diff options
Diffstat (limited to 'gcc/pointer-set.c')
| -rw-r--r-- | gcc/pointer-set.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/gcc/pointer-set.c b/gcc/pointer-set.c index 06592d741a6..f8023c7fc6c 100644 --- a/gcc/pointer-set.c +++ b/gcc/pointer-set.c @@ -46,8 +46,8 @@ struct pointer_set_t relatively prime to 2^sizeof(size_t). The result is two words. Discard the most significant word, and return the most significant N bits of the least significant word. As suggested by Knuth, our - choice for A is the integer part of 2^32 / phi, where phi is the - golden ratio. + choice for A is the integer part of (ULONG_MAX + 1.0) / phi, where phi + is the golden ratio. We don't need to do anything special for full-width multiplication because we're only interested in the least significant word of the @@ -56,8 +56,16 @@ struct pointer_set_t static inline size_t hash1 (const void *p, unsigned long max, unsigned long logmax) { +#if HOST_BITS_PER_LONG == 32 const unsigned long A = 0x9e3779b9u; - const unsigned long shift = sizeof(unsigned long) * CHAR_BIT - logmax; +#elif HOST_BITS_PER_LONG == 64 + const unsigned long A = 0x9e3779b97f4a7c16ul; +#else + const double M = (ULONG_MAX + 1.0); + const double B = M / ((sqrt (5) - 1) / 2.0); + const unsigned long A = B - (floor (B / M) * M); +#endif + const unsigned long shift = sizeof (unsigned long) * CHAR_BIT - logmax; return ((A * (unsigned long) p) >> shift) & (max - 1); } |