Multinomial parse (#2003)

src/include/migraphx/op/multinomial.hpp

 /*
  * The MIT License (MIT)
  *
- * Copyright (c) 2015-2022 Advanced Micro Devices, Inc. All rights reserved.
+ * Copyright (c) 2015-2023 Advanced Micro Devices, Inc. All rights reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -21,11 +21,52 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
+
+/**
+ *  * Multinomial or categorical distribution.  Performs a sampling of random input
+ *         and returns a count of
+ *         each category, or bucket.  This does not require the standard multinomial
+ *         distribution but instead takes a probability distribution, i.e. cumulative
+ *         distribution function (CDF) as its first input.
+ *
+ *      Inputs:   args[0] - a tensor of probabilities for each category.  Values are
+ *                          cumulative density function
+ *                          totals as provided by operation prefix_scan_sum.  Values are
+ *                          cumulative probabilities (i.e. start with any set of numbers > 0
+ *                          and then apply prefix_scan_sum).  Values do not need to be
+ *                          normalized to sum to 1; this is done in runtime computation.
+ *
+ *                          This input has Rank 2.  Dimension 0 is batch #, so that there can be
+ *                          a different CDF for each iteration in the batch.  The size of dimension
+ *                          1 is the number of categories.
+ *
+ *                args[1] - a tensor of random numbers.  The last dimension is the sample
+ *                          size, i.e. the number of
+ *                          random samples in each iteration of the batch.  Nominally
+ *                          has two dimensions where the first dimension is batch size, but
+ *                          any reshaping such that the total
+ *                          number of elements is (batch_size * sample_size) is legal.
+ *
+ *                          Values as created by a std::mt19937 like this:
+ *
+ *                           size_t sample_size = 100000;
+ *                           float seed         = 0.0f;
+ *                           std::mt19937 gen(seed);
+ *                           std::uniform_real_distribution<> dis(0.0, 1.0);
+ *                           std::vector<float> rand_samples(sample_size);
+ *                           std::generate(rand_samples.begin(), rand_samples.end(), [&]() { return
+ *                                dis(gen); });
+ *
+ *        Output:   A 2D vector of category each input.  Dimensions are (Input 1[first], Input
+ 2[last]).
+ *
+*/
 #ifndef MIGRAPHX_GUARD_OPERATORS_MULTINOMIAL_HPP
 #define MIGRAPHX_GUARD_OPERATORS_MULTINOMIAL_HPP
 
-#include <migraphx/check_shapes.hpp>
 #include <migraphx/argument.hpp>
+#include <migraphx/check_shapes.hpp>
+#include <migraphx/dyn_output.hpp>
 #include <migraphx/par_for.hpp>
 #include <migraphx/reflect.hpp>
 #include <random>
@@ -47,22 +88,35 @@ struct multinomial
     std::string name() const { return "multinomial"; }
     shape compute_shape(std::vector<shape> inputs) const
     {
-        check_shapes{inputs, *this}.has(2).only_dims(2);
-        size_t sample_size = inputs.back().lens().back();
+        check_shapes{inputs, *this, true}.has(2).only_dims(2);
 
-        if(not contains({shape::int32_type, shape::int64_type}, dtype))
-            MIGRAPHX_THROW(
-                "Multinomial: Invalid output type. Valid types are int32_type and int64_type.");
+        if(inputs.back().ndim() < 1)
+            MIGRAPHX_THROW("Multinomial: Second input shape (sample) has no dimensions");
+        if(dtype == shape::bool_type)
+            MIGRAPHX_THROW("Multinomial: boolean output type invalid.");
 
-        return {dtype, {inputs.front().lens().front(), sample_size}};
+        // Output takes one dimension from each of the two input shapes.  If they are both fixed,
+        // return a static shape
+        if((not inputs.front().dynamic()) or (inputs.front().dyn_dims().front().is_fixed()))
+        {
+            if((not inputs.back().dynamic()) or (inputs.back().dyn_dims().back().is_fixed()))
+            {
+                size_t batch = {inputs.front().max_lens().front()};
+                size_t sample_size{inputs.back().max_lens().back()};
+                return {dtype, {batch, sample_size}};
+            }
+        }
+        return {dtype,
+                {inputs.front().to_dynamic().dyn_dims().front(),
+                 inputs.back().to_dynamic().dyn_dims().back()}};
     }
 
-    argument compute(const shape& output_shape, std::vector<argument> args) const
+    argument compute(const dyn_output& dyn_out, std::vector<argument> args) const
     {
-        argument result{output_shape};
-        size_t batch_size  = output_shape.lens().front();
+        argument result{dyn_out.computed_shape};
+        size_t batch_size  = dyn_out.computed_shape.lens().front();
         size_t class_size  = args[0].get_shape().lens().back();
-        size_t sample_size = output_shape.lens().back();
+        size_t sample_size = dyn_out.computed_shape.lens().back();
 
         visit_all(args[0], args[1])([&](auto cdf, auto dist) {
             result.visit([&](auto output) {
@@ -70,13 +124,16 @@ struct multinomial
                     auto idx       = args[1].get_shape().multi(i);
                     auto cdf_begin = cdf.begin() + (idx[0] * class_size);
                     auto cdf_end   = cdf_begin + class_size;
+
+                    // std::upper_bound returns an iterator to the bucket the value belongs in,
+                    // when normalized by the probability distribution dist
                     auto sample_iter =
                         std::upper_bound(cdf_begin, cdf_end, dist[i] * *(std::prev(cdf_end)));
+                    // convert iterator to an integer index
                     output[i] = std::distance(cdf_begin, sample_iter);
                 });
             });
         });
-
         return result;
     }
 };

