_fetch (@var{type} *ptr, @var{type} value, ...)
 @itemx @var{type} __sync_or_and_fetch (@var{type} *ptr, @var{type} value, ...)
@@ -5794,9 +5797,13 @@ return the new value.  That is,
 
 @smallexample
 @{ *ptr @var{op}= value; return *ptr; @}
-@{ *ptr = ~*ptr & value; return *ptr; @}   // nand
+@{ *ptr = ~(*ptr & value); return *ptr; @}   // nand
 @end smallexample
 
+@emph{Note:} GCC 4.4 and later implement @code{__sync_nand_and_fetch}
+builtin as @code{*ptr = ~(*ptr & value)} instead of
+@code{*ptr = ~*ptr & value}.
+
 @item bool __sync_bool_compare_and_swap (@var{type} *ptr, @var{type} oldval @var{type} newval, ...)
 @itemx @var{type} __sync_val_compare_and_swap (@var{type} *ptr, @var{type} oldval @var{type} newval, ...)
 @findex __sync_bool_compare_and_swap
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index cc66b45c14b..476ab8cf92a 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -257,7 +257,7 @@ Objective-C and Objective-C++ Dialects}.
 -Wsign-compare  -Wsign-conversion  -Wstack-protector @gol
 -Wstrict-aliasing -Wstrict-aliasing=n @gol
 -Wstrict-overflow -Wstrict-overflow=@var{n} @gol
--Wswitch  -Wswitch-default  -Wswitch-enum @gol
+-Wswitch  -Wswitch-default  -Wswitch-enum -Wsync-nand @gol
 -Wsystem-headers  -Wtrigraphs  -Wtype-limits  -Wundef  -Wuninitialized @gol
 -Wunknown-pragmas  -Wno-pragmas -Wunreachable-code @gol
 -Wunused  -Wunused-function  -Wunused-label  -Wunused-parameter @gol
@@ -3127,6 +3127,12 @@ and lacks a @code{case} for one or more of the named codes of that
 enumeration.  @code{case} labels outside the enumeration range also
 provoke warnings when this option is used.
 
+@item -Wsync-nand
+@opindex Wsync-nand
+@opindex Wno-sync-nand
+Warn when @code{__sync_fetch_and_nand} and @code{__sync_nand_and_fetch}
+built-in functions are used.  These functions changed semantics in GCC 4.4.
+
 @item -Wtrigraphs
 @opindex Wtrigraphs
 @opindex Wno-trigraphs