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LLVMCFGIRMod.cpp
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123 lines (105 loc) · 3.86 KB
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#include "llvm/Analysis/CFG.h"
#include "llvm/Analysis/DomTreeUpdater.h"
#include "llvm/Analysis/PostDominators.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/PassManager.h"
#include "llvm/Passes/PassBuilder.h"
#include "llvm/Passes/PassPlugin.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
// only needed for printing
#include <assert.h>
#include <iostream>
using namespace llvm;
namespace {
struct ModifyBuildCFG : public PassInfoMixin<ModifyBuildCFG> {
PreservedAnalyses run(Function &F, FunctionAnalysisManager &FAM) {
if (F.getName() != "main")
return PreservedAnalyses::all();
// What precursors/pre-passes are needed. Define.
LoopInfo &getLI = FAM.getResult<llvm::LoopAnalysis>(F);
DominatorTree &DT = FAM.getResult<DominatorTreeAnalysis>(F);
PostDominatorTree &PDT = FAM.getResult<PostDominatorTreeAnalysis>(F);
/**
* @brief Loop Info Analysis
*/
if (getLI.empty())
std::cout << "No Loops ! \n\n";
else
getLI.print(errs());
/**
* @brief Print Dominator Tree to llvm::errs()
*/
DT.print(errs());
// What we intend do do in the pass starts here.
int found = 0;
LLVMContext &Ctx = F.getContext();
Instruction *binop = nullptr;
ReversePostOrderTraversal<Function *> RPOT(&F);
for (auto *BB : RPOT) {
errs() << "\t\tBasic Block : " << BB->getName().str() << "\n";
for (auto &I : *BB) {
errs() << "\tOperation : " << I.getOpcodeName() << "\n";
// Find the first "Add" Instruction.
if (strcmp(I.getOpcodeName(), "add") == 0) {
binop = &I;
found = 1;
break;
}
}
if (found == 1)
break;
}
// Use the operands of a binary operator to
// get the operands of Compare Not Equal Instruction.
if (binop != NULL) {
IRBuilder<> Builder(binop);
Value *lhs = binop->getOperand(0);
Value *rhs = binop->getOperand(1);
Value *xpv = Builder.CreateAlloca(llvm::Type::getInt32Ty(Ctx), nullptr,
"new_alloca_1");
Value *xpv2 = Builder.CreateAlloca(llvm::Type::getInt32Ty(Ctx), nullptr,
"new_alloca_2");
Value *add1 = Builder.CreateAdd(lhs, rhs);
Value *mul = Builder.CreateMul(lhs, rhs);
// Modify CFG to add compare and source/target basic blocks.
Value *icmp1 = Builder.CreateICmpEQ(add1, mul, "equals_compare");
Instruction *ThenTerm, *ElseTerm;
SplitBlockAndInsertIfThenElse(icmp1, binop, &ThenTerm, &ElseTerm,
nullptr);
Builder.SetInsertPoint(ThenTerm);
Value *xp1 = Builder.CreateStore(add1, xpv);
Builder.SetInsertPoint(ElseTerm);
Value *xp2 = Builder.CreateStore(mul, xpv2);
}
ReversePostOrderTraversal<Function *> RPOT1(&F);
for (auto *BB : RPOT1) {
errs() << "\t\tBasic Block : " << BB->getName().str() << "\n";
}
// Preserve previous analysis in the pass. Like Dominator information.
// THe pass we made does not modify that.
return PreservedAnalyses::none();
}
};
} // namespace
// Registering the pass.
extern "C" ::llvm::PassPluginLibraryInfo LLVM_ATTRIBUTE_WEAK
llvmGetPassPluginInfo() {
return {LLVM_PLUGIN_API_VERSION, "ModifyBuildCFG", "v0.1",
[](PassBuilder &PB) {
PB.registerPipelineParsingCallback(
[](StringRef Name, FunctionPassManager &FPM,
ArrayRef<PassBuilder::PipelineElement>) {
if (Name == "modifyncfg") {
FPM.addPass(ModifyBuildCFG());
return true;
}
return false;
});
}};
}