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DriverTool: add support for WebAssembly autolink entries #39502

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Sep 29, 2021
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DriverTool: add support for WebAssembly autolink entries #39502

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29 changes: 29 additions & 0 deletions lib/DriverTool/autolink_extract_main.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,8 @@
#include "llvm/Object/Archive.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Object/ELFObjectFile.h"
#include "llvm/Object/Wasm.h"
#include "llvm/BinaryFormat/Wasm.h"

using namespace swift;
using namespace llvm::opt;
Expand Down Expand Up @@ -145,6 +147,30 @@ extractLinkerFlagsFromObjectFile(const llvm::object::ObjectFile *ObjectFile,
return false;
}

/// Look inside the object file 'WasmObjectFile' and append any linker flags
/// found in its ".swift1_autolink_entries" section to 'LinkerFlags'. Return
/// 'true' if there was an error, and 'false' otherwise.
static bool
extractLinkerFlagsFromObjectFile(const llvm::object::WasmObjectFile *ObjectFile,
std::vector<std::string> &LinkerFlags,
CompilerInstance &Instance) {
// Search for the data segment we hold autolink entries in
for (const llvm::object::WasmSegment &Segment : ObjectFile->dataSegments()) {
if (Segment.Data.Name == ".swift1_autolink_entries") {

StringRef SegmentData = llvm::toStringRef(Segment.Data.Content);
// entries are null-terminated, so extract them and push them into
// the set.
llvm::SmallVector<llvm::StringRef, 4> SplitFlags;
SegmentData.split(SplitFlags, llvm::StringRef("\0", 1), -1,
/*KeepEmpty=*/false);
for (const auto &Flag : SplitFlags)
LinkerFlags.push_back(Flag.str());
}
}
return false;
}

/// Look inside the binary 'Bin' and append any linker flags found in its
/// ".swift1_autolink_entries" section to 'LinkerFlags'. If 'Bin' is an archive,
/// recursively look inside all children within the archive. Return 'true' if
Expand All @@ -155,6 +181,9 @@ static bool extractLinkerFlags(const llvm::object::Binary *Bin,
std::vector<std::string> &LinkerFlags) {
if (auto *ObjectFile = llvm::dyn_cast<llvm::object::ELFObjectFileBase>(Bin)) {
return extractLinkerFlagsFromObjectFile(ObjectFile, LinkerFlags, Instance);
} else if (auto *ObjectFile =
llvm::dyn_cast<llvm::object::WasmObjectFile>(Bin)) {
return extractLinkerFlagsFromObjectFile(ObjectFile, LinkerFlags, Instance);
} else if (auto *Archive = llvm::dyn_cast<llvm::object::Archive>(Bin)) {
llvm::Error Error = llvm::Error::success();
for (const auto &Child : Archive->children(Error)) {
Expand Down