JavaCPP Presets for GCC

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Introduction

This repository contains the JavaCPP Presets module for

• libgccjit 11.2.0: https://gcc.gnu.org/wiki/JIT

Please refer to the JavaCPP Presets README.md file for more detailed information about the JavaCPP Presets.

This preset is in development, snapshot artifacts and javadocs are coming soon.

Documentation

Java API documentation is currently not available.

Builds

The preset currently supports the following platforms (more platforms coming soon)

• Linux (x86-64)
• Linux (PowerPC 64-bit little endian) (experimental)

Experimental builds are builds run in a custom build environment, separated from the rest of the JavaCPP Presets CI envs. This is a temporary solution and primarily a proof-of-concept. Please open an issue/discussion if you're in need of these architectures or if an architecture you need is not available.

Sample Usage

Below is an example that shows how you can do code generation with libgccjit and execute function calls via jit.

A full index of samples can be found in the samples directory.

We can use Gradle to install the required dependencies and native binaries built by JavaCPP.

The build.gradle build file

plugins {
    id("application")
}

repositories {
    mavenLocal()
    mavenCentral()
    maven { url 'https://oss.sonatype.org/content/repositories/snapshots/' }
}

dependencies {
    implementation("org.bytedeco:gcc-platform:11.2.0-1.5.7-SNAPSHOT")
    implementation("org.bytedeco:libffi-platform:3.3-1.5.7-SNAPSHOT")
}

application {
    mainClass = 'JitExecution'
}

The preset for libffi is a required dependency to call the function addresses that we create using the libgccjit library.

The JitExecution.java source file

import org.bytedeco.gcc.gccjit.*;
import org.bytedeco.javacpp.*;
import org.bytedeco.libffi.ffi_cif;
import org.bytedeco.libffi.ffi_type;
import org.bytedeco.libffi.global.ffi;

import static org.bytedeco.gcc.global.gccjit.*;

public class JitExecution {
    public static void main(String[] unused) {
        gcc_jit_context ctxt = gcc_jit_context_acquire();

        gcc_jit_type int_type = gcc_jit_context_get_type(ctxt, GCC_JIT_TYPE_INT);
        BytePointer add_name = new BytePointer("add");
        PointerPointer<gcc_jit_param> args = new PointerPointer<>(
            gcc_jit_context_new_param(ctxt, null, int_type, "a"),
            gcc_jit_context_new_param(ctxt, null, int_type, "b")
        );
        gcc_jit_function add = gcc_jit_context_new_function(ctxt, null, GCC_JIT_FUNCTION_EXPORTED, int_type, add_name
            , 2, args, 0);

        gcc_jit_block entry = gcc_jit_function_new_block(add, "entry");
        gcc_jit_param a_param = gcc_jit_function_get_param(add, 0);
        gcc_jit_param b_param = gcc_jit_function_get_param(add, 1);
        gcc_jit_rvalue sum = gcc_jit_context_new_binary_op(
            ctxt, null, GCC_JIT_BINARY_OP_PLUS, int_type,
            gcc_jit_param_as_rvalue(a_param),
            gcc_jit_param_as_rvalue(b_param)
        );
        gcc_jit_block_end_with_return(entry, null, sum);

        gcc_jit_result result = gcc_jit_context_compile(ctxt);
        Pointer addr = gcc_jit_result_get_code(result, "add");

        ffi_cif cif = new ffi_cif();
        PointerPointer<ffi_type> arguments = new PointerPointer<>(2);
        PointerPointer<LongPointer> values = new PointerPointer<>(2);
        LongPointer res = new LongPointer(1);

        arguments.put(0, ffi.ffi_type_sint());
        arguments.put(1, ffi.ffi_type_sint());
        values.put(0, new LongPointer(1).put(10));
        values.put(1, new LongPointer(1).put(20));

        if (ffi.ffi_prep_cif(cif, ffi.FFI_DEFAULT_ABI(), 2, ffi.ffi_type_sint(), arguments) != ffi.FFI_OK) {
            throw new IllegalStateException("Failed to prepare libffi cif");
        }
        ffi.ffi_call(cif, addr, res, values);

        System.out.println("Evaluating add(10, 20) with JIT results in: " + res.get());

        gcc_jit_result_release(result);
        gcc_jit_context_release(ctxt);

        args.deallocate();
        add_name.deallocate();
    }
}