Cleanup in bitvec.h and bugfix in principal ideal generation

Makefile

@@ -1,6 +1,6 @@
 HEADERS=coxeter.h thickenings.h queue.h bitvec.h
-#OPTIONS=-O3 -m64 -march=native -flto -funroll-loops -std=gnu99
+OPTIONS=-O3 -m64 -march=native -flto -funroll-loops -std=gnu99 -Winline
-OPTIONS=-m64 -march=native -O0 -g -std=gnu99
+#OPTIONS=-m64 -march=native -O0 -g -std=gnu99
 #OPTIONS=-O3 -m64 -march=native -funroll-loops -fno-inline -std=gnu99 -pg
 
 all: generate process

bitvec.h

@@ -16,99 +16,39 @@
 #ifndef __BITVEC_H__
 #define __BITVEC_H__ 1
 
-// #define _GNU_SOURCE /* enable ffsll */
+#define _GNU_SOURCE
-// #include <string.h>
+#include <string.h>
 
 #include <inttypes.h>
 
 #include <stdio.h>
 #include <stdlib.h>
 
-/* For _mm_popcnt_u64 */
-#include <x86intrin.h>
-
 // FIRSTBITS(n) only yields useful result when 0 <= n < 64
-#define FIRSTBITS(n) ((1l << (n)) - 1l)
+#define BLOCKSIZE 64
+#define FIRSTBITS(n) (((uint64_t)1 << (n)) - 1l)
+#define BIT(n) (((uint64_t)1 << (n)))
 #define ALLBITS ((uint64_t)-1)
+#define BLOCK(n) ((n)/64)
+#define INDEX(n) ((n)%64)
 
 typedef struct {
   uint64_t v[BV_QWORD_RANK];
 } bitvec_t;
 
-/*
-static inline unsigned long bv_hash(bitvec_t S)
-{
-  unsigned long h = 5381;
-  int i,j;
-  uint8_t x;
-
-  for (i = 0; i < BV_QWORD_RANK*4; i++) {
-    x = (S.v[i/8] >> (8*(i % 8))) & 0xff;
-    h = ((h << 5) + h) ^ x;
-  }
-  return h;
-}
-
-static inline int bv_equal(bitvec_t x,bitvec_t y)
-{
-  int i;
-  for (i=0; i < BV_QWORD_RANK; i++) {
-    if (x.v[i] != y.v[i]) {
-      return 0;
-    }
-  }
-  return 1;
-  //  return ((x.v[0] == y.v[0]) && (x.v[1] == y.v[1]));
-}
-
-static inline void bv_difference(bitvec_t *pile, bitvec_t toremove)
-{
-  int i;
-  for (i=0; i < BV_QWORD_RANK; i++) {
-    pile->v[i] &= ~toremove.v[i];
-  }
-}
-*/
-
-/* /\* static inline *\/ int old_popcount64(uint64_t x) */
-/* { */
-/*   int i; */
-/*   for (i = 0; x; x >>= 1) { */
-/*     i += x & 1; */
-/*   } */
-/*   return i; */
-/* } */
-
-/*
-static inline int popcount64(uint64_t x)
-{
-  return _mm_popcnt_u64(x);
-}
-
-static inline int bv_popcount(bitvec_t x)
-{
-  int i;
-  int accum=0;
-  for (i=0; i<BV_QWORD_RANK; i++) {
-    accum += popcount64(x.v[i]);
-  }
-  return accum;
-}
-*/
-
 static inline void bv_clear_bit(bitvec_t *x, int k)
 {
-  x->v[k/64] &= ~((uint64_t)1 << (k % 64));
+  x->v[BLOCK(k)] &= ~BIT(INDEX(k));
 }
 
 static inline void bv_set_bit(bitvec_t *x, int k)
 {
-  x->v[k/64] |= ((uint64_t)1 << (k % 64));
+  x->v[BLOCK(k)] |= BIT(INDEX(k));
 }
 
 static inline int bv_get_bit(const bitvec_t *x, int k)
 {
-  return (x->v[k/64] >> (k % 64)) & 0x1;
+  return (x->v[BLOCK(k)] >> INDEX(k)) & 0x1;
 }
 
