Version v2.3.1

Fixes #119

.github/workflows/build.yaml

@@ -142,7 +142,11 @@ jobs:
         uses: actions/checkout@v4
       - name: Install cargo-zigbuild
         if: matrix.build == 'zigbuild'
-        run: pip install ziglang==0.13.0 cargo-zigbuild==0.19.1
+        run: |
+          python3 -m venv .venv
+          . .venv/bin/activate
+          echo PATH=$PATH >> $GITHUB_ENV
+          pip install ziglang==0.13.0 cargo-zigbuild==0.19.1
       - name: Setup Rust toolchain
         uses: dtolnay/rust-toolchain@stable
         with:

Cargo.lock

@@ -395,6 +395,15 @@ version = "0.22.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "72b3254f16251a8381aa12e40e3c4d2f0199f8c6508fbecb9d91f575e0fbb8c6"
 
+[[package]]
+name = "bimap"
+version = "0.6.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "230c5f1ca6a325a32553f8640d31ac9b49f2411e901e427570154868b46da4f7"
+dependencies = [
+ "serde",
+]
+
 [[package]]
 name = "bit-set"
 version = "0.6.0"
@@ -2852,7 +2861,7 @@ dependencies = [
 
 [[package]]
 name = "objdiff-cli"
-version = "2.2.2"
+version = "2.3.1"
 dependencies = [
  "anyhow",
  "argp",
@@ -2874,10 +2883,11 @@ dependencies = [
 
 [[package]]
 name = "objdiff-core"
-version = "2.2.2"
+version = "2.3.1"
 dependencies = [
  "anyhow",
  "arm-attr",
+ "bimap",
  "byteorder",
  "console_error_panic_hook",
  "console_log",
@@ -2913,7 +2923,7 @@ dependencies = [
 
 [[package]]
 name = "objdiff-gui"
-version = "2.2.2"
+version = "2.3.1"
 dependencies = [
  "anyhow",
  "bytes",

Cargo.toml

@@ -13,7 +13,7 @@ strip = "debuginfo"
 codegen-units = 1
 
 [workspace.package]
-version = "2.2.2"
+version = "2.3.1"
 authors = ["Luke Street <luke@street.dev>"]
 edition = "2021"
 license = "MIT OR Apache-2.0"

config.schema.json

@@ -133,6 +133,13 @@
         },
         "metadata": {
           "ref": "#/$defs/metadata"
+        },
+        "symbol_mappings": {
+          "type": "object",
+          "description": "Manual symbol mappings from target to base.",
+          "additionalProperties": {
+            "type": "string"
+          }
         }
       }
     },

objdiff-cli/src/cmd/diff.rs

@@ -102,26 +102,32 @@ pub fn run(args: Args) -> Result<()> {
                     let unit_path =
                         PathBuf::from_str(u).ok().and_then(|p| fs::canonicalize(p).ok());
 
-                    let Some(object) = project_config.objects.iter_mut().find_map(|obj| {
+                    let Some(object) = project_config
-                        if obj.name.as_deref() == Some(u) {
+                        .units
+                        .as_deref_mut()
+                        .unwrap_or_default()
+                        .iter_mut()
+                        .find_map(|obj| {
+                            if obj.name.as_deref() == Some(u) {
+                                resolve_paths(obj);
+                                return Some(obj);
+                            }
+
+                            let up = unit_path.as_deref()?;
+
                             resolve_paths(obj);
-                            return Some(obj);
-                        }
 
-                        let up = unit_path.as_deref()?;
+                            if [&obj.base_path, &obj.target_path]
+                                .into_iter()
+                                .filter_map(|p| p.as_ref().and_then(|p| p.canonicalize().ok()))
+                                .any(|p| p == up)
+                            {
+                                return Some(obj);
+                            }
 
-                        resolve_paths(obj);
+                            None
-
+                        })
-                        if [&obj.base_path, &obj.target_path]
+                    else {
-                            .into_iter()
-                            .filter_map(|p| p.as_ref().and_then(|p| p.canonicalize().ok()))
-                            .any(|p| p == up)
-                        {
-                            return Some(obj);
-                        }
-
-                        None
-                    }) else {
                         bail!("Unit not found: {}", u)
                     };
 
@@ -129,7 +135,13 @@ pub fn run(args: Args) -> Result<()> {
                 } else if let Some(symbol_name) = &args.symbol {
                     let mut idx = None;
                     let mut count = 0usize;
-                    for (i, obj) in project_config.objects.iter_mut().enumerate() {
+                    for (i, obj) in project_config
+                        .units
+                        .as_deref_mut()
+                        .unwrap_or_default()
+                        .iter_mut()
+                        .enumerate()
+                    {
                         resolve_paths(obj);
 
                         if obj
@@ -148,7 +160,7 @@ pub fn run(args: Args) -> Result<()> {
                     }
                     match (count, idx) {
                         (0, None) => bail!("Symbol not found: {}", symbol_name),
-                        (1, Some(i)) => &mut project_config.objects[i],
+                        (1, Some(i)) => &mut project_config.units_mut()[i],
                         (2.., Some(_)) => bail!(
                             "Multiple instances of {} were found, try specifying a unit",
                             symbol_name
@@ -303,7 +315,7 @@ fn find_function(obj: &ObjInfo, name: &str) -> Option<SymbolRef> {
     None
 }
 
-#[allow(dead_code)]
+#[expect(dead_code)]
 struct FunctionDiffUi {
     relax_reloc_diffs: bool,
     left_highlight: HighlightKind,
@@ -758,7 +770,7 @@ impl FunctionDiffUi {
         self.scroll_y += self.per_page / if half { 2 } else { 1 };
     }
 
-    #[allow(clippy::too_many_arguments)]
+    #[expect(clippy::too_many_arguments)]
     fn print_sym(
         &self,
         out: &mut Text<'static>,

objdiff-cli/src/cmd/report.rs

@@ -94,7 +94,7 @@ fn generate(args: GenerateArgs) -> Result<()> {
     };
     info!(
         "Generating report for {} units (using {} threads)",
-        project.objects.len(),
+        project.units().len(),
         if args.deduplicate { 1 } else { rayon::current_num_threads() }
     );
 
