LLVM-Examples/LLVMIRModify/LLVMCFGIRMod.cpp at master · codersguild/LLVM-Examples · GitHub

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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;

});

}};

}

LLVM-Examples/LLVMIRModify/LLVMCFGIRMod.cpp at master · codersguild/LLVM-Examples · GitHub

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