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/*!
Backend for [DOT][dot] (Graphviz).
This backend writes a graph in the DOT language, for the ease
of IR inspection and debugging.
*/
use crate::{
arena::Handle,
valid::{FunctionInfo, ModuleInfo},
};
use std::{
borrow::Cow,
fmt::{Error as FmtError, Write as _},
};
/// Configuration options for the dot backend
#[derive(Clone, Default)]
pub struct Options {
/// Only emit function bodies
pub cfg_only: bool,
}
/// Identifier used to address a graph node
type NodeId = usize;
/// Stores the target nodes for control flow statements
#[derive(Default, Clone, Copy)]
struct Targets {
/// The node, if some, where continue operations will land
continue_target: Option<usize>,
/// The node, if some, where break operations will land
break_target: Option<usize>,
}
/// Stores information about the graph of statements
#[derive(Default)]
struct StatementGraph {
/// List of node names
nodes: Vec<&'static str>,
/// List of edges of the control flow, the items are defined as
/// (from, to, label)
flow: Vec<(NodeId, NodeId, &'static str)>,
/// List of implicit edges of the control flow, used for jump
/// operations such as continue or break, the items are defined as
/// (from, to, label, color_id)
jumps: Vec<(NodeId, NodeId, &'static str, usize)>,
/// List of dependency relationships between a statement node and
/// expressions
dependencies: Vec<(NodeId, Handle<crate::Expression>, &'static str)>,
/// List of expression emitted by statement node
emits: Vec<(NodeId, Handle<crate::Expression>)>,
/// List of function call by statement node
calls: Vec<(NodeId, Handle<crate::Function>)>,
}
impl StatementGraph {
/// Adds a new block to the statement graph, returning the first and last node, respectively
fn add(&mut self, block: &[crate::Statement], targets: Targets) -> (NodeId, NodeId) {
use crate::Statement as S;
// The first node of the block isn't a statement but a virtual node
let root = self.nodes.len();
self.nodes.push(if root == 0 { "Root" } else { "Node" });
// Track the last placed node, this will be returned to the caller and
// will also be used to generate the control flow edges
let mut last_node = root;
for statement in block {
// Reserve a new node for the current statement and link it to the
// node of the previous statement
let id = self.nodes.len();
self.flow.push((last_node, id, ""));
self.nodes.push(""); // reserve space
// Track the node identifier for the merge node, the merge node is
// the last node of a statement, normally this is the node itself,
// but for control flow statements such as `if`s and `switch`s this
// is a virtual node where all branches merge back.
let mut merge_id = id;
self.nodes[id] = match *statement {
S::Emit(ref range) => {
for handle in range.clone() {
self.emits.push((id, handle));
}
"Emit"
}
S::Kill => "Kill", //TODO: link to the beginning
S::Break => {
// Try to link to the break target, otherwise produce
// a broken connection
if let Some(target) = targets.break_target {
self.jumps.push((id, target, "Break", 5))
} else {
self.jumps.push((id, root, "Broken", 7))
}
"Break"
}
S::Continue => {
// Try to link to the continue target, otherwise produce
// a broken connection
if let Some(target) = targets.continue_target {
self.jumps.push((id, target, "Continue", 5))
} else {
self.jumps.push((id, root, "Broken", 7))
}
"Continue"
}
S::Barrier(_flags) => "Barrier",
S::Block(ref b) => {
let (other, last) = self.add(b, targets);
self.flow.push((id, other, ""));
// All following nodes should connect to the end of the block
// statement so change the merge id to it.
merge_id = last;
"Block"
}
S::If {
condition,
ref accept,
ref reject,
} => {
self.dependencies.push((id, condition, "condition"));
let (accept_id, accept_last) = self.add(accept, targets);
self.flow.push((id, accept_id, "accept"));
let (reject_id, reject_last) = self.add(reject, targets);
self.flow.push((id, reject_id, "reject"));
// Create a merge node, link the branches to it and set it
// as the merge node to make the next statement node link to it
merge_id = self.nodes.len();
self.nodes.push("Merge");
self.flow.push((accept_last, merge_id, ""));
self.flow.push((reject_last, merge_id, ""));
"If"
}
S::Switch {
selector,
ref cases,
} => {
self.dependencies.push((id, selector, "selector"));
// Create a merge node and set it as the merge node to make
// the next statement node link to it
merge_id = self.nodes.len();
self.nodes.push("Merge");
// Create a new targets structure and set the break target
// to the merge node
let mut targets = targets;
targets.break_target = Some(merge_id);
for case in cases {
let (case_id, case_last) = self.add(&case.body, targets);
let label = match case.value {
crate::SwitchValue::Default => "default",
_ => "case",
};
self.flow.push((id, case_id, label));
// Link the last node of the branch to the merge node
self.flow.push((case_last, merge_id, ""));
}
"Switch"
}
S::Loop {
ref body,
ref continuing,
break_if,
} => {
// Create a new targets structure and set the break target
// to the merge node, this must happen before generating the
// continuing block since it can break.
