[GOOGLE] Remove size check when loop is very hot

[Dehao Chen]

This patch removes the size limit for loop unroll/peel when the loop
is truly hot. This makes the implementation easily maintanable between
FDO and AutoFDO.

Bootstrapped and loadtest perf show neutral impact.

OK for google-4_8?

Thanks,
Dehao

Index: gcc/loop-unroll.c
===
--- gcc/loop-unroll.c (revision 208233)
+++ gcc/loop-unroll.c (working copy)
@@ -347,11 +347,9 @@ code_size_limit_factor(struct loop *loop)
   /* Next, set the value of the codesize-based unroll factor divisor which in
  most loops will need to be set to a value that will reduce or eliminate
  unrolling/peeling.  */
-  if (num_hot_counters  size_threshold * 2
-   loop-header-count  0)
+  if (loop-header-count  0)
 {
-  /* For applications that are less than twice the codesize limit, allow
- limited unrolling for very hot loops.  */
+  /* Allow limited unrolling for very hot loops.  */
   sum_to_header_ratio = profile_info-sum_all / loop-header-count;
   hotness_ratio_threshold = PARAM_VALUE
(PARAM_UNROLLPEEL_HOTNESS_THRESHOLD);
   /* When the profile count sum to loop entry header ratio is smaller than

Re: [GOOGLE] Remove size check when loop is very hot

[Teresa Johnson]

Looks good to me.
Thanks, Teresa

On Fri, Feb 28, 2014 at 2:17 PM, Dehao Chen de...@google.com wrote:
 This patch removes the size limit for loop unroll/peel when the loop
 is truly hot. This makes the implementation easily maintanable between
 FDO and AutoFDO.

 Bootstrapped and loadtest perf show neutral impact.

 OK for google-4_8?

 Thanks,
 Dehao

 Index: gcc/loop-unroll.c
 ===
 --- gcc/loop-unroll.c (revision 208233)
 +++ gcc/loop-unroll.c (working copy)
 @@ -347,11 +347,9 @@ code_size_limit_factor(struct loop *loop)
/* Next, set the value of the codesize-based unroll factor divisor which in
   most loops will need to be set to a value that will reduce or eliminate
   unrolling/peeling.  */
 -  if (num_hot_counters  size_threshold * 2
 -   loop-header-count  0)
 +  if (loop-header-count  0)
  {
 -  /* For applications that are less than twice the codesize limit, allow
 - limited unrolling for very hot loops.  */
 +  /* Allow limited unrolling for very hot loops.  */
sum_to_header_ratio = profile_info-sum_all / loop-header-count;
hotness_ratio_threshold = PARAM_VALUE
 (PARAM_UNROLLPEEL_HOTNESS_THRESHOLD);
/* When the profile count sum to loop entry header ratio is smaller 
 than



-- 
Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413