Recommit r324455 "[ThinLTO] - Simplify code in ThinLTOBitcodeWriter."

With fix: reimplemented.

Original commit message:
Recently introduced convertToDeclaration is very similar
to code used in filterModule function.
Patch reuses it to reduce duplication.

Differential revision: https://reviews.llvm.org/D42971

llvm-svn: 324574

1 files changed, 12 insertions, 40 deletions

diff --git a/llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp b/llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp
index d2ce97abdd4..7cc1e06964b 100644
--- a/llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp
+++ b/llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp
@@ -23,6 +23,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/IPO.h"
 #include "llvm/Transforms/IPO/FunctionAttrs.h"
+#include "llvm/Transforms/IPO/FunctionImport.h"
 #include "llvm/Transforms/Utils/Cloning.h"
 #include "llvm/Transforms/Utils/ModuleUtils.h"
 using namespace llvm;
@@ -169,46 +170,17 @@ void simplifyExternals(Module &M) {
   }
 }
 
-void filterModule(
-    Module *M, function_ref<bool(const GlobalValue *)> ShouldKeepDefinition) {
-  for (Module::alias_iterator I = M->alias_begin(), E = M->alias_end();
-       I != E;) {
-    GlobalAlias *GA = &*I++;
-    if (ShouldKeepDefinition(GA))
-      continue;
-
-    GlobalObject *GO;
-    if (GA->getValueType()->isFunctionTy())
-      GO = Function::Create(cast<FunctionType>(GA->getValueType()),
-                            GlobalValue::ExternalLinkage, "", M);
-    else
-      GO = new GlobalVariable(
-          *M, GA->getValueType(), false, GlobalValue::ExternalLinkage,
-          nullptr, "", nullptr,
-          GA->getThreadLocalMode(), GA->getType()->getAddressSpace());
-    GO->takeName(GA);
-    GA->replaceAllUsesWith(GO);
-    GA->eraseFromParent();
-  }
-
-  for (Function &F : *M) {
-    if (ShouldKeepDefinition(&F))
-      continue;
-
-    F.deleteBody();
-    F.setComdat(nullptr);
-    F.clearMetadata();
-  }
-
-  for (GlobalVariable &GV : M->globals()) {
-    if (ShouldKeepDefinition(&GV))
-      continue;
-
-    GV.setInitializer(nullptr);
-    GV.setLinkage(GlobalValue::ExternalLinkage);
-    GV.setComdat(nullptr);
-    GV.clearMetadata();
-  }
+static void
+filterModule(Module *M,
+             function_ref<bool(const GlobalValue *)> ShouldKeepDefinition) {
+  std::vector<GlobalValue *> V;
+  for (GlobalValue &GV : M->global_values())
+    if (!ShouldKeepDefinition(&GV))
+      V.push_back(&GV);
+
+  for (GlobalValue *GV : V)
+    if (!convertToDeclaration(*GV))
+      GV->eraseFromParent();
 }
 
 void forEachVirtualFunction(Constant *C, function_ref<void(Function *)> Fn) {