Revert "[WebAssembly] Implement build-id feature"

This reverts commit 41e3146
due to a build failure on Windows.

Author: dschuff

lld/test/wasm/build-id.test

@@ -26,9 +26,6 @@ namespace wasm {
 // For --unresolved-symbols.
 enum class UnresolvedPolicy { ReportError, Warn, Ignore, ImportDynamic };
 
-// For --build-id.
-enum class BuildIdKind { None, Fast, Sha1, Hexstring, Uuid };
-
 // This struct contains the global configuration for the linker.
 // Most fields are direct mapping from the command line options
 // and such fields have the same name as the corresponding options.
@@ -75,7 +72,6 @@ struct Configuration {
   llvm::StringRef thinLTOJobs;
   bool ltoDebugPassManager;
   UnresolvedPolicy unresolvedSymbols;
-  BuildIdKind buildId = BuildIdKind::None;
 
   llvm::StringRef entry;
   llvm::StringRef mapFile;
@@ -89,7 +85,6 @@ struct Configuration {
   llvm::CachePruningPolicy thinLTOCachePolicy;
   std::optional<std::vector<std::string>> features;
   std::optional<std::vector<std::string>> extraFeatures;
-  llvm::SmallVector<uint8_t, 0> buildIdVector;
 
   // The following config options do not directly correspond to any
   // particular command line options.

lld/wasm/Config.h

@@ -385,33 +385,6 @@ static UnresolvedPolicy getUnresolvedSymbolPolicy(opt::InputArgList &args) {
   return errorOrWarn;
 }
 
-// Parse --build-id or --build-id=<style>. We handle "tree" as a
-// synonym for "sha1" because all our hash functions including
-// -build-id=sha1 are actually tree hashes for performance reasons.
-static std::pair<BuildIdKind, SmallVector<uint8_t, 0>>
-getBuildId(opt::InputArgList &args) {
-  auto *arg = args.getLastArg(OPT_build_id, OPT_build_id_eq);
-  if (!arg)
-    return {BuildIdKind::None, {}};
-
-  if (arg->getOption().getID() == OPT_build_id)
-    return {BuildIdKind::Fast, {}};
-
-  StringRef s = arg->getValue();
-  if (s == "fast")
-    return {BuildIdKind::Fast, {}};
-  if (s == "sha1" || s == "tree")
-    return {BuildIdKind::Sha1, {}};
-  if (s == "uuid")
-    return {BuildIdKind::Uuid, {}};
-  if (s.startswith("0x"))
-    return {BuildIdKind::Hexstring, parseHex(s.substr(2))};
-
-  if (s != "none")
-    error("unknown --build-id style: " + s);
-  return {BuildIdKind::None, {}};
-}
-
 // Initializes Config members by the command line options.
 static void readConfigs(opt::InputArgList &args) {
   config->bsymbolic = args.hasArg(OPT_Bsymbolic);
@@ -546,8 +519,6 @@ static void readConfigs(opt::InputArgList &args) {
 
   if (args.hasArg(OPT_print_map))
     config->mapFile = "-";
-
-  std::tie(config->buildId, config->buildIdVector) = getBuildId(args);
 }
 
 // Some Config members do not directly correspond to any particular

lld/wasm/Driver.cpp

@@ -42,11 +42,6 @@ def Bdynamic: F<"Bdynamic">, HelpText<"Link against shared libraries (default)">
 
 def Bstatic: F<"Bstatic">, HelpText<"Do not link against shared libraries">;
 
-def build_id: F<"build-id">, HelpText<"Alias for --build-id=fast">;
-
-def build_id_eq: J<"build-id=">, HelpText<"Generate build ID note">,
-  MetaVarName<"[fast,sha1,uuid,0x<hexstring>]">;
-
 defm color_diagnostics: B<"color-diagnostics",
   "Alias for --color-diagnostics=always",
   "Alias for --color-diagnostics=never">;

lld/wasm/Options.td

@@ -888,39 +888,5 @@ void RelocSection::writeBody() {
   sec->writeRelocations(bodyOutputStream);
 }
 
