Revert [ThinLTO] Optimize writeonly globals out

This reverts r365040 (git commit 5cacb914758c7f436b47c8362100f10cef14bbc4)

Speculatively reverting, since this appears to have broken check-lld on
Linux. Partial analysis in https://crbug.com/981168.

llvm-svn: 365097

2 files changed, 11 insertions, 14 deletions

diff --git a/llvm/lib/Transforms/IPO/FunctionImport.cpp b/llvm/lib/Transforms/IPO/FunctionImport.cpp
index 62c7fbd0722..9207f5fe0ef 100644
--- a/llvm/lib/Transforms/IPO/FunctionImport.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionImport.cpp
@@ -850,16 +850,14 @@ void llvm::computeDeadSymbolsWithConstProp(
     bool ImportEnabled) {
   computeDeadSymbols(Index, GUIDPreservedSymbols, isPrevailing);
   if (ImportEnabled) {
-    Index.propagateAttributes(GUIDPreservedSymbols);
+    Index.propagateConstants(GUIDPreservedSymbols);
   } else {
-    // If import is disabled we should drop read/write-only attribute
+    // If import is disabled we should drop read-only attribute
     // from all summaries to prevent internalization.
     for (auto &P : Index)
       for (auto &S : P.second.SummaryList)
-        if (auto *GVS = dyn_cast<GlobalVarSummary>(S.get())) {
+        if (auto *GVS = dyn_cast<GlobalVarSummary>(S.get()))
           GVS->setReadOnly(false);
-          GVS->setWriteOnly(false);
-        }
   }
 }
 
@@ -1066,7 +1064,7 @@ static Function *replaceAliasWithAliasee(Module *SrcModule, GlobalAlias *GA) {
 
 // Internalize values that we marked with specific attribute
 // in processGlobalForThinLTO.
-static void internalizeGVsAfterImport(Module &M) {
+static void internalizeImmutableGVs(Module &M) {
   for (auto &GV : M.globals())
     // Skip GVs which have been converted to declarations
     // by dropDeadSymbols.
@@ -1199,7 +1197,7 @@ Expected<bool> FunctionImporter::importFunctions(
     NumImportedModules++;
   }
 
-  internalizeGVsAfterImport(DestModule);
+  internalizeImmutableGVs(DestModule);
 
   NumImportedFunctions += (ImportedCount - ImportedGVCount);
   NumImportedGlobalVars += ImportedGVCount;
diff --git a/llvm/lib/Transforms/Utils/FunctionImportUtils.cpp b/llvm/lib/Transforms/Utils/FunctionImportUtils.cpp
index c9cc0990f23..8e80ee2c549 100644
--- a/llvm/lib/Transforms/Utils/FunctionImportUtils.cpp
+++ b/llvm/lib/Transforms/Utils/FunctionImportUtils.cpp
@@ -229,11 +229,11 @@ void FunctionImportGlobalProcessing::processGlobalForThinLTO(GlobalValue &GV) {
     }
   }
 
-  // Mark read/write-only variables which can be imported with specific
-  // attribute. We can't internalize them now because IRMover will fail
-  // to link variable definitions to their external declarations during
-  // ThinLTO import. We'll internalize read-only variables later, after
-  // import is finished. See internalizeGVsAfterImport.
+  // Mark read-only variables which can be imported with specific attribute.
+  // We can't internalize them now because IRMover will fail to link variable
+  // definitions to their external declarations during ThinLTO import. We'll
+  // internalize read-only variables later, after import is finished.
+  // See internalizeImmutableGVs.
   //
   // If global value dead stripping is not enabled in summary then
   // propagateConstants hasn't been run. We can't internalize GV
@@ -241,8 +241,7 @@ void FunctionImportGlobalProcessing::processGlobalForThinLTO(GlobalValue &GV) {
   if (!GV.isDeclaration() && VI && ImportIndex.withGlobalValueDeadStripping()) {
     const auto &SL = VI.getSummaryList();
     auto *GVS = SL.empty() ? nullptr : dyn_cast<GlobalVarSummary>(SL[0].get());
-    // At this stage "maybe" is "definitely"
-    if (GVS && (GVS->maybeReadOnly() || GVS->maybeWriteOnly()))
+    if (GVS && GVS->isReadOnly())
       cast<GlobalVariable>(&GV)->addAttribute("thinlto-internalize");
   }