* predict.c (expensive_function_p): New.

	* rtl.h (expensive_function_p): Declare.
	* i386.c (FAST_PROLOGUE_INSN_COUNT): New constant.
	(use_fast_prologue_epilogue): New static variable.
	(expand_prologue): Set it; emit short prologues if unset.
	(expand_epilogue): Likewise.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@45176 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 45 insertions, 0 deletions

diff --git a/gcc/predict.c b/gcc/predict.c
index f7e8b6d77a4..70460ab3b46 100644
--- a/gcc/predict.c
+++ b/gcc/predict.c
@@ -782,6 +782,51 @@ counts_to_freqs ()
     }
 }
 
+/* Return true if function is likely to be expensive, so there is no point
+   to optimizer performance of prologue, epilogue or do inlining at the
+   expense of code size growth.  THRESHOLD is the limit of number
+   of isntructions function can execute at average to be still considered
+   not expensive.  */
+bool
+expensive_function_p (threshold)
+	int threshold;
+{
+  unsigned int sum = 0;
+  int i;
+  int limit;
+
+  /* We can not compute accurately for large thresholds due to scaled
+     frequencies.  */
+  if (threshold > BB_FREQ_MAX)
+    abort ();
+
+  /* Frequencies are out of range.  This eighter means that function contains
+     internal loop executing more than BB_FREQ_MAX times or profile feedback
+     is available and function has not been executed at all.  */
+  if (ENTRY_BLOCK_PTR->frequency == 0)
+    return true;
+    
+  /* Maximally BB_FREQ_MAX^2 so overflow won't happen.  */
+  limit = ENTRY_BLOCK_PTR->frequency * threshold;
+  for (i = 0; i < n_basic_blocks; i++)
+    {
+      basic_block bb = BASIC_BLOCK (i);
+      rtx insn;
+
+      for (insn = bb->head; insn != NEXT_INSN (bb->end);
+	   insn = NEXT_INSN (insn))
+	{
+	  if (active_insn_p (insn))
+	    {
+	      sum += bb->frequency;
+	      if (sum > limit)
+		return true;
+	    }
+	}
+    }
+  return false;
+}
+
 /* Estimate basic blocks frequency by given branch probabilities.  */
 static void
 estimate_bb_frequencies (loops)