* doc/invoke.texi: Document new MIPS -mllsc and -mno-llsc options.

	* doc/install.texi: Document new --with-llsc and --without-llsc
	options.
	* config.gcc: Handle --with-llsc and --without-llsc configure options.
	* config/mips/mips.md (sync, memory_barrier): Wrap sync instrunction
	in %| and %- operand codes.  Depend on GENERATE_SYNC instead of
	ISA_HAS_SYNC.
	(sync_compare_and_swap<mode>, sync_add<mode>, sync_sub<mode>,
	sync_old_add<mode>, sync_old_sub<mode>, sync_new_add<mode>,
	sync_new_sub<mode>, sync_<optab><mode>, sync_old_<optab><mode>,
	sync_new_<optab><mode>, sync_nand<mode>, sync_old_nand<mode>,
	sync_new_nand<mode>, sync_lock_test_and_set<mode>): Depend on
	GENERATE_LL_SC instead of ISA_HAS_LL_SC.
	* config/mips/mips.opt (mllsc): New option.
	* config/mips/mips.c (mips_llsc): Define variable.
	(mips_handle_option): Handle mllsc option.
	(override_options): Set mips_print_operand_punct for '|' and '-'.
	(print_operand): Add new %| and %- operand codes.
	* config/mips/mips.h (mips_llsc_setting): New enum type.
	(mips_llsc): Declare.
	(OPTION_DEFAULT_SPECS): Add llsc handling.
	(GENERATE_SYNC): New macro.
	(GENERATE_LL_SC): New macro.
	(MIPS_COMPARE_AND_SWAP, MIPS_SYNC_OP, MIPS_SYNC_OLD_OP,
	MIPS_SYNC_NEW_OP, MIPS_SYNC_NAND, MIPS_SYNC_OLD_NAND,
	MIPS_SYNC_NEW_NAND, MIPS_SYNC_EXCHANGE): Wrap instructions
	in %| and %- operand codes.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@128392 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 27 insertions, 0 deletions

diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index bac3bb20a55..2517303260f 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -1062,6 +1062,19 @@ systems that support conditional traps).
 Division by zero checks use the break instruction.
 @end table
 
+@c If you make --with-llsc the default for additional targets,
+@c update the --with-llsc description in the MIPS section below.
+
+@item --with-llsc
+On MIPS targets, make @option{-mllsc} the default when no
+@option{-mno-lsc} option is passed.  This is the default for
+Linux-based targets, as the kernel will emulate them if the ISA does
+not provide them.
+
+@item --without-llsc
+On MIPS targets, make @option{-mno-llsc} the default when no
+@option{-mllsc} option is passed.
+
 @item --enable-__cxa_atexit
 Define if you want to use __cxa_atexit, rather than atexit, to
 register C++ destructors for local statics and global objects.
@@ -3610,6 +3623,20 @@ configure for @samp{mipsel-elf} as a workaround.  The
 @samp{mips*-*-linux*} target continues to use the MIPS II routines.  More
 work on this is expected in future releases.
 
+@c If you make --with-llsc the default for another target, please also
+@c update the description of the --with-llsc option.
+
+The built-in @code{__sync_*} functions are available on MIPS II and
+later systems and others that support the @samp{ll}, @samp{sc} and
+@samp{sync} instructions.  This can be overridden by passing
+@option{--with-llsc} or @option{--without-llsc} when configuring GCC.
+Since the Linux kernel emulates these instructions if they are
+missing, the default for @samp{mips*-*-linux*} targets is
+@option{--with-llsc}.  The @option{--with-llsc} and
+@option{--without-llsc} configure options may be overridden at compile
+time by passing the @option{-mllsc} or @option{-mno-llsc} options to
+the compiler.
+
 MIPS systems check for division by zero (unless
 @option{-mno-check-zero-division} is passed to the compiler) by
 generating either a conditional trap or a break instruction.  Using