src/include/migraphx/op/prefix_scan_op.hpp

@@ -22,6 +22,12 @@
  * THE SOFTWARE.
  */
 
+/**
+ * Parent struct for prefix scan ops.  A prefix scan is a mathematical entity useful
+ * in parallelizing various computations.  Given a list of numbers, a prefix scan
+ * op returns an equal size list of running totals of the values.  Other operations
+ * besides addition can be supported by child ops.
+ */
 #ifndef MIGRAPHX_GUARD_OPERATORS_SCAN_OP_HPP
 #define MIGRAPHX_GUARD_OPERATORS_SCAN_OP_HPP
 

src/include/migraphx/op/random_uniform.hpp

@@ -65,11 +65,10 @@ struct random_uniform
         return inputs.at(1);
     }
 
-    argument compute(const shape&, std::vector<argument> args) const
+    argument compute(const dyn_output& dyn_out, std::vector<argument> args) const
     {
         // Output goes into the passed buffer, not the shape output.
-        auto result = args[1];
-
+        argument result{dyn_out.computed_shape};
         uint64_t local_seed = args[0].at<uint64_t>(0);
         std::mt19937 gen(local_seed);
 

src/onnx/parse_clip.cpp

 /*
  * The MIT License (MIT)
  *
- * Copyright (c) 2015-2022 Advanced Micro Devices, Inc. All rights reserved.
+ * Copyright (c) 2015-2023 Advanced Micro Devices, Inc. All rights reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

src/onnx/parse_multinomial.cpp

 /*
  * The MIT License (MIT)
  *
- * Copyright (c) 2015-2022 Advanced Micro Devices, Inc. All rights reserved.
+ * Copyright (c) 2015-2023 Advanced Micro Devices, Inc. All rights reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -41,6 +41,9 @@ struct parse_multinomial : op_parser<parse_multinomial>
                           const onnx_parser::node_info& info,
                           std::vector<instruction_ref> args) const
     {
+        if(args.empty())
+            MIGRAPHX_THROW("PARSE_MULTINOMIAL: no arguments given");
+
         int dtype = 6;
         if(contains(info.attributes, "dtype"))
             dtype = info.attributes.at("dtype").i();
@@ -49,35 +52,90 @@ struct parse_multinomial : op_parser<parse_multinomial>
         size_t sample_size = 1;
         if(contains(info.attributes, "sample_size"))
             sample_size = info.attributes.at("sample_size").i();
+        else
+            MIGRAPHX_THROW("PARSE_MULTINOMIAL: sample_size not given");
+
+        // Use logarithmic math to scale probabilities while avoiding division by very
+        // small numbers.  Scaling by the maximum makes very tiny ranges more
+        // tractable; any constant factor gives equivalent distr. since the Multinomial op.
+        // normalizes at runtime.
 
         // Subtract the per-batch maximum log-probability, making the per-batch max 0
         auto maxes =
             info.add_instruction(migraphx::make_op("reduce_max", {{"axes", {1}}}), args[0]);
-        auto mb_maxes = info.add_instruction(
-            migraphx::make_op("multibroadcast", {{"out_lens", args[0]->get_shape().lens()}}),
-            maxes);
-        auto cdf = info.add_instruction(migraphx::make_op("sub"), args[0], mb_maxes);
+        auto cdf = info.add_common_op("sub", args[0], maxes);
         // Take the element-wise exponent to get probabilities in the range (0, 1]
         cdf = info.add_instruction(migraphx::make_op("exp"), cdf);
-        // Compute the cumulative density function
+        // Compute the cumulative distribution function
         cdf = info.add_instruction(
             migraphx::make_op("prefix_scan_sum", {{"axis", 1}, {"exclusive", false}}), cdf);
 
-        // Pre-compute random distribution
-        std::mt19937 gen(std::chrono::high_resolution_clock::now().time_since_epoch().count());
+        instruction_ref seed_input;
         if(contains(info.attributes, "seed"))
-            gen.seed(info.attributes.at("seed").f());
+        {
+            float seed = info.attributes.at("seed").f();
+            migraphx::shape s{migraphx::shape::float_type, {1}};
+            std::vector<float> data = {seed};
+            seed_input              = info.add_literal(migraphx::literal(s, data));
+        }
+        else
+        {
+            seed_input = info.add_instruction(migraphx::make_op("random_seed"));
+        }
+        instruction_ref randoms;
+
+        shape s0 = args[0]->get_shape();
+
+        if(s0.dynamic())
+        {
+            //  Dynamic batch_size will be taken from args[0].  The input argument to this should
+            // have a second dimension of sample_size.
+            std::vector<shape::dynamic_dimension> dyn_dim_set;
+            dyn_dim_set.emplace_back(s0.dyn_dims().front());
+            dyn_dim_set.emplace_back(shape::dynamic_dimension{sample_size, sample_size});
+
+            // read the input dimensions
+            auto dim_of =
+                info.add_instruction(migraphx::make_op("dimensions_of", {{"end", 2}}), args[0]);
+
+            // The next two operations insert the value sample_size into the second array position
+
+            // make an argument of (1, 0)
+            shape s(shape::int64_type, {2});
+            std::vector<int64_t> data1{1, 0};
+            auto l1        = info.add_literal(s, data1);
+            auto batch_arg = info.add_instruction(migraphx::make_op("mul"), dim_of, l1);
+            std::vector<int64_t> data2(2, 0);
+            // make an argument of (0, sample_size)
+            data2[1]         = sample_size;
+            auto l2          = info.add_literal(s, data2);
+            auto alloc_shape = info.add_instruction(migraphx::make_op("add"), batch_arg, l2);
+            // alloc_shape should contain the input-based shape dimensions as its values at runtime,
+            // and its own shape is {2}
 
