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[experiment ]Address taken functions as opt. #296

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[experiment ]Address taken functions as opt. #296

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22 changes: 16 additions & 6 deletions llvm/lib/Transforms/Yk/ModuleClone.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,8 @@
//
// Sometimes we are unable to clone a function. For example when a function has
// its address taken. Cloning such a function would break "function pointer
// identity", which the program may be relying on.
// identity", which the program may be relying on. In this case, we mark the
// original function as yk_outline to prevent tracing calls from being added.
//===----------------------------------------------------------------------===//

#include "llvm/Transforms/Yk/ModuleClone.h"
Expand All @@ -28,6 +29,7 @@
#include "llvm/IR/Verifier.h"
#include "llvm/Linker/Linker.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Yk/ControlPoint.h"
#include "llvm/YkIR/YkIRWriter.h"
Expand Down Expand Up @@ -56,11 +58,7 @@ bool ModuleClonePass::shouldClone(Function &F) {
if (F.isDeclaration()) {
return false;
}
// If the address of a function is taken, then cloning it would break
// function pointer identity, which the program may rely on.
if (F.hasAddressTaken()) {
return false;
}
// Note: address-taken functions are handled separately in cloneFunctionsInModule.
// For now we don't clone functions that contain a call to the control
// point.
if (containsControlPoint(F)) {
Expand All @@ -85,6 +83,18 @@ ModuleClonePass::cloneFunctionsInModule(Module &M) {
for (Function *F : Funcs) {
auto OrigName = F->getName().str();

// If the address of a function is taken, then cloning it would break
// function pointer identity, which the program may rely on. We mark the
// original as yk_outline to prevent tracing calls from being added.
if (F->hasAddressTaken()) {
// Debug print
// errs() << "yk-module-clone: address-taken function: " << F->getName() << "\n";
F->addFnAttr(YK_OUTLINE_FNATTR);
F->setMetadata(YK_SWT_OPT_MD, OptMD);
CloneMap[F] = nullptr;
continue;
}

// Maybe clone the function.
Function *ClonedOptFunc = nullptr;
if (shouldClone(*F)) {
Expand Down