heuristically determine int_fastN_t

Signed-off-by: Mattias Andrée <maandree@operamail.com>

2 files changed, 112 insertions, 15 deletions

diff --git a/gen/bits/intconf.c b/gen/bits/intconf.c
index 5955d38..2ba2754 100644
--- a/gen/bits/intconf.c
+++ b/gen/bits/intconf.c
@@ -16,24 +16,118 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 #include <stdio.h>
+#include <string.h>
+#include <time.h>
 
 
 
-int main(void)
+/**
+ * On my amd64 machine, the usual result is:
+ *   int_fast8_t  = int32_t
+ *   int_fast16_t = int32_t
+ *   int_fast32_t = int32_t
+ *   int_fast64_t = int64_t
+ */
+
+
+#define FAST_TEST(VAR)  \
+  n = 0, *VAR##p = 0; \
+  if (clock_gettime(CLOCK_THREAD_CPUTIME_ID, &start)) \
+    return perror(NULL), -1; \
+  for (;;) \
+    { \
+      for (m = 1000; m--;) \
+	VAR = 50, VAR += 50, VAR -= 50, VAR *= 50, VAR /= 50, VAR <<= 1, VAR >>= 1, *VAR##p |= 1; \
+      n++; \
+      if (clock_gettime(CLOCK_THREAD_CPUTIME_ID, &end)) \
+	return perror(NULL), -1; \
+      if (end.tv_sec > start.tv_sec + 2) \
+	break; \
+      if (end.tv_sec > start.tv_sec + 1) \
+	if (end.tv_nsec >= start.tv_nsec) \
+	  break; \
+    } \
+  time_elapsed = (long long int)(end.tv_sec) * 1000000000LL; \
+  time_elapsed += (long long int)(end.tv_nsec); \
+  time_elapsed -= (long long int)(start.tv_sec) * 1000000000LL; \
+  time_elapsed -= (long long int)(start.tv_nsec); \
+  adjn = (double)n, adjn /= (double)time_elapsed / 1000000000.; \
+  fprintf(stderr, "int%zu_t:%s %i000 op:s in %lli.%09lli s = %lf op:s/s\n", \
+	  8 * sizeof(VAR), 8 * sizeof(VAR) < 10 ? " " : "", 8 * n, \
+	  time_elapsed / 1000000000LL, time_elapsed % 1000000000LL, adjn * 8000.); \
+  if (adjn > bestn) \
+    bestn = adjn, best = 8 * sizeof(VAR); \
+  last = this
+
+
+#define TEST(VAR)  (this = 8 * (int)sizeof(VAR), ((this >= bits) && (this > last)))
+#ifdef __GNUC__
+__attribute__((optimize("-O0")))
+#endif
+static int fast(int bits)
 {
-  printf("CHAR_BIT %zu\n",      8 * sizeof(char));
-  printf("SHORT_BIT %zu\n",     8 * sizeof(short int));
-  printf("INT_BIT %zu\n",       8 * sizeof(int));
-  printf("LONG_BIT %zu\n",      8 * sizeof(long int));
-  printf("LONG_LONG_BIT %zu\n", 8 * sizeof(long long int));
-  printf("PTR_BIT %zu\n",       8 * sizeof(void*));
+  int last = 0, this = 0, best = 0, n, m;
+  float bestn;
+  float adjn;
+  struct timespec start, end;
+  long long int time_elapsed;
   
-  printf("INT%zu %s\n", 8 * sizeof(char), "char");
-  printf("INT%zu %s\n", 8 * sizeof(short int), "short int");
-  printf("INT%zu %s\n", 8 * sizeof(int), "int");
-  printf("INT%zu %s\n", 8 * sizeof(long int), "long int");
-  printf("INT%zu %s\n", 8 * sizeof(long long int), "long long int");
+  register volatile char hhi;
+  register volatile short int hi;
+  register volatile int i;
+  register volatile long int li;
+  register volatile long long int lli;
+  volatile char hhip[1];
+  volatile short int hip[1];
+  volatile int ip[1];
+  volatile long int lip[1];
+  volatile long long int llip[1];
+  
+  if (TEST(hhi))    { FAST_TEST(hhi); }
+  if (TEST(hi))     { FAST_TEST(hi);  }
+  if (TEST(i))      { FAST_TEST(i);   }
+  if (TEST(li))     { FAST_TEST(li);  }
+  if (best) {
+    if (TEST(lli))  { FAST_TEST(lli); }
+  } else
+    best = 64;
+  fprintf(stderr, "int_fast%i_t = int%i_t\n\n", bits, best);
+  
+  return best;
+}
+#undef TEST
+
+
+int main(int argc, char* argv[])
+{
+  int r = 0;
+  if (argc < 2)
+    {
+      r |= printf("CHAR_BIT %zu\n",      8 * sizeof(char));
+      r |= printf("SHORT_BIT %zu\n",     8 * sizeof(short int));
+      r |= printf("INT_BIT %zu\n",       8 * sizeof(int));
+      r |= printf("LONG_BIT %zu\n",      8 * sizeof(long int));
+      r |= printf("LONG_LONG_BIT %zu\n", 8 * sizeof(long long int));
+      r |= printf("PTR_BIT %zu\n",       8 * sizeof(void*));
+      
+      r |= printf("INT%zu %s\n", 8 * sizeof(char), "char");
+      r |= printf("INT%zu %s\n", 8 * sizeof(short int), "short int");
+      r |= printf("INT%zu %s\n", 8 * sizeof(int), "int");
+      r |= printf("INT%zu %s\n", 8 * sizeof(long int), "long int");
+      r |= printf("INT%zu %s\n", 8 * sizeof(long long int), "long long int");
+      return r < 0 ? 1 : 0;
+    }
+  else if (argc == 2)
+    {
+      if      (!strcmp(argv[1], "fast8"))   r = fast(8);
+      else if (!strcmp(argv[1], "fast16"))  r = fast(16);
+      else if (!strcmp(argv[1], "fast32"))  r = fast(32);
+      else if (!strcmp(argv[1], "fast64"))  r = fast(64);
+      if (r <= 0)
+	return 1;
+      return printf("%i\n", r) < 0 ? 1 : 0;
+    }
   
-  return 0;
+  return 1;
 }
 
diff --git a/gen/bits/intconf.h b/gen/bits/intconf.h
index 2dca3b5..eb7b5b5 100644
--- a/gen/bits/intconf.h
+++ b/gen/bits/intconf.h
@@ -18,7 +18,11 @@
 #ifndef _BITS_INTCONF_H
 #define _BITS_INTCONF_H
 //>set -e
-//>FAST8=8; FAST16=64; FAST32=64; FAST64=64
+
+//>FAST8=$(bin/gen/bits/intconf fast8)
+//>FAST16=$(bin/gen/bits/intconf fast16)
+//>FAST32=$(bin/gen/bits/intconf fast32)
+//>FAST64=$(bin/gen/bits/intconf fast64)
 
 #define __MAX_TO_MIN(max)  (-(max) - 1)
 #define __CHAR_BIT         //(bin/gen/bits/intconf | grep ^CHAR_BIT      | sed "s/^[^ ]* //")
@@ -45,6 +49,5 @@
 #define __UINT_FAST64_MAX  UINT//{FAST64}_MAX
 
 
-
 #endif