targhooks - provide an alternative hook for targets that never execute speculatively

This hook adds an alternative implementation for the target hook
TARGET_HAVE_SPECULATION_SAFE_VALUE; it can be used by targets that have no
CPU implementations that execute code speculatively.  All that is needed for
such targets now is to add:

 #undef TARGET_HAVE_SPECULATION_SAFE_VALUE
 #define TARGET_HAVE_SPECULATION_SAFE_VALUE speculation_safe_value_not_needed.

to where you have your other target hooks and you're done.

gcc:
	* targhooks.h (speculation_safe_value_not_needed): New prototype.
	* targhooks.c (speculation_safe_value_not_needed): New function.
	* target.def (have_speculation_safe_value): Update documentation.
	* doc/tm.texi: Regenerated.

From-SVN: r263175

1 files changed, 5 insertions, 0 deletions

diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 351f0b3..a40f45a 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -11935,6 +11935,11 @@ This hook is used to determine the level of target support for
  a pattern named @code{speculation_barrier}.  Else it returns true
  for the first case and whether the pattern is enabled for the current
  compilation for the second case.
+ 
+ For targets that have no processors that can execute instructions
+ speculatively an alternative implemenation of this hook is available:
+ simply redefine this hook to @code{speculation_safe_value_not_needed}
+ along with your other target hooks.
 @end deftypefn
 
 @deftypefn {Target Hook} rtx TARGET_SPECULATION_SAFE_VALUE (machine_mode @var{mode}, rtx @var{result}, rtx @var{val}, rtx @var{failval})