From cceae7feda8e33194d1a6c5963bd4114bb8d2b36 Mon Sep 17 00:00:00 2001
From: Peter Collingbourne <peter@pcc.me.uk>
Date: Tue, 31 May 2016 23:01:54 +0000
Subject: Add support for metadata attachments for global variables.

This patch adds an IR, assembly and bitcode representation for metadata
attachments for globals. Future patches will port existing features to use
these new attachments.

Differential Revision: http://reviews.llvm.org/D20074

llvm-svn: 271348
---
 llvm/lib/Bitcode/Writer/BitcodeWriter.cpp | 42 ++++++++++++++++++++++---------
 1 file changed, 30 insertions(+), 12 deletions(-)

(limited to 'llvm/lib/Bitcode/Writer/BitcodeWriter.cpp')

diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index ec3ecb2287e..d65e924507c 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -223,7 +223,10 @@ private:
                             SmallVectorImpl<uint64_t> &Record);
   void writeModuleMetadata();
   void writeFunctionMetadata(const Function &F);
-  void writeMetadataAttachment(const Function &F);
+  void writeFunctionMetadataAttachment(const Function &F);
+  void writeGlobalVariableMetadataAttachment(const GlobalVariable &GV);
+  void pushGlobalMetadataAttachment(SmallVectorImpl<uint64_t> &Record,
+                                    const GlobalObject &GO);
   void writeModuleMetadataStore();
   void writeOperandBundleTags();
   void writeConstants(unsigned FirstVal, unsigned LastVal, bool isGlobal);
@@ -1831,24 +1834,31 @@ void ModuleBitcodeWriter::writeFunctionMetadata(const Function &F) {
   Stream.ExitBlock();
 }
 
-void ModuleBitcodeWriter::writeMetadataAttachment(const Function &F) {
+void ModuleBitcodeWriter::pushGlobalMetadataAttachment(
+    SmallVectorImpl<uint64_t> &Record, const GlobalObject &GO) {
+  // [n x [id, mdnode]]
+  SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
+  GO.getAllMetadata(MDs);
+  for (const auto &I : MDs) {
+    Record.push_back(I.first);
+    Record.push_back(VE.getMetadataID(I.second));
+  }
+}
+
+void ModuleBitcodeWriter::writeFunctionMetadataAttachment(const Function &F) {
   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
 
   SmallVector<uint64_t, 64> Record;
 
-  // Write metadata attachments
-  // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
-  SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
-  F.getAllMetadata(MDs);
-  if (!MDs.empty()) {
-    for (const auto &I : MDs) {
-      Record.push_back(I.first);
-      Record.push_back(VE.getMetadataID(I.second));
-    }
+  if (F.hasMetadata()) {
+    pushGlobalMetadataAttachment(Record, F);
     Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
     Record.clear();
   }
 
+  // Write metadata attachments
+  // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
+  SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
   for (const BasicBlock &BB : F)
     for (const Instruction &I : BB) {
       MDs.clear();
@@ -2894,7 +2904,7 @@ void ModuleBitcodeWriter::writeFunction(
   writeValueSymbolTable(F.getValueSymbolTable());
 
   if (NeedsMetadataAttachment)
-    writeMetadataAttachment(F);
+    writeFunctionMetadataAttachment(F);
   if (VE.shouldPreserveUseListOrder())
     writeUseListBlock(&F);
   VE.purgeFunction();
@@ -3597,6 +3607,14 @@ void ModuleBitcodeWriter::writeModule() {
   writeValueSymbolTable(M.getValueSymbolTable(),
                         /* IsModuleLevel */ true, &FunctionToBitcodeIndex);
 
+  for (const GlobalVariable &GV : M.globals())
+    if (GV.hasMetadata()) {
+      SmallVector<uint64_t, 4> Record;
+      Record.push_back(VE.getValueID(&GV));
+      pushGlobalMetadataAttachment(Record, GV);
+      Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR_ATTACHMENT, Record);
+    }
+
   if (GenerateHash) {
     writeModuleHash(BlockStartPos);
   }
-- 
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