let mut targets = targets;
targets.break_target = Some(id);
let (continuing_id, continuing_last) = self.add(continuing, targets);
// Set the the continue target to the beginning
// of the newly generated continuing block
targets.continue_target = Some(continuing_id);
let (body_id, body_last) = self.add(body, targets);
self.flow.push((id, body_id, "body"));
// Link the last node of the body to the continuing block
self.flow.push((body_last, continuing_id, "continuing"));
// Link the last node of the continuing block back to the
// beginning of the loop body
self.flow.push((continuing_last, body_id, "continuing"));
if let Some(expr) = break_if {
self.dependencies.push((continuing_id, expr, "break if"));
}
"Loop"
}
S::Return { value } => {
if let Some(expr) = value {
self.dependencies.push((id, expr, "value"));
}
"Return"
}
S::Store { pointer, value } => {
self.dependencies.push((id, value, "value"));
self.emits.push((id, pointer));
"Store"
}
S::ImageStore {
image,
coordinate,
array_index,
value,
} => {
self.dependencies.push((id, image, "image"));
self.dependencies.push((id, coordinate, "coordinate"));
if let Some(expr) = array_index {
self.dependencies.push((id, expr, "array_index"));
}
self.dependencies.push((id, value, "value"));
"ImageStore"
}
S::Call {
function,
ref arguments,
result,
} => {
for &arg in arguments {
self.dependencies.push((id, arg, "arg"));
}
if let Some(expr) = result {
self.emits.push((id, expr));
}
self.calls.push((id, function));
"Call"
}
S::Atomic {
pointer,
ref fun,
value,
result,
} => {
if let Some(result) = result {
self.emits.push((id, result));
}
self.dependencies.push((id, pointer, "pointer"));
self.dependencies.push((id, value, "value"));
if let crate::AtomicFunction::Exchange { compare: Some(cmp) } = *fun {
self.dependencies.push((id, cmp, "cmp"));
}
"Atomic"
}
S::WorkGroupUniformLoad { pointer, result } => {
self.emits.push((id, result));
self.dependencies.push((id, pointer, "pointer"));
"WorkGroupUniformLoad"
}
S::RayQuery { query, ref fun } => {
self.dependencies.push((id, query, "query"));
match *fun {
crate::RayQueryFunction::Initialize {
acceleration_structure,
descriptor,
} => {
self.dependencies.push((
id,
acceleration_structure,
"acceleration_structure",
));
self.dependencies.push((id, descriptor, "descriptor"));
"RayQueryInitialize"
}
crate::RayQueryFunction::Proceed { result } => {
self.emits.push((id, result));
"RayQueryProceed"
}
crate::RayQueryFunction::Terminate => "RayQueryTerminate",
}
}
S::SubgroupBallot { result, predicate } => {
if let Some(predicate) = predicate {
self.dependencies.push((id, predicate, "predicate"));
}
self.emits.push((id, result));
"SubgroupBallot"
}
S::SubgroupCollectiveOperation {
op,
collective_op,
argument,
result,
} => {
self.dependencies.push((id, argument, "arg"));
self.emits.push((id, result));
match (collective_op, op) {
(crate::CollectiveOperation::Reduce, crate::SubgroupOperation::All) => {
"SubgroupAll"
}
(crate::CollectiveOperation::Reduce, crate::SubgroupOperation::Any) => {
"SubgroupAny"
}
(crate::CollectiveOperation::Reduce, crate::SubgroupOperation::Add) => {
"SubgroupAdd"
}
(crate::CollectiveOperation::Reduce, crate::SubgroupOperation::Mul) => {
"SubgroupMul"
}
(crate::CollectiveOperation::Reduce, crate::SubgroupOperation::Max) => {
"SubgroupMax"
}
(crate::CollectiveOperation::Reduce, crate::SubgroupOperation::Min) => {
"SubgroupMin"
}
(crate::CollectiveOperation::Reduce, crate::SubgroupOperation::And) => {
"SubgroupAnd"
}
(crate::CollectiveOperation::Reduce, crate::SubgroupOperation::Or) => {
"SubgroupOr"
}
