Bitcode: Introduce a BitcodeFileContents data type. NFCI.

This data type includes the contents of a bitcode file.
Right now a bitcode file can only contain modules, but
a later change will add a symbol table.

Differential Revision: https://reviews.llvm.org/D33969

llvm-svn: 305019

2 files changed, 18 insertions, 10 deletions

diff --git a/llvm/lib/Object/IRObjectFile.cpp b/llvm/lib/Object/IRObjectFile.cpp
index 9996661fbde..e7807b03833 100644
--- a/llvm/lib/Object/IRObjectFile.cpp
+++ b/llvm/lib/Object/IRObjectFile.cpp
@@ -147,16 +147,15 @@ Expected<IRSymtabFile> object::readIRSymtab(MemoryBufferRef MBRef) {
   if (!BCOrErr)
     return errorCodeToError(BCOrErr.getError());
 
-  Expected<std::vector<BitcodeModule>> BMsOrErr =
-      getBitcodeModuleList(*BCOrErr);
-  if (!BMsOrErr)
-    return BMsOrErr.takeError();
+  Expected<BitcodeFileContents> BFCOrErr = getBitcodeFileContents(*BCOrErr);
+  if (!BFCOrErr)
+    return BFCOrErr.takeError();
 
-  Expected<irsymtab::FileContents> FCOrErr = irsymtab::readBitcode(*BMsOrErr);
+  Expected<irsymtab::FileContents> FCOrErr = irsymtab::readBitcode(*BFCOrErr);
   if (!FCOrErr)
     return FCOrErr.takeError();
 
-  F.Mods = std::move(*BMsOrErr);
+  F.Mods = std::move(BFCOrErr->Mods);
   F.Symtab = std::move(FCOrErr->Symtab);
   F.Strtab = std::move(FCOrErr->Strtab);
   F.TheReader = std::move(FCOrErr->TheReader);
diff --git a/llvm/lib/Object/IRSymtab.cpp b/llvm/lib/Object/IRSymtab.cpp
index fa343618caf..94f13490939 100644
--- a/llvm/lib/Object/IRSymtab.cpp
+++ b/llvm/lib/Object/IRSymtab.cpp
@@ -262,11 +262,10 @@ Error irsymtab::build(ArrayRef<Module *> Mods, SmallVector<char, 0> &Symtab,
   return Builder(Symtab, Strtab).build(Mods);
 }
 
-Expected<FileContents> irsymtab::readBitcode(ArrayRef<BitcodeModule> BMs) {
+// Upgrade a vector of bitcode modules created by an old version of LLVM by
+// creating an irsymtab for them in the current format.
+static Expected<FileContents> upgrade(ArrayRef<BitcodeModule> BMs) {
   FileContents FC;
-  if (BMs.empty())
-    return make_error<StringError>("Bitcode file does not contain any modules",
-                                   inconvertibleErrorCode());
 
   LLVMContext Ctx;
   std::vector<Module *> Mods;
@@ -293,3 +292,13 @@ Expected<FileContents> irsymtab::readBitcode(ArrayRef<BitcodeModule> BMs) {
                   {FC.Strtab.data(), FC.Strtab.size()}};
   return std::move(FC);
 }
+
+Expected<FileContents> irsymtab::readBitcode(const BitcodeFileContents &BFC) {
+  if (BFC.Mods.empty())
+    return make_error<StringError>("Bitcode file does not contain any modules",
+                                   inconvertibleErrorCode());
+
+  // Right now we have no on-disk representation of symbol tables, so we always
+  // upgrade.
+  return upgrade(BFC.Mods);
+}