802fcb4167
After fixing up the runtime pseudo relocation, the .refptr.<var> will be a plain pointer with the same value as the IAT entry itself. To save a little binary size and reduce the number of runtime pseudo relocations, redirect references to the IAT entry (via the __imp_<var> symbol) itself and discard the .refptr.<var> chunk (as long as the same section chunk doesn't contain anything else than the single pointer). As there are now cases for both setting the Live variable to true and false externally, remove the accessors and setters and just make the variable public instead. Differential Revision: https://reviews.llvm.org/D51456 llvm-svn: 341175
75 lines
2.1 KiB
C++
75 lines
2.1 KiB
C++
//===- MarkLive.cpp -------------------------------------------------------===//
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//
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// The LLVM Linker
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "Chunks.h"
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#include "Symbols.h"
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#include "lld/Common/Timer.h"
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#include "llvm/ADT/STLExtras.h"
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#include <vector>
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namespace lld {
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namespace coff {
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static Timer GCTimer("GC", Timer::root());
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// Set live bit on for each reachable chunk. Unmarked (unreachable)
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// COMDAT chunks will be ignored by Writer, so they will be excluded
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// from the final output.
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void markLive(ArrayRef<Chunk *> Chunks) {
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ScopedTimer T(GCTimer);
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// We build up a worklist of sections which have been marked as live. We only
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// push into the worklist when we discover an unmarked section, and we mark
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// as we push, so sections never appear twice in the list.
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SmallVector<SectionChunk *, 256> Worklist;
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// COMDAT section chunks are dead by default. Add non-COMDAT chunks.
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for (Chunk *C : Chunks)
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if (auto *SC = dyn_cast<SectionChunk>(C))
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if (SC->Live)
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Worklist.push_back(SC);
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auto Enqueue = [&](SectionChunk *C) {
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if (C->Live)
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return;
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C->Live = true;
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Worklist.push_back(C);
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};
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auto AddSym = [&](Symbol *B) {
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if (auto *Sym = dyn_cast<DefinedRegular>(B))
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Enqueue(Sym->getChunk());
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else if (auto *Sym = dyn_cast<DefinedImportData>(B))
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Sym->File->Live = true;
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else if (auto *Sym = dyn_cast<DefinedImportThunk>(B))
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Sym->WrappedSym->File->Live = Sym->WrappedSym->File->ThunkLive = true;
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};
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// Add GC root chunks.
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for (Symbol *B : Config->GCRoot)
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AddSym(B);
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while (!Worklist.empty()) {
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SectionChunk *SC = Worklist.pop_back_val();
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assert(SC->Live && "We mark as live when pushing onto the worklist!");
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// Mark all symbols listed in the relocation table for this section.
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for (Symbol *B : SC->symbols())
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if (B)
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AddSym(B);
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// Mark associative sections if any.
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for (SectionChunk *C : SC->children())
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Enqueue(C);
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}
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}
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}
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}
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