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hrx: the alias fallback of the alternate-value lookup compares the scale (a miss in #298) #312

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Merged
bong-water-water-bong merged 1 commit into from
Nov 11, 2026
Merged

hrx: the alias fallback of the alternate-value lookup compares the scale (a miss in #298) #312

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3 changes: 2 additions & 1 deletion ggml/src/ggml-hrx/dispatch/command-plan.h
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Original file line number Diff line number Diff line change
Expand Up @@ -103,7 +103,8 @@ inline const CommandPlanAlternateValue * find_alternate_value(const Graph &
}

for (const CommandPlanAlternateValue & alternate : plan.metadata.alternate_values()) {
if (alternate.type != type || alternate.byte_count != byte_count) {
// the scale is part of what a reader asks for: a copy stored at another scale is a different value (engine #2159)
if (alternate.type != type || alternate.byte_count != byte_count || alternate.scale_log2 != scale_log2) {
continue;
}
const Value * alternate_value = graph.values().find(alternate.graph_value);
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19 changes: 19 additions & 0 deletions tests/hrx-backend-test.cpp
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Expand Up @@ -8469,6 +8469,25 @@ static void run_alias_value_import_checks() {
REQUIRE(aliased_binding->offset == 64);
REQUIRE(aliased_binding->length == 8 * sizeof(float));

// engine #2159: an alternate stored at a scale is found only by a reader that asks for that scale, also through an
// alias. Value 1 aliases value 0; value 0 has an f16 copy stored at 2^-6.
{
ggml::hrx::Graph alias_graph;
alias_graph.values() = value_map;
ggml::hrx::CommandPlan alias_plan;
ggml::hrx::Status alias_status;
REQUIRE(alias_plan.metadata.append_alternate_value(
{ ggml::hrx::ValueId(0), ggml::hrx::ValueId(7), GGML_TYPE_F16, 16, "test.scaled_f16", 6 }, alias_status));
const auto * scaled =
ggml::hrx::find_alternate_value(alias_graph, alias_plan, ggml::hrx::ValueId(1), GGML_TYPE_F16, 16, 6);
REQUIRE(scaled != nullptr);
REQUIRE(scaled->scale_log2 == 6);
REQUIRE(ggml::hrx::find_alternate_value(alias_graph, alias_plan, ggml::hrx::ValueId(1), GGML_TYPE_F16, 16) ==
nullptr);
REQUIRE(ggml::hrx::find_alternate_value(alias_graph, alias_plan, ggml::hrx::ValueId(0), GGML_TYPE_F16, 16) ==
nullptr);
}

ggml_free(ctx);
}

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