 static inline void bv_clear(bitvec_t *x)
@@ -132,8 +72,24 @@ static inline void bv_print(FILE *f, const bitvec_t *x, int len)
 {
   for(int i = 0; i < len; i++) {
     fputc(bv_get_bit(x, i) ? '1' : '0', f);
-    if(i % 64 == 63)
+    //    if(i % BLOCKSIZE == BLOCKSIZE - 1)
-      fputc('-',f);
+    //    fputc('-',f);
+  }
+}
+
+static inline void bv_print_nice(FILE *f, const bitvec_t *pos, const bitvec_t *neg, int special, int len)
+{
+  for(int i = 0; i < len; i++) {
+    if(i == special)
+      fputc('X', f);
+    else if(bv_get_bit(pos, i) && !bv_get_bit(neg, i))
+      fputc('1', f);
+    else if(!bv_get_bit(pos, i) && bv_get_bit(neg, i))
+      fputc('0', f);
+    else if(!bv_get_bit(pos, i) && !bv_get_bit(neg, i))
+      fputc(' ', f);
+    else
+      fputc('-', f);
   }
 }
 
@@ -165,23 +121,36 @@ static inline int bv_disjoint(const bitvec_t *x, const bitvec_t *y)
 static inline int bv_full(const bitvec_t *x, int len)
 {
   int i;
-  for(i = 0; i < len/64; i++)
+  for(i = 0; i < BLOCK(len); i++)
     if(x->v[i] != ALLBITS)
       return 0;
 
-  return (x->v[i] & FIRSTBITS(len%64)) == FIRSTBITS(len%64);
+  return (x->v[i] & FIRSTBITS(INDEX(len))) == FIRSTBITS(INDEX(len));
 }
 
 // set bits in range start...end (including start and excluding end)
 static inline void bv_set_range(bitvec_t *x, int start, int end)
 {
-  if(start/64 == end/64)
+  if(BLOCK(start) == BLOCK(end))
-    x->v[start/64] |= ~FIRSTBITS(start % 64) & FIRSTBITS(end % 64);
+    x->v[BLOCK(start)] |= ~FIRSTBITS(INDEX(start)) & FIRSTBITS(INDEX(end));
   else {
-    x->v[start/64] |= ~FIRSTBITS(start % 64);
+    x->v[BLOCK(start)] |= ~FIRSTBITS(INDEX(start));
-    for(int i = start/64 + 1; i < end/64; i++)
+    for(int i = BLOCK(start) + 1; i < BLOCK(end); i++)
       x->v[i] = ALLBITS;
-    x->v[end/64] |= FIRSTBITS(end % 64);
+    x->v[BLOCK(end)] |= FIRSTBITS(INDEX(end));
+  }
+}
+
+// set bits in range start...end (including start and excluding end), except if they are set in mask
+static inline void bv_set_range_except(bitvec_t *x, const bitvec_t *mask, int start, int end)
+{
+  if(BLOCK(start) == BLOCK(end))
+    x->v[BLOCK(start)] |= ~FIRSTBITS(INDEX(start)) & FIRSTBITS(INDEX(end)) & ~mask->v[BLOCK(start)];
+  else {
+    x->v[BLOCK(start)] |= ~FIRSTBITS(INDEX(start)) & ~mask->v[BLOCK(start)];
+    for(int i = BLOCK(start) + 1; i < BLOCK(end); i++)
+      x->v[i] |= ~mask->v[i];
+    x->v[BLOCK(end)] |= FIRSTBITS(INDEX(end)) & ~mask->v[BLOCK(end)];
   }
 }
 
@@ -190,15 +159,15 @@ static inline int bv_next_zero(const bitvec_t *x, int start)
 {
   int position;
 
-  position = ffsll(~(x->v[start/64] | FIRSTBITS(start % 64)));
+  position = ffsll(~(x->v[BLOCK(start)] | FIRSTBITS(INDEX(start))));
 
   if(position)
-    return (start/64)*64 + position - 1; // found zero in same chunk
+    return BLOCK(start)*BLOCKSIZE + position - 1; // found zero in same chunk
 
-  for(int i = start/64 + 1; i < BV_QWORD_RANK; i++) {
+  for(int i = BLOCK(start) + 1; i < BV_QWORD_RANK; i++) {
     position = ffsll(~x->v[i]);
     if(position) // found a 0
-      return i*64 + position - 1;
+      return i*BLOCKSIZE + position - 1;
   }
 
   return BV_QWORD_RANK; // found nothing

thickenings.c

@@ -567,21 +567,15 @@ void graph_free(semisimple_type_t type, node_t *graph)
 /*********************************** THE ACTUAL ENUMERATION ****************************************/
 
 typedef struct {
-  int rank;
+  int size;        // the size of the weyl group. We store however only the first size/2 elements
-  int order;
-  int size;        // the size of the graph; this can vary from the order if we take quotients beforehand
-  const node_t *graph;
-  int printstep;
-  const char *alphabet;
   FILE *outfile;
   bitvec_t *principal_pos;
   bitvec_t *principal_neg;
+  int *principal_is_slim;
 } enumeration_info_t;
 
