[ThinLTO] Attempt to recommit r365040 after caching fix

It's possible that some function can load and store the same
variable using the same constant expression:

store %Derived* @foo, %Derived** bitcast (%Base** @bar to %Derived**)
%42 = load %Derived*, %Derived** bitcast (%Base** @bar to %Derived**)

The bitcast expression was mistakenly cached while processing loads,
and never examined later when processing store. This caused @bar to
be mistakenly treated as read-only variable. See load-store-caching.ll.

llvm-svn: 365188

1 files changed, 7 insertions, 5 deletions

diff --git a/llvm/lib/Transforms/IPO/FunctionImport.cpp b/llvm/lib/Transforms/IPO/FunctionImport.cpp
index 9207f5fe0ef..62c7fbd0722 100644
--- a/llvm/lib/Transforms/IPO/FunctionImport.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionImport.cpp
@@ -850,14 +850,16 @@ void llvm::computeDeadSymbolsWithConstProp(
     bool ImportEnabled) {
   computeDeadSymbols(Index, GUIDPreservedSymbols, isPrevailing);
   if (ImportEnabled) {
-    Index.propagateConstants(GUIDPreservedSymbols);
+    Index.propagateAttributes(GUIDPreservedSymbols);
   } else {
-    // If import is disabled we should drop read-only attribute
+    // If import is disabled we should drop read/write-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);
+        }
   }
 }
 
@@ -1064,7 +1066,7 @@ static Function *replaceAliasWithAliasee(Module *SrcModule, GlobalAlias *GA) {
 
 // Internalize values that we marked with specific attribute
 // in processGlobalForThinLTO.
-static void internalizeImmutableGVs(Module &M) {
+static void internalizeGVsAfterImport(Module &M) {
   for (auto &GV : M.globals())
     // Skip GVs which have been converted to declarations
     // by dropDeadSymbols.
@@ -1197,7 +1199,7 @@ Expected<bool> FunctionImporter::importFunctions(
     NumImportedModules++;
   }
 
-  internalizeImmutableGVs(DestModule);
+  internalizeGVsAfterImport(DestModule);
 
   NumImportedFunctions += (ImportedCount - ImportedGVCount);
   NumImportedGlobalVars += ImportedGVCount;