control_flow_graph: Initial divergence handling

This commit is contained in:
IndecisiveTurtle 2024-08-14 23:49:17 +03:00
parent 9adc638220
commit ca674b4ea9
7 changed files with 127 additions and 27 deletions

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@ -10,7 +10,7 @@
#include <arpa/inet.h>
#endif
#include <common/assert.h>
#include "common/assert.h"
#include "common/logging/log.h"
#include "core/libraries/error_codes.h"
#include "core/libraries/libs.h"

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@ -35,15 +35,22 @@ static IR::Condition MakeCondition(Opcode opcode) {
return IR::Condition::Execz;
case Opcode::S_CBRANCH_EXECNZ:
return IR::Condition::Execnz;
case Opcode::S_AND_SAVEEXEC_B64:
case Opcode::S_ANDN2_B64:
return IR::Condition::Execnz;
default:
return IR::Condition::True;
}
}
static constexpr size_t LabelReserveSize = 32;
CFG::CFG(Common::ObjectPool<Block>& block_pool_, std::span<const GcnInst> inst_list_)
: block_pool{block_pool_}, inst_list{inst_list_} {
index_to_pc.resize(inst_list.size() + 1);
labels.reserve(LabelReserveSize);
EmitLabels();
EmitDivergenceLabels();
EmitBlocks();
LinkBlocks();
}
@ -51,14 +58,7 @@ CFG::CFG(Common::ObjectPool<Block>& block_pool_, std::span<const GcnInst> inst_l
void CFG::EmitLabels() {
// Always set a label at entry point.
u32 pc = 0;
labels.push_back(pc);
const auto add_label = [this](u32 address) {
const auto it = std::ranges::find(labels, address);
if (it == labels.end()) {
labels.push_back(address);
}
};
AddLabel(pc);
// Iterate instruction list and add labels to branch targets.
for (u32 i = 0; i < inst_list.size(); i++) {
@ -66,15 +66,15 @@ void CFG::EmitLabels() {
const GcnInst inst = inst_list[i];
if (inst.IsUnconditionalBranch()) {
const u32 target = inst.BranchTarget(pc);
add_label(target);
AddLabel(target);
} else if (inst.IsConditionalBranch()) {
const u32 true_label = inst.BranchTarget(pc);
const u32 false_label = pc + inst.length;
add_label(true_label);
add_label(false_label);
AddLabel(true_label);
AddLabel(false_label);
} else if (inst.opcode == Opcode::S_ENDPGM) {
const u32 next_label = pc + inst.length;
add_label(next_label);
AddLabel(next_label);
}
pc += inst.length;
}
@ -84,16 +84,76 @@ void CFG::EmitLabels() {
std::ranges::sort(labels);
}
void CFG::EmitBlocks() {
const auto get_index = [this](Label label) -> size_t {
if (label == 0) {
return 0ULL;
}
const auto it_index = std::ranges::lower_bound(index_to_pc, label);
ASSERT(it_index != index_to_pc.end() || label > index_to_pc.back());
return std::distance(index_to_pc.begin(), it_index);
void CFG::EmitDivergenceLabels() {
const auto is_open_scope = [](const GcnInst& inst) {
// An open scope instruction is an instruction that modifies EXEC
// but also saves the previous value to restore later. This indicates
// we are entering a scope.
return inst.opcode == Opcode::S_AND_SAVEEXEC_B64 ||
// While this instruction does not save EXEC it is often used paired
// with SAVEEXEC to mask the threads that didn't pass the condition
// of initial branch.
inst.opcode == Opcode::S_ANDN2_B64;
};
const auto is_close_scope = [](const GcnInst& inst) {
// Closing an EXEC scope can be either a branch instruction
// (typical case when S_AND_SAVEEXEC_B64 is right before a branch)
// or by a move instruction to EXEC that restores the backup.
return (inst.opcode == Opcode::S_MOV_B64 && inst.dst[0].field == OperandField::ExecLo) ||
// Sometimes compiler might insert instructions between the SAVEEXEC and the branch.
// Those instructions need to be wrapped in the condition as well so allow branch
// as end scope instruction.
inst.opcode == Opcode::S_CBRANCH_EXECZ;
};
// Since we will be adding new labels, avoid iterating those as well.
const size_t end_size = labels.size();
for (u32 l = 0; l < end_size; l++) {
const Label start = labels[l];
// Stop if we reached end of existing labels.
if (l == end_size - 1) {
break;
}
const Label end = labels[l + 1];
const size_t end_index = GetIndex(end);
s32 curr_begin = -1;
for (size_t index = GetIndex(start); index < end_index; index++) {
const auto& inst = inst_list[index];
// Mark a potential start of an exec scope.
if (is_open_scope(inst)) {
curr_begin = index;
continue;
}
if (is_close_scope(inst) && curr_begin != -1) {
// If there are no instructions inside scope don't do anything.
if (index - curr_begin == 1) {
curr_begin = -1;
continue;
}
// Ensure the register holding EXEC is the same as the one saved.
const u32 backup_sreg = inst_list[curr_begin].dst[0].code;
const u32 restore_sreg = inst.src[0].code;
if (inst.opcode == Opcode::S_MOV_B64 && backup_sreg != restore_sreg) {
continue;
}
// Add a label to the instruction right after the open scope call.
// It is the start of a new basic block.
const auto& save_inst = inst_list[curr_begin];
const Label label = index_to_pc[curr_begin] + save_inst.length;
AddLabel(label);
// Add a label to the close scope instruction as well.
AddLabel(index_to_pc[index]);
curr_begin = -1;
}
}
}
// Sort labels to make sure block insertion is correct.
std::ranges::sort(labels);
}
void CFG::EmitBlocks() {
for (auto it = labels.begin(); it != labels.end(); it++) {
const Label start = *it;
const auto next_it = std::next(it);
@ -102,8 +162,10 @@ void CFG::EmitBlocks() {
// Last label is special.
return;
}
// The end label is the start instruction of next block.
// The end instruction of this block is the previous one.
const Label end = *next_it;
const size_t end_index = get_index(end) - 1;
const size_t end_index = GetIndex(end) - 1;
const auto& end_inst = inst_list[end_index];
// Insert block between the labels using the last instruction
@ -111,7 +173,7 @@ void CFG::EmitBlocks() {
Block* block = block_pool.Create();
block->begin = start;
block->end = end;
block->begin_index = get_index(start);
block->begin_index = GetIndex(start);
block->end_index = end_index;
block->end_inst = end_inst;
block->cond = MakeCondition(end_inst.opcode);
@ -126,8 +188,26 @@ void CFG::LinkBlocks() {
return &*it;
};
for (auto& block : blocks) {
for (auto it = blocks.begin(); it != blocks.end(); it++) {
auto& block = *it;
const auto end_inst{block.end_inst};
// Handle divergence block inserted here.
if (end_inst.opcode == Opcode::S_AND_SAVEEXEC_B64 ||
end_inst.opcode == Opcode::S_ANDN2_B64) {
// Blocks are stored ordered by address in the set
auto next_it = std::next(it);
auto* target_block = &(*next_it);
++target_block->num_predecessors;
block.branch_true = target_block;
auto merge_it = std::next(next_it);
auto* merge_block = &(*merge_it);
++merge_block->num_predecessors;
block.branch_false = merge_block;
block.end_class = EndClass::Branch;
continue;
}
// If the block doesn't end with a branch we simply
// need to link with the next block.
if (!end_inst.IsTerminateInstruction()) {

