[llvm] r268671 - Degrade assertions to a warning in LTOCodeGenerator for preserved linkonce

[Mehdi Amini via llvm-commits]

Author: mehdi_amini
Date: Thu May  5 15:05:33 2016
New Revision: 268671

URL: http://llvm.org/viewvc/llvm-project?rev=268671&view=rev
Log:
Degrade assertions to a warning in LTOCodeGenerator for preserved linkonce

The assertions were assuming that the linker will not ask to preserve
a global that is internal or available_externally, as it does not
really make sense. In practice this break the bootstrap of clang,
I degrade to a warning for now.

From: Mehdi Amini <mehdi.amini at apple.com>

Modified:
    llvm/trunk/include/llvm/LTO/LTOCodeGenerator.h
    llvm/trunk/lib/LTO/LTOCodeGenerator.cpp

Modified: llvm/trunk/include/llvm/LTO/LTOCodeGenerator.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/LTO/LTOCodeGenerator.h?rev=268671&r1=268670&r2=268671&view=diff
==============================================================================
--- llvm/trunk/include/llvm/LTO/LTOCodeGenerator.h (original)
+++ llvm/trunk/include/llvm/LTO/LTOCodeGenerator.h Thu May  5 15:05:33 2016
@@ -190,6 +190,10 @@ private:
   bool compileOptimizedToFile(const char **Name);
   void restoreLinkageForExternals();
   void applyScopeRestrictions();
+  void preserveDiscardableGVs(
+      Module &TheModule,
+      llvm::function_ref<bool(const GlobalValue &)> mustPreserveGV);
+
   bool determineTarget();
   std::unique_ptr<TargetMachine> createTargetMachine();
 
@@ -198,6 +202,7 @@ private:
   void DiagnosticHandler2(const DiagnosticInfo &DI);
 
   void emitError(const std::string &ErrMsg);
+  void emitWarning(const std::string &ErrMsg);
 
   LLVMContext &Context;
   std::unique_ptr<Module> MergedModule;

Modified: llvm/trunk/lib/LTO/LTOCodeGenerator.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/LTO/LTOCodeGenerator.cpp?rev=268671&r1=268670&r2=268671&view=diff
==============================================================================
--- llvm/trunk/lib/LTO/LTOCodeGenerator.cpp (original)
+++ llvm/trunk/lib/LTO/LTOCodeGenerator.cpp Thu May  5 15:05:33 2016
@@ -351,7 +351,7 @@ std::unique_ptr<TargetMachine> LTOCodeGe
 // If a linkonce global is present in the MustPreserveSymbols, we need to make
 // sure we honor this. To force the compiler to not drop it, we add it to the
 // "llvm.compiler.used" global.
-static void preserveDiscardableGVs(
+void LTOCodeGenerator::preserveDiscardableGVs(
     Module &TheModule,
     llvm::function_ref<bool(const GlobalValue &)> mustPreserveGV) {
   SetVector<Constant *> UsedValuesSet;
@@ -368,7 +368,17 @@ static void preserveDiscardableGVs(
       return;
     if (!mustPreserveGV(GV))
       return;
-    assert(!GV.hasAvailableExternallyLinkage() && !GV.hasInternalLinkage());
+    if (GV.hasAvailableExternallyLinkage()) {
+      emitWarning(
+          (Twine("Linker asked to preserve available_externally global: '") +
+           GV.getName() + "'").str());
+      return;
+    }
+    if (GV.hasInternalLinkage()) {
+      emitWarning((Twine("Linker asked to preserve internal global: '") +
+                   GV.getName() + "'").str());
+      return;
+    }
     UsedValuesSet.insert(ConstantExpr::getBitCast(&GV, i8PTy));
   };
   for (auto &GV : TheModule)
@@ -643,3 +653,10 @@ void LTOCodeGenerator::emitError(const s
   else
     Context.diagnose(LTODiagnosticInfo(ErrMsg));
 }
+
+void LTOCodeGenerator::emitWarning(const std::string &ErrMsg) {
+  if (DiagHandler)
+    (*DiagHandler)(LTO_DS_WARNING, ErrMsg.c_str(), DiagContext);
+  else
+    Context.diagnose(LTODiagnosticInfo(ErrMsg, DS_Warning));
+}