e8e499f5f9
This came up in This came up in https://reviews.llvm.org/D146776#inline-1489091 and is slightly related to https://reviews.llvm.org/D153855. In both patches, there is the observation that some modifications of the module should not invalidate analysis, such as when adding a declaration or some metadata the won't be used when compiling the current module. This patch implements the suggestion that we should ignore globals that have the `llvm.` prefix when calculating the module hash. Fixes https://github.com/llvm/llvm-project/issues/63590 Reviewed By: aeubanks Differential Revision: https://reviews.llvm.org/D154019
93 lines
2.5 KiB
C++
93 lines
2.5 KiB
C++
//===-- StructuralHash.cpp - IR Hashing -------------------------*- 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
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/IR/StructuralHash.h"
|
|
#include "llvm/IR/Function.h"
|
|
#include "llvm/IR/GlobalVariable.h"
|
|
#include "llvm/IR/Module.h"
|
|
|
|
using namespace llvm;
|
|
|
|
namespace {
|
|
|
|
// 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 StructuralHashImpl {
|
|
hash_code Hash;
|
|
|
|
template <typename T> void hash(const T &V) { Hash = hash_combine(Hash, V); }
|
|
|
|
public:
|
|
StructuralHashImpl() : Hash(4) {}
|
|
|
|
void update(const Function &F) {
|
|
// Declarations don't affect analyses.
|
|
if (F.isDeclaration())
|
|
return;
|
|
|
|
hash(12345); // Function header
|
|
|
|
hash(F.isVarArg());
|
|
hash(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();
|
|
hash(45798); // Block header
|
|
for (auto &Inst : *BB)
|
|
hash(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 GlobalVariable &GV) {
|
|
// Declarations and used/compiler.used don't affect analyses.
|
|
// Since there are several `llvm.*` metadata, like `llvm.embedded.object`,
|
|
// we ignore anything with the `.llvm` prefix
|
|
if (GV.isDeclaration() || GV.getName().starts_with("llvm."))
|
|
return;
|
|
hash(23456); // Global header
|
|
hash(GV.getValueType()->getTypeID());
|
|
}
|
|
|
|
void update(const Module &M) {
|
|
for (const GlobalVariable &GV : M.globals())
|
|
update(GV);
|
|
for (const Function &F : M)
|
|
update(F);
|
|
}
|
|
|
|
uint64_t getHash() const { return Hash; }
|
|
};
|
|
|
|
} // namespace
|
|
|
|
uint64_t llvm::StructuralHash(const Function &F) {
|
|
StructuralHashImpl H;
|
|
H.update(F);
|
|
return H.getHash();
|
|
}
|
|
|
|
uint64_t llvm::StructuralHash(const Module &M) {
|
|
StructuralHashImpl H;
|
|
H.update(M);
|
|
return H.getHash();
|
|
}
|