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shader: Move recursive SSA rewrite to the heap

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This commit is contained in:
ReinUsesLisp 2021-04-05 19:10:55 -03:00 committed by ameerj
parent 72daa2a039
commit 417fb5d385
1 changed files with 89 additions and 29 deletions
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118
src/shader_recompiler/ir_opt/ssa_rewrite_pass.cpp
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@ -119,6 +119,26 @@ IR::Opcode UndefOpcode(IndirectBranchVariable) noexcept {
return inst.Opcode() == IR::Opcode::Phi;
}
enum class Status {
Start,
SetValue,
PreparePhiArgument,
PushPhiArgument,
};
template <typename Type>
struct ReadState {
ReadState(IR::Block* block_) : block{block_} {}
ReadState() = default;
IR::Block* block{};
IR::Value result{};
IR::Inst* phi{};
IR::Block* const* pred_it{};
IR::Block* const* pred_end{};
Status pc{Status::Start};
};
class Pass {
public:
template <typename Type>
@ -127,12 +147,75 @@ public:
}
template <typename Type>
IR::Value ReadVariable(Type variable, IR::Block* block) {
const ValueMap& def{current_def[variable]};
if (const auto it{def.find(block)}; it != def.end()) {
return it->second;
}
return ReadVariableRecursive(variable, block);
IR::Value ReadVariable(Type variable, IR::Block* root_block) {
boost::container::small_vector<ReadState<Type>, 64> stack{
ReadState<Type>(nullptr),
ReadState<Type>(root_block),
};
const auto prepare_phi_operand{[&] {
if (stack.back().pred_it == stack.back().pred_end) {
IR::Inst* const phi{stack.back().phi};
IR::Block* const block{stack.back().block};
const IR::Value result{TryRemoveTrivialPhi(*phi, block, UndefOpcode(variable))};
stack.pop_back();
stack.back().result = result;
WriteVariable(variable, block, result);
} else {
IR::Block* const imm_pred{*stack.back().pred_it};
stack.back().pc = Status::PushPhiArgument;
stack.emplace_back(imm_pred);
}
}};
do {
IR::Block* const block{stack.back().block};
switch (stack.back().pc) {
case Status::Start: {
const ValueMap& def{current_def[variable]};
if (const auto it{def.find(block)}; it != def.end()) {
stack.back().result = it->second;
} else if (!sealed_blocks.contains(block)) {
// Incomplete CFG
IR::Inst* phi{&*block->PrependNewInst(block->begin(), IR::Opcode::Phi)};
incomplete_phis[block].insert_or_assign(variable, phi);
stack.back().result = IR::Value{&*phi};
} else if (const std::span imm_preds{block->ImmediatePredecessors()};
imm_preds.size() == 1) {
// Optimize the common case of one predecessor: no phi needed
stack.back().pc = Status::SetValue;
stack.emplace_back(imm_preds.front());
break;
} else {
// Break potential cycles with operandless phi
IR::Inst* const phi{&*block->PrependNewInst(block->begin(), IR::Opcode::Phi)};
WriteVariable(variable, block, IR::Value{phi});
stack.back().phi = phi;
stack.back().pred_it = imm_preds.data();
stack.back().pred_end = imm_preds.data() + imm_preds.size();
prepare_phi_operand();
break;
}
}
[[fallthrough]];
case Status::SetValue: {
const IR::Value result{stack.back().result};
WriteVariable(variable, block, result);
stack.pop_back();
stack.back().result = result;
break;
}
case Status::PushPhiArgument: {
IR::Inst* const phi{stack.back().phi};
phi->AddPhiOperand(*stack.back().pred_it, stack.back().result);
++stack.back().pred_it;
}
[[fallthrough]];
case Status::PreparePhiArgument:
prepare_phi_operand();
break;
}
} while (stack.size() > 1);
return stack.back().result;
}
void SealBlock(IR::Block* block) {
@ -146,29 +229,6 @@ public:
}
private:
template <typename Type>
IR::Value ReadVariableRecursive(Type variable, IR::Block* block) {
IR::Value val;
if (!sealed_blocks.contains(block)) {
// Incomplete CFG
IR::Inst* phi{&*block->PrependNewInst(block->begin(), IR::Opcode::Phi)};
incomplete_phis[block].insert_or_assign(variable, phi);
val = IR::Value{&*phi};
} else if (const std::span imm_preds{block->ImmediatePredecessors()};
imm_preds.size() == 1) {
// Optimize the common case of one predecessor: no phi needed
val = ReadVariable(variable, imm_preds.front());
} else {
// Break potential cycles with operandless phi
IR::Inst& phi_inst{*block->PrependNewInst(block->begin(), IR::Opcode::Phi)};
val = IR::Value{&phi_inst};
WriteVariable(variable, block, val);
val = AddPhiOperands(variable, phi_inst, block);
}
WriteVariable(variable, block, val);
return val;
}
template <typename Type>
IR::Value AddPhiOperands(Type variable, IR::Inst& phi, IR::Block* block) {
for (IR::Block* const imm_pred : block->ImmediatePredecessors()) {