llvm-capstone/lld/COFF/MarkLive.cpp
Chandler Carruth 2946cd7010 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00

74 lines
2.2 KiB
C++

//===- MarkLive.cpp -------------------------------------------------------===//
//
// 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 "Chunks.h"
#include "Symbols.h"
#include "lld/Common/Timer.h"
#include "llvm/ADT/STLExtras.h"
#include <vector>
namespace lld {
namespace coff {
static Timer GCTimer("GC", Timer::root());
// Set live bit on for each reachable chunk. Unmarked (unreachable)
// COMDAT chunks will be ignored by Writer, so they will be excluded
// from the final output.
void markLive(ArrayRef<Chunk *> Chunks) {
ScopedTimer T(GCTimer);
// We build up a worklist of sections which have been marked as live. We only
// push into the worklist when we discover an unmarked section, and we mark
// as we push, so sections never appear twice in the list.
SmallVector<SectionChunk *, 256> Worklist;
// COMDAT section chunks are dead by default. Add non-COMDAT chunks.
for (Chunk *C : Chunks)
if (auto *SC = dyn_cast<SectionChunk>(C))
if (SC->Live)
Worklist.push_back(SC);
auto Enqueue = [&](SectionChunk *C) {
if (C->Live)
return;
C->Live = true;
Worklist.push_back(C);
};
auto AddSym = [&](Symbol *B) {
if (auto *Sym = dyn_cast<DefinedRegular>(B))
Enqueue(Sym->getChunk());
else if (auto *Sym = dyn_cast<DefinedImportData>(B))
Sym->File->Live = true;
else if (auto *Sym = dyn_cast<DefinedImportThunk>(B))
Sym->WrappedSym->File->Live = Sym->WrappedSym->File->ThunkLive = true;
};
// Add GC root chunks.
for (Symbol *B : Config->GCRoot)
AddSym(B);
while (!Worklist.empty()) {
SectionChunk *SC = Worklist.pop_back_val();
assert(SC->Live && "We mark as live when pushing onto the worklist!");
// Mark all symbols listed in the relocation table for this section.
for (Symbol *B : SC->symbols())
if (B)
AddSym(B);
// Mark associative sections if any.
for (SectionChunk *C : SC->children())
Enqueue(C);
}
}
}
}