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Replace llvm::MD5 with StableHasher

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This commit is contained in:
Robert Widmann
2021-01-05 15:17:55 -08:00
parent f5cb08e3d1
commit 73ac8d3531
11 changed files with 53 additions and 42 deletions
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33
include/swift/Basic/Fingerprint.h
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@@ -13,10 +13,10 @@
#ifndef SWIFT_BASIC_FINGERPRINT_H
#define SWIFT_BASIC_FINGERPRINT_H
#include "swift/Basic/StableHasher.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/MD5.h"
#include <string>
@@ -52,11 +52,6 @@ namespace swift {
/// iterable decl contexts to detect when the tokens in their bodies have
/// changed. This makes them a coarse - yet safe - overapproximation for when a
/// decl has changed semantically.
///
/// \c Fingerprints are currently implemented as a thin wrapper around an MD5
/// hash. MD5 is known to be neither the fastest nor the most
/// cryptographically capable algorithm, but it does afford us the avalanche
/// effect we desire. We should revisit the modeling decision here.
class Fingerprint final {
public:
/// The size (in bytes) of the raw value of all fingerprints.
@@ -66,6 +61,8 @@ public:
private:
Core core;
friend struct StableHasher::Combiner<swift::Fingerprint>;
public:
/// Creates a fingerprint value from a pair of 64-bit integers.
explicit Fingerprint(Fingerprint::Core value) : core(value) {}
@@ -76,9 +73,9 @@ public:
/// Strings that violate this invariant will return a null optional.
static llvm::Optional<Fingerprint> fromString(llvm::StringRef value);
/// Creates a fingerprint value by consuming the given \c MD5Result from LLVM.
explicit Fingerprint(llvm::MD5::MD5Result &&MD5Value)
: core{MD5Value.words()} {}
/// Creates a fingerprint value by consuming the given \c StableHasher.
explicit Fingerprint(StableHasher &&stableHasher)
: core{std::move(stableHasher).finalize()} {}
public:
/// Retrieve the raw underlying bytes of this fingerprint.
@@ -100,7 +97,7 @@ public:
public:
/// The fingerprint value consisting of 32 bytes of zeroes.
///
/// This fingerprint is a perfectly fine value for an MD5 hash, but it is
/// This fingerprint is a perfectly fine value for a hash, but it is
/// completely arbitrary.
static Fingerprint ZERO() {
return Fingerprint(Fingerprint::Core{0, 0});
@@ -118,6 +115,22 @@ private:
void simple_display(llvm::raw_ostream &out, const Fingerprint &fp);
}; // namespace swift
namespace swift {
template <> struct StableHasher::Combiner<Fingerprint> {
static void combine(StableHasher &hasher, const Fingerprint &Val) {
// Our underlying buffer is already byte-swapped. Combine the
// raw bytes from the core by hand.
uint8_t buffer[8];
memcpy(buffer, &Val.core.first, sizeof(buffer));
hasher.combine(buffer);
memcpy(buffer, &Val.core.second, sizeof(buffer));
hasher.combine(buffer);
}
};
}; // namespace swift
namespace llvm {
class raw_ostream;
raw_ostream &operator<<(raw_ostream &OS, const swift::Fingerprint &fp);