@@ -103,7 +103,7 @@ fn generate(args: GenerateArgs) -> Result<()> {
     let mut existing_functions: HashSet<String> = HashSet::new();
     if args.deduplicate {
         // If deduplicating, we need to run single-threaded
-        for object in &mut project.objects {
+        for object in project.units.as_deref_mut().unwrap_or_default() {
             if let Some(unit) = report_object(
                 object,
                 project_dir,
@@ -116,7 +116,9 @@ fn generate(args: GenerateArgs) -> Result<()> {
         }
     } else {
         let vec = project
-            .objects
+            .units
+            .as_deref_mut()
+            .unwrap_or_default()
             .par_iter_mut()
             .map(|object| {
                 report_object(
@@ -132,7 +134,7 @@ fn generate(args: GenerateArgs) -> Result<()> {
     }
     let measures = units.iter().flat_map(|u| u.measures.into_iter()).collect();
     let mut categories = Vec::new();
-    for category in &project.progress_categories {
+    for category in project.progress_categories() {
         categories.push(ReportCategory {
             id: category.id.clone(),
             name: category.name.clone(),

objdiff-core/Cargo.toml

@@ -17,8 +17,8 @@ crate-type = ["cdylib", "rlib"]
 
 [features]
 all = ["config", "dwarf", "mips", "ppc", "x86", "arm", "bindings"]
-any-arch = [] # Implicit, used to check if any arch is enabled
+any-arch = ["bimap"] # Implicit, used to check if any arch is enabled
-config = ["globset", "semver", "serde_json", "serde_yaml"]
+config = ["bimap", "globset", "semver", "serde_json", "serde_yaml"]
 dwarf = ["gimli"]
 mips = ["any-arch", "rabbitizer"]
 ppc = ["any-arch", "cwdemangle", "cwextab", "ppc750cl"]
@@ -32,6 +32,7 @@ features = ["all"]
 
 [dependencies]
 anyhow = "1.0"
+bimap = { version = "0.6", features = ["serde"], optional = true }
 byteorder = "1.5"
 filetime = "0.2"
 flagset = "0.4"

objdiff-core/src/config/mod.rs

@@ -1,77 +1,100 @@
 use std::{
+    fs,
     fs::File,
-    io::{BufReader, Read},
+    io::{BufReader, BufWriter, Read},
     path::{Path, PathBuf},
 };
 
 use anyhow::{anyhow, Context, Result};
+use bimap::BiBTreeMap;
 use filetime::FileTime;
 use globset::{Glob, GlobSet, GlobSetBuilder};
 
-#[inline]
+#[derive(Default, Clone, serde::Serialize, serde::Deserialize)]
-fn bool_true() -> bool { true }
-
-#[derive(Default, Clone, serde::Deserialize)]
 pub struct ProjectConfig {
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub min_version: Option<String>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub custom_make: Option<String>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub custom_args: Option<Vec<String>>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub target_dir: Option<PathBuf>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub base_dir: Option<PathBuf>,
-    #[serde(default = "bool_true")]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub build_base: bool,
+    pub build_base: Option<bool>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub build_target: bool,
+    pub build_target: Option<bool>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub watch_patterns: Option<Vec<Glob>>,
-    #[serde(default, alias = "units")]
+    #[serde(default, alias = "objects", skip_serializing_if = "Option::is_none")]
-    pub objects: Vec<ProjectObject>,
+    pub units: Option<Vec<ProjectObject>>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub progress_categories: Vec<ProjectProgressCategory>,
+    pub progress_categories: Option<Vec<ProjectProgressCategory>>,
 }
 
-#[derive(Default, Clone, serde::Deserialize)]
+impl ProjectConfig {
+    #[inline]
+    pub fn units(&self) -> &[ProjectObject] { self.units.as_deref().unwrap_or_default() }
+
+    #[inline]
+    pub fn units_mut(&mut self) -> &mut Vec<ProjectObject> {
+        self.units.get_or_insert_with(Vec::new)
+    }
+
+    #[inline]
+    pub fn progress_categories(&self) -> &[ProjectProgressCategory] {
+        self.progress_categories.as_deref().unwrap_or_default()
+    }
+
+    #[inline]
+    pub fn progress_categories_mut(&mut self) -> &mut Vec<ProjectProgressCategory> {
+        self.progress_categories.get_or_insert_with(Vec::new)
+    }
+}
+
+#[derive(Default, Clone, serde::Serialize, serde::Deserialize)]
 pub struct ProjectObject {
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub name: Option<String>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub path: Option<PathBuf>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub target_path: Option<PathBuf>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub base_path: Option<PathBuf>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     #[deprecated(note = "Use metadata.reverse_fn_order")]
     pub reverse_fn_order: Option<bool>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     #[deprecated(note = "Use metadata.complete")]
     pub complete: Option<bool>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub scratch: Option<ScratchConfig>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub metadata: Option<ProjectObjectMetadata>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub symbol_mappings: Option<SymbolMappings>,
 }
 
-#[derive(Default, Clone, serde::Deserialize)]
+pub type SymbolMappings = BiBTreeMap<String, String>;
+
+#[derive(Default, Clone, serde::Serialize, serde::Deserialize)]
 pub struct ProjectObjectMetadata {
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub complete: Option<bool>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub reverse_fn_order: Option<bool>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub source_path: Option<String>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub progress_categories: Option<Vec<String>>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub auto_generated: Option<bool>,
 }
 
-#[derive(Default, Clone, serde::Deserialize)]
+#[derive(Default, Clone, serde::Serialize, serde::Deserialize)]
 pub struct ProjectProgressCategory {
     #[serde(default)]
     pub id: String,
@@ -112,12 +135,12 @@ impl ProjectObject {
     }
 
     pub fn complete(&self) -> Option<bool> {
-        #[allow(deprecated)]
+        #[expect(deprecated)]
         self.metadata.as_ref().and_then(|m| m.complete).or(self.complete)
     }
 
     pub fn reverse_fn_order(&self) -> Option<bool> {
-        #[allow(deprecated)]
+        #[expect(deprecated)]
         self.metadata.as_ref().and_then(|m| m.reverse_fn_order).or(self.reverse_fn_order)
     }
 
