* loop.c: Include predict.h

	(strength_reduce): Drop branch prediction note in case
	number of iterations is known.
	* predict.def (PRED_LOOP_ITERATIONS): new.
	* Makefile.in (loop.o): Add dependancy on predict.h


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@43251 138bc75d-0d04-0410-961f-82ee72b054a4

3 files changed, 15 insertions, 1 deletions

diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index a9af1e1cdf9..6ed6e3f9283 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -1438,7 +1438,7 @@ profile.o : profile.c $(CONFIG_H) $(SYSTEM_H) $(RTL_H) $(TREE_H) flags.h \
    insn-config.h output.h $(REGS_H) $(EXPR_H) function.h \
    gcov-io.h toplev.h $(GGC_H) hard-reg-set.h $(BASIC_BLOCK_H)
 loop.o : loop.c $(CONFIG_H) $(SYSTEM_H) $(RTL_H) flags.h $(LOOP_H) insn-config.h \
-   $(REGS_H) hard-reg-set.h $(RECOG_H) $(EXPR_H) real.h \
+   $(REGS_H) hard-reg-set.h $(RECOG_H) $(EXPR_H) real.h $(PREDICT_H) \
    $(BASIC_BLOCK_H) function.h toplev.h varray.h except.h cselib.h $(TM_P_H)
 doloop.o : doloop.c $(CONFIG_H) $(SYSTEM_H) $(RTL_H) flags.h $(LOOP_H) \
    $(EXPR_H) hard-reg-set.h $(BASIC_BLOCK_H) $(TM_P_H) toplev.h
diff --git a/gcc/loop.c b/gcc/loop.c
index 34bc862b5ac..fac9a840bc8 100644
--- a/gcc/loop.c
+++ b/gcc/loop.c
@@ -52,6 +52,7 @@ Boston, MA 02111-1307, USA.  */
 #include "cselib.h"
 #include "except.h"
 #include "toplev.h"
+#include "predict.h"
 
 #define LOOP_REG_LIFETIME(LOOP, REGNO) \
 ((REGNO_LAST_LUID (REGNO) - REGNO_FIRST_LUID (REGNO)))
@@ -4498,6 +4499,18 @@ strength_reduce (loop, flags)
     doloop_optimize (loop);
 #endif  /* HAVE_doloop_end  */
 
+  /* In case number of iterations is known, drop branch prediction note
+     in the branch.  Do that only in second loop pass, as loop unrolling
+     may change the number of iterations performed.  */
+  if ((flags & LOOP_BCT)
+      && loop_info->n_iterations / loop_info->unroll_number > 1)
+    {
+      int n = loop_info->n_iterations / loop_info->unroll_number - 1;
+      predict_insn (PREV_INSN (loop->end),
+		    PRED_LOOP_ITERATIONS,
+		    REG_BR_PROB_BASE - REG_BR_PROB_BASE / n);
+    }
+
   if (loop_dump_stream)
     fprintf (loop_dump_stream, "\n");
 
diff --git a/gcc/predict.def b/gcc/predict.def
index f910f3ba72f..01d87a4c3f0 100644
--- a/gcc/predict.def
+++ b/gcc/predict.def
@@ -38,6 +38,7 @@ Boston, MA 02111-1307, USA.  */
 
 DEF_PREDICTOR (PRED_FIRST_MATCH, "first match", PROB_ALWAYS)
 DEF_PREDICTOR (PRED_UNCONDITIONAL, "unconditional jump", PROB_ALWAYS)
+DEF_PREDICTOR (PRED_LOOP_ITERATIONS, "loop iterations", PROB_ALWAYS)
 DEF_PREDICTOR (PRED_BUILTIN_EXPECT, "__builtin_expect", PROB_VERY_LIKELY)
 DEF_PREDICTOR (PRED_NORETURN, "noreturn call", PROB_ALWAYS)
 DEF_PREDICTOR (PRED_LOOP_BRANCH, "loop branch", PROB_VERY_LIKELY)