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Add type description and default value to specialization constants #330

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Sep 21, 2025
Merged

Add type description and default value to specialization constants #330

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92 changes: 65 additions & 27 deletions spirv_reflect.c
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Original file line number Diff line number Diff line change
Expand Up @@ -225,6 +225,7 @@ typedef struct SpvReflectPrvParser {
uint32_t type_count;
uint32_t descriptor_count;
uint32_t push_constant_count;
uint32_t spec_constant_count;

SpvReflectTypeDescription* physical_pointer_check[MAX_RECURSIVE_PHYSICAL_POINTER_CHECK];
uint32_t physical_pointer_count;
Expand Down Expand Up @@ -1420,7 +1421,7 @@ static bool UserTypeMatches(const char* user_type, const char* pattern) {
return false;
}

static SpvReflectResult ParseDecorations(SpvReflectPrvParser* p_parser, SpvReflectShaderModule* p_module) {
static SpvReflectResult ParseDecorations(SpvReflectPrvParser* p_parser) {
uint32_t spec_constant_count = 0;
for (uint32_t i = 0; i < p_parser->node_count; ++i) {
SpvReflectPrvNode* p_node = &(p_parser->nodes[i]);
Expand Down Expand Up @@ -1722,31 +1723,7 @@ static SpvReflectResult ParseDecorations(SpvReflectPrvParser* p_parser, SpvRefle
}
}

if (spec_constant_count > 0) {
p_module->spec_constants = (SpvReflectSpecializationConstant*)calloc(spec_constant_count, sizeof(*p_module->spec_constants));
if (IsNull(p_module->spec_constants)) {
return SPV_REFLECT_RESULT_ERROR_ALLOC_FAILED;
}
}
for (uint32_t i = 0; i < p_parser->node_count; ++i) {
SpvReflectPrvNode* p_node = &(p_parser->nodes[i]);
if (p_node->op == SpvOpDecorate) {
uint32_t decoration = (uint32_t)INVALID_VALUE;
CHECKED_READU32(p_parser, p_node->word_offset + 2, decoration);
if (decoration == SpvDecorationSpecId) {
const uint32_t count = p_module->spec_constant_count;
CHECKED_READU32(p_parser, p_node->word_offset + 1, p_module->spec_constants[count].spirv_id);
CHECKED_READU32(p_parser, p_node->word_offset + 3, p_module->spec_constants[count].constant_id);
// If being used for a OpSpecConstantComposite (ex. LocalSizeId), there won't be a name
SpvReflectPrvNode* target_node = FindNode(p_parser, p_module->spec_constants[count].spirv_id);
if (IsNotNull(target_node)) {
p_module->spec_constants[count].name = target_node->name;
}
p_module->spec_constant_count++;
}
}
}

p_parser->spec_constant_count = spec_constant_count;
return SPV_REFLECT_RESULT_SUCCESS;
}

Expand Down Expand Up @@ -4055,6 +4032,63 @@ static SpvReflectResult ParsePushConstantBlocks(SpvReflectPrvParser* p_parser, S
return SPV_REFLECT_RESULT_SUCCESS;
}

static SpvReflectResult ParseSpecConstants(SpvReflectPrvParser* p_parser, SpvReflectShaderModule* p_module) {
if (p_parser->spec_constant_count > 0) {
p_module->spec_constants = (SpvReflectSpecializationConstant*)calloc(p_parser->spec_constant_count, sizeof(*p_module->spec_constants));
if (IsNull(p_module->spec_constants)) {
return SPV_REFLECT_RESULT_ERROR_ALLOC_FAILED;
}
} else {
return SPV_REFLECT_RESULT_SUCCESS;
}
for (uint32_t i = 0; i < p_parser->node_count; ++i) {
SpvReflectPrvNode* p_node = &(p_parser->nodes[i]);
if (p_node->op == SpvOpDecorate) {
uint32_t decoration = (uint32_t)INVALID_VALUE;
CHECKED_READU32(p_parser, p_node->word_offset + 2, decoration);
if (decoration == SpvDecorationSpecId) {
SpvReflectSpecializationConstant* p_spec_constant = &(p_module->spec_constants[p_module->spec_constant_count]);
CHECKED_READU32(p_parser, p_node->word_offset + 1, p_spec_constant->spirv_id);
CHECKED_READU32(p_parser, p_node->word_offset + 3, p_spec_constant->constant_id);
SpvReflectPrvNode* target_node = FindNode(p_parser, p_spec_constant->spirv_id);
if (IsNotNull(target_node)) {
// If being used for a OpSpecConstantComposite (ex. LocalSizeId), there won't be a name
p_spec_constant->name = target_node->name;