@@ -132,16 +155,16 @@ impl ProjectObject {
 
 #[derive(Default, Clone, Eq, PartialEq, serde::Deserialize, serde::Serialize)]
 pub struct ScratchConfig {
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub platform: Option<String>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub compiler: Option<String>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub c_flags: Option<String>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub ctx_path: Option<PathBuf>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub build_ctx: bool,
+    pub build_ctx: Option<bool>,
 }
 
 pub const CONFIG_FILENAMES: [&str; 3] = ["objdiff.json", "objdiff.yml", "objdiff.yaml"];
@@ -154,7 +177,7 @@ pub const DEFAULT_WATCH_PATTERNS: &[&str] = &[
 #[derive(Clone, Eq, PartialEq)]
 pub struct ProjectConfigInfo {
     pub path: PathBuf,
-    pub timestamp: FileTime,
+    pub timestamp: Option<FileTime>,
 }
 
 pub fn try_project_config(dir: &Path) -> Option<(Result<ProjectConfig>, ProjectConfigInfo)> {
@@ -180,12 +203,41 @@ pub fn try_project_config(dir: &Path) -> Option<(Result<ProjectConfig>, ProjectC
                     result = Err(e);
                 }
             }
-            return Some((result, ProjectConfigInfo { path: config_path, timestamp: ts }));
+            return Some((result, ProjectConfigInfo { path: config_path, timestamp: Some(ts) }));
         }
     }
     None
 }
 
+pub fn save_project_config(
+    config: &ProjectConfig,
+    info: &ProjectConfigInfo,
+) -> Result<ProjectConfigInfo> {
+    if let Some(last_ts) = info.timestamp {
+        // Check if the file has changed since we last read it
+        if let Ok(metadata) = fs::metadata(&info.path) {
+            let ts = FileTime::from_last_modification_time(&metadata);
+            if ts != last_ts {
+                return Err(anyhow!("Config file has changed since last read"));
+            }
+        }
+    }
+    let mut writer =
+        BufWriter::new(File::create(&info.path).context("Failed to create config file")?);
+    let ext = info.path.extension().and_then(|ext| ext.to_str()).unwrap_or("json");
+    match ext {
+        "json" => serde_json::to_writer_pretty(&mut writer, config).context("Failed to write JSON"),
+        "yml" | "yaml" => {
+            serde_yaml::to_writer(&mut writer, config).context("Failed to write YAML")
+        }
+        _ => Err(anyhow!("Unknown config file extension: {ext}")),
+    }?;
+    let file = writer.into_inner().context("Failed to flush file")?;
+    let metadata = file.metadata().context("Failed to get file metadata")?;
+    let ts = FileTime::from_last_modification_time(&metadata);
+    Ok(ProjectConfigInfo { path: info.path.clone(), timestamp: Some(ts) })
+}
+
 fn validate_min_version(config: &ProjectConfig) -> Result<()> {
     let Some(min_version) = &config.min_version else { return Ok(()) };
     let version = semver::Version::parse(env!("CARGO_PKG_VERSION"))

objdiff-core/src/diff/code.rs

@@ -41,7 +41,7 @@ pub fn no_diff_code(out: &ProcessCodeResult, symbol_ref: SymbolRef) -> Result<Ob
         });
     }
     resolve_branches(&mut diff);
-    Ok(ObjSymbolDiff { symbol_ref, diff_symbol: None, instructions: diff, match_percent: None })
+    Ok(ObjSymbolDiff { symbol_ref, target_symbol: None, instructions: diff, match_percent: None })
 }
 
 pub fn diff_code(
@@ -67,7 +67,7 @@ pub fn diff_code(
         right.arg_diff = result.right_args_diff;
     }
 
-    let total = left_out.insts.len();
+    let total = left_out.insts.len().max(right_out.insts.len());
     let percent = if diff_state.diff_count >= total {
         0.0
     } else {
@@ -77,13 +77,13 @@ pub fn diff_code(
     Ok((
         ObjSymbolDiff {
             symbol_ref: left_symbol_ref,
-            diff_symbol: Some(right_symbol_ref),
+            target_symbol: Some(right_symbol_ref),
             instructions: left_diff,
             match_percent: Some(percent),
         },
         ObjSymbolDiff {
             symbol_ref: right_symbol_ref,
-            diff_symbol: Some(left_symbol_ref),
+            target_symbol: Some(left_symbol_ref),
             instructions: right_diff,
             match_percent: Some(percent),
         },
@@ -211,7 +211,7 @@ fn arg_eq(
     left_diff: &ObjInsDiff,
     right_diff: &ObjInsDiff,
 ) -> bool {
-    return match left {
+    match left {
         ObjInsArg::PlainText(l) => match right {
             ObjInsArg::PlainText(r) => l == r,
             _ => false,
@@ -236,7 +236,7 @@ fn arg_eq(
             left_diff.branch_to.as_ref().map(|b| b.ins_idx)
                 == right_diff.branch_to.as_ref().map(|b| b.ins_idx)
         }
-    };
+    }
 }
 
 #[derive(Default)]

objdiff-core/src/diff/data.rs

@@ -20,13 +20,13 @@ pub fn diff_bss_symbol(
     Ok((
         ObjSymbolDiff {
             symbol_ref: left_symbol_ref,
-            diff_symbol: Some(right_symbol_ref),
+            target_symbol: Some(right_symbol_ref),
             instructions: vec![],
             match_percent: Some(percent),
         },
         ObjSymbolDiff {
             symbol_ref: right_symbol_ref,
-            diff_symbol: Some(left_symbol_ref),
+            target_symbol: Some(left_symbol_ref),
             instructions: vec![],
             match_percent: Some(percent),
         },
@@ -34,7 +34,7 @@ pub fn diff_bss_symbol(
 }
 
 pub fn no_diff_symbol(_obj: &ObjInfo, symbol_ref: SymbolRef) -> ObjSymbolDiff {
-    ObjSymbolDiff { symbol_ref, diff_symbol: None, instructions: vec![], match_percent: None }
+    ObjSymbolDiff { symbol_ref, target_symbol: None, instructions: vec![], match_percent: None }
 }
 