-static size_t getHashSize() {
-  switch (config->buildId) {
-  case BuildIdKind::Fast:
-  case BuildIdKind::Uuid:
-    return 16;
-  case BuildIdKind::Sha1:
-    return 20;
-  case BuildIdKind::Hexstring:
-    return config->buildIdVector.size();
-  case BuildIdKind::None:
-    return 0;
-  }
-}
-
-BuildIdSection::BuildIdSection()
-    : SyntheticSection(llvm::wasm::WASM_SEC_CUSTOM, buildIdSectionName),
-      hashSize(getHashSize()) {}
-
-void BuildIdSection::writeBody() {
-  LLVM_DEBUG(llvm::dbgs() << "BuildId writebody\n");
-  // Write hash size
-  auto &os = bodyOutputStream;
-  writeUleb128(os, hashSize, "build id size");
-  writeBytes(os, std::vector<char>(hashSize, ' ').data(), hashSize,
-   "placeholder");
-}
-
-void BuildIdSection::writeBuildId(llvm::ArrayRef<uint8_t> buf) {
-  assert(buf.size() == hashSize);
-  LLVM_DEBUG(dbgs() << "buildid write " << buf.size() << " "
-                    << hashPlaceholderPtr << '\n');
-  memcpy(hashPlaceholderPtr, buf.data(), hashSize);
-}
-
 } // namespace wasm
 } // namespace lld

lld/wasm/SyntheticSections.cpp

@@ -429,34 +429,6 @@ class RelocSection : public SyntheticSection {
   OutputSection *sec;
 };
 
-class BuildIdSection : public SyntheticSection {
-public:
-  BuildIdSection();
-  void writeBody() override;
-  bool isNeeded() const override {
-    return config->buildId != BuildIdKind::None;
-  }
-  void writeBuildId(llvm::ArrayRef<uint8_t> buf);
-  void writeTo(uint8_t *buf) override {
-    LLVM_DEBUG(llvm::dbgs() << "BuildId writeto buf " << buf << " offset "
-               << offset << " headersize " << header.size() << '\n');
-    // The actual build ID is derived from a hash of all of the output
-    // sections, so it can't be calculated until they are written. Here
-    // we write the section leaving zeros in place of the hash.
-    SyntheticSection::writeTo(buf);
-    // Calculate and store the location where the hash will be written.
-    hashPlaceholderPtr = buf + offset + header.size() +
-                         +sizeof(buildIdSectionName) /*name string*/ +
-                         1 /* hash size */;
-  }
-
-  const uint32_t hashSize;
-
-private:
-  static constexpr char buildIdSectionName[] = "build_id";
-  uint8_t *hashPlaceholderPtr = nullptr;
-};
-
 // Linker generated output sections
 struct OutStruct {
   DylinkSection *dylinkSec;
@@ -475,7 +447,6 @@ struct OutStruct {
   NameSection *nameSec;
   ProducersSection *producersSec;
   TargetFeaturesSection *targetFeaturesSec;
-  BuildIdSection *buildIdSec;
 };
 
 extern OutStruct out;

lld/wasm/SyntheticSections.h

@@ -17,10 +17,8 @@
 #include "SymbolTable.h"
 #include "SyntheticSections.h"
 #include "WriterUtils.h"
-#include "lld/Common/Arrays.h"
 #include "lld/Common/CommonLinkerContext.h"
 #include "lld/Common/Strings.h"
-#include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/SmallVector.h"
@@ -32,9 +30,6 @@
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/LEB128.h"
 #include "llvm/Support/Parallel.h"
-#include "llvm/Support/RandomNumberGenerator.h"
-#include "llvm/Support/SHA1.h"
-#include "llvm/Support/xxhash.h"
 
 #include <cstdarg>
 #include <map>
@@ -108,7 +103,6 @@ class Writer {
 
   void writeHeader();
   void writeSections();
-  void writeBuildId();
 
   uint64_t fileSize = 0;
 
