cranelift_codegen/
cfg_printer.rs

1//! The `CFGPrinter` utility.
2
3use alloc::vec::Vec;
4use core::fmt::{Display, Formatter, Result, Write};
5
6use crate::entity::SecondaryMap;
7use crate::flowgraph::{BlockPredecessor, ControlFlowGraph};
8use crate::ir::Function;
9use crate::write::{FuncWriter, PlainWriter};
10
11/// A utility for pretty-printing the CFG of a `Function`.
12pub struct CFGPrinter<'a> {
13    func: &'a Function,
14    cfg: ControlFlowGraph,
15}
16
17/// A utility for pretty-printing the CFG of a `Function`.
18impl<'a> CFGPrinter<'a> {
19    /// Create a new CFGPrinter.
20    pub fn new(func: &'a Function) -> Self {
21        Self {
22            func,
23            cfg: ControlFlowGraph::with_function(func),
24        }
25    }
26
27    /// Write the CFG for this function to `w`.
28    pub fn write(&self, w: &mut dyn Write) -> Result {
29        self.header(w)?;
30        self.block_nodes(w)?;
31        self.cfg_connections(w)?;
32        writeln!(w, "}}")
33    }
34
35    fn header(&self, w: &mut dyn Write) -> Result {
36        writeln!(w, "digraph \"{}\" {{", self.func.name)?;
37        if let Some(entry) = self.func.layout.entry_block() {
38            writeln!(w, "    {{rank=min; {entry}}}")?;
39        }
40        Ok(())
41    }
42
43    fn block_nodes(&self, w: &mut dyn Write) -> Result {
44        let mut aliases = SecondaryMap::<_, Vec<_>>::new();
45        for v in self.func.dfg.values() {
46            // VADFS returns the immediate target of an alias
47            if let Some(k) = self.func.dfg.value_alias_dest_for_serialization(v) {
48                aliases[k].push(v);
49            }
50        }
51
52        for block in &self.func.layout {
53            write!(w, "    {block} [shape=record, label=\"{{")?;
54            crate::write::write_block_header(w, self.func, block, 4)?;
55            // Add all outgoing branch instructions to the label.
56            if let Some(inst) = self.func.layout.last_inst(block) {
57                write!(w, " | <{inst}>")?;
58                PlainWriter.write_instruction(w, self.func, &aliases, inst, 0)?;
59            }
60            writeln!(w, "}}\"]")?
61        }
62        Ok(())
63    }
64
65    fn cfg_connections(&self, w: &mut dyn Write) -> Result {
66        for block in &self.func.layout {
67            for BlockPredecessor {
68                block: parent,
69                inst,
70            } in self.cfg.pred_iter(block)
71            {
72                writeln!(w, "    {parent}:{inst} -> {block}")?;
73            }
74        }
75        Ok(())
76    }
77}
78
79impl<'a> Display for CFGPrinter<'a> {
80    fn fmt(&self, f: &mut Formatter) -> Result {
81        self.write(f)
82    }
83}
cranelift_codegen/cfg_printer.rs

cranelift_codegen/
cfg_printer.rs