(crate::CollectiveOperation::Reduce, crate::SubgroupOperation::Xor) => {
"SubgroupXor"
}
(
crate::CollectiveOperation::ExclusiveScan,
crate::SubgroupOperation::Add,
) => "SubgroupExclusiveAdd",
(
crate::CollectiveOperation::ExclusiveScan,
crate::SubgroupOperation::Mul,
) => "SubgroupExclusiveMul",
(
crate::CollectiveOperation::InclusiveScan,
crate::SubgroupOperation::Add,
) => "SubgroupInclusiveAdd",
(
crate::CollectiveOperation::InclusiveScan,
crate::SubgroupOperation::Mul,
) => "SubgroupInclusiveMul",
_ => unimplemented!(),
}
}
S::SubgroupGather {
mode,
argument,
result,
} => {
match mode {
crate::GatherMode::BroadcastFirst => {}
crate::GatherMode::Broadcast(index)
| crate::GatherMode::Shuffle(index)
| crate::GatherMode::ShuffleDown(index)
| crate::GatherMode::ShuffleUp(index)
| crate::GatherMode::ShuffleXor(index) => {
self.dependencies.push((id, index, "index"))
}
}
self.dependencies.push((id, argument, "arg"));
self.emits.push((id, result));
match mode {
crate::GatherMode::BroadcastFirst => "SubgroupBroadcastFirst",
crate::GatherMode::Broadcast(_) => "SubgroupBroadcast",
crate::GatherMode::Shuffle(_) => "SubgroupShuffle",
crate::GatherMode::ShuffleDown(_) => "SubgroupShuffleDown",
crate::GatherMode::ShuffleUp(_) => "SubgroupShuffleUp",
crate::GatherMode::ShuffleXor(_) => "SubgroupShuffleXor",
}
}
};
// Set the last node to the merge node
last_node = merge_id;
}
(root, last_node)
}
}
fn name(option: &Option<String>) -> &str {
option.as_deref().unwrap_or_default()
}
const COLORS: &[&str] = &[
"white", // pattern starts at 1
"#8dd3c7", "#ffffb3", "#bebada", "#fb8072", "#80b1d3", "#fdb462", "#b3de69", "#fccde5",
"#d9d9d9",
];
struct Prefixed<T>(Handle<T>);
impl std::fmt::Display for Prefixed<crate::Expression> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
self.0.write_prefixed(f, "e")
}
}
impl std::fmt::Display for Prefixed<crate::LocalVariable> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
self.0.write_prefixed(f, "l")
}
}
impl std::fmt::Display for Prefixed<crate::GlobalVariable> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
self.0.write_prefixed(f, "g")
}
}
impl std::fmt::Display for Prefixed<crate::Function> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
self.0.write_prefixed(f, "f")
}
}
fn write_fun(
output: &mut String,
prefix: String,
fun: &crate::Function,
info: Option<&FunctionInfo>,
options: &Options,
) -> Result<(), FmtError> {
writeln!(output, "\t\tnode [ style=filled ]")?;
if !options.cfg_only {
for (handle, var) in fun.local_variables.iter() {
writeln!(
output,
"\t\t{}_{} [ shape=hexagon label=\"{:?} '{}'\" ]",
prefix,
Prefixed(handle),
handle,
name(&var.name),
)?;
}
write_function_expressions(output, &prefix, fun, info)?;
}
let mut sg = StatementGraph::default();
sg.add(&fun.body, Targets::default());
for (index, label) in sg.nodes.into_iter().enumerate() {
writeln!(
output,
"\t\t{prefix}_s{index} [ shape=square label=\"{label}\" ]",
)?;
}
for (from, to, label) in sg.flow {
writeln!(
output,
"\t\t{prefix}_s{from} -> {prefix}_s{to} [ arrowhead=tee label=\"{label}\" ]",
)?;
}
for (from, to, label, color_id) in sg.jumps {
writeln!(
output,
"\t\t{}_s{} -> {}_s{} [ arrowhead=tee style=dashed color=\"{}\" label=\"{}\" ]",
prefix, from, prefix, to, COLORS[color_id], label,
)?;
}
if !options.cfg_only {
for (to, expr, label) in sg.dependencies {
writeln!(
output,
"\t\t{}_{} -> {}_s{} [ label=\"{}\" ]",
prefix,
Prefixed(expr),
prefix,
to,
label,
)?;
}
for (from, to) in sg.emits {
writeln!(
output,
"\t\t{}_s{} -> {}_{} [ style=dotted ]",
prefix,
from,
prefix,
Prefixed(to),
)?;
}
}
