Add __builtin_speculation_safe_value

This patch defines a new intrinsic function
__builtin_speculation_safe_value.  A generic default implementation is
defined which will attempt to use the backend pattern
"speculation_safe_barrier".  If this pattern is not defined, or if it
is not available, then the compiler will emit a warning, but
compilation will continue.

Note that the test spec-barrier-1.c will currently fail on all
targets.  This is deliberate, the failure will go away when
appropriate action is taken for each target backend.

gcc:
	* builtin-types.def (BT_FN_PTR_PTR_VAR): New function type.
	(BT_FN_I1_I1_VAR, BT_FN_I2_I2_VAR, BT_FN_I4_I4_VAR): Likewise.
	(BT_FN_I8_I8_VAR, BT_FN_I16_I16_VAR): Likewise.
	* builtin-attrs.def (ATTR_NOVOPS_NOTHROW_LEAF_LIST): New attribute
	list.
	* builtins.def (BUILT_IN_SPECULATION_SAFE_VALUE_N): New builtin.
	(BUILT_IN_SPECULATION_SAFE_VALUE_PTR): New internal builtin.
	(BUILT_IN_SPECULATION_SAFE_VALUE_1): Likewise.
	(BUILT_IN_SPECULATION_SAFE_VALUE_2): Likewise.
	(BUILT_IN_SPECULATION_SAFE_VALUE_4): Likewise.
	(BUILT_IN_SPECULATION_SAFE_VALUE_8): Likewise.
	(BUILT_IN_SPECULATION_SAFE_VALUE_16): Likewise.
	* builtins.c (expand_speculation_safe_value): New function.
	(expand_builtin): Call it.
	* doc/cpp.texi: Document predefine __HAVE_SPECULATION_SAFE_VALUE.
	* doc/extend.texi: Document __builtin_speculation_safe_value.
	* doc/md.texi: Document "speculation_barrier" pattern.
	* doc/tm.texi.in: Pull in TARGET_SPECULATION_SAFE_VALUE and
	TARGET_HAVE_SPECULATION_SAFE_VALUE.
	* doc/tm.texi: Regenerated.
	* target.def (have_speculation_safe_value, speculation_safe_value): New
	hooks.
	* targhooks.c (default_have_speculation_safe_value): New function.
	(default_speculation_safe_value): New function.
	* targhooks.h (default_have_speculation_safe_value): Add prototype.
	(default_speculation_safe_value): Add prototype.

c-family:
	* c-common.c (speculation_safe_resolve_call): New function.
	(speculation_safe_resolve_params): New function.
	(speculation_safe_resolve_return): New function.
	(resolve_overloaded_builtin): Handle __builtin_speculation_safe_value.
	* c-cppbuiltin.c (c_cpp_builtins): Add pre-define for
	__HAVE_SPECULATION_SAFE_VALUE.

testsuite:
	* c-c++-common/spec-barrier-1.c: New test.
	* c-c++-common/spec-barrier-2.c: New test.
	* gcc.dg/spec-barrier-3.c: New test.

From-SVN: r263168

1 files changed, 22 insertions, 0 deletions

diff --git a/gcc/builtins.def b/gcc/builtins.def
index aacbd513a16..ad90d4458a1 100644
--- a/gcc/builtins.def
+++ b/gcc/builtins.def
@@ -1003,6 +1003,28 @@ DEF_BUILTIN (BUILT_IN_EMUTLS_REGISTER_COMMON,
 	     true, true, true, ATTR_NOTHROW_LEAF_LIST, false,
 	     !targetm.have_tls)
 
+/* Suppressing speculation.  Users are expected to use the first (N)
+   variant, which will be translated internally into one of the other
+   types.  */
+
+DEF_GCC_BUILTIN (BUILT_IN_SPECULATION_SAFE_VALUE_N, "speculation_safe_value",
+		 BT_FN_VOID_VAR, ATTR_NOVOPS_NOTHROW_LEAF_LIST)
+
+DEF_GCC_BUILTIN (BUILT_IN_SPECULATION_SAFE_VALUE_PTR,
+		 "speculation_safe_value_ptr", BT_FN_PTR_PTR_VAR,
+		 ATTR_NOVOPS_NOTHROW_LEAF_LIST)
+DEF_GCC_BUILTIN (BUILT_IN_SPECULATION_SAFE_VALUE_1, "speculation_safe_value_1",
+		 BT_FN_I1_I1_VAR, ATTR_NOVOPS_NOTHROW_LEAF_LIST)
+DEF_GCC_BUILTIN (BUILT_IN_SPECULATION_SAFE_VALUE_2, "speculation_safe_value_2",
+		 BT_FN_I2_I2_VAR, ATTR_NOVOPS_NOTHROW_LEAF_LIST)
+DEF_GCC_BUILTIN (BUILT_IN_SPECULATION_SAFE_VALUE_4, "speculation_safe_value_4",
+		 BT_FN_I4_I4_VAR, ATTR_NOVOPS_NOTHROW_LEAF_LIST)
+DEF_GCC_BUILTIN (BUILT_IN_SPECULATION_SAFE_VALUE_8, "speculation_safe_value_8",
+		 BT_FN_I8_I8_VAR, ATTR_NOVOPS_NOTHROW_LEAF_LIST)
+DEF_GCC_BUILTIN (BUILT_IN_SPECULATION_SAFE_VALUE_16,
+		 "speculation_safe_value_16", BT_FN_I16_I16_VAR,
+		 ATTR_NOVOPS_NOTHROW_LEAF_LIST)
+
 /* Exception support.  */
 DEF_BUILTIN_STUB (BUILT_IN_UNWIND_RESUME, "__builtin_unwind_resume")
 DEF_BUILTIN_STUB (BUILT_IN_CXA_END_CLEANUP, "__builtin_cxa_end_cleanup")