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//===-- StructuralHash.cpp - IR Hash for expensive checks -------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
#ifdef EXPENSIVE_CHECKS
#include "llvm/IR/StructuralHash.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Module.h"
using namespace llvm;
namespace {
namespace details {
// Basic hashing mechanism to detect structural change to the IR, used to verify
// pass return status consistency with actual change. Loosely copied from
// llvm/lib/Transforms/Utils/FunctionComparator.cpp
class StructuralHash {
uint64_t Hash = 0x6acaa36bef8325c5ULL;
void update(uint64_t V) { Hash = hashing::detail::hash_16_bytes(Hash, V); }
public:
StructuralHash() = default;
void update(const Function &F) {
if (F.empty())
return;
update(F.isVarArg());
update(F.arg_size());
SmallVector<const BasicBlock *, 8> BBs;
SmallPtrSet<const BasicBlock *, 16> VisitedBBs;
BBs.push_back(&F.getEntryBlock());
VisitedBBs.insert(BBs[0]);
while (!BBs.empty()) {
const BasicBlock *BB = BBs.pop_back_val();
update(45798); // Block header
for (auto &Inst : *BB)
update(Inst.getOpcode());
const Instruction *Term = BB->getTerminator();
for (unsigned i = 0, e = Term->getNumSuccessors(); i != e; ++i) {
if (!VisitedBBs.insert(Term->getSuccessor(i)).second)
continue;
BBs.push_back(Term->getSuccessor(i));
}
}
}
void update(const Module &M) {
for (const Function &F : M)
update(F);
}
uint64_t getHash() const { return Hash; }
};
} // namespace details
} // namespace
uint64_t llvm::StructuralHash(const Function &F) {
details::StructuralHash H;
H.update(F);
return H.getHash();
}
uint64_t llvm::StructuralHash(const Module &M) {
details::StructuralHash H;
H.update(M);
return H.getHash();
}
#endif
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