Contributing to MIGraphX

Contributing to MIGraphX#

Applies to Linux

2024-02-27

8 min read time

This document explains the internal implementation of some commonly used MIGraphX APIs. You can utilize the information provided in this document and other documents under “Contributing to MIGraphX” section to contribute to the MIGraphX API implementation. Here is how some basic operations in the MIGraphX framework are performed.

Performing basic operations#

A program is a collection of modules, which are collections of instructions to be executed when calling eval. Each instruction has an associated operation which represents the computation to be performed by the instruction.

The following code snippets demonstrate some basic operations using MIGraphX.

Adding literals#

Here is a add_two_literals() function:

// create the program and get a pointer to the main module
migraphx::program p;
auto* mm = p.get_main_module();

// add two literals to the program
auto one = mm->add_literal(1);
auto two = mm->add_literal(2);

// make the add operation between the two literals and add it to the program
mm->add_instruction(migraphx::make_op("add"), one, two);

// compile the program on the reference device
p.compile(migraphx::ref::target{});

// evaulate the program and retreive the result
auto result = p.eval({}).back();
std::cout << "add_two_literals: 1 + 2 = " << result << "\n";

In the above function, a simple program object is created along with a pointer to the main module of it. The program is a collection of modules which starts execution from the main module, so instructions are added to the modules rather than the program object directly. The add_literal function is used to add an instruction that stores the literal number 1 while returning an instruction_ref. The returned instruction_ref can be used in another instruction as an input. The same add_literal function is used to add the literal 2 to the program. After the literals are created, the instruction is created to add the numbers. This is done by using the add_instruction function with the add operation created by make_op and the previously created literals passed as the arguments for the instruction. You can run this program by compiling it for the reference target (CPU) and then running it with eval. This prints the result on the console.

To compile the program for the GPU, move the file to test/gpu/ directory and include the given target:

#include <migraphx/gpu/target.hpp>

Adding Parameters#

While the add_two_literals() function above demonstrates add operation on constant values 1 and 2, the following program demonstrates how to pass a parameter (x) to a module using add_parameter() function .

migraphx::program p; auto* mm = p.get_main_module(); migraphx::shape s{migraphx::shape::int32_type, {1}};

// add parameter “x” with the shape s auto x = mm->add_parameter(“x”, s); auto two = mm->add_literal(2);

// add the “add” instruction between the “x” parameter and “two” to the module mm->add_instruction(migraphx::make_op(“add”), x, two); p.compile(migraphx::ref::target{});

In the code snippet above, an add operation is performed on a parameter of type int32 and literal 2 followed by compilation for the CPU. To run the program, pass the parameter as a parameter_map while calling eval. To map the parameter x to an argument object with an int data type, a parameter_map is created as shown below:

// create a parameter_map object for passing a value to the "x" parameter
std::vector<int> data = {4};
migraphx::parameter_map params;
params["x"] = migraphx::argument(s, data.data());

auto result = p.eval(params).back();
std::cout << "add_parameters: 4 + 2 = " << result << "\n";
EXPECT(result.at<int>() == 6);

Handling Tensor Data#

The above two examples demonstrate scalar operations. To describe multi-dimensional tensors, use the shape class to compute a simple convolution as shown below:

migraphx::program p;
auto* mm = p.get_main_module();

// create shape objects for the input tensor and weights
migraphx::shape input_shape{migraphx::shape::float_type, {2, 3, 4, 4}};
migraphx::shape weights_shape{migraphx::shape::float_type, {3, 3, 3, 3}};

// create the parameters and add the "convolution" operation to the module
auto input   = mm->add_parameter("X", input_shape);
auto weights = mm->add_parameter("W", weights_shape);
mm->add_instruction(migraphx::make_op("convolution", {{"padding", {1, 1}}, {"stride", {2, 2}}}), input, weights);

Most programs take data from allocated buffers that are usually on the GPU. To pass the buffer data as an argument, create argument objects directly from the pointers to the buffers:

// Compile the program
p.compile(migraphx::ref::target{});

// Allocated buffers by the user
std::vector<float> a = ...;
std::vector<float> c = ...;

// Solution vector
std::vector<float> sol = ...;

// Create the arguments in a parameter_map
migraphx::parameter_map params;
params["X"] = migraphx::argument(input_shape, a.data());
params["W"] = migraphx::argument(weights_shape, c.data());

// Evaluate and confirm the result
auto result = p.eval(params).back();
std::vector<float> results_vector(64);
result.visit([&](auto output) { results_vector.assign(output.begin(), output.end()); });

EXPECT(migraphx::verify::verify_rms_range(results_vector, sol));

An argument can handle memory buffers from either the GPU or the CPU. When running the program, buffers are allocated on the corresponding target by default. By default, the buffers are allocated on the CPU when compiling for CPU and on the GPU when compiling for GPU. To locate the buffers on the CPU even when compiling for GPU, set the option offload_copy=true.

Importing From ONNX#

To make it convenient to use neural networks directly from other frameworks, MIGraphX ONNX parser allows you to build a program directly from an ONNX file. For usage, refer to the parse_onnx() function below:

program p = migraphx::parse_onnx("model.onnx");
p.compile(migraphx::gpu::target{});

Sample programs#

You can find all the MIGraphX examples in the Examples directory.

Build MIGraphX source code#

To build a sample program ref_dev_examples.cpp, use:

make -j$(nproc) test_ref_dev_examples

This creates an executable file test_ref_dev_examples in the bin/ of the build directory.

To verify the build, use:

make -j$(nproc) check

For detailed instructions on building MIGraphX from source, refer to the README file.

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