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[ET-VK][test] Allow FP16 underflow in SwiGLU comparisons #23719

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[ET-VK][test] Allow FP16 underflow in SwiGLU comparisons #23719

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28 changes: 24 additions & 4 deletions backends/vulkan/test/vulkan_compute_api_test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4316,15 +4316,35 @@ TEST_P(VulkanSwiGLUTest, MatchesUnfusedAcrossResizes) {
const float y = float(up_data[broadcast ? i % width : i]);
const float reference = (x / (1.0f + std::exp(-x))) * y;
if (dtype == vkapi::kHalf) {
constexpr float fp16_min_normal = 0x1p-14f;
constexpr float unfused_rtol = 3e-3f;
ASSERT_NEAR(
float(actual[i]), reference, 1e-3f * std::abs(reference) + 1e-7f)
float(actual[i]),
reference,
1e-3f * std::abs(reference) + fp16_min_normal)
<< "element " << i;
// The unfused path rounds twice more, including subnormal sigmoid.
const float atol = 6e-8f * (std::abs(x * y) + std::abs(y) + 1.0f);
const float sigmoid_reference = 1.0f / (1.0f + std::exp(-x));
const auto is_subnormal = [](const float value) {
return value != 0.0f && std::abs(value) < fp16_min_normal;
};
const auto may_underflow = [](const float value) {
return value != 0.0f &&
std::abs(value) < fp16_min_normal * (1.0f + unfused_rtol);
};
float atol = 6e-8f * (std::abs(x * y) + std::abs(y) + 1.0f);
if (is_subnormal(x) || is_subnormal(y) ||
may_underflow(sigmoid_reference) ||
may_underflow(x * sigmoid_reference) ||
may_underflow(reference)) {
// Flushing the unfused path to zero can lose the full reference
// magnitude. Its relative tolerance then vanishes, so the extra
// 1e-3 covers the fused result's relative error.
atol += (1.0f + 1e-3f) * std::abs(reference);
}
ASSERT_NEAR(
float(actual[i]),
float(expected[i]),
3e-3f * std::abs(float(expected[i])) + atol)
unfused_rtol * std::abs(float(expected[i])) + atol)
<< "element " << i;
} else {
ASSERT_NEAR(
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