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Make it possible to use the linker without destroying the source modu…
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…le. This is so the source module can be linked to multiple other destination modules. For all that used LinkModules() before, they will continue to destroy the source module as before.

This line, and those below, will be ignored--

M    include/llvm/Linker.h
M    tools/bugpoint/Miscompilation.cpp
M    tools/bugpoint/BugDriver.cpp
M    tools/llvm-link/llvm-link.cpp
M    lib/Linker/LinkModules.cpp


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141606 91177308-0d34-0410-b5e6-96231b3b80d8
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@tlattner
tlattner committed Oct 11, 2011
1 parent fad138d commit f1f1a4f
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Showing 5 changed files with 73 additions and 38 deletions.
12 changes: 9 additions & 3 deletions include/llvm/Linker.h
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Original file line number Diff line number Diff line change
Expand Up @@ -57,7 +57,12 @@ class Linker {
QuietWarnings = 2, ///< Don't print warnings to stderr.
QuietErrors = 4 ///< Don't print errors to stderr.
};


enum LinkerMode {
DestroySource = 0, // Allow source module to be destroyed.
PreserveSource = 1 // Preserve the source module.
};

/// @}
/// @name Constructors
/// @{
Expand Down Expand Up @@ -245,7 +250,7 @@ class Linker {
Module* Src, ///< Module linked into \p Dest
std::string* ErrorMsg = 0 /// Error/diagnostic string
) {
return LinkModules(Composite, Src, ErrorMsg );
return LinkModules(Composite, Src, Linker::DestroySource, ErrorMsg );
}

/// This is the heart of the linker. This method will take unconditional
Expand All @@ -259,7 +264,8 @@ class Linker {
/// error.
/// @returns True if an error occurs, false otherwise.
/// @brief Generically link two modules together.
static bool LinkModules(Module* Dest, Module* Src, std::string* ErrorMsg);
static bool LinkModules(Module* Dest, Module* Src, unsigned Mode,
std::string* ErrorMsg);

/// This function looks through the Linker's LibPaths to find a library with
/// the name \p Filename. If the library cannot be found, the returned path
Expand Down
85 changes: 55 additions & 30 deletions lib/Linker/LinkModules.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -14,9 +14,12 @@
#include "llvm/Linker.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
#include "llvm/Module.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/Path.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/ValueMapper.h"
using namespace llvm;

Expand Down Expand Up @@ -333,10 +336,16 @@ namespace {

std::vector<AppendingVarInfo> AppendingVars;

unsigned Mode; // Mode to treat source module.

// Set of items not to link in from source.
SmallPtrSet<const Value*, 16> DoNotLinkFromSource;

public:
std::string ErrorMsg;

ModuleLinker(Module *dstM, Module *srcM) : DstM(dstM), SrcM(srcM) { }
ModuleLinker(Module *dstM, Module *srcM, unsigned mode)
: DstM(dstM), SrcM(srcM), Mode(mode) { }

bool run();

Expand Down Expand Up @@ -596,9 +605,9 @@ bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
DstGV->eraseFromParent();

// Zap the initializer in the source variable so we don't try to link it.
SrcGV->setInitializer(0);
SrcGV->setLinkage(GlobalValue::ExternalLinkage);
// Track the source variable so we don't try to link it.
DoNotLinkFromSource.insert(SrcGV);

return false;
}

Expand Down Expand Up @@ -633,11 +642,10 @@ bool ModuleLinker::linkGlobalProto(GlobalVariable *SGV) {
// Make sure to remember this mapping.
ValueMap[SGV] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGV->getType()));

// Destroy the source global's initializer (and convert it to a prototype)
// so that we don't attempt to copy it over when processing global
// initializers.
SGV->setInitializer(0);
SGV->setLinkage(GlobalValue::ExternalLinkage);
// Track the source global so that we don't attempt to copy it over when
// processing global initializers.
DoNotLinkFromSource.insert(SGV);

return false;
}
}
Expand Down Expand Up @@ -682,8 +690,10 @@ bool ModuleLinker::linkFunctionProto(Function *SF) {
// Make sure to remember this mapping.
ValueMap[SF] = ConstantExpr::getBitCast(DGV, TypeMap.get(SF->getType()));

// Remove the body from the source module so we don't attempt to remap it.
SF->deleteBody();
// Track the function from the source module so we don't attempt to remap
// it.
DoNotLinkFromSource.insert(SF);

return false;
}
}
Expand Down Expand Up @@ -722,8 +732,9 @@ bool ModuleLinker::linkAliasProto(GlobalAlias *SGA) {
// Make sure to remember this mapping.
ValueMap[SGA] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGA->getType()));

// Remove the body from the source module so we don't attempt to remap it.
SGA->setAliasee(0);
// Track the alias from the source module so we don't attempt to remap it.
DoNotLinkFromSource.insert(SGA);

return false;
}
}
Expand Down Expand Up @@ -779,7 +790,9 @@ void ModuleLinker::linkGlobalInits() {
// Loop over all of the globals in the src module, mapping them over as we go
for (Module::const_global_iterator I = SrcM->global_begin(),
E = SrcM->global_end(); I != E; ++I) {
if (!I->hasInitializer()) continue; // Only process initialized GV's.