assert!(sg.calls.is_empty());
for (from, function) in sg.calls {
writeln!(
output,
"\t\t{}_s{} -> {}_s0",
prefix,
from,
Prefixed(function),
)?;
}
Ok(())
}
fn write_function_expressions(
output: &mut String,
prefix: &str,
fun: &crate::Function,
info: Option<&FunctionInfo>,
) -> Result<(), FmtError> {
enum Payload<'a> {
Arguments(&'a [Handle<crate::Expression>]),
Local(Handle<crate::LocalVariable>),
Global(Handle<crate::GlobalVariable>),
}
let mut edges = crate::FastHashMap::<&str, _>::default();
let mut payload = None;
for (handle, expression) in fun.expressions.iter() {
use crate::Expression as E;
let (label, color_id) = match *expression {
E::Literal(_) => ("Literal".into(), 2),
E::Constant(_) => ("Constant".into(), 2),
E::Override(_) => ("Override".into(), 2),
E::ZeroValue(_) => ("ZeroValue".into(), 2),
E::Compose { ref components, .. } => {
payload = Some(Payload::Arguments(components));
("Compose".into(), 3)
}
E::Access { base, index } => {
edges.insert("base", base);
edges.insert("index", index);
("Access".into(), 1)
}
E::AccessIndex { base, index } => {
edges.insert("base", base);
(format!("AccessIndex[{index}]").into(), 1)
}
E::Splat { size, value } => {
edges.insert("value", value);
(format!("Splat{size:?}").into(), 3)
}
E::Swizzle {
size,
vector,
pattern,
} => {
edges.insert("vector", vector);
(format!("Swizzle{:?}", &pattern[..size as usize]).into(), 3)
}
E::FunctionArgument(index) => (format!("Argument[{index}]").into(), 1),
E::GlobalVariable(h) => {
payload = Some(Payload::Global(h));
("Global".into(), 2)
}
E::LocalVariable(h) => {
payload = Some(Payload::Local(h));
("Local".into(), 1)
}
E::Load { pointer } => {
edges.insert("pointer", pointer);
("Load".into(), 4)
}
E::ImageSample {
image,
sampler,
gather,
coordinate,
array_index,
offset: _,
level,
depth_ref,
} => {
edges.insert("image", image);
edges.insert("sampler", sampler);
edges.insert("coordinate", coordinate);
if let Some(expr) = array_index {
edges.insert("array_index", expr);
}
match level {
crate::SampleLevel::Auto => {}
crate::SampleLevel::Zero => {}
crate::SampleLevel::Exact(expr) => {
edges.insert("level", expr);
}
crate::SampleLevel::Bias(expr) => {
edges.insert("bias", expr);
}
crate::SampleLevel::Gradient { x, y } => {
edges.insert("grad_x", x);
edges.insert("grad_y", y);
}
}
if let Some(expr) = depth_ref {
edges.insert("depth_ref", expr);
}
let string = match gather {
Some(component) => Cow::Owned(format!("ImageGather{component:?}")),
_ => Cow::Borrowed("ImageSample"),
};
(string, 5)
}
E::ImageLoad {
image,
coordinate,
array_index,
sample,
level,
} => {
edges.insert("image", image);
edges.insert("coordinate", coordinate);
if let Some(expr) = array_index {
edges.insert("array_index", expr);
}
if let Some(sample) = sample {
edges.insert("sample", sample);
}
if let Some(level) = level {
edges.insert("level", level);
}
("ImageLoad".into(), 5)
}
E::ImageQuery { image, query } => {
edges.insert("image", image);
let args = match query {
crate::ImageQuery::Size { level } => {
if let Some(expr) = level {
edges.insert("level", expr);
}
Cow::from("ImageSize")
}
_ => Cow::Owned(format!("{query:?}")),
};
(args, 7)
}
E::Unary { op, expr } => {
edges.insert("expr", expr);
(format!("{op:?}").into(), 6)
}
E::Binary { op, left, right } => {
edges.insert("left", left);
edges.insert("right", right);
(format!("{op:?}").into(), 6)
}
E::Select {
condition,
accept,
reject,
} => {
edges.insert("condition", condition);
edges.insert("accept", accept);
edges.insert("reject", reject);
("Select".into(), 3)
}
E::Derivative { axis, ctrl, expr } => {
edges.insert("", expr);