 /// Compare the data sections of two object files.
@@ -158,13 +158,13 @@ pub fn diff_data_symbol(
     Ok((
         ObjSymbolDiff {
             symbol_ref: left_symbol_ref,
-            diff_symbol: Some(right_symbol_ref),
+            target_symbol: Some(right_symbol_ref),
             instructions: vec![],
             match_percent: Some(match_percent),
         },
         ObjSymbolDiff {
             symbol_ref: right_symbol_ref,
-            diff_symbol: Some(left_symbol_ref),
+            target_symbol: Some(left_symbol_ref),
             instructions: vec![],
             match_percent: Some(match_percent),
         },

objdiff-core/src/diff/display.rs

@@ -29,7 +29,7 @@ pub enum DiffText<'a> {
     Eol,
 }
 
-#[derive(Default, Clone, PartialEq, Eq)]
+#[derive(Debug, Default, Clone, PartialEq, Eq)]
 pub enum HighlightKind {
     #[default]
     None,

objdiff-core/src/diff/mod.rs

@@ -3,6 +3,7 @@ use std::collections::HashSet;
 use anyhow::Result;
 
 use crate::{
+    config::SymbolMappings,
     diff::{
         code::{diff_code, no_diff_code, process_code_symbol},
         data::{
@@ -161,6 +162,8 @@ pub struct DiffObjConfig {
     #[serde(default = "default_true")]
     pub space_between_args: bool,
     pub combine_data_sections: bool,
+    #[serde(default)]
+    pub symbol_mappings: MappingConfig,
     // x86
     pub x86_formatter: X86Formatter,
     // MIPS
@@ -182,6 +185,7 @@ impl Default for DiffObjConfig {
             relax_reloc_diffs: false,
             space_between_args: true,
             combine_data_sections: false,
+            symbol_mappings: Default::default(),
             x86_formatter: Default::default(),
             mips_abi: Default::default(),
             mips_instr_category: Default::default(),
@@ -223,8 +227,10 @@ impl ObjSectionDiff {
 
 #[derive(Debug, Clone, Default)]
 pub struct ObjSymbolDiff {
+    /// The symbol ref this object
     pub symbol_ref: SymbolRef,
-    pub diff_symbol: Option<SymbolRef>,
+    /// The symbol ref in the _other_ object that this symbol was diffed against
+    pub target_symbol: Option<SymbolRef>,
     pub instructions: Vec<ObjInsDiff>,
     pub match_percent: Option<f32>,
 }
@@ -294,8 +300,13 @@ pub struct ObjInsBranchTo {
 
 #[derive(Default)]
 pub struct ObjDiff {
+    /// A list of all section diffs in the object.
     pub sections: Vec<ObjSectionDiff>,
+    /// Common BSS symbols don't live in a section, so they're stored separately.
     pub common: Vec<ObjSymbolDiff>,
+    /// If `selecting_left` or `selecting_right` is set, this is the list of symbols
+    /// that are being mapped to the other object.
+    pub mapping_symbols: Vec<ObjSymbolDiff>,
 }
 
 impl ObjDiff {
@@ -303,13 +314,14 @@ impl ObjDiff {
         let mut result = Self {
             sections: Vec::with_capacity(obj.sections.len()),
             common: Vec::with_capacity(obj.common.len()),
+            mapping_symbols: vec![],
         };
         for (section_idx, section) in obj.sections.iter().enumerate() {
             let mut symbols = Vec::with_capacity(section.symbols.len());
             for (symbol_idx, _) in section.symbols.iter().enumerate() {
                 symbols.push(ObjSymbolDiff {
                     symbol_ref: SymbolRef { section_idx, symbol_idx },
-                    diff_symbol: None,
+                    target_symbol: None,
                     instructions: vec![],
                     match_percent: None,
                 });
@@ -328,7 +340,7 @@ impl ObjDiff {
         for (symbol_idx, _) in obj.common.iter().enumerate() {
             result.common.push(ObjSymbolDiff {
                 symbol_ref: SymbolRef { section_idx: obj.sections.len(), symbol_idx },
-                diff_symbol: None,
+                target_symbol: None,
                 instructions: vec![],
                 match_percent: None,
             });
@@ -378,7 +390,7 @@ pub fn diff_objs(
     right: Option<&ObjInfo>,
     prev: Option<&ObjInfo>,
 ) -> Result<DiffObjsResult> {
-    let symbol_matches = matching_symbols(left, right, prev)?;
+    let symbol_matches = matching_symbols(left, right, prev, &config.symbol_mappings)?;
     let section_matches = matching_sections(left, right)?;
     let mut left = left.map(|p| (p, ObjDiff::new_from_obj(p)));
     let mut right = right.map(|p| (p, ObjDiff::new_from_obj(p)));
@@ -529,6 +541,17 @@ pub fn diff_objs(
         }
     }
 
+    if let (Some((right_obj, right_out)), Some((left_obj, left_out))) =
+        (right.as_mut(), left.as_mut())
+    {
+        if let Some(right_name) = &config.symbol_mappings.selecting_left {
+            generate_mapping_symbols(right_obj, right_name, left_obj, left_out, config)?;
+        }
+        if let Some(left_name) = &config.symbol_mappings.selecting_right {
+            generate_mapping_symbols(left_obj, left_name, right_obj, right_out, config)?;
+        }
+    }
+
     Ok(DiffObjsResult {
         left: left.map(|(_, o)| o),
         right: right.map(|(_, o)| o),
@@ -536,6 +559,63 @@ pub fn diff_objs(
     })
 }
 
+/// When we're selecting a symbol to use as a comparison, we'll create comparisons for all
+/// symbols in the other object that match the selected symbol's section and kind. This allows
+/// us to display match percentages for all symbols in the other object that could be selected.
+fn generate_mapping_symbols(
+    base_obj: &ObjInfo,
+    base_name: &str,
+    target_obj: &ObjInfo,
+    target_out: &mut ObjDiff,
+    config: &DiffObjConfig,
+) -> Result<()> {
+    let Some(base_symbol_ref) = symbol_ref_by_name(base_obj, base_name) else {
+        return Ok(());
+    };
+    let (base_section, base_symbol) = base_obj.section_symbol(base_symbol_ref);
+    let Some(base_section) = base_section else {
+        return Ok(());
+    };
+    let base_code = match base_section.kind {
+        ObjSectionKind::Code => Some(process_code_symbol(base_obj, base_symbol_ref, config)?),
+        _ => None,
+    };
+    for (target_section_index, target_section) in
+        target_obj.sections.iter().enumerate().filter(|(_, s)| s.kind == base_section.kind)
+    {
+        for (target_symbol_index, _target_symbol) in
+            target_section.symbols.iter().enumerate().filter(|(_, s)| s.kind == base_symbol.kind)
+        {
+            let target_symbol_ref =
+                SymbolRef { section_idx: target_section_index, symbol_idx: target_symbol_index };
+            match base_section.kind {
+                ObjSectionKind::Code => {
+                    let target_code = process_code_symbol(target_obj, target_symbol_ref, config)?;
+                    let (left_diff, _right_diff) = diff_code(
+                        &target_code,
+                        base_code.as_ref().unwrap(),
+                        target_symbol_ref,
+                        base_symbol_ref,
+                        config,
+                    )?;
+                    target_out.mapping_symbols.push(left_diff);
+                }
+                ObjSectionKind::Data => {
+                    let (left_diff, _right_diff) =
+                        diff_data_symbol(target_obj, base_obj, target_symbol_ref, base_symbol_ref)?;
+                    target_out.mapping_symbols.push(left_diff);
+                }
+                ObjSectionKind::Bss => {
+                    let (left_diff, _right_diff) =
+                        diff_bss_symbol(target_obj, base_obj, target_symbol_ref, base_symbol_ref)?;
+                    target_out.mapping_symbols.push(left_diff);
+                }
+            }
+        }
+    }
+    Ok(())
+}
+
 #[derive(Copy, Clone, Eq, PartialEq)]
 struct SymbolMatch {
     left: Option<SymbolRef>,
@@ -551,19 +631,115 @@ struct SectionMatch {
     section_kind: ObjSectionKind,
 }
 