 /*
 
-   ok this is screwed up, let's start over:
-
    pos and neg are bitvectors of size info.size/2
    they stand for the first (shortest) info.size/2 elements of the weyl group
    the least siginficant bit is the identity
@@ -595,8 +589,11 @@ typedef struct {
 // returns number of found balanced ideals
 // next_neg can be info.size/2; in that case, everything between known_until and info.size/2 is required to be in the ideal, but it does not mean that next_neg is really not contained in the ideal
 // next_neg must be strictly greater than known_until, and less or equal to info.size/2
+// we use bv_union, bv_copy, bv_set_range_except, bv_disjoint, bv_next_zero
+
 static long enumerate_tree(const enumeration_info_t *info, const bitvec_t *pos, const bitvec_t *neg, int first_unknown, int next_neg)
 {
+  static long totcount = 0;
   bitvec_t newpos, newneg, known;
   int next_next_neg;
   long count = 0;
@@ -604,6 +601,8 @@ static long enumerate_tree(const enumeration_info_t *info, const bitvec_t *pos,
   // the omission of next_neg means inclusion of info->size - 1 - next_neg
   // add its principal ideal to pos and the opposite to neg
   if(next_neg != info->size/2) {
+    //     if(!info->principal_is_slim[info->size - 1 - next_neg]) // if the principal ideal we want to add is not slim by itself, we don't even have to try; but there is not really a performance benefit
+    //      return 0;
     bv_union(&info->principal_pos[info->size - 1 - next_neg], pos, &newpos);
     bv_union(&info->principal_neg[info->size - 1 - next_neg], neg, &newneg);
   } else { // or, if there is no next_neg, just copy
@@ -611,8 +610,8 @@ static long enumerate_tree(const enumeration_info_t *info, const bitvec_t *pos,
     bv_copy(neg, &newneg);
   }
 
-  // add the range from first_unknown to next_neg to newpos
+  // everything before next_neg which was unknown should be set to positive; to speed this up, we can start with first_unknown
-  bv_set_range(&newpos, first_unknown, next_neg); // including the start, excluding end
+  bv_set_range_except(&newpos, neg, first_unknown, next_neg);
 
   // check if this leads to any conflicts (equivalently, violates slimness)
   if(!bv_disjoint(&newpos, &newneg))
@@ -621,30 +620,23 @@ static long enumerate_tree(const enumeration_info_t *info, const bitvec_t *pos,
   // what do we know so far?
   bv_union(&newpos, &newneg, &known);
 
-  // do we know everything already? we have a balanced ideal then
+  next_next_neg = bv_next_zero(&known, next_neg + 1);
-  if(bv_full(&known, info->size/2)) {
 
+  if(next_next_neg >= info->size/2) {
+
+    if((++totcount) % 100000000 == 0) {
       fprintf(stderr, "Found balanced ideal: ");
       bv_print(stderr, &newpos, info->size/2);
-    fprintf(stderr, " ");
-    bv_print(stderr, &newneg, info->size/2);
       fprintf(stderr, "\n");
+    }
 
     return 1;
   }
 
-  next_next_neg = next_neg;
+  do {
-  while(next_next_neg < info->size/2) {
-    int tmp = bv_next_zero(&known, next_next_neg + 1); // this could return info->size/2, but that's fine for enumerate_tree
-    if(tmp <= next_next_neg) {
-      fprintf(stderr, "%d <= %d\n", tmp, next_next_neg);
-      bv_print(stderr, &known, info->size/2);
-      fprintf(stderr, "\n");
-      exit(-1);
-    }
-    next_next_neg = tmp;
     count += enumerate_tree(info, &newpos, &newneg, next_neg + 1, next_next_neg);
-  }
+    next_next_neg = bv_next_zero(&known, next_next_neg + 1);
+  } while(next_next_neg <= info->size/2);
 
   return count;
 }
@@ -658,16 +650,15 @@ long enumerate_balanced_thickenings(semisimple_type_t type, node_t *graph, int s
   int current;
   edgelist_t *edge;
 