// During external specialization, Boolean values are true if non-zero and false if zero.
static uint32_t true_value = 1;
static uint32_t false_value = 0;
switch (target_node->op) {
default:
// Unexpected, since Spec states:
// (SpecId) Apply only to a scalar specialization constant
SPV_REFLECT_ASSERT(false);
return SPV_REFLECT_RESULT_ERROR_SPIRV_INVALID_INSTRUCTION;
case SpvOpSpecConstantTrue:
p_spec_constant->default_value_size = sizeof(uint32_t);
p_spec_constant->default_value = &true_value;
break;
case SpvOpSpecConstantFalse:
p_spec_constant->default_value_size = sizeof(uint32_t);
p_spec_constant->default_value = &false_value;
break;
case SpvOpSpecConstant:
p_spec_constant->default_value_size = (target_node->word_count - 3) * sizeof(uint32_t);
p_spec_constant->default_value = p_parser->spirv_code + target_node->word_offset + 3;
break;
}
p_spec_constant->type_description = FindType(p_module, target_node->result_type_id);
} else {
// Decoration target not found
return SPV_REFLECT_RESULT_ERROR_SPIRV_INVALID_ID_REFERENCE;
}
p_module->spec_constant_count++;
}
}
}
return SPV_REFLECT_RESULT_SUCCESS;
}

static int SortCompareDescriptorSet(const void* a, const void* b) {
const SpvReflectDescriptorSet* p_elem_a = (const SpvReflectDescriptorSet*)a;
const SpvReflectDescriptorSet* p_elem_b = (const SpvReflectDescriptorSet*)b;
Expand Down Expand Up @@ -4307,7 +4341,7 @@ static SpvReflectResult CreateShaderModule(uint32_t flags, size_t size, const vo
SPV_REFLECT_ASSERT(result == SPV_REFLECT_RESULT_SUCCESS);
}
if (result == SPV_REFLECT_RESULT_SUCCESS) {
result = ParseDecorations(&parser, p_module);
result = ParseDecorations(&parser);
SPV_REFLECT_ASSERT(result == SPV_REFLECT_RESULT_SUCCESS);
}

Expand Down Expand Up @@ -4348,6 +4382,10 @@ static SpvReflectResult CreateShaderModule(uint32_t flags, size_t size, const vo
result = ParsePushConstantBlocks(&parser, p_module);
SPV_REFLECT_ASSERT(result == SPV_REFLECT_RESULT_SUCCESS);
}
if (result == SPV_REFLECT_RESULT_SUCCESS) {
result = ParseSpecConstants(&parser, p_module);
SPV_REFLECT_ASSERT(result == SPV_REFLECT_RESULT_SUCCESS);
}
if (result == SPV_REFLECT_RESULT_SUCCESS) {
result = ParseEntryPoints(&parser, p_module);
SPV_REFLECT_ASSERT(result == SPV_REFLECT_RESULT_SUCCESS);
Expand Down
15 changes: 15 additions & 0 deletions spirv_reflect.h
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Original file line number Diff line number Diff line change
Expand Up @@ -580,6 +580,21 @@ typedef struct SpvReflectSpecializationConstant {
uint32_t spirv_id;
uint32_t constant_id;
const char* name;
SpvReflectTypeDescription* type_description;

// Size of the default value in bytes (always a multiple of 4).
// Will be 4 for 8/16/32-bit constants and 8 for 64-bit constants.
uint32_t default_value_size;

// Pointer to the raw default value data.
// The interpretation of this data depends on type_description->op:
// - SpvOpSpecConstantTrue: size = 4, data = uint32_t(1)
// - SpvOpSpecConstantFalse: size = 4, data = uint32_t(0)
// - SpvOpSpecConstant: data contains the bit pattern of the default value
// * The type will be a scalar integer or float.
// * Types 32 bits wide or smaller take one word.
// * Larger types take multiple words, with low-order words appearing first.
void* default_value;
} SpvReflectSpecializationConstant;

/*! @struct SpvReflectShaderModule
Expand Down
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