From c3ee6e27c2c06543aeaeba21f2516ad52cfbd1b2 Mon Sep 17 00:00:00 2001
From: Karl Williamson <khw@cpan.org>
Date: Wed, 22 Jan 2020 16:06:32 -0700
Subject: grok_bin_oct_hex: Add some branch predictions

This led to about a 7% improvement, number of branches went 2.3kk->1.9kk
in perf, thanks to Sergey Aleynikov.  cachegrind shows:

Key:
    Ir   Instruction read
    Dr   Data read
    Dw   Data write
    COND conditional branches
    IND  indirect branches
    _m   branch predict miss

The numbers represent raw counts per loop iteration.

eight_hex_digits
87654321

       blead latest Ratio %
       ----- ------ -------
    Ir 306.0  297.0   103.0
    Dr  76.0   76.0   100.0
    Dw  41.0   39.0   105.1
  COND  26.0   26.0   100.0
   IND   2.0    2.0   100.0

COND_m   0.1    0.0     Inf
 IND_m   3.0    3.0   100.0
---
 numeric.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

(limited to 'numeric.c')

diff --git a/numeric.c b/numeric.c
index 03bc3a34bc..51a0edfbe6 100644
--- a/numeric.c
+++ b/numeric.c
@@ -429,42 +429,42 @@ Perl_grok_bin_oct_hex(pTHX_ const char *start,
       case 0:
           return 0;
       default:
-          if (! _generic_isCC(*s, class_bit))  break;
+          if (UNLIKELY(! _generic_isCC(*s, class_bit)))  break;
           value = (value << shift) | XDIGIT_VALUE(*s);
           s++;
           /* FALLTHROUGH */
       case 7:
-          if (! _generic_isCC(*s, class_bit))  break;
+          if (UNLIKELY(! _generic_isCC(*s, class_bit)))  break;
           value = (value << shift) | XDIGIT_VALUE(*s);
           s++;
           /* FALLTHROUGH */
       case 6:
-          if (! _generic_isCC(*s, class_bit))  break;
+          if (UNLIKELY(! _generic_isCC(*s, class_bit)))  break;
           value = (value << shift) | XDIGIT_VALUE(*s);
           s++;
           /* FALLTHROUGH */
       case 5:
-          if (! _generic_isCC(*s, class_bit))  break;
+          if (UNLIKELY(! _generic_isCC(*s, class_bit)))  break;
           value = (value << shift) | XDIGIT_VALUE(*s);
           s++;
           /* FALLTHROUGH */
       case 4:
-          if (! _generic_isCC(*s, class_bit))  break;
+          if (UNLIKELY(! _generic_isCC(*s, class_bit)))  break;
           value = (value << shift) | XDIGIT_VALUE(*s);
           s++;
           /* FALLTHROUGH */
       case 3:
-          if (! _generic_isCC(*s, class_bit))  break;
+          if (UNLIKELY(! _generic_isCC(*s, class_bit)))  break;
           value = (value << shift) | XDIGIT_VALUE(*s);
           s++;
           /* FALLTHROUGH */
       case 2:
-          if (! _generic_isCC(*s, class_bit))  break;
+          if (UNLIKELY(! _generic_isCC(*s, class_bit)))  break;
           value = (value << shift) | XDIGIT_VALUE(*s);
           s++;
           /* FALLTHROUGH */
       case 1:
-          if (! _generic_isCC(*s, class_bit))  break;
+          if (UNLIKELY(! _generic_isCC(*s, class_bit)))  break;
           value = (value << shift) | XDIGIT_VALUE(*s);
 
           if (LIKELY(len <= 8)) {
-- 
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