-  info.rank = coxeter_rank(type);
-  info.order = coxeter_order(type);
   info.size = size;
-  info.graph = graph;
-  info.alphabet = (char*)alphabet;
   info.outfile = outfile;
+  info.principal_pos = (bitvec_t*)malloc(info.size*sizeof(bitvec_t));
+  info.principal_neg = (bitvec_t*)malloc(info.size*sizeof(bitvec_t));
+  info.principal_is_slim = (int*)malloc(info.size*sizeof(int));
 
-  info.printstep = 0;
+  //  info.printstep = 0;
-  if(getenv("PRINTSTEP"))
+  //  if(getenv("PRINTSTEP"))
-    info.printstep = atoi(getenv("PRINTSTEP"));
+  //    info.printstep = atoi(getenv("PRINTSTEP"));
 
   // the algorithm only works if the opposition pairing does not stabilize any element
   // if this happens, there can be no balanced thickenings
@@ -675,39 +666,39 @@ long enumerate_balanced_thickenings(semisimple_type_t type, node_t *graph, int s
     if(graph[i].opposite == i)
       return 0;
 
-  // we can only handle bitvectors up to 64*BV_QWORD_RANK bits
+ // we can only handle bitvectors up to 64*BV_QWORD_RANK bits, but we only store half of the weyl group
   if(info.size > 128*BV_QWORD_RANK)
     return -1;
 
-  // generate principal ideals, needed bitvec operations: bv_clear, bv_set_bit, bv_get_bit
+  // generate principal ideals
-  bitvec_t *principal_pos = (bitvec_t*)malloc(info.size*sizeof(bitvec_t));
+  int *principal = (int*)malloc(info.size*sizeof(int));
-  bitvec_t *principal_neg = (bitvec_t*)malloc(info.size*sizeof(bitvec_t));
   for(int i = 0; i < info.size; i++) {
-    bv_clear(&principal_pos[i]);
+    memset(principal, 0, info.size*sizeof(int));
-    bv_clear(&principal_neg[i]);
+    principal[i] = 1;
-    bv_set_bit(&principal_pos[i], i);
-    bv_set_bit(&principal_neg[i], info.size - 1 - i);
     queue_init(&queue);
     queue_put(&queue, i);
-    while((current = queue_get(&queue)) != -1) {
+    while((current = queue_get(&queue)) != -1)
       for(edge = graph[current].bruhat_lower; edge; edge = edge->next)
-	if(!bv_get_bit(&principal_pos[i], edge->to)) {
+	if(!principal[edge->to]) {
-	  bv_set_bit(&principal_pos[i], edge->to);
+	  principal[edge->to] = 1;
-	  bv_set_bit(&principal_neg[i], info.size - 1 - edge->to);
 	  queue_put(&queue, edge->to);
 	}
-    }
-  }
 
-  // truncate them, as we only need the first info.size/2 elements
+    // copy the first half into bitvectors
-  for(int i = 0; i < info.size; i++)
+    bv_clear(&info.principal_pos[i]);
-    for(int j = info.size/2; j < info.size; j++) {
+    bv_clear(&info.principal_neg[i]);
-      bv_clear_bit(&principal_pos[i], j);
+    info.principal_is_slim[i] = 1;
-      bv_clear_bit(&principal_neg[i], j);
+    for(int j = 0; j < info.size/2; j++)
+      if(principal[j])
+	bv_set_bit(&info.principal_pos[i], j);
+    for(int j = 0; j < info.size/2; j++)
+      if(principal[info.size - 1 - j]) {
+	bv_set_bit(&info.principal_neg[i], j);
+	if(bv_get_bit(&info.principal_pos[i], j))
+	  info.principal_is_slim[i] = 0;
       }
-
+  }
-  info.principal_pos = principal_pos;
+  free(principal);
-  info.principal_neg = principal_neg;
 
   // enumerate balanced ideals
   bitvec_t pos, neg;
@@ -716,8 +707,9 @@ long enumerate_balanced_thickenings(semisimple_type_t type, node_t *graph, int s
   for(int i = 0; i <= info.size/2; i++)
     count += enumerate_tree(&info, &pos, &neg, 0, i);
 
-  free(principal_pos);
+  free(info.principal_is_slim);
-  free(principal_neg);
+  free(info.principal_pos);
+  free(info.principal_neg);
 
   return count;
 }