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// Copyright 2024 The Dawn & Tint Authors
//
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#include "src/tint/lang/hlsl/writer/raise/promote_initializers.h"
#include "src/tint/lang/core/ir/builder.h"
#include "src/tint/lang/core/ir/validator.h"
using namespace tint::core::fluent_types; // NOLINT
using namespace tint::core::number_suffixes; // NOLINT
namespace tint::hlsl::writer::raise {
namespace {
/// PIMPL state for the transform.
struct State {
/// The IR module.
core::ir::Module& ir;
/// The IR builder.
core::ir::Builder b{ir};
/// The type manager.
core::type::Manager& ty{ir.Types()};
/// Process the module.
void Process() {
for (auto* block : ir.blocks.Objects()) {
// In the root block, all structs need to be split out, no nested structs
bool is_root_block = block == ir.root_block;
Process(block, is_root_block);
}
}
struct ValueInfo {
core::ir::Instruction* inst;
size_t index;
core::ir::Value* val;
};
void Process(core::ir::Block* block, bool is_root_block) {
Vector<ValueInfo, 4> worklist;
for (auto* inst : *block) {
if (inst->Is<core::ir::Let>()) {
continue;
}
if (inst->Is<core::ir::Var>()) {
// In the root block we need to split struct and array vars out to turn them into
// `static const` variables.
if (!is_root_block) {
continue;
}
}
// Check each operand of the instruction to determine if it's a struct or array.
auto operands = inst->Operands();
for (size_t i = 0; i < operands.Length(); ++i) {
auto* operand = operands[i];
if (!operand || !operand->Type() ||
!operand->Type()->IsAnyOf<core::type::Struct, core::type::Array>()) {
continue;
}
if (operand->IsAnyOf<core::ir::InstructionResult, core::ir::Constant>()) {
worklist.Push({inst, i, operand});
}
}
}
Vector<core::ir::Construct*, 4> const_worklist;
for (auto& item : worklist) {
if (auto* res = As<core::ir::InstructionResult>(item.val)) {
PutInLet(item.inst, item.index, res);
} else if (auto* val = As<core::ir::Constant>(item.val)) {
auto* let = PutInLet(item.inst, item.index, val);
auto ret = HoistModuleScopeLetToConstruct(is_root_block, item.inst, let, val);
if (ret.has_value()) {
const_worklist.Insert(0, *ret);
}
}
}
// If any element in the constant is `struct` or `array` it needs to be pulled out
// into it's own `let`. That also means the `constant` value needs to turn into a
// `Construct`.
while (!const_worklist.IsEmpty()) {
auto item = const_worklist.Pop();
tint::Slice<core::ir::Value* const> args = item->Args();
for (size_t i = 0; i < args.Length(); ++i) {
auto ret = ProcessConstant(args[i], item, i);
if (ret.has_value()) {
const_worklist.Insert(0, *ret);
}
}
}
}
// Process a constant operand and replace if it's a struct initializer
std::optional<core::ir::Construct*> ProcessConstant(core::ir::Value* operand,
core::ir::Construct* parent,
size_t idx) {
auto* const_val = operand->As<core::ir::Constant>();
TINT_ASSERT(const_val);
if (!const_val->Type()->Is<core::type::Struct>()) {
return std::nullopt;
}
auto* let = b.Let(const_val->Type());
Vector<core::ir::Value*, 4> new_args = GatherArgs(const_val);
auto* construct = b.Construct(const_val->Type(), new_args);
let->SetValue(construct->Result(0));
// Put the `let` in before the `construct` value that we're based off of
let->InsertBefore(parent);
// Put the new `construct` in before the `let`.
construct->InsertBefore(let);
// Replace the argument in the originating `construct` with the new `let`.
parent->SetArg(idx, let->Result(0));
return {construct};
}
// Determine if this is a root block var which contains a struct initializer and, if
// so, setup the instruction for the needed replacement.
std::optional<core::ir::Construct*> HoistModuleScopeLetToConstruct(bool is_root_block,
core::ir::Instruction* inst,
core::ir::Let* let,
core::ir::Constant* val) {
// Only care about root-block variables
if (!is_root_block || !inst->Is<core::ir::Var>()) {
return std::nullopt;
}
// Only care about struct constants
if (!val->Type()->Is<core::type::Struct>()) {
return std::nullopt;
}
// This may not actually need to be a `construct` but pull it out now to
// make further changes, if they're necessary, easier.
Vector<core::ir::Value*, 4> args = GatherArgs(val);
// Turn the `constant` into a `construct` call and replace the value of the `let` that
// was created.
auto* construct = b.Construct(val->Type(), args);
let->SetValue(construct->Result(0));
construct->InsertBefore(let);
return {construct};
}
// Gather the arguments to the constant and create a `ir::Value` array from them which can
// be used in a `construct`.
Vector<core::ir::Value*, 4> GatherArgs(core::ir::Constant* val) {
Vector<core::ir::Value*, 4> args;
if (auto* const_val = val->Value()->As<core::constant::Composite>()) {
for (auto v : const_val->elements) {
args.Push(b.Constant(v));
}
} else if (auto* splat_val = val->Value()->As<core::constant::Splat>()) {
for (uint32_t i = 0; i < splat_val->NumElements(); i++) {
args.Push(b.Constant(splat_val->el));
}
}
return args;
}
core::ir::Let* MakeLet(core::ir::Value* value) {
auto* let = b.Let(value->Type());
let->SetValue(value);
auto name = b.ir.NameOf(value);
if (name.IsValid()) {
b.ir.SetName(let->Result(0), name);
b.ir.ClearName(value);
}
return let;
}
core::ir::Let* PutInLet(core::ir::Instruction* inst, size_t index, core::ir::Value* value) {
auto* let = MakeLet(value);
let->InsertBefore(inst);
inst->SetOperand(index, let->Result(0));
return let;
}
};
} // namespace
Result<SuccessType> PromoteInitializers(core::ir::Module& ir) {
auto result = ValidateAndDumpIfNeeded(ir, "PromoteInitializers transform",
core::ir::Capabilities{
core::ir::Capability::kAllowVectorElementPointer,
});
if (result != Success) {
return result;
}
State{ir}.Process();
return Success;
}
} // namespace tint::hlsl::writer::raise