+#[derive(Debug, Clone, PartialEq, Eq, Hash, Default, serde::Deserialize, serde::Serialize)]
+pub struct MappingConfig {
+    /// Manual symbol mappings
+    pub mappings: SymbolMappings,
+    /// The right object symbol name that we're selecting a left symbol for
+    pub selecting_left: Option<String>,
+    /// The left object symbol name that we're selecting a right symbol for
+    pub selecting_right: Option<String>,
+}
+
+fn symbol_ref_by_name(obj: &ObjInfo, name: &str) -> Option<SymbolRef> {
+    for (section_idx, section) in obj.sections.iter().enumerate() {
+        for (symbol_idx, symbol) in section.symbols.iter().enumerate() {
+            if symbol.name == name {
+                return Some(SymbolRef { section_idx, symbol_idx });
+            }
+        }
+    }
+    None
+}
+
+fn apply_symbol_mappings(
+    left: &ObjInfo,
+    right: &ObjInfo,
+    mapping_config: &MappingConfig,
+    left_used: &mut HashSet<SymbolRef>,
+    right_used: &mut HashSet<SymbolRef>,
+    matches: &mut Vec<SymbolMatch>,
+) -> Result<()> {
+    // If we're selecting a symbol to use as a comparison, mark it as used
+    // This ensures that we don't match it to another symbol at any point
+    if let Some(left_name) = &mapping_config.selecting_left {
+        if let Some(left_symbol) = symbol_ref_by_name(left, left_name) {
+            left_used.insert(left_symbol);
+        }
+    }
+    if let Some(right_name) = &mapping_config.selecting_right {
+        if let Some(right_symbol) = symbol_ref_by_name(right, right_name) {
+            right_used.insert(right_symbol);
+        }
+    }
+
+    // Apply manual symbol mappings
+    for (left_name, right_name) in &mapping_config.mappings {
+        let Some(left_symbol) = symbol_ref_by_name(left, left_name) else {
+            continue;
+        };
+        if left_used.contains(&left_symbol) {
+            continue;
+        }
+        let Some(right_symbol) = symbol_ref_by_name(right, right_name) else {
+            continue;
+        };
+        if right_used.contains(&right_symbol) {
+            continue;
+        }
+        let left_section = &left.sections[left_symbol.section_idx];
+        let right_section = &right.sections[right_symbol.section_idx];
+        if left_section.kind != right_section.kind {
+            log::warn!(
+                "Symbol section kind mismatch: {} ({:?}) vs {} ({:?})",
+                left_name,
+                left_section.kind,
+                right_name,
+                right_section.kind
+            );
+            continue;
+        }
+        matches.push(SymbolMatch {
+            left: Some(left_symbol),
+            right: Some(right_symbol),
+            prev: None, // TODO
+            section_kind: left_section.kind,
+        });
+        left_used.insert(left_symbol);
+        right_used.insert(right_symbol);
+    }
+    Ok(())
+}
+
 /// Find matching symbols between each object.
 fn matching_symbols(
     left: Option<&ObjInfo>,
     right: Option<&ObjInfo>,
     prev: Option<&ObjInfo>,
+    mappings: &MappingConfig,
 ) -> Result<Vec<SymbolMatch>> {
     let mut matches = Vec::new();
+    let mut left_used = HashSet::new();
     let mut right_used = HashSet::new();
     if let Some(left) = left {
+        if let Some(right) = right {
+            apply_symbol_mappings(
+                left,
+                right,
+                mappings,
+                &mut left_used,
+                &mut right_used,
+                &mut matches,
+            )?;
+        }
         for (section_idx, section) in left.sections.iter().enumerate() {
             for (symbol_idx, symbol) in section.symbols.iter().enumerate() {
+                let symbol_ref = SymbolRef { section_idx, symbol_idx };
+                if left_used.contains(&symbol_ref) {
+                    continue;
+                }
                 let symbol_match = SymbolMatch {
-                    left: Some(SymbolRef { section_idx, symbol_idx }),
+                    left: Some(symbol_ref),
                     right: find_symbol(right, symbol, section, Some(&right_used)),
                     prev: find_symbol(prev, symbol, section, None),
                     section_kind: section.kind,
@@ -575,8 +751,12 @@ fn matching_symbols(
             }
         }
         for (symbol_idx, symbol) in left.common.iter().enumerate() {
+            let symbol_ref = SymbolRef { section_idx: left.sections.len(), symbol_idx };
+            if left_used.contains(&symbol_ref) {
+                continue;
+            }
             let symbol_match = SymbolMatch {
-                left: Some(SymbolRef { section_idx: left.sections.len(), symbol_idx }),
+                left: Some(symbol_ref),
                 right: find_common_symbol(right, symbol),
                 prev: find_common_symbol(prev, symbol),
                 section_kind: ObjSectionKind::Bss,

objdiff-core/src/obj/mod.rs

@@ -112,6 +112,15 @@ pub struct ObjIns {
     pub orig: Option<String>,
 }
 
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash, Default)]
+pub enum ObjSymbolKind {
+    #[default]
+    Unknown,
+    Function,
+    Object,
+    Section,
+}
+
 #[derive(Debug, Clone)]
 pub struct ObjSymbol {
     pub name: String,
@@ -120,6 +129,7 @@ pub struct ObjSymbol {
     pub section_address: u64,
     pub size: u64,
     pub size_known: bool,
+    pub kind: ObjSymbolKind,
     pub flags: ObjSymbolFlagSet,
     pub addend: i64,
     /// Original virtual address (from .note.split section)

objdiff-core/src/obj/read.rs

@@ -23,6 +23,7 @@ use crate::{
     obj::{
         split_meta::{SplitMeta, SPLITMETA_SECTION},
         ObjInfo, ObjReloc, ObjSection, ObjSectionKind, ObjSymbol, ObjSymbolFlagSet, ObjSymbolFlags,
+        ObjSymbolKind,
     },
     util::{read_u16, read_u32},
 };
@@ -94,6 +95,13 @@ fn to_obj_symbol(
         })
         .unwrap_or(&[]);
 
