Implement linker. It's 95% working now.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@810 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 267 insertions, 1 deletions

diff --git a/lib/VMCore/Linker.cpp b/lib/VMCore/Linker.cpp
index 5957d69..f2c08dc 100644
--- a/lib/VMCore/Linker.cpp
+++ b/lib/VMCore/Linker.cpp
@@ -9,14 +9,280 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Transforms/Linker.h"
+#include "llvm/Module.h"
+#include "llvm/Method.h"
+#include "llvm/GlobalVariable.h"
+#include "llvm/SymbolTable.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/iOther.h"
+
+// Error - Simple wrapper function to conditionally assign to E and return true.
+// This just makes error return conditions a little bit simpler...
+//
+static inline bool Error(string *E, string Message) {
+  if (E) *E = Message;
+  return true;
+}
+
+#include "llvm/Assembly/Writer.h" // TODO: REMOVE
+
+// RemapOperand - Use LocalMap and GlobalMap to convert references from one
+// module to another.  This is somewhat sophisticated in that it can
+// automatically handle constant references correctly as well...
+//
+static Value *RemapOperand(Value *In, map<const Value*, Value*> &LocalMap,
+                           const map<const Value*, Value*> *GlobalMap = 0) {
+  map<const Value*,Value*>::const_iterator I = LocalMap.find(In);
+  if (I != LocalMap.end()) return I->second;
+
+  if (GlobalMap) {
+    I = GlobalMap->find(In);
+    if (I != GlobalMap->end()) return I->second;
+  }
+
+  if (!isa<ConstPoolVal>(In))
+    cerr << "Couldn't remap value: " << In << endl;
+  return In;
+}
+
+
+// LinkGlobals - Loop through the global variables in the src module and merge
+// them into the dest module...
+//
+static bool LinkGlobals(Module *Dest, const Module *Src,
+                        map<const Value*, Value*> &ValueMap, string *Err = 0) {
+  // We will need a module level symbol table if the src module has a module
+  // level symbol table...
+  SymbolTable *ST = Src->getSymbolTable() ? Dest->getSymbolTableSure() : 0;
+  
+  // Loop over all of the globals in the src module, mapping them over as we go
+  //
+  for (Module::const_giterator I = Src->gbegin(), E = Src->gend(); I != E; ++I){
+    const GlobalVariable *GV = *I;
+    Value *V;
+
+    // If the global variable has a name, and that name is already in use in the
+    // Dest module, make sure that the name is a compatible global variable...
+    //
+    if (GV->hasName() && (V = ST->lookup(GV->getType(), GV->getName()))) {
+      // The same named thing is a global variable, because the only two things
+      // that may be in a module level symbol table are Global Vars and Methods,
+      // and they both have distinct, nonoverlapping, possible types.
+      // 
+      GlobalVariable *DGV = cast<GlobalVariable>(V);
+
+      // Check to see if the two GV's have the same Const'ness...
+      if (GV->isConstant() != DGV->isConstant())
+        return Error(Err, "Global Variable Collision on '" + 
+                     GV->getType()->getDescription() + "':%" + GV->getName() +
+                     " - Global variables differ in const'ness");
+
+      // Check to make sure that they both have the same initializer if they are
+      // both initialized...
+      //
+ // TODO: Check to see if they have DEEP equality.  For Module level constants
+      if (GV->hasInitializer() && DGV->hasInitializer() &&
+          GV->getInitializer() != DGV->getInitializer())
+        return Error(Err, "Global Variable Collision on '" + 
+                     GV->getType()->getDescription() + "':%" + GV->getName() +
+                     " - Global variables have different initializers");
+
+      // Okay, everything is cool, remember the mapping and update the
+      // initializer if neccesary...
+      //
+// TODO: We might have to map module level constants here!
+      if (GV->hasInitializer() && !DGV->hasInitializer())
+        DGV->setInitializer(GV->getInitializer());
+
+      ValueMap.insert(make_pair(GV, DGV));
+    } else {
+      // No linking to be performed, simply create an identical version of the
+      // symbol over in the dest module...
+// TODO: Provide constpoolval mapping for initializer if using module local
+// initializers!
+      GlobalVariable *NGV = 
+        new GlobalVariable(GV->getType()->getValueType(), GV->isConstant(),
+                           GV->hasInitializer() ? GV->getInitializer() : 0,
+                           GV->getName());
+
+      // Add the new global to the dest module
+      Dest->getGlobalList().push_back(NGV);
+
+      // Make sure to remember this mapping...
+      ValueMap.insert(make_pair(GV, NGV));
+    }
+  }
+  return false;
+}
+
+
+
+// LinkMethodProtos - Link the methods together between the two modules, without
+// doing method bodies... this just adds external method prototypes to the Dest
+// method...
+//
+static bool LinkMethodProtos(Module *Dest, const Module *Src,
+                             map<const Value*, Value*> &ValueMap,
+                             string *Err = 0) {
+  // We will need a module level symbol table if the src module has a module
+  // level symbol table...
+  SymbolTable *ST = Src->getSymbolTable() ? Dest->getSymbolTableSure() : 0;
+  
+  // Loop over all of the methods in the src module, mapping them over as we go
+  //
+  for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) {
+    const Method *SM = *I;   // SrcMethod
+    Value *V;
+
+    // If the method has a name, and that name is already in use in the
+    // Dest module, make sure that the name is a compatible method...
+    //
+    if (SM->hasName() && (V = ST->lookup(SM->getType(), SM->getName()))) {
+      // The same named thing is a Method, because the only two things
+      // that may be in a module level symbol table are Global Vars and Methods,
+      // and they both have distinct, nonoverlapping, possible types.
+      // 
+      Method *DM = cast<Method>(V);   // DestMethod
+
+      // Check to make sure the method is not defined in both modules...
+      if (!SM->isExternal() && !DM->isExternal())
+        return Error(Err, "Method '" + 
+                     SM->getMethodType()->getDescription() + "':\"" + 
+                     SM->getName() + "\" - Method is already defined!");
+
+      // Otherwise, just remember this mapping...
+      ValueMap.insert(make_pair(SM, DM));
+    } else {
+      // Method does not already exist, simply insert an external method
+      // signature identical to SM into the dest module...
+      Method *DM = new Method(SM->getMethodType(), SM->getName());
+
+      // Add the method signature to the dest module...
+      Dest->getMethodList().push_back(DM);
+
+      // ... and remember this mapping...
+      ValueMap.insert(make_pair(SM, DM));
+    }
+  }
+  return false;
+}
+
+// LinkMethodBody - Copy the source method over into the dest method and fix up
+// references to values.  At this point we know that Dest is an external method,
+// and that Src is not.
+//
+static bool LinkMethodBody(Method *Dest, const Method *Src,
+                           const map<const Value*, Value*> &GlobalMap,
+                           string *Err = 0) {
+  assert(Src && Dest && Dest->isExternal() && !Src->isExternal());
+  map<const Value*, Value*> LocalMap;   // Map for method local values
+
+  // Go through and convert method arguments over...
+  for (Method::ArgumentListType::const_iterator 
+         I = Src->getArgumentList().begin(),
+         E = Src->getArgumentList().end(); I != E; ++I) {
+    const MethodArgument *SMA = *I;
+
+    // Create the new method argument and add to the dest method...
+    MethodArgument *DMA = new MethodArgument(SMA->getType(), SMA->getName());
+    Dest->getArgumentList().push_back(DMA);
+
+    // Add a mapping to our local map
+    LocalMap.insert(make_pair(SMA, DMA));
+  }
+
+  // Loop over all of the basic blocks, copying the instructions over...
+  //
+  for (Method::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) {
+    const BasicBlock *SBB = *I;
+
+    // Create new basic block and add to mapping and the Dest method...
+    BasicBlock *DBB = new BasicBlock(SBB->getName(), Dest);
+    LocalMap.insert(make_pair(SBB, DBB));
+
+    // Loop over all of the instructions in the src basic block, copying them
+    // over.  Note that this is broken in a strict sense because the cloned
+    // instructions will still be referencing values in the Src module, not
+    // the remapped values.  In our case, however, we will not get caught and 
+    // so we can delay patching the values up until later...
+    //
+    for (BasicBlock::const_iterator II = SBB->begin(), IE = SBB->end(); 
+         II != IE; ++II) {
+      const Instruction *SI = *II;
+      Instruction *DI = SI->clone();
+      DBB->getInstList().push_back(DI);
+      LocalMap.insert(make_pair(SI, DI));
+    }
+  }
+
+  // At this point, all of the instructions and values of the method are now
+  // copied over.  The only problem is that they are still referencing values
+  // in the Source method as operands.  Loop through all of the operands of the
+  // methods and patch them up to point to the local versions...
+  //
+  for (Method::inst_iterator I = Dest->inst_begin(), E = Dest->inst_end();
+       I != E; ++I) {
+    Instruction *Inst = *I;
+
+    for (Instruction::op_iterator OI = Inst->op_begin(), OE = Inst->op_end();
+         OI != OE; ++OI)
+      *OI = RemapOperand(*OI, LocalMap, &GlobalMap);
+  }
+
+  return false;
+}
+
+
+// LinkMethodBodies - Link in the method bodies that are defined in the source
+// module into the DestModule.  This consists basically of copying the method
+// over and fixing up references to values.
+//
+static bool LinkMethodBodies(Module *Dest, const Module *Src,
+                             map<const Value*, Value*> &ValueMap,
+                             string *Err = 0) {
+
+  // Loop over all of the methods in the src module, mapping them over as we go
+  //
+  for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) {
+    const Method *SM = *I;                   // Source Method
+    Method *DM = cast<Method>(ValueMap[SM]); // Destination method
+
+    assert(DM && DM->isExternal() && "LinkMethodProtos failed!");
+    if (!SM->isExternal())  // External methods are already done
+      if (LinkMethodBody(DM, SM, ValueMap, Err)) return true;
+  }
+  return false;
+}
+
 
