[libmath-prime-util-perl] 42/181: Small comment changes

[Partha P. Mukherjee]

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ppm-guest pushed a commit to annotated tag v0.36
in repository libmath-prime-util-perl.

commit 18302e13dba55e3d6ae189b8c6f0fe8258ff718d
Author: Dana Jacobsen <dana at acm.org>
Date:   Tue Dec 24 21:21:31 2013 -0800

    Small comment changes
---
 Changes  | 3 ++-
 lehmer.c | 2 +-
 lmo.c    | 8 ++++----
 3 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/Changes b/Changes
index bafbab2..9d2d570 100644
--- a/Changes
+++ b/Changes
@@ -33,7 +33,8 @@ Revision history for Perl module Math::Prime::Util
       lehmer.c.  Really only affects LMOS and Legendre, but it's significant
       for them.  Thanks to Kim Walisch for questioning my earlier decision.
 
-    - Rewrite sieve composite map.  Segment sieving is faster.
+    - Rewrite sieve composite map.  Segment sieving is faster.  It's a little
+      faster than primegen for me, but still slower than primesieve and yafu.
 
 
 0.35  2013-12-08
diff --git a/lehmer.c b/lehmer.c
index 40cbf14..c4d0a59 100644
--- a/lehmer.c
+++ b/lehmer.c
@@ -33,7 +33,7 @@
  *
  * Times and memory use for prime_count(10^15) on a Haswell 4770K, asterisk
  * indicates parallel operation.  The standalone versions of my code use
- * Kim Walisch's excellent primesieve, which faster than my sieve.
+ * Kim Walisch's excellent primesieve, which is faster than my sieve.
  * His Lehmer/Meissel/Legendre seem a bit slower in serial, but
  * parallelize much better.
  *
diff --git a/lmo.c b/lmo.c
index 518876f..43993a6 100644
--- a/lmo.c
+++ b/lmo.c
@@ -86,10 +86,10 @@ typedef UV sword_t;
 #define SWORD_MASKBIT(bits)  (UVCONST(1) << ((bits) % SWORD_BITS))
 #define SWORD_CLEAR(s,bits)  s[bits/SWORD_BITS] &= ~SWORD_MASKBIT(bits)
 
-/* GCC 3.4-4.1 has broken 64-bit popcount.  4.2+ can generate awful code when
- * it doesn't have asm.  4.8 seems to generate similar code to the below.
- * Hence, only use the builtin when we have asm.
- * Compile with -march=native to get a big speedup on newer processors. */
+/* GCC 3.4 - 4.1 has broken 64-bit popcount.
+ * GCC 4.2+ can generate awful code when it doesn't have asm (GCC bug 36041).
+ * When the asm is present (e.g. compile with -march=native on a platform that
+ * has them, like Nahelem+), then it is almost as fast as the direct asm. */
 #if SWORD_BITS == 64
  #if defined(__POPCNT__) && defined(__GNUC__) && (__GNUC__> 4 || (__GNUC__== 4 && __GNUC_MINOR__> 1))
    #define bitcount(b)  __builtin_popcountll(b)

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