Add support to the linker to lazily link in functions. This change only links functio...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143524 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Linker/LinkModules.cpp b/lib/Linker/LinkModules.cpp
index bcc6782129ce905e0e4b8cea40a63b089200290e..ab099bbfaf8926a36f324839957da711a2f32c02 100644 (file)
--- a/lib/Linker/LinkModules.cpp
+++ b/lib/Linker/LinkModules.cpp
@@ -341,6 +341,9 @@ namespace {
     // Set of items not to link in from source.
     SmallPtrSet<const Value*, 16> DoNotLinkFromSource;
     
+    // Vector of functions to lazily link in.
+    std::vector<Function*> LazilyLinkFunctions;
+    
   public:
     std::string ErrorMsg;
     
@@ -708,6 +711,13 @@ bool ModuleLinker::linkFunctionProto(Function *SF) {
     // Any uses of DF need to change to NewDF, with cast.
     DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, DGV->getType()));
     DGV->eraseFromParent();
+  } else {
+    // Internal, LO_ODR, or LO linkage - stick in set to ignore and lazily link.
+    if (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() ||
+        SF->hasAvailableExternallyLinkage()) {
+      DoNotLinkFromSource.insert(SF);
+      LazilyLinkFunctions.push_back(SF);
+    }
   }
   
   ValueMap[SF] = NewDF;
@@ -974,6 +984,54 @@ bool ModuleLinker::run() {
   // are properly remapped.
   linkNamedMDNodes();
 
+  // Process vector of lazily linked in functions.
+  bool LinkedInAnyFunctions;
+  do {
+    LinkedInAnyFunctions = false;
+    
+    for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(),
+        E = LazilyLinkFunctions.end(); I != E; ++I) {
+      if (!*I)
+        continue;
+      
+      Function *SF = *I;
+      Function *DF = cast<Function>(ValueMap[SF]);
+      
+      if (!DF->use_empty()) {
+        
+        // Materialize if necessary.
+        if (SF->isDeclaration()) {
+          if (!SF->isMaterializable())
+            continue;
+          if (SF->Materialize(&ErrorMsg))
+            return true;
+        }
+        
+        // Link in function body.
+        linkFunctionBody(DF, SF);
+        
+        // "Remove" from vector by setting the element to 0.
+        *I = 0;
+        
+        // Set flag to indicate we may have more functions to lazily link in
+        // since we linked in a function.
+        LinkedInAnyFunctions = true;
+      }
+    }
+  } while (LinkedInAnyFunctions);
+  
+  // Remove any prototypes of functions that were not actually linked in.
+  for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(),
+      E = LazilyLinkFunctions.end(); I != E; ++I) {
+    if (!*I)
+      continue;
+    
+    Function *SF = *I;
+    Function *DF = cast<Function>(ValueMap[SF]);
+    if (DF->use_empty())
+      DF->eraseFromParent();
+  }
+  
   // Now that all of the types from the source are used, resolve any structs
   // copied over to the dest that didn't exist there.
   TypeMap.linkDefinedTypeBodies();