-        std::uniform_real_distribution<> dis(0.0, 1.0);
-        size_t batch_size = args[0]->get_shape().lens().front();
-        migraphx::shape dist_shape{migraphx::shape::float_type, {batch_size, sample_size}};
+            // compile_shape is the shape used when compiling the Allocate op, and may be dynamic
+            migraphx::shape compile_shape =
+                migraphx::shape(s0.type(), {s0.dyn_dims().front(), {sample_size, sample_size}});
 
-        std::vector<float> random_dist(batch_size * sample_size);
-        std::generate(random_dist.begin(), random_dist.end(), [&]() { return dis(gen); });
-        auto dist_lit = info.add_literal(migraphx::literal{dist_shape, random_dist});
+            // Allocate on-device storage for the random values
+            auto alloc = info.add_instruction(
+                migraphx::make_op("allocate", {{"shape", to_value(compile_shape)}}), alloc_shape);
+            randoms = info.add_instruction(migraphx::make_op("random_uniform"), seed_input, alloc);
+        }
+        else
+        {
+            // use literal.  The array populated by random_uniform may have any shape, as long its
+            // number of elements is batch_size * sample_size .
+            size_t batch_size = s0.lens().front();
+            auto rand_dummy   = info.add_literal(
+                migraphx::literal{migraphx::shape::float_type, {batch_size * sample_size}});
+
+            randoms =
+                info.add_instruction(migraphx::make_op("random_uniform"), seed_input, rand_dummy);
+        }
 
         return info.add_instruction(
-            migraphx::make_op("multinomial", {{"dtype", output_type}}), cdf, dist_lit);
+            migraphx::make_op("multinomial", {{"dtype", output_type}}), cdf, randoms);
     }
 };
 

test/onnx/gen_onnx.py

@@ -4883,9 +4883,9 @@ def mod_test_fmod_different_dtypes():
 
 @onnx_test()
 def multinomial_test():
-    sample_size = 10
-    seed = 0.0
-    input = helper.make_tensor_value_info("input", TensorProto.FLOAT, [1, 10])
+    sample_size = 13
+    seed = 0.
+    input = helper.make_tensor_value_info("input", TensorProto.FLOAT, [3, 10])
     output = helper.make_tensor_value_info("output", TensorProto.INT32,
                                            [1, 10])
 
@@ -4898,6 +4898,44 @@ def multinomial_test():
     return ([node], [input], [output])
 
 
+@onnx_test()
+def multinomial_dyn_test():
+    sample_size = 100000
+    seed = 1.3
+    categories = 5
+    input = helper.make_tensor_value_info("input", TensorProto.FLOAT,
+                                          [None, categories])
+    output = helper.make_tensor_value_info("output", TensorProto.FLOAT,
+                                           [None, categories])
+
+    node = onnx.helper.make_node(
+        'Multinomial',
+        inputs=['input'],
+        sample_size=sample_size,
+        dtype=1,  # shape::float_type
+        seed=seed,
+        outputs=['output'])
+
+    return ([node], [input], [output])
+
+
+@onnx_test()
+def multinomial_autoseed_dyn_test():
+    # If seed attribute is not given, device should auto generate one at runtime
+    sample_size = 12
+    input = helper.make_tensor_value_info("input", TensorProto.FLOAT,
+                                          [None, 10])
+    output = helper.make_tensor_value_info("output", TensorProto.INT32,
+                                           [None, 10])
+
+    node = onnx.helper.make_node('Multinomial',
+                                 inputs=['input'],
+                                 sample_size=sample_size,
+                                 outputs=['output'])
+
+    return ([node], [input], [output])
+
+
 @onnx_test()
 def multinomial_generated_seed_test():
     sample_size = 10

test/onnx/onnx_test.cpp

@@ -4679,32 +4679,140 @@ TEST_CASE(multinomial_test)
 {
     migraphx::program p;
     auto* mm           = p.get_main_module();
-    size_t sample_size = 10;
-    float seed         = 0.0f;
+    size_t sample_size = 13;
+    size_t batch_size  = 3;
+    size_t categories  = 10;
+    float seed         = 0;
 
-    auto input = mm->add_parameter("input", migraphx::shape{migraphx::shape::float_type, {1, 10}});
+    auto input = mm->add_parameter(
+        "input", migraphx::shape{migraphx::shape::float_type, {batch_size, categories}});
     auto maxes    = mm->add_instruction(migraphx::make_op("reduce_max", {{"axes", {1}}}), input);
-    auto mb_maxes =
-        mm->add_instruction(migraphx::make_op("multibroadcast", {{"out_lens", {1, 10}}}), maxes);
+    auto mb_maxes = mm->add_instruction(
+        migraphx::make_op("multibroadcast", {{"out_lens", {batch_size, 10}}}), maxes);
     auto cdf = mm->add_instruction(migraphx::make_op("sub"), input, mb_maxes);
     cdf      = mm->add_instruction(migraphx::make_op("exp"), cdf);
     cdf      = mm->add_instruction(
         migraphx::make_op("prefix_scan_sum", {{"axis", 1}, {"exclusive", false}}), cdf);
 
-    std::mt19937 gen(seed);
-    std::uniform_real_distribution<> dis(0.0, 1.0);
-    std::vector<float> rand_samples(sample_size);
-    std::generate(rand_samples.begin(), rand_samples.end(), [&]() { return dis(gen); });
-    migraphx::shape rs{migraphx::shape::float_type, {1, sample_size}};
-    auto rs_lit = mm->add_literal(migraphx::literal{rs, rand_samples});
-
-    mm->add_instruction(migraphx::make_op("multinomial"), cdf, rs_lit);
+    migraphx::shape s{migraphx::shape::float_type, {1}};
+    std::vector<float> seed_data = {seed};
+    auto seed_input              = mm->add_literal(migraphx::literal(s, seed_data));
+    auto rand_dummy =
+        mm->add_literal(migraphx::literal{migraphx::shape::float_type, {batch_size * sample_size}});
 
