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

1 files changed, 13 insertions, 4 deletions

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);
+}