[GPU] use stable seed hash algorithm for different platforms

[yuanxion]

Details:

Reduce platform-dependent randomness in GPU test data generation by making testcase-name-based seed generation stable for GPU tests.

Description of the issue

Symptom

4 fully_connected compressed_int4_scale testcases passed on Ubuntu 22.04 with UHD 770, but failed on Windows 11 with UHD 770.

Root cause

The testcase seed was derived from std::hash<std::string>, which is platform-dependent and may produce different values across different standard library implementations.

As a result, the same testcase name could map to different seed values on Ubuntu and Windows. That caused the affected testcases to generate different random inputs on different platforms, which led to inconsistent results.

How to fix it

Reduce the platform-dependent part in testcase-name-based seed generation:

• use a stable string-to-seed function based on FNV-1a
• replace the previous std::hash<std::string> std::string-based seed derivation in GPU test random data generation

This change reduces cross-platform differences caused by testcase-name-based seed generation and improves reproducibility of the affected tests.

The code and line that caused this issue

openvino/src/plugins/intel_gpu/tests/common/random_generator.hpp

Lines 28 to 35 in 1bbe690

	void set_seed(const std::string& seed) {
	auto seed_hash = std::hash<std::string>{}(seed);
	set_seed(static_cast<uint32_t>(seed_hash));
	}
	void set_seed(const uint32_t seed) {
	generator = std::default_random_engine{seed};
	}

Reproduction step and snapshot

./ov_gpu_unit_tests --gtest_filter='fully_connected_gpu_tests.compressed_int4_scale*'

Problematic graph

N/A

Checklist

• Is it a proper fix? (not a workaround)
• Did you include test case for this fix, if necessary?
• Did you review existing test that can be extended to cover this scenario? Which test did you review?

Tickets:

• CVS-185375

AI Assistance:

• AI assistance used: yes
• AI help to root cause and human check to confirm

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.

Comments suppressed due to low confidence (1)

src/plugins/intel_gpu/tests/common/random_generator.hpp:47

• [MEDIUM] PR title/description suggests stable random generation across platforms, but random_generator still relies on std::default_random_engine, whose algorithm is implementation-defined and can differ between libstdc++/libc++/MSVC. Even with a stable seed, random sequences may still vary across platforms. If full reproducibility is required, consider switching to an explicitly specified engine (e.g., std::mt19937 or std::minstd_rand0) or clarify in the PR description/title that only the seed derivation is stabilized.

    std::default_random_engine& get_generator() {
        return generator;
    }

    void set_seed(const std::string& seed) {
        set_seed(stable_string_seed(seed));
    }

    void set_seed(const uint32_t seed) {
        generator = std::default_random_engine{seed};

[yuanxion]

This PR can make the following testcases passed on Windows11 + UHD770 (iGPU driver: 32.0.101.7085):

fully_connected_gpu_tests.compressed_int4_scale_dynamic
fusings_gpu/activation_eltwise_activation_quantize_u8.per_channel/15
fusings_gpu/conv_fp32_eltwise_fusing_extend_ops.pattern01_simple_sub/3
fusings_gpu/conv_fp32_multi_eltwise_4_clamp.basic/4

[wilson-seok]

LGTM