Make the LTO comdat api more symbol table friendly.

In an IR symbol table I would expect the comdats to be represented as:

- A table of strings, one for each comdat name.
- Each symbol has an optional index into that table.

The natural api for accessing that would be

InputFile:
ArrayRef<StringRef> getComdatTable() const;

Symbol:
int getComdatIndex() const;

This patch implements an API as close to that as possible.  The
implementation on top of the current IRObjectFile is a bit hackish,
but should map just fine over a symbol table and is very convenient to
use.

llvm-svn: 285061

1 files changed, 29 insertions, 2 deletions

diff --git a/llvm/lib/LTO/LTO.cpp b/llvm/lib/LTO/LTO.cpp
index b4efb4a4db6..d43b4d56ff1 100644
--- a/llvm/lib/LTO/LTO.cpp
+++ b/llvm/lib/LTO/LTO.cpp
@@ -218,9 +218,36 @@ Expected<std::unique_ptr<InputFile>> InputFile::create(MemoryBufferRef Object) {
 
   File->Ctx.setDiagnosticHandler(nullptr, nullptr);
 
+  for (const auto &C : File->Obj->getModule().getComdatSymbolTable()) {
+    auto P =
+        File->ComdatMap.insert(std::make_pair(&C.second, File->Comdats.size()));
+    assert(P.second);
+    File->Comdats.push_back(C.first());
+  }
+
   return std::move(File);
 }
 
+Expected<int> InputFile::Symbol::getComdatIndex() const {
+  if (!GV)
+    return -1;
+  const GlobalObject *GO;
+  if (auto *GA = dyn_cast<GlobalAlias>(GV)) {
+    GO = GA->getBaseObject();
+    if (!GO)
+      return make_error<StringError>("Unable to determine comdat of alias!",
+                                     inconvertibleErrorCode());
+  } else {
+    GO = cast<GlobalObject>(GV);
+  }
+  if (const Comdat *C = GO->getComdat()) {
+    auto I = File->ComdatMap.find(C);
+    assert(I != File->ComdatMap.end());
+    return I->second;
+  }
+  return -1;
+}
+
 LTO::RegularLTOState::RegularLTOState(unsigned ParallelCodeGenParallelismLevel,
                                       Config &Conf)
     : ParallelCodeGenParallelismLevel(ParallelCodeGenParallelismLevel),
@@ -332,8 +359,8 @@ Error LTO::addRegularLTO(std::unique_ptr<InputFile> Input,
 
   auto ResI = Res.begin();
   for (const InputFile::Symbol &Sym :
-       make_range(InputFile::symbol_iterator(Obj->symbol_begin()),
-                  InputFile::symbol_iterator(Obj->symbol_end()))) {
+       make_range(InputFile::symbol_iterator(Obj->symbol_begin(), nullptr),
+                  InputFile::symbol_iterator(Obj->symbol_end(), nullptr))) {
     assert(ResI != Res.end());
     SymbolResolution Res = *ResI++;
     addSymbolToGlobalRes(Obj.get(), Used, Sym, Res, 0);