+    auto randoms = mm->add_instruction(migraphx::make_op("random_uniform"), seed_input, rand_dummy);
+    mm->add_instruction(migraphx::make_op("multinomial"), cdf, randoms);
     auto prog = optimize_onnx("multinomial_test.onnx");
 
     EXPECT(p == prog);
 }
 
+TEST_CASE(multinomial_dyn_test)
+{
+    // compile-time random seed
+    migraphx::program p;
+    auto* mm           = p.get_main_module();
+    size_t sample_size = 100000;
+    size_t categories  = 5;
+    float seed         = 1.3f;
+
+    auto input = mm->add_parameter(
+        "input",
+        migraphx::shape{migraphx::shape::float_type, {{1, categories}, {categories, categories}}});
+
+    auto maxes = mm->add_instruction(migraphx::make_op("reduce_max", {{"axes", {1}}}), input);
+
+    auto cdf = add_common_op(*mm, migraphx::make_op("sub"), {input, maxes});
+    cdf      = mm->add_instruction(migraphx::make_op("exp"), cdf);
+    cdf      = mm->add_instruction(
+        migraphx::make_op("prefix_scan_sum", {{"axis", 1}, {"exclusive", false}}), cdf);
+
+    migraphx::shape s{migraphx::shape::float_type, {1}};
+    std::vector<float> seed_data = {seed};
+    auto seed_input              = mm->add_literal(migraphx::literal(s, seed_data));
+
+    // dynamic input only:  must calculate alloc_shape as (batch_size, sample_size)
+    //                read the runtime input dimensions
+    auto dim_of = mm->add_instruction(migraphx::make_op("dimensions_of", {{"end", 2}}), input);
+    // make an argument of (1, 0)
+    migraphx::shape lit_shape(migraphx::shape::int64_type, {2});
+    std::vector<int64_t> data1{1, 0};
+    auto l1        = mm->add_literal(lit_shape, data1);
+    auto batch_arg = mm->add_instruction(migraphx::make_op("mul"), dim_of, l1);
+    std::vector<int64_t> data2(2, 0);
+    // make an argument of (0, sample_size)
+    data2[1]         = sample_size;
+    auto l2          = mm->add_literal(lit_shape, data2);
+    auto alloc_shape = mm->add_instruction(migraphx::make_op("add"), batch_arg, l2);
+    migraphx::shape compile_shape =
+        migraphx::shape(migraphx::shape::float_type,
+                        {input->get_shape().dyn_dims().front(), {sample_size, sample_size}});
+
+    auto alloc = mm->add_instruction(
+        migraphx::make_op("allocate", {{"shape", to_value(compile_shape)}}), alloc_shape);
+
+    auto randoms = mm->add_instruction(migraphx::make_op("random_uniform"), seed_input, alloc);
+    auto ret     = mm->add_instruction(
+        migraphx::make_op("multinomial", {{"dtype", migraphx::shape::float_type}}), cdf, randoms);
+    mm->add_return({ret});
+
+    migraphx::onnx_options options;
+    options.default_dyn_dim_value  = {1, categories};
+    options.print_program_on_error = true;
+    auto prog                      = migraphx::parse_onnx("multinomial_dyn_test.onnx", options);
+    EXPECT(p == prog);
+}
+
+TEST_CASE(multinomial_autoseed_dyn_test)
+{
+    // runtime random seed
+    migraphx::program p;
+    auto* mm           = p.get_main_module();
+    size_t sample_size = 12;
+    size_t categories  = 10;
+
+    auto input = mm->add_parameter(
+        "input", migraphx::shape{migraphx::shape::float_type, {{1, 10}, {10, 10}}});
+
+    auto maxes = mm->add_instruction(migraphx::make_op("reduce_max", {{"axes", {1}}}), input);
+
+    auto cdf = add_common_op(*mm, migraphx::make_op("sub"), {input, maxes});
+    cdf      = mm->add_instruction(migraphx::make_op("exp"), cdf);
+    cdf      = mm->add_instruction(
+        migraphx::make_op("prefix_scan_sum", {{"axis", 1}, {"exclusive", false}}), cdf);
+    auto seed_input = mm->add_instruction(migraphx::make_op("random_seed"));
+
+    // dynamic input only:  must calculate alloc_shape as (batch_size, sample_size)
+    //                read the runtime input dimensions
+    auto dim_of = mm->add_instruction(migraphx::make_op("dimensions_of", {{"end", 2}}), input);
+    // make an argument of (1, 0)
+    migraphx::shape lit_shape(migraphx::shape::int64_type, {2});
+    std::vector<int64_t> data1{1, 0};
+    auto l1        = mm->add_literal(lit_shape, data1);
+    auto batch_arg = mm->add_instruction(migraphx::make_op("mul"), dim_of, l1);
+    std::vector<int64_t> data2(2, 0);
+    // make an argument of (0, sample_size)
+    data2[1]         = sample_size;
+    auto l2          = mm->add_literal(lit_shape, data2);
+    auto alloc_shape = mm->add_instruction(migraphx::make_op("add"), batch_arg, l2);
+    migraphx::shape compile_shape =
+        migraphx::shape(migraphx::shape::float_type,
+                        {input->get_shape().dyn_dims().front(), {sample_size, sample_size}});
+
+    auto alloc = mm->add_instruction(
+        migraphx::make_op("allocate", {{"shape", to_value(compile_shape)}}), alloc_shape);
+
+    auto randoms = mm->add_instruction(migraphx::make_op("random_uniform"), seed_input, alloc);
+    auto ret     = mm->add_instruction(migraphx::make_op("multinomial"), cdf, randoms);
+    mm->add_return({ret});
+
+    migraphx::onnx_options options;
+    options.default_dyn_dim_value  = {1, categories};
+    options.print_program_on_error = true;
+    auto prog = migraphx::parse_onnx("multinomial_autoseed_dyn_test.onnx", options);
+    EXPECT(p == prog);
+}
+
 TEST_CASE(multinomial_dtype_error_test)
 {
     EXPECT(test::throws([&] { migraphx::parse_onnx("multinomial_dtype_error_test.onnx"); }));
@@ -4712,10 +4820,11 @@ TEST_CASE(multinomial_dtype_error_test)
 
