Add predict_doloop_p target hook

    Add one target hook predict_doloop_p, it return true if we can predict it
    is possible to use a low-overhead loop, it can help ivopts to make some
    better decisions.

    PR middle-end/80791
    * target.def (predict_doloop_p): New hook.
    * targhooks.h (default_predict_doloop_p): New declaration.
    * targhooks.c (default_predict_doloop_p): New function.
    * doc/tm.texi.in (TARGET_PREDICT_DOLOOP_P): New hook.
    * doc/tm.texi: Regenerate.
    * config/rs6000/rs6000.c (rs6000_predict_doloop_p): New function.
    (TARGET_PREDICT_DOLOOP_P): New macro.
    * tree-ssa-loop-ivopts.c (generic_predict_doloop_p): New function.

From-SVN: r272405

1 files changed, 13 insertions, 0 deletions

diff --git a/gcc/targhooks.c b/gcc/targhooks.c
index b27111639f4..0da885ec152 100644
--- a/gcc/targhooks.c
+++ b/gcc/targhooks.c
@@ -643,6 +643,19 @@ default_has_ifunc_p (void)
   return HAVE_GNU_INDIRECT_FUNCTION;
 }
 
+/* Return true if we predict the loop LOOP will be transformed to a
+   low-overhead loop, otherwise return false.
+
+   By default, false is returned, as this hook's applicability should be
+   verified for each target.  Target maintainers should re-define the hook
+   if the target can take advantage of it.  */
+
+bool
+default_predict_doloop_p (struct loop *loop ATTRIBUTE_UNUSED)
+{
+  return false;
+}
+
 /* NULL if INSN insn is valid within a low-overhead loop, otherwise returns
    an error message.