decompiler

name	decompiler
description	Decompile Binary Ninja functions via HLIL: pseudocode text, local variables, call sites. Always filter by func_addr.
allowed-tools	["Bash","Read","Glob","Grep"]

Decompiler (HLIL)

Binary Ninja's High Level IL is the closest thing to C-like pseudocode in BN. BNSQL exposes it through one SQL function and three tables.

Surfaces

Surface	Description	Required filter
decompile(addr) UDF	Full-function decompiled text	— (single address)
decompile(addr, limit) UDF	Limit-aware variant	—
pseudocode table	Line-level filtering by func_addr / ea	func_addr = X
hlil_vars table	Local variables; writable (name, type, comment)	func_addr = X
hlil_calls table	Call sites discovered in HLIL	func_addr = X

Always filter decompiler tables by func_addr — without it, BN decompiles every function in the binary.

Quick patterns

Decompile one function

-- Full function as one text block
SELECT decompile(0x401000);

-- Limit to 40 lines (good for surveys)
SELECT decompile(0x401000, 40);

Local variables

SELECT name, type, storage
FROM hlil_vars
WHERE func_addr = 0x401000;

Call sites inside a function

SELECT DISTINCT callee_name
FROM hlil_calls
WHERE func_addr = 0x401000;

Decompile + line-level filter

SELECT line_text
FROM pseudocode
WHERE func_addr = 0x401000
  AND line_text LIKE '%CreateFile%';

Find functions calling a target

SELECT DISTINCT func_at(func_addr) AS caller
FROM hlil_calls
WHERE callee_name = 'malloc';

Mutation surface (annotations)

hlil_vars is writable on name, type, comment. Apply edits inside the mutation loop:

-- 1. Read current state
SELECT name, type FROM hlil_vars
WHERE func_addr = 0x401000 AND storage = 'var_8';

-- 2. Apply mutation
UPDATE hlil_vars
SET name = 'user_buffer', type = 'char *'
WHERE func_addr = 0x401000 AND storage = 'var_8';

-- 3. Re-read to verify
SELECT name, type FROM hlil_vars
WHERE func_addr = 0x401000 AND storage = 'var_8';

-- 4. Persist
SELECT save();

Writes to hlil_vars, pseudocode, or names that affect a function invalidate the decompiler cache for that function. The next decompile re-runs HLIL on the updated state — no manual refresh needed.

Related skills

• annotations for the broader mutation workflow (renames, comments, types)
• xrefs for the surrounding call graph context
• types for type creation and application to variables

Performance

Decompiler tables are on-demand virtual tables — each row requires decompiling its containing function. Unconstrained queries iterate every function and decompile each one. On a medium binary that's minutes-to-hours. Always pin to a specific func_addr.