[ThinLTO] Use NoPromote flag in summary during promotion

Summary:
Replace the check of whether a GV has a section with the flag check
in the summary. This is in preparation for using the NoPromote flag
to convey other situations when we can't promote (e.g. locals used in
inline asm).

Reviewers: mehdi_amini

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D26063

llvm-svn: 285507

1 files changed, 19 insertions, 13 deletions

diff --git a/llvm/lib/Transforms/Utils/FunctionImportUtils.cpp b/llvm/lib/Transforms/Utils/FunctionImportUtils.cpp
index fcb25baf321..f1af20a62ac 100644
--- a/llvm/lib/Transforms/Utils/FunctionImportUtils.cpp
+++ b/llvm/lib/Transforms/Utils/FunctionImportUtils.cpp
@@ -67,9 +67,9 @@ bool FunctionImportGlobalProcessing::doPromoteLocalToGlobal(
   if (GVar && GVar->isConstant() && GVar->hasGlobalUnnamedAddr())
     return false;
 
-  if (GVar && GVar->hasSection())
-    // Some sections like "__DATA,__cfstring" are "magic" and promotion is not
-    // allowed. Just disable promotion on any GVar with sections right now.
+  auto *Summary = ImportIndex.getGlobalValueSummary(SGV->getGUID());
+  assert(Summary && "Missing summary for global value");
+  if (Summary->noRename())
     return false;
 
   // Eventually we only need to promote functions in the exporting module that
@@ -78,14 +78,14 @@ bool FunctionImportGlobalProcessing::doPromoteLocalToGlobal(
   return true;
 }
 
-std::string FunctionImportGlobalProcessing::getName(const GlobalValue *SGV) {
+std::string FunctionImportGlobalProcessing::getName(const GlobalValue *SGV,
+                                                    bool DoPromote) {
   // For locals that must be promoted to global scope, ensure that
   // the promoted name uniquely identifies the copy in the original module,
   // using the ID assigned during combined index creation. When importing,
   // we rename all locals (not just those that are promoted) in order to
   // avoid naming conflicts between locals imported from different modules.
-  if (SGV->hasLocalLinkage() &&
-      (doPromoteLocalToGlobal(SGV) || isPerformingImport()))
+  if (SGV->hasLocalLinkage() && (DoPromote || isPerformingImport()))
     return ModuleSummaryIndex::getGlobalNameForLocal(
         SGV->getName(),
         ImportIndex.getModuleHash(SGV->getParent()->getModuleIdentifier()));
@@ -93,13 +93,14 @@ std::string FunctionImportGlobalProcessing::getName(const GlobalValue *SGV) {
 }
 
 GlobalValue::LinkageTypes
-FunctionImportGlobalProcessing::getLinkage(const GlobalValue *SGV) {
+FunctionImportGlobalProcessing::getLinkage(const GlobalValue *SGV,
+                                           bool DoPromote) {
   // Any local variable that is referenced by an exported function needs
   // to be promoted to global scope. Since we don't currently know which
   // functions reference which local variables/functions, we must treat
   // all as potentially exported if this module is exporting anything.
   if (isModuleExporting()) {
-    if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV))
+    if (SGV->hasLocalLinkage() && DoPromote)
       return GlobalValue::ExternalLinkage;
     return SGV->getLinkage();
   }
@@ -164,7 +165,7 @@ FunctionImportGlobalProcessing::getLinkage(const GlobalValue *SGV) {
   case GlobalValue::PrivateLinkage:
     // If we are promoting the local to global scope, it is handled
     // similarly to a normal externally visible global.
-    if (doPromoteLocalToGlobal(SGV)) {
+    if (DoPromote) {
       if (doImportAsDefinition(SGV) && !dyn_cast<GlobalAlias>(SGV))
         return GlobalValue::AvailableExternallyLinkage;
       else
@@ -190,14 +191,19 @@ FunctionImportGlobalProcessing::getLinkage(const GlobalValue *SGV) {
 }
 
 void FunctionImportGlobalProcessing::processGlobalForThinLTO(GlobalValue &GV) {
+  bool DoPromote = false;
   if (GV.hasLocalLinkage() &&
-      (doPromoteLocalToGlobal(&GV) || isPerformingImport())) {
-    GV.setName(getName(&GV));
-    GV.setLinkage(getLinkage(&GV));
+      ((DoPromote = doPromoteLocalToGlobal(&GV)) || isPerformingImport())) {
+    // Once we change the name or linkage it is difficult to determine
+    // again whether we should promote since doPromoteLocalToGlobal needs
+    // to locate the summary (based on GUID from name and linkage). Therefore,
+    // use DoPromote result saved above.
+    GV.setName(getName(&GV, DoPromote));
+    GV.setLinkage(getLinkage(&GV, DoPromote));
     if (!GV.hasLocalLinkage())
       GV.setVisibility(GlobalValue::HiddenVisibility);
   } else
-    GV.setLinkage(getLinkage(&GV));
+    GV.setLinkage(getLinkage(&GV, /* DoPromote */ false));
 
   // Remove functions imported as available externally defs from comdats,
   // as this is a declaration for the linker, and will be dropped eventually.