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Add structs to eliminate dead input components
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Will eliminate all trailing members of input struct that are not
referenced.
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@greg-lunarg
greg-lunarg committed Aug 12, 2022
1 parent 3a8a961 commit 917b601
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Showing 3 changed files with 129 additions and 20 deletions.
79 changes: 60 additions & 19 deletions source/opt/eliminate_dead_input_components_pass.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -56,21 +56,31 @@ Pass::Status EliminateDeadInputComponentsPass::Process() {
continue;
}
const analysis::Array* arr_type = ptr_type->pointee_type()->AsArray();
if (arr_type == nullptr) {
if (arr_type != nullptr) {
unsigned arr_len_id = arr_type->LengthId();
Instruction* arr_len_inst = def_use_mgr->GetDef(arr_len_id);
if (arr_len_inst->opcode() != SpvOpConstant) {
continue;
}
// SPIR-V requires array size is >= 1, so this works for signed or
// unsigned size
unsigned original_max =
arr_len_inst->GetSingleWordInOperand(kConstantValueInIdx) - 1;
unsigned max_idx = FindMaxIndex(var, original_max);
if (max_idx != original_max) {
ChangeArrayLength(var, max_idx + 1);
modified = true;
}
continue;
}
unsigned arr_len_id = arr_type->LengthId();
Instruction* arr_len_inst = def_use_mgr->GetDef(arr_len_id);
if (arr_len_inst->opcode() != SpvOpConstant) {
const analysis::Struct* struct_type = ptr_type->pointee_type()->AsStruct();
if (struct_type == nullptr)
continue;
}
// SPIR-V requires array size is >= 1, so this works for signed or
// unsigned size
unsigned original_max =
arr_len_inst->GetSingleWordInOperand(kConstantValueInIdx) - 1;
const auto elt_types = struct_type->element_types();
unsigned original_max = static_cast<unsigned>(elt_types.size()) - 1;
unsigned max_idx = FindMaxIndex(var, original_max);
if (max_idx != original_max) {
ChangeArrayLength(var, max_idx + 1);
ChangeStructLength(var, max_idx + 1);
modified = true;
}
}
Expand Down Expand Up @@ -116,12 +126,12 @@ unsigned EliminateDeadInputComponentsPass::FindMaxIndex(Instruction& var,
return seen_non_const_ac ? original_max : max;
}

void EliminateDeadInputComponentsPass::ChangeArrayLength(Instruction& arr,
void EliminateDeadInputComponentsPass::ChangeArrayLength(Instruction& arr_var,
unsigned length) {
analysis::TypeManager* type_mgr = context()->get_type_mgr();
analysis::ConstantManager* const_mgr = context()->get_constant_mgr();
analysis::DefUseManager* def_use_mgr = context()->get_def_use_mgr();
analysis::Pointer* ptr_type = type_mgr->GetType(arr.type_id())->AsPointer();
analysis::Pointer* ptr_type = type_mgr->GetType(arr_var.type_id())->AsPointer();
const analysis::Array* arr_ty = ptr_type->pointee_type()->AsArray();
assert(arr_ty && "expecting array type");
uint32_t length_id = const_mgr->GetUIntConst(length);
Expand All @@ -131,15 +141,46 @@ void EliminateDeadInputComponentsPass::ChangeArrayLength(Instruction& arr,
analysis::Pointer new_ptr_ty(reg_new_arr_ty, SpvStorageClassInput);
analysis::Type* reg_new_ptr_ty = type_mgr->GetRegisteredType(&new_ptr_ty);
uint32_t new_ptr_ty_id = type_mgr->GetTypeInstruction(reg_new_ptr_ty);
arr.SetResultType(new_ptr_ty_id);
def_use_mgr->AnalyzeInstUse(&arr);
// Move array OpVariable instruction after its new type to preserve order
USE_ASSERT(arr.GetSingleWordInOperand(kVariableStorageClassInIdx) !=
arr_var.SetResultType(new_ptr_ty_id);
def_use_mgr->AnalyzeInstUse(&arr_var);
// Move arr_var after its new type to preserve order
USE_ASSERT(arr_var.GetSingleWordInOperand(kVariableStorageClassInIdx) !=
SpvStorageClassFunction &&
"cannot move Function variable");
"cannot move Function variable");
Instruction* new_ptr_ty_inst = def_use_mgr->GetDef(new_ptr_ty_id);
arr_var.RemoveFromList();
arr_var.InsertAfter(new_ptr_ty_inst);
}