 TEST_CASE(multinomial_generated_seed_test)
 {
+    // multinomial op. no longer generates its own randoms
     auto p1 = optimize_onnx("multinomial_generated_seed_test.onnx");
     auto p2 = optimize_onnx("multinomial_generated_seed_test.onnx");
 
-    EXPECT(p1 != p2);
+    EXPECT(p1 == p2);
 }
 
 TEST_CASE(multinomial_int64_test)
@@ -4723,27 +4832,27 @@ TEST_CASE(multinomial_int64_test)
     migraphx::program p;
     auto* mm                      = p.get_main_module();
     size_t sample_size            = 10;
-    float seed                    = 1.0f;
+    float seed                    = 1.0;
+    uint32_t batch_size           = 1;
     migraphx::shape::type_t dtype = migraphx::shape::type_t::int64_type;
 
     auto input = mm->add_parameter("input", migraphx::shape{migraphx::shape::float_type, {1, 10}});
     auto maxes = mm->add_instruction(migraphx::make_op("reduce_max", {{"axes", {1}}}), input);
-    auto mb_maxes =
-        mm->add_instruction(migraphx::make_op("multibroadcast", {{"out_lens", {1, 10}}}), maxes);
-    auto cdf = mm->add_instruction(migraphx::make_op("sub"), input, mb_maxes);
+
+    auto cdf = add_common_op(*mm, migraphx::make_op("sub"), {input, maxes});
     cdf      = mm->add_instruction(migraphx::make_op("exp"), cdf);
     cdf      = mm->add_instruction(
         migraphx::make_op("prefix_scan_sum", {{"axis", 1}, {"exclusive", false}}), cdf);
 
-    std::mt19937 gen(seed);
-    std::uniform_real_distribution<> dis(0.0, 1.0);
-    std::vector<float> rand_samples(sample_size);
-    std::generate(rand_samples.begin(), rand_samples.end(), [&]() { return dis(gen); });
-    migraphx::shape rs{migraphx::shape::float_type, {1, sample_size}};
-    auto rs_lit = mm->add_literal(migraphx::literal{rs, rand_samples});
-
-    mm->add_instruction(migraphx::make_op("multinomial", {{"dtype", dtype}}), cdf, rs_lit);
+    migraphx::shape s{migraphx::shape::float_type, {1}};
+    std::vector<float> data = {seed};
+    auto seed_input         = mm->add_literal(migraphx::literal(s, data));
 
+    // static size
+    auto rand_dummy =
+        mm->add_literal(migraphx::literal{migraphx::shape::float_type, {batch_size * sample_size}});
+    auto randoms = mm->add_instruction(migraphx::make_op("random_uniform"), seed_input, rand_dummy);
+    mm->add_instruction(migraphx::make_op("multinomial", {{"dtype", dtype}}), cdf, randoms);
     auto prog = optimize_onnx("multinomial_int64_test.onnx");
 
     EXPECT(p == prog);

test/onnx/verify_onnx.cpp

@@ -1434,6 +1434,77 @@ TEST_CASE(mod_test_fmod_different_types)
     EXPECT(migraphx::verify::verify_rms_range(result_vector, gold));
 }
 
+TEST_CASE(multinomial_dyn_test)
+{
+    migraphx::onnx_options options;
+    options.default_dyn_dim_value = {1, 4};
+    auto p                        = migraphx::parse_onnx("multinomial_dyn_test.onnx", options);
+    const size_t batch_size(2);
+    const size_t categories(5);
+    const size_t sample_size(100000);
+    p.compile(migraphx::make_target("ref"));
+
+    // Distribution function (2 distributions of 5 categories each)
+    std::vector<int> dist{15, 25, 15, 25, 20, 20, 20, 10, 25, 25};
+    EXPECT(dist.size() == categories * batch_size);
+    std::vector<float> data(categories * batch_size);
+
+    std::transform(dist.begin(), dist.end(), data.begin(), [&](auto d) { return log(d); });
+    // Shape of the probability distribution, which also defines the number of categories
+    migraphx::shape s{migraphx::shape::float_type, {batch_size, categories}};
+
+    migraphx::parameter_map pp;
+    pp["input"] = migraphx::argument(s, data.data());
+
+    auto result = p.eval(pp).back();
+
+    std::vector<int32_t> result_vec(batch_size * sample_size);
+    result.visit([&](auto output) { result_vec.assign(output.begin(), output.end()); });
+
+    // Make a categorical histogram of output
+    // for first result in batch
+    std::vector<int> res_dist(categories, 0);
+    size_t r = 0;
+    for(r = 0; r < result_vec.size() / 2; r++)
+        res_dist[result_vec[r]]++;
+
+    // normalizing factors for original and measured distributions
+    auto dist_sum     = std::accumulate(dist.begin(), dist.begin() + 5, 0);
+    auto res_dist_sum = std::accumulate(res_dist.begin(), res_dist.end(), 0);
+
+    //  Values approximate the distribution in dist
+    std::vector<float> norm(5);
+    std::vector<float> res_norm(5);
+
+    std::transform(dist.begin(), dist.begin() + 5, norm.begin(), [&](auto n) {
+        return static_cast<double>(n) / dist_sum;
+    });
+    std::transform(res_dist.begin(), res_dist.end(), res_norm.begin(), [&](auto n) {
+        return static_cast<double>(n) / res_dist_sum;
+    });
+
+    EXPECT(migraphx::verify::verify_range_with_tolerance(
+        norm, migraphx::verify::expected{res_norm}, migraphx::verify::tolerance{0.01}));
+
+    // Make a categorical histogram of output
+    // for second result in batch
+    std::fill(res_dist.begin(), res_dist.end(), 0);
+    for(; r < result_vec.size(); r++)
+        res_dist[result_vec[r]]++;
+
+    dist_sum     = std::accumulate(dist.begin() + 5, dist.end(), 0);
+    res_dist_sum = std::accumulate(res_dist.begin(), res_dist.end(), 0);
+    std::transform(dist.begin() + 5, dist.end(), norm.begin(), [&](auto n) {
+        return static_cast<double>(n) / dist_sum;
+    });
+    std::transform(res_dist.begin(), res_dist.end(), res_norm.begin(), [&](auto n) {
+        return static_cast<double>(n) / res_dist_sum;
+    });
+
+    EXPECT(migraphx::verify::verify_range_with_tolerance(
+        res_norm, migraphx::verify::expected{norm}, migraphx::verify::tolerance{0.01}));
+}
+
 TEST_CASE(nonzero_test)
 {
     migraphx::program p = migraphx::parse_onnx("nonzero_dynamic_test.onnx");

