Fix overflow on huge sieves

danaj · Jan 31, 2018 · f7354b2 · f7354b2
1 parent d1e0575
commit f7354b2
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Showing 3 changed files with 18 additions and 3 deletions.
diff --git a/Changes b/Changes
@@ -1,5 +1,18 @@
 Revision history for Perl module Math::Prime::Util
 
+0.71 2018-?
+
+    [FIXES]
+
+    - Monolithic sieves beyond 30*2^32 (~ 1.2 * 10^11) overflowed.
+
+    [OTHER]
+
+    - Added ability to use -DBENCH_SEG for benchmarking sieves using
+      ntheory::_segment_pi without table optimizations.
+
+
+
 0.70 2017-12-02
 
     [FIXES]

diff --git a/prime_nth_count.c b/prime_nth_count.c
@@ -273,6 +273,7 @@ UV segment_prime_count(UV low, UV high)
 
   if (low > high)  return count;
 
+#if !defined(BENCH_SEGCOUNT)
   if (low == 7 && high <= 30*NPRIME_SIEVE30) {
     count += count_segment_ranged(prime_sieve30, NPRIME_SIEVE30, low, high);
     return count;
@@ -285,6 +286,7 @@ UV segment_prime_count(UV low, UV high)
    * to sieve all the rest.  We should be using LMO or Lehmer much earlier. */
 #ifdef APPLY_TABLES
   APPLY_TABLES
+#endif
 #endif
 
   low_d = low/30;

diff --git a/sieve.c b/sieve.c
@@ -165,8 +165,8 @@ static const unsigned char qinit30[30] =
 
 typedef struct {
   uint32_t prime;
-  uint32_t offset;
-  uint8_t index;
+  UV       offset;
+  uint8_t  index;
 } wheel_t;
 
 #define CROSS_INDEX(v, b0,b1,b2,b3,b4,b5,b6,b7,  i0,i1,i2,i3,i4,i5,i6,i7, it) \
@@ -216,7 +216,7 @@ static wheel_t create_wheel(UV startp, uint32_t prime)
   return w;
 }
 
-static void mark_primes(unsigned char* s, uint32_t bytes, wheel_t* w)
+static void mark_primes(unsigned char* s, UV bytes, wheel_t* w)
 {
   if (w->offset >= bytes) {
     w->offset -= bytes;