void EliminateDeadInputComponentsPass::ChangeStructLength(Instruction& struct_var,
unsigned length) {
analysis::TypeManager* type_mgr = context()->get_type_mgr();
analysis::Pointer* ptr_type = type_mgr->GetType(struct_var.type_id())->AsPointer();
const analysis::Struct* struct_ty = ptr_type->pointee_type()->AsStruct();
assert(struct_ty && "expecting struct type");
const auto orig_elt_types = struct_ty->element_types();
std::vector<const analysis::Type*> new_elt_types;
for (unsigned u = 0; u < length; ++u)
new_elt_types.push_back(orig_elt_types[u]);
analysis::Struct new_struct_ty(new_elt_types);
analysis::Type* reg_new_struct_ty = type_mgr->GetRegisteredType(&new_struct_ty);
uint32_t new_struct_ty_id = type_mgr->GetTypeInstruction(reg_new_struct_ty);
uint32_t old_struct_ty_id = type_mgr->GetTypeInstruction(struct_ty);
analysis::DecorationManager* deco_mgr = context()->get_decoration_mgr();
deco_mgr->CloneDecorations(old_struct_ty_id, new_struct_ty_id);
analysis::Pointer new_ptr_ty(reg_new_struct_ty, SpvStorageClassInput);
analysis::Type* reg_new_ptr_ty = type_mgr->GetRegisteredType(&new_ptr_ty);
uint32_t new_ptr_ty_id = type_mgr->GetTypeInstruction(reg_new_ptr_ty);
struct_var.SetResultType(new_ptr_ty_id);
analysis::DefUseManager* def_use_mgr = context()->get_def_use_mgr();
def_use_mgr->AnalyzeInstUse(&struct_var);
// Move struct_var after its new type to preserve order
USE_ASSERT(struct_var.GetSingleWordInOperand(kVariableStorageClassInIdx) !=
SpvStorageClassFunction &&
"cannot move Function variable");
Instruction* new_ptr_ty_inst = def_use_mgr->GetDef(new_ptr_ty_id);
arr.RemoveFromList();
arr.InsertAfter(new_ptr_ty_inst);
struct_var.RemoveFromList();
struct_var.InsertAfter(new_ptr_ty_inst);
}

} // namespace opt
Expand Down
6 changes: 5 additions & 1 deletion source/opt/eliminate_dead_input_components_pass.h
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Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,8 @@ class EliminateDeadInputComponentsPass : public Pass {
public:
explicit EliminateDeadInputComponentsPass() {}

const char* name() const override { return "reduce-load-size"; }
const char* name() const override { return "eliminate-dead-input-components"; }

Status Process() override;

// Return the mask of preserved Analyses.
Expand All @@ -51,6 +52,9 @@ class EliminateDeadInputComponentsPass : public Pass {

// Change the length of the array |inst| to |length|
void ChangeArrayLength(Instruction& inst, unsigned length);

// Change the length of the struct |struct_var| to |length|
void ChangeStructLength(Instruction& struct_var, unsigned length);
};

} // namespace opt
Expand Down
64 changes: 64 additions & 0 deletions test/opt/eliminate_dead_input_components_test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -399,6 +399,70 @@ TEST_F(ElimDeadInputComponentsTest, NoElimNonIndexedAccessChain) {
SinglePassRunAndMatch<EliminateDeadInputComponentsPass>(text, true);
}

TEST_F(ElimDeadInputComponentsTest, ElimStructMember) {
// Should eliminate uv
//
// #version 450
//
// in Vertex {
// vec4 Cd;
// vec2 uv;
// } iVert;
//
// out vec4 fragColor;
//
// void main()
// {
// vec4 color = vec4(iVert.Cd);
// fragColor = color;
// }
const std::string text = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %main "main" %iVert %fragColor
OpExecutionMode %main OriginUpperLeft
OpSource GLSL 450
OpName %main "main"
OpName %Vertex "Vertex"
OpMemberName %Vertex 0 "Cd"
OpMemberName %Vertex 1 "uv"
OpName %iVert "iVert"
OpName %fragColor "fragColor"
OpDecorate %Vertex Block
OpDecorate %iVert Location 0
OpDecorate %fragColor Location 0
%void = OpTypeVoid
%3 = OpTypeFunction %void
%float = OpTypeFloat 32
%v4float = OpTypeVector %float 4
%v2float = OpTypeVector %float 2
%Vertex = OpTypeStruct %v4float %v2float
; CHECK: %Vertex = OpTypeStruct %v4float %v2float
; CHECK: [[sty:%\w+]] = OpTypeStruct %v4float
%_ptr_Input_Vertex = OpTypePointer Input %Vertex
; CHECK: [[pty:%\w+]] = OpTypePointer Input [[sty]]
%iVert = OpVariable %_ptr_Input_Vertex Input
; CHECK: %iVert = OpVariable [[pty]] Input
%int = OpTypeInt 32 1
%int_0 = OpConstant %int 0
%_ptr_Input_v4float = OpTypePointer Input %v4float
%_ptr_Output_v4float = OpTypePointer Output %v4float
%fragColor = OpVariable %_ptr_Output_v4float Output
%main = OpFunction %void None %3
%5 = OpLabel
%17 = OpAccessChain %_ptr_Input_v4float %iVert %int_0
%18 = OpLoad %v4float %17
OpStore %fragColor %18
OpReturn
OpFunctionEnd
)";

SetTargetEnv(SPV_ENV_VULKAN_1_3);
SetAssembleOptions(SPV_TEXT_TO_BINARY_OPTION_PRESERVE_NUMERIC_IDS);
SinglePassRunAndMatch<EliminateDeadInputComponentsPass>(text, true, false, false);
}

} // namespace
} // namespace opt
} // namespace spvtools

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