test/op_shape_test.cpp

@@ -1957,12 +1957,42 @@ TEST_CASE(multibroadcast_3in_dyn_dyn)
     expect_shape(expected_shape, migraphx::make_op("multibroadcast"), c_shape, a_shape, b_shape);
 }
 
-TEST_CASE(multinomial)
+TEST_CASE(multinomial_bool_type)
 {
-    migraphx::shape s{migraphx::shape::float_type, {2, 5}};
+    migraphx::shape s1{migraphx::shape::float_type, {1, 2}};
+    migraphx::shape s2{migraphx::shape::float_type, {3, 4}};
     int dtype = 0;
 
-    throws_shape(migraphx::make_op("multinomial", {{"dtype", dtype}}), s, s);
+    throws_shape(migraphx::make_op("multinomial", {{"dtype", dtype}}), s1, s2);
+}
+
+TEST_CASE(multinomial)
+{
+    migraphx::shape s1{migraphx::shape::float_type, {1, 2}};
+    migraphx::shape s2{migraphx::shape::float_type, {3, 4}};
+    migraphx::shape s3{migraphx::shape::float_type, {1, 4}};
+    int dtype = 2;
+
+    expect_shape(s3, migraphx::make_op("multinomial", {{"dtype", dtype}}), s1, s2);
+}
+
+TEST_CASE(multinomial_0size_input)
+{
+    migraphx::shape s1{migraphx::shape::float_type, {1, 2}};
+    migraphx::shape s2{migraphx::shape::float_type, {}};
+    int dtype = 2;
+
+    throws_shape(migraphx::make_op("multinomial", {{"dtype", dtype}}), s1, s2);
+}
+
+TEST_CASE(multinomial_dyn)
+{
+    migraphx::shape s1{migraphx::shape::int32_type, {{2, 3}, {5, 6}}};
+    migraphx::shape s2{migraphx::shape::int32_type, {{7, 8}, {9, 10}}};
+    migraphx::shape s3{migraphx::shape::int32_type, {{2, 3}, {9, 10}}};
+
+    expect_shape(
+        s3, migraphx::make_op("multinomial", {{"dtype", migraphx::shape::int32_type}}), s1, s2);
 }
 
 TEST_CASE(nms_shape)

test/ref/multinomial.cpp

@@ -24,9 +24,10 @@
 #include <migraphx/instruction.hpp>
 #include <migraphx/literal.hpp>
 #include <migraphx/make_op.hpp>
-#include <migraphx/program.hpp>
+#include <migraphx/onnx.hpp>
 #include <migraphx/register_target.hpp>
 #include <migraphx/verify.hpp>
+#include <numeric>
 #include <random>
 
 #include <test.hpp>
@@ -48,27 +49,37 @@ TEST_CASE(multinomial_test)
     migraphx::shape s{migraphx::shape::float_type, {1, 5}};
     std::vector<int> dist{15, 25, 15, 25, 20};
     std::vector<float> data(5);
-    std::transform(dist.begin(), dist.end(), data.begin(), [&](auto d) { return std::log(d); });
-    auto input = mm->add_literal(migraphx::literal(s, data));
+    std::vector<float> sum(5);
+    // convert to float
+    std::transform(dist.begin(), dist.end(), data.begin(), [&](auto d) { return d; });
+    // take cumulative sum
+    std::partial_sum(data.begin(), data.end(), sum.begin(), std::plus<float>());
+    // scale probabilities arbitrarily
+    float odd_scale = 10000.;
+    std::transform(sum.begin(), sum.end(), data.begin(), [&](auto d) { return d * odd_scale; });
 
-    auto maxes = mm->add_instruction(migraphx::make_op("reduce_max", {{"axes", {1}}}), input);
-    auto mb_maxes =
-        mm->add_instruction(migraphx::make_op("multibroadcast", {{"out_lens", {1, 5}}}), maxes);
-    auto cdf = mm->add_instruction(migraphx::make_op("sub"), input, mb_maxes);
-    cdf      = mm->add_instruction(migraphx::make_op("exp"), cdf);
-    cdf      = mm->add_instruction(
-        migraphx::make_op("prefix_scan_sum", {{"axis", 1}, {"exclusive", false}}), cdf);
+    auto input = mm->add_literal(migraphx::literal(s, data));
 
