Skip to content

[DenseMap] Update combineHashValue #95970

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 4 commits into from
Jun 19, 2024
Merged

[DenseMap] Update combineHashValue #95970

Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
2ede7c1
[𝘀𝗽𝗿] initial version
MaskRay Jun 18, 2024
2d24f5c
rebase after statepoint fix 8ea31db27211ed0c8207b4b4b0839e5cbe780c73
MaskRay Jun 19, 2024
ac95ae7
simpler mixer
MaskRay Jun 19, 2024
7cf9dfb
rebase
MaskRay Jun 19, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
24 changes: 13 additions & 11 deletions llvm/include/llvm/ADT/DenseMapInfo.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -23,20 +23,22 @@

namespace llvm {

namespace densemap::detail {
// A bit mixer with very low latency using one multiplications and one
// xor-shift. The constant is from splitmix64.
inline uint64_t mix(uint64_t x) {
x *= 0xbf58476d1ce4e5b9u;
x ^= x >> 31;
return x;
}
} // namespace densemap::detail

namespace detail {

/// Simplistic combination of 32-bit hash values into 32-bit hash values.
static inline unsigned combineHashValue(unsigned a, unsigned b) {
uint64_t key = (uint64_t)a << 32 | (uint64_t)b;
key += ~(key << 32);
key ^= (key >> 22);
key += ~(key << 13);
key ^= (key >> 8);
key += (key << 3);
key ^= (key >> 15);
key += ~(key << 27);
key ^= (key >> 31);
return (unsigned)key;
inline unsigned combineHashValue(unsigned a, unsigned b) {
uint64_t x = (uint64_t)a << 32 | (uint64_t)b;
return (unsigned)densemap::detail::mix(x);
}

} // end namespace detail
Expand Down