(format!("d{axis:?}{ctrl:?}").into(), 8)
}
E::Relational { fun, argument } => {
edges.insert("arg", argument);
(format!("{fun:?}").into(), 6)
}
E::Math {
fun,
arg,
arg1,
arg2,
arg3,
} => {
edges.insert("arg", arg);
if let Some(expr) = arg1 {
edges.insert("arg1", expr);
}
if let Some(expr) = arg2 {
edges.insert("arg2", expr);
}
if let Some(expr) = arg3 {
edges.insert("arg3", expr);
}
(format!("{fun:?}").into(), 7)
}
E::As {
kind,
expr,
convert,
} => {
edges.insert("", expr);
let string = match convert {
Some(width) => format!("Convert<{kind:?},{width}>"),
None => format!("Bitcast<{kind:?}>"),
};
(string.into(), 3)
}
E::CallResult(_function) => ("CallResult".into(), 4),
E::AtomicResult { .. } => ("AtomicResult".into(), 4),
E::WorkGroupUniformLoadResult { .. } => ("WorkGroupUniformLoadResult".into(), 4),
E::ArrayLength(expr) => {
edges.insert("", expr);
("ArrayLength".into(), 7)
}
E::RayQueryProceedResult => ("rayQueryProceedResult".into(), 4),
E::RayQueryGetIntersection { query, committed } => {
edges.insert("", query);
let ty = if committed { "Committed" } else { "Candidate" };
(format!("rayQueryGet{ty}Intersection").into(), 4)
}
E::SubgroupBallotResult => ("SubgroupBallotResult".into(), 4),
E::SubgroupOperationResult { .. } => ("SubgroupOperationResult".into(), 4),
};
// give uniform expressions an outline
let color_attr = match info {
Some(info) if info[handle].uniformity.non_uniform_result.is_none() => "fillcolor",
_ => "color",
};
writeln!(
output,
"\t\t{}_{} [ {}=\"{}\" label=\"{:?} {}\" ]",
prefix,
Prefixed(handle),
color_attr,
COLORS[color_id],
handle,
label,
)?;
for (key, edge) in edges.drain() {
writeln!(
output,
"\t\t{}_{} -> {}_{} [ label=\"{}\" ]",
prefix,
Prefixed(edge),
prefix,
Prefixed(handle),
key,
)?;
}
match payload.take() {
Some(Payload::Arguments(list)) => {
write!(output, "\t\t{{")?;
for &comp in list {
write!(output, " {}_{}", prefix, Prefixed(comp))?;
}
writeln!(output, " }} -> {}_{}", prefix, Prefixed(handle))?;
}
Some(Payload::Local(h)) => {
writeln!(
output,
"\t\t{}_{} -> {}_{}",
prefix,
Prefixed(h),
prefix,
Prefixed(handle),
)?;
}
Some(Payload::Global(h)) => {
writeln!(
output,
"\t\t{} -> {}_{} [fillcolor=gray]",
Prefixed(h),
prefix,
Prefixed(handle),
)?;
}
None => {}
}
}
Ok(())
}
/// Write shader module to a [`String`].
pub fn write(
module: &crate::Module,
mod_info: Option<&ModuleInfo>,
options: Options,
) -> Result<String, FmtError> {
use std::fmt::Write as _;
let mut output = String::new();
output += "digraph Module {\n";
if !options.cfg_only {
writeln!(output, "\tsubgraph cluster_globals {{")?;
writeln!(output, "\t\tlabel=\"Globals\"")?;
for (handle, var) in module.global_variables.iter() {
writeln!(
output,
"\t\t{} [ shape=hexagon label=\"{:?} {:?}/'{}'\" ]",
Prefixed(handle),
handle,
var.space,
name(&var.name),
)?;
}
writeln!(output, "\t}}")?;
}
for (handle, fun) in module.functions.iter() {
let prefix = Prefixed(handle).to_string();
writeln!(output, "\tsubgraph cluster_{prefix} {{")?;
writeln!(
output,
"\t\tlabel=\"Function{:?}/'{}'\"",
handle,
name(&fun.name)
)?;
let info = mod_info.map(|a| &a[handle]);
write_fun(&mut output, prefix, fun, info, &options)?;
writeln!(output, "\t}}")?;
}
for (ep_index, ep) in module.entry_points.iter().enumerate() {
let prefix = format!("ep{ep_index}");
writeln!(output, "\tsubgraph cluster_{prefix} {{")?;
writeln!(output, "\t\tlabel=\"{:?}/'{}'\"", ep.stage, ep.name)?;
let info = mod_info.map(|a| a.get_entry_point(ep_index));
write_fun(&mut output, prefix, &ep.function, info, &options)?;
writeln!(output, "\t}}")?;
}
output += "}\n";
Ok(output)
}