-    mm->add_instruction(migraphx::make_op("multinomial"), cdf, rs_lit);
+    mm->add_instruction(migraphx::make_op("multinomial"), input, rs_lit);
     p.compile(migraphx::make_target("ref"));
     auto result = p.eval({}).back();
+    // result_vec contains an index, or category label, for each random input value
     std::vector<int32_t> result_vec(sample_size);
     result.visit([&](auto output) { result_vec.assign(output.begin(), output.end()); });
 
+    // res_dist is a count, or histogram, of the number of samples in each category.  This is the
+    // sampled distribution.
     std::vector<int> res_dist(5, 0);
     for(const auto& r : result_vec)
         res_dist[r]++;
+
+    // To check the result, normalize the original probability distribution dist
+    // and the sampling result res_dist; they should be close
+
+    // Total the unnormalized probabilities
     auto dist_sum = std::accumulate(dist.begin(), dist.end(), 0);
+
+    // Total the number of values returned
     auto res_dist_sum = std::accumulate(res_dist.begin(), res_dist.end(), 0);
     std::vector<float> norm(5);
     std::vector<float> res_norm(5);
@@ -78,6 +89,204 @@ TEST_CASE(multinomial_test)
     std::transform(res_dist.begin(), res_dist.end(), res_norm.begin(), [&](auto n) {
         return static_cast<double>(n) / res_dist_sum;
     });
+
+    EXPECT(migraphx::verify::verify_range_with_tolerance(
+        res_norm, migraphx::verify::expected{norm}, migraphx::verify::tolerance{0.01}));
+}
+
+TEST_CASE(multinomial_dyn_test)
+{
+    // Invokes random_uniform and multinomial ops together, to verify the interface
+    // Dynamic Batch dimension input of 2 means there are 2 different probability
+    // distribution functions contained in Input_2
+    migraphx::program p;
+    auto* mm = p.get_main_module();
+
+    size_t sample_size = 100000;
+    size_t batch_size  = 2;
+
+    //      Shape of the random data
+    migraphx::shape rs{migraphx::shape::float_type, {{1, 2}, {2, sample_size + 1}}};
+    auto input = mm->add_parameter("Input_1", rs);
+
+    // Runtime randomization seed
+    // To seed the random_uniform, we can provide a value by literal or input,
+    // or ask the system to auto-seed with random_seed op.
+    migraphx::shape seed_shape{migraphx::shape::uint32_type,
+                               {migraphx::shape::dynamic_dimension{0, 1}}};
+    auto seed_input = mm->add_parameter("Seed", seed_shape);
+
+    // Shape of the probability distribution, which also defines the number of categories
+    migraphx::shape s{migraphx::shape::float_type, {{2, 2}, {5, 6}}};
+
+    // Unnormalized distributions for batch size 2:
+    //   15, 25, 15, 15, 20
+    //   20, 20, 10, 25, 25
+    std::vector<int> dist{15, 25, 15, 25, 20, 20, 20, 10, 25, 25};
+    // Hard-coded non-normalized, accumulated distribution follows:
+    std::vector<float> data{.15f, .40f, .55f, .80f, 1.0f, 20.f, 40.f, 50.f, 75.f, 100.f};
+
+    auto input2 = mm->add_parameter("Input_2", s);
+
+    auto randoms = mm->add_instruction(migraphx::make_op("random_uniform"), seed_input, input);
+    mm->add_instruction(migraphx::make_op("multinomial"), input2, randoms);
+
+    p.compile(migraphx::make_target("ref"));
+
+    // Create a dummy input in the shape we want for the random data
+    std::vector<float> dummy(sample_size, 0);
+    migraphx::shape input_fixed_shape1{migraphx::shape::float_type, {batch_size, sample_size}};
+    migraphx::shape input_fixed_shape2{migraphx::shape::float_type, {batch_size, 5}};
+    migraphx::parameter_map params0;
+    params0["Input_1"] = migraphx::argument(input_fixed_shape1, dummy.data());
+
+    migraphx::shape seed_fixed_shape{migraphx::shape::uint32_type, {1}};
+    std::vector<uint32_t> seed_data = {4};
+    params0["Seed"]                 = migraphx::argument(seed_fixed_shape, seed_data.data());
+
+    params0["Input_2"] = migraphx::argument(input_fixed_shape2, data.data());
+    auto result        = p.eval(params0).back();
+
+    std::vector<float> result_vec(input_fixed_shape2.elements());
+    result.visit([&](auto output) { result_vec.assign(output.begin(), output.end()); });
+
+    // Make a categorical histogram of output
+    std::vector<int> res_dist(5, 0);
+    size_t r = 0;
+    for(r = 0; r < result_vec.size() / 2; r++)
+        res_dist[result_vec[r]]++;
+
+    //  histogram for second set of batch
+    std::vector<int> res_dist2(5, 0);
+    for(; r < result_vec.size(); r++)
+        res_dist2[result_vec[r]]++;
+
+    // Rescale or normalize both the input probability distribution and the output
+    // histogram, and compare.  Should be close but not identical.
+    auto dist_sum     = std::accumulate(dist.begin(), dist.begin() + 5, 0);
+    auto res_dist_sum = std::accumulate(res_dist.begin(), res_dist.end(), 0);
+    std::vector<float> norm(5);
+    std::vector<float> res_norm(5);
+
+    std::transform(dist.begin(), dist.begin() + 5, norm.begin(), [&](auto n) {
+        return static_cast<double>(n) / dist_sum;
+    });
+    std::transform(res_dist.begin(), res_dist.end(), res_norm.begin(), [&](auto n) {
+        return static_cast<double>(n) / res_dist_sum;
+    });
+
+    EXPECT(migraphx::verify::verify_range_with_tolerance(
