Parsing LLVM Bitcode JavaCPP

build.gradle

plugins {
    id("application")
}

repositories {
    mavenCentral()
}

dependencies {
    implementation("org.bytedeco:llvm-platform:11.1.0-1.5.5")
}

main.c

#include <stdio.h>
#include <stdlib.h>
#include "llvm-c/Types.h"
#include "llvm-c/Core.h"
#include "llvm-c/Support.h"
#include "llvm-c/BitReader.h"

LLVMModuleRef test(char* filename)
{
    LLVMMemoryBufferRef memoryBuffer;
    char *message;
    if(LLVMCreateMemoryBufferWithContentsOfFile(filename, &memoryBuffer, &message))
    {
        printf("Error during bitcode file parsing\n");
        free(message);
    }

    LLVMModuleRef module;
    if(LLVMParseBitcode2(memoryBuffer, &module)) {
        printf("Bitcode file maybe in wrong format\n");
    }
    LLVMDisposeMemoryBuffer(memoryBuffer);
    printf("DONE\n");
    return module;
}

int main(int argc, char** argv) {
    char* file = argv[1];
    test(file);
}

program.ll

; ModuleID = 'example_addition.bc'
source_filename = "example_addition.c"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-linux-gnu"

; Function Attrs: noinline nounwind optnone sspstrong uwtable
define dso_local i32 @main() #0 !dbg !9 {
  %1 = alloca i32, align 4
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  store i32 0, i32* %1, align 4
  call void @llvm.dbg.declare(metadata i32* %2, metadata !13, metadata !DIExpression()), !dbg !14
  store i32 2, i32* %2, align 4, !dbg !14
  call void @llvm.dbg.declare(metadata i32* %3, metadata !15, metadata !DIExpression()), !dbg !16
  store i32 3, i32* %3, align 4, !dbg !16
  call void @llvm.dbg.declare(metadata i32* %4, metadata !17, metadata !DIExpression()), !dbg !18
  %5 = load i32, i32* %2, align 4, !dbg !19
  %6 = load i32, i32* %3, align 4, !dbg !20
  %7 = add nsw i32 %5, %6, !dbg !21
  store i32 %7, i32* %4, align 4, !dbg !18
  ret i32 0, !dbg !22
}

; Function Attrs: nounwind readnone speculatable willreturn
declare void @llvm.dbg.declare(metadata, metadata, metadata) #1

attributes #0 = { noinline nounwind optnone sspstrong uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #1 = { nounwind readnone speculatable willreturn }

!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4, !5, !6, !7}
!llvm.ident = !{!8}

!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 11.1.0", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
!1 = !DIFile(filename: "example_addition.c", directory: "/home/solarowl/Research/IR-CFA-proto/src/main/resources")
!2 = !{}
!3 = !{i32 7, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = !{i32 1, !"wchar_size", i32 4}
!6 = !{i32 7, !"PIC Level", i32 2}
!7 = !{i32 7, !"PIE Level", i32 2}
!8 = !{!"clang version 11.1.0"}
!9 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 1, type: !10, scopeLine: 1, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
!10 = !DISubroutineType(types: !11)
!11 = !{!12}
!12 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!13 = !DILocalVariable(name: "a", scope: !9, file: !1, line: 2, type: !12)
!14 = !DILocation(line: 2, column: 9, scope: !9)
!15 = !DILocalVariable(name: "b", scope: !9, file: !1, line: 3, type: !12)
!16 = !DILocation(line: 3, column: 9, scope: !9)
!17 = !DILocalVariable(name: "c", scope: !9, file: !1, line: 4, type: !12)
!18 = !DILocation(line: 4, column: 9, scope: !9)
!19 = !DILocation(line: 4, column: 13, scope: !9)
!20 = !DILocation(line: 4, column: 15, scope: !9)
!21 = !DILocation(line: 4, column: 14, scope: !9)
!22 = !DILocation(line: 5, column: 5, scope: !9)

src-main-java-MainApp.java

import static org.bytedeco.llvm.global.LLVM.*;
import org.bytedeco.llvm.LLVM.*;
import org.bytedeco.javacpp.*;

public class MainApp {
    public static void main(String[] args) {
        String filename = args[0];

        // Your code referred to some unknown variable 'module'. We want to pass an empty (null pointer)
        // module to LLVMParseBitCode2 because we wish to insert the MemBuf module into it.
        LLVMModuleRef module = new LLVMModuleRef();
        LLVMMemoryBufferRef memBuffer = new LLVMMemoryBufferRef();
        BytePointer message = new BytePointer();
        BytePointer fname = new BytePointer(filename);
        // This is unused
        PointerPointer<LLVMMemoryBufferRef> memBufPtr = new PointerPointer<>(memBuffer);
        if(LLVMCreateMemoryBufferWithContentsOfFile(fname, memBuffer, message)!=0) {
            throw new RuntimeException("Error during bitcode file parsing");
        }
        if(LLVMParseBitcode2(memBuffer, module)!=0) {
            throw new RuntimeException("Bitcode file may be in the wrong format");
        }
        LLVMDisposeMemoryBuffer(memBuffer);
        // I added this so you can see LLVM dumping your program through the created module.
        LLVMDumpModule(module);
    }
}