+    let kind = match symbol.kind() {
+        SymbolKind::Text => ObjSymbolKind::Function,
+        SymbolKind::Data => ObjSymbolKind::Object,
+        SymbolKind::Section => ObjSymbolKind::Section,
+        _ => ObjSymbolKind::Unknown,
+    };
+
     Ok(ObjSymbol {
         name: name.to_string(),
         demangled_name,
@@ -101,6 +109,7 @@ fn to_obj_symbol(
         section_address,
         size: symbol.size(),
         size_known: symbol.size() != 0,
+        kind,
         flags,
         addend,
         virtual_address,
@@ -152,26 +161,23 @@ fn symbols_by_section(
     arch: &dyn ObjArch,
     obj_file: &File<'_>,
     section: &ObjSection,
+    section_symbols: &[Symbol<'_, '_>],
     split_meta: Option<&SplitMeta>,
     name_counts: &mut HashMap<String, u32>,
 ) -> Result<Vec<ObjSymbol>> {
     let mut result = Vec::<ObjSymbol>::new();
-    for symbol in obj_file.symbols() {
+    for symbol in section_symbols {
         if symbol.kind() == SymbolKind::Section {
             continue;
         }
-        if let Some(index) = symbol.section().index() {
+        if symbol.is_local() && section.kind == ObjSectionKind::Code {
-            if index.0 == section.orig_index {
+            // TODO strip local syms in diff?
-                if symbol.is_local() && section.kind == ObjSectionKind::Code {
+            let name = symbol.name().context("Failed to process symbol name")?;
-                    // TODO strip local syms in diff?
+            if symbol.size() == 0 || name.starts_with("lbl_") {
-                    let name = symbol.name().context("Failed to process symbol name")?;
+                continue;
-                    if symbol.size() == 0 || name.starts_with("lbl_") {
-                        continue;
-                    }
-                }
-                result.push(to_obj_symbol(arch, obj_file, &symbol, 0, split_meta)?);
             }
         }
+        result.push(to_obj_symbol(arch, obj_file, symbol, 0, split_meta)?);
     }
     result.sort_by(|a, b| a.address.cmp(&b.address).then(a.size.cmp(&b.size)));
     let mut iter = result.iter_mut().peekable();
@@ -182,6 +188,13 @@ fn symbols_by_section(
             } else {
                 symbol.size = (section.address + section.size) - symbol.address;
             }
+            // Set symbol kind if we ended up with a non-zero size
+            if symbol.kind == ObjSymbolKind::Unknown && symbol.size > 0 {
+                symbol.kind = match section.kind {
+                    ObjSectionKind::Code => ObjSymbolKind::Function,
+                    ObjSectionKind::Data | ObjSectionKind::Bss => ObjSymbolKind::Object,
+                };
+            }
         }
     }
     if result.is_empty() {
@@ -199,6 +212,10 @@ fn symbols_by_section(
             section_address: 0,
             size: section.size,
             size_known: true,
+            kind: match section.kind {
+                ObjSectionKind::Code => ObjSymbolKind::Function,
+                ObjSectionKind::Data | ObjSectionKind::Bss => ObjSymbolKind::Object,
+            },
             flags: Default::default(),
             addend: 0,
             virtual_address: None,
@@ -221,47 +238,72 @@ fn common_symbols(
         .collect::<Result<Vec<ObjSymbol>>>()
 }
 