@@ -225,91 +219,6 @@ void Writer::writeSections() {
   });
 }
 
-// Computes a hash value of Data using a given hash function.
-// In order to utilize multiple cores, we first split data into 1MB
-// chunks, compute a hash for each chunk, and then compute a hash value
-// of the hash values.
-
-static void
-computeHash(llvm::MutableArrayRef<uint8_t> hashBuf,
-            llvm::ArrayRef<uint8_t> data,
-            std::function<void(uint8_t *dest, ArrayRef<uint8_t> arr)> hashFn) {
-  std::vector<ArrayRef<uint8_t>> chunks = split(data, 1024 * 1024);
-  std::vector<uint8_t> hashes(chunks.size() * hashBuf.size());
-
-  // Compute hash values.
-  parallelFor(0, chunks.size(), [&](size_t i) {
-    hashFn(hashes.data() + i * hashBuf.size(), chunks[i]);
-  });
-
-  // Write to the final output buffer.
-  hashFn(hashBuf.data(), hashes);
-}
-
-static void makeUUID(unsigned version, llvm::ArrayRef<uint8_t> fileHash,
-                     llvm::MutableArrayRef<uint8_t> output) {
-  assert(version == 4 || version == 5 && "Unknown UUID version");
-  assert(output.size() == 16 && "Wrong size for UUID output");
-  if (version == 5) {
-    // Build a valid v5 UUID from a hardcoded (randomly-generated) namespace
-    // UUID, and the computed hash of the output.
-    std::vector<uint8_t> namespaceUUID{0xA1, 0xFA, 0x48, 0x2D, 0x0E, 0x22,
-                                       0x03, 0x8D, 0x33, 0x8B, 0x52, 0x1C,
-                                       0xD6, 0xD2, 0x12, 0xB2};
-    SHA1 sha;
-    sha.update(namespaceUUID);
-    sha.update(fileHash);
-    auto s = sha.final();
-    std::copy(s.begin(), &s[output.size()], output.begin());
-  } else if (version == 4) {
-    if (auto ec = llvm::getRandomBytes(output.data(), output.size()))
-      error("entropy source failure: " + ec.message());
-  }
-  // Set the UUID version and variant fields.
-  // The version is the upper nibble of byte 6 (0b0101xxxx or 0b0100xxxx)
-  output[6] = (static_cast<uint8_t>(version) << 4) | (output[6] & 0xF);
-
-  // The variant is DCE 1.1/ISO 11578 (0b10xxxxxx)
-  output[8] &= 0xBF;
-  output[8] |= 0x80;
-}
-
-void Writer::writeBuildId() {
-  if (!out.buildIdSec->isNeeded())
-    return;
-  if (config->buildId == BuildIdKind::Hexstring) {
-    out.buildIdSec->writeBuildId(config->buildIdVector);
-    return;
-  }
-
-  // Compute a hash of all sections of the output file.
-  size_t hashSize = out.buildIdSec->hashSize;
-  std::vector<uint8_t> buildId(hashSize);
-  llvm::ArrayRef<uint8_t> buf{buffer->getBufferStart(), size_t(fileSize)};
-
-  switch (config->buildId) {
-   case BuildIdKind::Fast:{
-    std::vector<uint8_t> fileHash(8);
-    computeHash(fileHash, buf, [](uint8_t *dest, ArrayRef<uint8_t> arr) {
-      support::endian::write64le(dest, xxHash64(arr));
-    });
-    makeUUID(5, fileHash, buildId);
-    break;
-   }
-  case BuildIdKind::Sha1:
-    computeHash(buildId, buf, [&](uint8_t *dest, ArrayRef<uint8_t> arr) {
-      memcpy(dest, SHA1::hash(arr).data(), hashSize);
-    });
-    break;
-  case BuildIdKind::Uuid:
-    makeUUID(4, {}, buildId);
-    break;
-  default:
-    llvm_unreachable("unknown BuildIdKind");
-  }
-  out.buildIdSec->writeBuildId(buildId);
-}
-
 static void setGlobalPtr(DefinedGlobal *g, uint64_t memoryPtr) {
   LLVM_DEBUG(dbgs() << "setGlobalPtr " << g->getName() << " -> " << memoryPtr << "\n");
   g->global->setPointerValue(memoryPtr);
@@ -547,7 +456,6 @@ void Writer::addSections() {
   addSection(out.nameSec);
   addSection(out.producersSec);
   addSection(out.targetFeaturesSec);
-  addSection(out.buildIdSec);
 }
 
 void Writer::finalizeSections() {
@@ -1669,7 +1577,6 @@ void Writer::createSyntheticSections() {
   out.elemSec = make<ElemSection>();
   out.producersSec = make<ProducersSection>();
   out.targetFeaturesSec = make<TargetFeaturesSection>();
-  out.buildIdSec = make<BuildIdSection>();
 }
 
 void Writer::createSyntheticSectionsPostLayout() {
@@ -1831,7 +1738,6 @@ void Writer::run() {
 
   log("-- writeSections");
   writeSections();
-  writeBuildId();
   if (errorCount())
     return;