+        res_norm, migraphx::verify::expected{norm}, migraphx::verify::tolerance{0.01}));
+
+    // Do the same rescaling for the 2nd in batch, which has a different probability distribution
+    dist_sum     = std::accumulate(dist.begin() + 5, dist.end(), 0);
+    res_dist_sum = std::accumulate(res_dist2.begin(), res_dist2.end(), 0);
+    std::transform(dist.begin() + 5, dist.end(), norm.begin(), [&](auto n) {
+        return static_cast<double>(n) / dist_sum;
+    });
+    std::transform(res_dist2.begin(), res_dist2.end(), res_norm.begin(), [&](auto n) {
+        return static_cast<double>(n) / res_dist_sum;
+    });
+
+    EXPECT(migraphx::verify::verify_range_with_tolerance(
+        res_norm, migraphx::verify::expected{norm}, migraphx::verify::tolerance{0.01}));
+}
+
+TEST_CASE(multinomial_float_dyn_test)
+{
+    // int data type for random_uniform op and float data type for multinomial.
+
+    migraphx::program p;
+    auto* mm = p.get_main_module();
+
+    size_t sample_size = 100000;
+    size_t batch_size  = 2;
+
+    //      Shape of the random data
+    migraphx::shape rs{migraphx::shape::int32_type, {{1, 2}, {2, sample_size + 1}}};
+    auto input = mm->add_parameter("Input_1", rs);
+
+    // Runtime randomization seed
+    // To seed the random_uniform, we can provide a value by literal or input,
+    // or ask the system to auto-seed with random_seed op.
+    migraphx::shape seed_shape{migraphx::shape::uint32_type,
+                               {migraphx::shape::dynamic_dimension{0, 1}}};
+    auto seed_input = mm->add_parameter("Seed", seed_shape);
+
+    // Shape of the probability distribution, which also defines the number of categories
+    migraphx::shape s{migraphx::shape::float_type, {{2, 2}, {5, 6}}};
+
+    // Unnormalized distributions for batch size 2:
+    //   15, 25, 15, 15, 20
+    //   20, 20, 10, 25, 25
+    std::vector<int> dist{15, 25, 15, 25, 20, 20, 20, 10, 25, 25};
+    // Hard-coded normalized, accumulated distribution follows:
+    std::vector<float> data{.15f, .40f, .55f, .80f, 1.0f, .20f, .40f, .50f, .75f, 1.0f};
+
+    auto input2 = mm->add_parameter("Input_2", s);
+
+    auto randoms = mm->add_instruction(migraphx::make_op("random_uniform"), seed_input, input);
+    mm->add_instruction(migraphx::make_op("multinomial", {{"dtype", migraphx::shape::float_type}}),
+                        input2,
+                        randoms);
+
+    p.compile(migraphx::make_target("ref"));
+
+    // Create a dummy input in the shape we want for the random data
+    std::vector<float> dummy(sample_size, 0);
+    migraphx::shape input_fixed_shape1{migraphx::shape::float_type, {batch_size, sample_size}};
+    migraphx::shape input_fixed_shape2{migraphx::shape::float_type, {batch_size, 5}};
+    migraphx::parameter_map params0;
+    params0["Input_1"] = migraphx::argument(input_fixed_shape1, dummy.data());
+
+    migraphx::shape seed_fixed_shape{migraphx::shape::uint32_type, {1}};
+    std::vector<uint32_t> seed_data = {4};
+    params0["Seed"]                 = migraphx::argument(seed_fixed_shape, seed_data.data());
+
+    params0["Input_2"] = migraphx::argument(input_fixed_shape2, data.data());
+    auto result        = p.eval(params0).back();
+
+    std::vector<float> result_vec(input_fixed_shape2.elements());
+    result.visit([&](auto output) { result_vec.assign(output.begin(), output.end()); });
+
+    // Make a categorical histogram of output
+    std::vector<int> res_dist(5, 0);
+    size_t r = 0;
+    for(r = 0; r < result_vec.size() / 2; r++)
+        res_dist[result_vec[r]]++;
+
+    //  histogram for second set of batch
+    std::vector<int> res_dist2(5, 0);
+    for(; r < result_vec.size(); r++)
+        res_dist2[result_vec[r]]++;
+
+    // Rescale or normalize both the input probability distribution and the output
+    // histogram, and compare.  Should be close but not identical.
+    auto dist_sum     = std::accumulate(dist.begin(), dist.begin() + 5, 0);
+    auto res_dist_sum = std::accumulate(res_dist.begin(), res_dist.end(), 0);
+    std::vector<float> norm(5);
+    std::vector<float> res_norm(5);
+
+    std::transform(dist.begin(), dist.begin() + 5, norm.begin(), [&](auto n) {
+        return static_cast<double>(n) / dist_sum;
+    });
+    std::transform(res_dist.begin(), res_dist.end(), res_norm.begin(), [&](auto n) {
+        return static_cast<double>(n) / res_dist_sum;
+    });
+
+    EXPECT(migraphx::verify::verify_range_with_tolerance(
+        res_norm, migraphx::verify::expected{norm}, migraphx::verify::tolerance{0.01}));
+
+    // Do the same rescaling for the 2nd in batch, which has a different probability distribution
+    dist_sum     = std::accumulate(dist.begin() + 5, dist.end(), 0);
+    res_dist_sum = std::accumulate(res_dist2.begin(), res_dist2.end(), 0);
+    std::transform(dist.begin() + 5, dist.end(), norm.begin(), [&](auto n) {
+        return static_cast<double>(n) / dist_sum;
+    });
+    std::transform(res_dist2.begin(), res_dist2.end(), res_norm.begin(), [&](auto n) {
+        return static_cast<double>(n) / res_dist_sum;
+    });
+
     EXPECT(migraphx::verify::verify_range_with_tolerance(
         res_norm, migraphx::verify::expected{norm}, migraphx::verify::tolerance{0.01}));
 }