+const LOW_PRIORITY_SYMBOLS: &[&str] =
+    &["__gnu_compiled_c", "__gnu_compiled_cplusplus", "gcc2_compiled."];
+
+fn best_symbol<'r, 'data, 'file>(
+    symbols: &'r [Symbol<'data, 'file>],
+    address: u64,
+) -> Option<&'r Symbol<'data, 'file>> {
+    let closest_symbol_index = match symbols.binary_search_by_key(&address, |s| s.address()) {
+        Ok(index) => Some(index),
+        Err(index) => index.checked_sub(1),
+    }?;
+    let mut best_symbol: Option<&'r Symbol<'data, 'file>> = None;
+    for symbol in symbols.iter().skip(closest_symbol_index) {
+        if symbol.address() > address {
+            break;
+        }
+        if symbol.kind() == SymbolKind::Section
+            || (symbol.size() > 0 && (symbol.address() + symbol.size()) <= address)
+        {
+            continue;
+        }
+        // TODO priority ranking with visibility, etc
+        if let Some(best) = best_symbol {
+            if LOW_PRIORITY_SYMBOLS.contains(&best.name().unwrap_or_default())
+                && !LOW_PRIORITY_SYMBOLS.contains(&symbol.name().unwrap_or_default())
+            {
+                best_symbol = Some(symbol);
+            }
+        } else {
+            best_symbol = Some(symbol);
+        }
+    }
+    best_symbol
+}
+
 fn find_section_symbol(
     arch: &dyn ObjArch,
     obj_file: &File<'_>,
+    section_symbols: &[Symbol<'_, '_>],
     target: &Symbol<'_, '_>,
     address: u64,
     split_meta: Option<&SplitMeta>,
 ) -> Result<ObjSymbol> {
+    if let Some(symbol) = best_symbol(section_symbols, address) {
+        return to_obj_symbol(
+            arch,
+            obj_file,
+            symbol,
+            address as i64 - symbol.address() as i64,
+            split_meta,
+        );
+    }
+    // Fallback to section symbol
     let section_index =
         target.section_index().ok_or_else(|| anyhow::Error::msg("Unknown section index"))?;
     let section = obj_file.section_by_index(section_index)?;
-    let mut closest_symbol: Option<Symbol<'_, '_>> = None;
-    for symbol in obj_file.symbols() {
-        if !matches!(symbol.section_index(), Some(idx) if idx == section_index) {
-            continue;
-        }
-        if symbol.kind() == SymbolKind::Section || symbol.address() != address {
-            if symbol.address() < address
-                && symbol.size() != 0
-                && (closest_symbol.is_none()
-                    || matches!(&closest_symbol, Some(s) if s.address() <= symbol.address()))
-            {
-                closest_symbol = Some(symbol);
-            }
-            continue;
-        }
-        return to_obj_symbol(arch, obj_file, &symbol, 0, split_meta);
-    }
-    let (name, offset) = closest_symbol
-        .and_then(|s| s.name().map(|n| (n, s.address())).ok())
-        .or_else(|| section.name().map(|n| (n, section.address())).ok())
-        .unwrap_or(("<unknown>", 0));
-    let offset_addr = address - offset;
     Ok(ObjSymbol {
-        name: name.to_string(),
+        name: section.name()?.to_string(),
         demangled_name: None,
-        address: offset,
+        address: section.address(),
-        section_address: address - section.address(),
+        section_address: 0,
         size: 0,
         size_known: false,
+        kind: ObjSymbolKind::Section,
         flags: Default::default(),
-        addend: offset_addr as i64,
+        addend: address as i64 - section.address() as i64,
         virtual_address: None,
         original_index: None,
         bytes: Vec::new(),
@@ -272,6 +314,7 @@ fn relocations_by_section(
     arch: &dyn ObjArch,
     obj_file: &File<'_>,
     section: &ObjSection,
+    section_symbols: &[Symbol<'_, '_>],
     split_meta: Option<&SplitMeta>,
 ) -> Result<Vec<ObjReloc>> {
     let obj_section = obj_file.section_by_index(SectionIndex(section.orig_index))?;
@@ -315,7 +358,14 @@ fn relocations_by_section(
             }
             SymbolKind::Section => {
                 ensure!(addend >= 0, "Negative addend in reloc: {addend}");
-                find_section_symbol(arch, obj_file, &symbol, addend as u64, split_meta)
+                find_section_symbol(
+                    arch,
+                    obj_file,
+                    section_symbols,
+                    &symbol,
+                    addend as u64,
+                    split_meta,
+                )
             }
             kind => Err(anyhow!("Unhandled relocation symbol type {kind:?}")),
         }?;
@@ -539,6 +589,7 @@ fn update_combined_symbol(symbol: ObjSymbol, address_change: i64) -> Result<ObjS
         section_address: (symbol.section_address as i64 + address_change).try_into()?,
         size: symbol.size,
         size_known: symbol.size_known,
+        kind: symbol.kind,
         flags: symbol.flags,
         addend: symbol.addend,
         virtual_address: if let Some(virtual_address) = symbol.virtual_address {
@@ -650,15 +701,26 @@ pub fn parse(data: &[u8], config: &DiffObjConfig) -> Result<ObjInfo> {
     let mut sections = filter_sections(&obj_file, split_meta.as_ref())?;
     let mut name_counts: HashMap<String, u32> = HashMap::new();
     for section in &mut sections {
+        let mut symbols = obj_file
+            .symbols()
+            .filter(|s| s.section_index() == Some(SectionIndex(section.orig_index)))
+            .collect::<Vec<_>>();
+        symbols.sort_by_key(|s| s.address());
         section.symbols = symbols_by_section(
             arch.as_ref(),
             &obj_file,
             section,
+            &symbols,
             split_meta.as_ref(),
             &mut name_counts,
         )?;
-        section.relocations =
+        section.relocations = relocations_by_section(
-            relocations_by_section(arch.as_ref(), &obj_file, section, split_meta.as_ref())?;
+            arch.as_ref(),
+            &obj_file,
+            section,
+            &symbols,
+            split_meta.as_ref(),
+        )?;
     }
     if config.combine_data_sections {
         combine_data_sections(&mut sections)?;

objdiff-gui/src/app.rs

@@ -15,7 +15,8 @@ use globset::{Glob, GlobSet};
 use notify::{RecursiveMode, Watcher};
 use objdiff_core::{
     config::{
-        build_globset, ProjectConfigInfo, ProjectObject, ScratchConfig, DEFAULT_WATCH_PATTERNS,
+        build_globset, save_project_config, ProjectConfig, ProjectConfigInfo, ProjectObject,
+        ScratchConfig, SymbolMappings, DEFAULT_WATCH_PATTERNS,
     },
     diff::DiffObjConfig,
 };
@@ -42,11 +43,10 @@ use crate::{
         graphics::{graphics_window, GraphicsConfig, GraphicsViewState},
         jobs::{jobs_menu_ui, jobs_window},
         rlwinm::{rlwinm_decode_window, RlwinmDecodeViewState},
-        symbol_diff::{symbol_diff_ui, DiffViewState, View},
+        symbol_diff::{symbol_diff_ui, DiffViewAction, DiffViewNavigation, DiffViewState, View},
     },
 };
 
-#[derive(Default)]
 pub struct ViewState {
     pub jobs: JobQueue,
     pub config_state: ConfigViewState,
@@ -63,10 +63,34 @@ pub struct ViewState {
     pub show_debug: bool,
     pub show_graphics: bool,
     pub show_jobs: bool,
+    pub show_side_panel: bool,
+}
+
+impl Default for ViewState {
+    fn default() -> Self {
+        Self {
+            jobs: Default::default(),
+            config_state: Default::default(),
+            demangle_state: Default::default(),
+            rlwinm_decode_state: Default::default(),
+            diff_state: Default::default(),
+            graphics_state: Default::default(),
+            frame_history: Default::default(),
+            show_appearance_config: false,
+            show_demangle: false,
+            show_rlwinm_decode: false,
+            show_project_config: false,
+            show_arch_config: false,
+            show_debug: false,
+            show_graphics: false,
+            show_jobs: false,
+            show_side_panel: true,
+        }
+    }
 }
 
 /// The configuration for a single object file.
-#[derive(Clone, Eq, PartialEq, serde::Deserialize, serde::Serialize)]
+#[derive(Default, Clone, Eq, PartialEq, serde::Deserialize, serde::Serialize)]
 pub struct ObjectConfig {
     pub name: String,
     pub target_path: Option<PathBuf>,
@@ -75,6 +99,23 @@ pub struct ObjectConfig {
     pub complete: Option<bool>,
     pub scratch: Option<ScratchConfig>,
     pub source_path: Option<String>,
+    #[serde(default)]
+    pub symbol_mappings: SymbolMappings,
+}
+
+impl From<&ProjectObject> for ObjectConfig {
+    fn from(object: &ProjectObject) -> Self {
+        Self {
+            name: object.name().to_string(),
+            target_path: object.target_path.clone(),
+            base_path: object.base_path.clone(),
+            reverse_fn_order: object.reverse_fn_order(),
+            complete: object.complete(),
+            scratch: object.scratch.clone(),
+            source_path: object.source_path().cloned(),
+            symbol_mappings: object.symbol_mappings.clone().unwrap_or_default(),
+        }
+    }
 }
 
