LowerTypeTests: Propagate symver directives

Summary:
This change fixes https://crbug.com/834474, a build failure caused by
LowerTypeTests not preserving .symver symbol versioning directives for
exported functions. Emit symver information to ThinLTO summary data and
then propagate symver directives for exported functions to the merged
module.

Emitting symver information to the summaries increases the size of
intermediate build artifacts for a Chromium build by less than 0.2%.

Reviewers: pcc

Reviewed By: pcc

Subscribers: tejohnson, mehdi_amini, eraman, llvm-commits, eugenis, kcc

Differential Revision: https://reviews.llvm.org/D45798

llvm-svn: 330387

1 files changed, 49 insertions, 32 deletions

diff --git a/llvm/lib/Object/ModuleSymbolTable.cpp b/llvm/lib/Object/ModuleSymbolTable.cpp
index f0d70aefd42..b353ef3c835 100644
--- a/llvm/lib/Object/ModuleSymbolTable.cpp
+++ b/llvm/lib/Object/ModuleSymbolTable.cpp
@@ -68,9 +68,9 @@ void ModuleSymbolTable::addModule(Module *M) {
   });
 }
 
-void ModuleSymbolTable::CollectAsmSymbols(
-    const Module &M,
-    function_ref<void(StringRef, BasicSymbolRef::Flags)> AsmSymbol) {
+static void
+initializeRecordStreamer(const Module &M,
+                         function_ref<void(RecordStreamer &)> Init) {
   StringRef InlineAsm = M.getModuleInlineAsm();
   if (InlineAsm.empty())
     return;
@@ -119,36 +119,53 @@ void ModuleSymbolTable::CollectAsmSymbols(
   if (Parser->Run(false))
     return;
 
-  Streamer.flushSymverDirectives();
-
-  for (auto &KV : Streamer) {
-    StringRef Key = KV.first();
-    RecordStreamer::State Value = KV.second;
-    // FIXME: For now we just assume that all asm symbols are executable.
-    uint32_t Res = BasicSymbolRef::SF_Executable;
-    switch (Value) {
-    case RecordStreamer::NeverSeen:
-      llvm_unreachable("NeverSeen should have been replaced earlier");
-    case RecordStreamer::DefinedGlobal:
-      Res |= BasicSymbolRef::SF_Global;
-      break;
-    case RecordStreamer::Defined:
-      break;
-    case RecordStreamer::Global:
-    case RecordStreamer::Used:
-      Res |= BasicSymbolRef::SF_Undefined;
-      Res |= BasicSymbolRef::SF_Global;
-      break;
-    case RecordStreamer::DefinedWeak:
-      Res |= BasicSymbolRef::SF_Weak;
-      Res |= BasicSymbolRef::SF_Global;
-      break;
-    case RecordStreamer::UndefinedWeak:
-      Res |= BasicSymbolRef::SF_Weak;
-      Res |= BasicSymbolRef::SF_Undefined;
+  Init(Streamer);
+}
+
+void ModuleSymbolTable::CollectAsmSymbols(
+    const Module &M,
+    function_ref<void(StringRef, BasicSymbolRef::Flags)> AsmSymbol) {
+  initializeRecordStreamer(M, [&](RecordStreamer &Streamer) {
+    Streamer.flushSymverDirectives();
+
+    for (auto &KV : Streamer) {
+      StringRef Key = KV.first();
+      RecordStreamer::State Value = KV.second;
+      // FIXME: For now we just assume that all asm symbols are executable.
+      uint32_t Res = BasicSymbolRef::SF_Executable;
+      switch (Value) {
+      case RecordStreamer::NeverSeen:
+        llvm_unreachable("NeverSeen should have been replaced earlier");
+      case RecordStreamer::DefinedGlobal:
+        Res |= BasicSymbolRef::SF_Global;
+        break;
+      case RecordStreamer::Defined:
+        break;
+      case RecordStreamer::Global:
+      case RecordStreamer::Used:
+        Res |= BasicSymbolRef::SF_Undefined;
+        Res |= BasicSymbolRef::SF_Global;
+        break;
+      case RecordStreamer::DefinedWeak:
+        Res |= BasicSymbolRef::SF_Weak;
+        Res |= BasicSymbolRef::SF_Global;
+        break;
+      case RecordStreamer::UndefinedWeak:
+        Res |= BasicSymbolRef::SF_Weak;
+        Res |= BasicSymbolRef::SF_Undefined;
+      }
+      AsmSymbol(Key, BasicSymbolRef::Flags(Res));
     }
-    AsmSymbol(Key, BasicSymbolRef::Flags(Res));
-  }
+  });
+}
+
+void ModuleSymbolTable::CollectAsmSymvers(
+    const Module &M, function_ref<void(StringRef, StringRef)> AsmSymver) {
+  initializeRecordStreamer(M, [&](RecordStreamer &Streamer) {
+    for (auto &KV : Streamer.symverAliases())
+      for (auto &Alias : KV.second)
+        AsmSymver(KV.first->getName(), Alias);
+  });
 }
 
 void ModuleSymbolTable::printSymbolName(raw_ostream &OS, Symbol S) const {