// Only process initialized GV's or ones not already in dest.
if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue;

// Grab destination global variable.
GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]);
Expand All @@ -805,31 +818,42 @@ void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) {
ValueMap[I] = DI;
}

// Splice the body of the source function into the dest function.
Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList());

// At this point, all of the instructions and values of the function are now
// copied over. The only problem is that they are still referencing values in
// the Source function as operands. Loop through all of the operands of the
// functions and patch them up to point to the local versions.
for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB)
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries, &TypeMap);

if (Mode == Linker::DestroySource) {
// Splice the body of the source function into the dest function.
Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList());

// At this point, all of the instructions and values of the function are now
// copied over. The only problem is that they are still referencing values in
// the Source function as operands. Loop through all of the operands of the
// functions and patch them up to point to the local versions.
for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB)
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries, &TypeMap);

} else {
// Clone the body of the function into the dest function.
SmallVector<ReturnInst*, 8> Returns; // Ignore returns.
CloneFunctionInto(Dst, Src, ValueMap, false, Returns);
}

// There is no need to map the arguments anymore.
for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
I != E; ++I)
ValueMap.erase(I);

}


void ModuleLinker::linkAliasBodies() {
for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end();
I != E; ++I)
I != E; ++I) {
if (DoNotLinkFromSource.count(I))
continue;
if (Constant *Aliasee = I->getAliasee()) {
GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]);
DA->setAliasee(MapValue(Aliasee, ValueMap, RF_None, &TypeMap));
}
}
}

/// linkNamedMDNodes - Insert all of the named mdnodes in Src into the Dest
Expand Down Expand Up @@ -891,7 +915,6 @@ bool ModuleLinker::run() {
StringRef ModuleId = SrcM->getModuleIdentifier();
if (!ModuleId.empty())
DstM->removeLibrary(sys::path::stem(ModuleId));


// Loop over all of the linked values to compute type mappings.
computeTypeMapping();
Expand Down Expand Up @@ -928,7 +951,8 @@ bool ModuleLinker::run() {
// Link in the function bodies that are defined in the source module into
// DstM.
for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) {
if (SF->isDeclaration()) continue; // No body if function is external.
// Skip if no body (function is external) or marked to skip.
if (SF->isDeclaration() || DoNotLinkFromSource.count(SF)) continue;

linkFunctionBody(cast<Function>(ValueMap[SF]), SF);
}
Expand Down Expand Up @@ -957,8 +981,9 @@ bool ModuleLinker::run() {
// error occurs, true is returned and ErrorMsg (if not null) is set to indicate
// the problem. Upon failure, the Dest module could be in a modified state, and
// shouldn't be relied on to be consistent.
bool Linker::LinkModules(Module *Dest, Module *Src, std::string *ErrorMsg) {
ModuleLinker TheLinker(Dest, Src);
bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Mode,
std::string *ErrorMsg) {
ModuleLinker TheLinker(Dest, Src, Mode);
if (TheLinker.run()) {
if (ErrorMsg) *ErrorMsg = TheLinker.ErrorMsg;
return true;
Expand Down
3 changes: 2 additions & 1 deletion tools/bugpoint/BugDriver.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -127,7 +127,8 @@ bool BugDriver::addSources(const std::vector<std::string> &Filenames) {

outs() << "Linking in input file: '" << Filenames[i] << "'\n";
std::string ErrorMessage;
if (Linker::LinkModules(Program, M.get(), &ErrorMessage)) {
if (Linker::LinkModules(Program, M.get(), Linker::DestroySource,
&ErrorMessage)) {
errs() << ToolName << ": error linking in '" << Filenames[i] << "': "
<< ErrorMessage << '\n';
return true;
Expand Down
8 changes: 5 additions & 3 deletions tools/bugpoint/Miscompilation.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -222,7 +222,7 @@ static Module *TestMergedProgram(const BugDriver &BD, Module *M1, Module *M2,
M1 = CloneModule(M1);
M2 = CloneModule(M2);
}
if (Linker::LinkModules(M1, M2, &ErrorMsg)) {
if (Linker::LinkModules(M1, M2, Linker::DestroySource, &ErrorMsg)) {
errs() << BD.getToolName() << ": Error linking modules together:"
<< ErrorMsg << '\n';
exit(1);
Expand Down Expand Up @@ -396,7 +396,8 @@ static bool ExtractLoops(BugDriver &BD,
// Replace the current program with the loop extracted version, and try to
// extract another loop.
std::string ErrorMsg;
if (Linker::LinkModules(ToNotOptimize, ToOptimizeLoopExtracted, &ErrorMsg)){
if (Linker::LinkModules(ToNotOptimize, ToOptimizeLoopExtracted,
Linker::DestroySource, &ErrorMsg)){
errs() << BD.getToolName() << ": Error linking modules together:"
<< ErrorMsg << '\n';
exit(1);
Expand Down Expand Up @@ -575,7 +576,8 @@ static bool ExtractBlocks(BugDriver &BD,
I->getFunctionType()));

std::string ErrorMsg;
if (Linker::LinkModules(ProgClone, Extracted, &ErrorMsg)) {
if (Linker::LinkModules(ProgClone, Extracted, Linker::DestroySource,
&ErrorMsg)) {
errs() << BD.getToolName() << ": Error linking modules together:"
<< ErrorMsg << '\n';
exit(1);
Expand Down
3 changes: 2 additions & 1 deletion tools/llvm-link/llvm-link.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -103,7 +103,8 @@ int main(int argc, char **argv) {

if (Verbose) errs() << "Linking in '" << InputFilenames[i] << "'\n";

if (Linker::LinkModules(Composite.get(), M.get(), &ErrorMessage)) {
if (Linker::LinkModules(Composite.get(), M.get(), Linker::DestroySource,
&ErrorMessage)) {
errs() << argv[0] << ": link error in '" << InputFilenames[i]
<< "': " << ErrorMessage << "\n";
return 1;
Expand Down

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