 
 // LinkModules - This function links two modules together, with the resulting
 // left module modified to be the composite of the two input modules.  If an
 // error occurs, true is returned and ErrorMsg (if not null) is set to indicate
-// the problem.
+// the problem.  Upon failure, the Dest module could be in a modified state, and
+// shouldn't be relied on to be consistent.
 //
 bool LinkModules(Module *Dest, const Module *Src, string *ErrorMsg = 0) {
+  // ValueMap - Mapping of values from what they used to be in Src, to what they
+  // are now in Dest.
+  //
+  map<const Value*, Value*> ValueMap;
+
+  // Link the globals variables together between the two modules...
+  if (LinkGlobals(Dest, Src, ValueMap, ErrorMsg)) return true;
+
+  // Link the methods together between the two modules, without doing method
+  // bodies... this just adds external method prototypes to the Dest method...
+  // We do this so that when we begin processing method bodies, all of the
+  // global values that may be referenced are available in our ValueMap.
+  //
+  if (LinkMethodProtos(Dest, Src, ValueMap, ErrorMsg)) return true;
+
+  // Link in the method bodies that are defined in the source module into the
+  // DestModule.  This consists basically of copying the method over and fixing
+  // up references to values.
+  //
+  if (LinkMethodBodies(Dest, Src, ValueMap, ErrorMsg)) return true;
 
   return false;
 }