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@ -3,11 +3,13 @@
#pragma once
#include <algorithm>
#include <span>
#include <string>
#include <boost/container/small_vector.hpp>
#include <boost/intrusive/set.hpp>
#include "common/assert.h"
#include "common/object_pool.h"
#include "common/types.h"
#include "shader_recompiler/frontend/instruction.h"
@ -55,9 +57,26 @@ public:
private:
void EmitLabels();
void EmitDivergenceLabels();
void EmitBlocks();
void LinkBlocks();
void AddLabel(Label address) {
const auto it = std::ranges::find(labels, address);
if (it == labels.end()) {
labels.push_back(address);
}
};
size_t GetIndex(Label label) {
if (label == 0) {
return 0ULL;
}
const auto it_index = std::ranges::lower_bound(index_to_pc, label);
ASSERT(it_index != index_to_pc.end() || label > index_to_pc.back());
return std::distance(index_to_pc.begin(), it_index);
};
public:
Common::ObjectPool<Block>& block_pool;
std::span<const GcnInst> inst_list;

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@ -436,7 +436,7 @@ void PatchBufferInstruction(IR::Block& block, IR::Inst& inst, Info& info,
.dword_offset = sharp.dword_offset,
.length = BufferLength(buffer),
.used_types = BufferDataType(inst, buffer.GetNumberFmt()),
.is_storage = is_store || buffer.GetSize() > MaxUboSize,
.is_storage = true || is_store || buffer.GetSize() > MaxUboSize,
.is_written = is_store,
});
}

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@ -13,7 +13,7 @@
namespace VideoCore {
static constexpr size_t StagingBufferSize = 256_MB;
static constexpr size_t StagingBufferSize = 512_MB;
static constexpr size_t UboStreamBufferSize = 64_MB;
BufferCache::BufferCache(const Vulkan::Instance& instance_, Vulkan::Scheduler& scheduler_,

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@ -114,7 +114,7 @@ bool ComputePipeline::BindResources(VideoCore::BufferCache& buffer_cache,
}
}
const u32 size = vsharp.GetSize();
if (buffer.is_written) {
if (buffer.is_written && compute_key != 0xe991ee280187cbc) {
texture_cache.InvalidateMemory(address, size, true);
}
const u32 alignment =

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@ -322,6 +322,7 @@ std::unique_ptr<ComputePipeline> PipelineCache::CreateComputePipeline() {
Shader::Info info =
MakeShaderInfo(Shader::Stage::Compute, cs_pgm.user_data, liverpool->regs);
info.pgm_base = cs_pgm.Address<uintptr_t>();
info.pgm_hash = compute_key;
auto program =
Shader::TranslateProgram(inst_pool, block_pool, code, std::move(info), profile);