 #[inline]
@@ -94,8 +135,14 @@ pub struct AppState {
     pub obj_change: bool,
     pub queue_build: bool,
     pub queue_reload: bool,
+    pub current_project_config: Option<ProjectConfig>,
     pub project_config_info: Option<ProjectConfigInfo>,
     pub last_mod_check: Instant,
+    /// The right object symbol name that we're selecting a left symbol for
+    pub selecting_left: Option<String>,
+    /// The left object symbol name that we're selecting a right symbol for
+    pub selecting_right: Option<String>,
+    pub config_error: Option<String>,
 }
 
 impl Default for AppState {
@@ -109,8 +156,12 @@ impl Default for AppState {
             obj_change: false,
             queue_build: false,
             queue_reload: false,
+            current_project_config: None,
             project_config_info: None,
             last_mod_check: Instant::now(),
+            selecting_left: None,
+            selecting_right: None,
+            config_error: None,
         }
     }
 }
@@ -191,7 +242,10 @@ impl AppState {
         self.config_change = true;
         self.obj_change = true;
         self.queue_build = false;
+        self.current_project_config = None;
         self.project_config_info = None;
+        self.selecting_left = None;
+        self.selecting_right = None;
     }
 
     pub fn set_target_obj_dir(&mut self, path: PathBuf) {
@@ -199,6 +253,8 @@ impl AppState {
         self.config.selected_obj = None;
         self.obj_change = true;
         self.queue_build = false;
+        self.selecting_left = None;
+        self.selecting_right = None;
     }
 
     pub fn set_base_obj_dir(&mut self, path: PathBuf) {
@@ -206,12 +262,132 @@ impl AppState {
         self.config.selected_obj = None;
         self.obj_change = true;
         self.queue_build = false;
+        self.selecting_left = None;
+        self.selecting_right = None;
     }
 
-    pub fn set_selected_obj(&mut self, object: ObjectConfig) {
+    pub fn set_selected_obj(&mut self, config: ObjectConfig) {
-        self.config.selected_obj = Some(object);
+        let mut unit_changed = true;
+        if let Some(existing) = self.config.selected_obj.as_ref() {
+            if existing == &config {
+                // Don't reload the object if there were no changes
+                return;
+            }
+            if existing.name == config.name {
+                unit_changed = false;
+            }
+        }
+        self.config.selected_obj = Some(config);
+        if unit_changed {
+            self.obj_change = true;
+            self.queue_build = false;
+            self.selecting_left = None;
+            self.selecting_right = None;
+        } else {
+            self.queue_build = true;
+        }
+    }
+
+    pub fn clear_selected_obj(&mut self) {
+        self.config.selected_obj = None;
         self.obj_change = true;
         self.queue_build = false;
+        self.selecting_left = None;
+        self.selecting_right = None;
+    }
+
+    pub fn set_selecting_left(&mut self, right: &str) {
+        let Some(object) = self.config.selected_obj.as_mut() else {
+            return;
+        };
+        object.symbol_mappings.remove_by_right(right);
+        self.selecting_left = Some(right.to_string());
+        self.queue_reload = true;
+        self.save_config();
+    }
+
+    pub fn set_selecting_right(&mut self, left: &str) {
+        let Some(object) = self.config.selected_obj.as_mut() else {
+            return;
+        };
+        object.symbol_mappings.remove_by_left(left);
+        self.selecting_right = Some(left.to_string());
+        self.queue_reload = true;
+        self.save_config();
+    }
+
+    pub fn set_symbol_mapping(&mut self, left: String, right: String) {
+        let Some(object) = self.config.selected_obj.as_mut() else {
+            log::warn!("No selected object");
+            return;
+        };
+        self.selecting_left = None;
+        self.selecting_right = None;
+        if left == right {
+            object.symbol_mappings.remove_by_left(&left);
+            object.symbol_mappings.remove_by_right(&right);
+        } else {
+            object.symbol_mappings.insert(left.clone(), right.clone());
+        }
+        self.queue_reload = true;
+        self.save_config();
+    }
+
+    pub fn clear_selection(&mut self) {
+        self.selecting_left = None;
+        self.selecting_right = None;
+        self.queue_reload = true;
+    }
+
+    pub fn clear_mappings(&mut self) {
+        self.selecting_left = None;
+        self.selecting_right = None;
+        if let Some(object) = self.config.selected_obj.as_mut() {
+            object.symbol_mappings.clear();
+        }
+        self.queue_reload = true;
+        self.save_config();
+    }
+
+    pub fn is_selecting_symbol(&self) -> bool {
+        self.selecting_left.is_some() || self.selecting_right.is_some()
+    }
+
+    pub fn save_config(&mut self) {
+        let (Some(config), Some(info)) =
+            (self.current_project_config.as_mut(), self.project_config_info.as_mut())
+        else {
+            return;
+        };
+        // Update the project config with the current state
+        if let Some(object) = self.config.selected_obj.as_ref() {
+            if let Some(existing) = config.units.as_mut().and_then(|v| {
+                v.iter_mut().find(|u| u.name.as_ref().is_some_and(|n| n == &object.name))
+            }) {
+                existing.symbol_mappings = if object.symbol_mappings.is_empty() {
+                    None
+                } else {
+                    Some(object.symbol_mappings.clone())
+                };
+            }
+            if let Some(existing) =
+                self.objects.iter_mut().find(|u| u.name.as_ref().is_some_and(|n| n == &object.name))
+            {
+                existing.symbol_mappings = if object.symbol_mappings.is_empty() {
+                    None
+                } else {
+                    Some(object.symbol_mappings.clone())
+                };
+            }
+        }
+        // Save the updated project config
+        match save_project_config(config, info) {
+            Ok(new_info) => *info = new_info,
+            Err(e) => {
+                log::error!("Failed to save project config: {e}");
+                self.config_error = Some(format!("Failed to save project config: {e}"));
+            }
+        }
     }
 }
 
@@ -350,31 +526,41 @@ impl App {
         debug_assert!(jobs.results.is_empty());
     }
 
-    fn post_update(&mut self, ctx: &egui::Context) {
+    fn post_update(&mut self, ctx: &egui::Context, action: Option<DiffViewAction>) {
         self.appearance.post_update(ctx);
 
         let ViewState { jobs, diff_state, config_state, graphics_state, .. } = &mut self.view_state;
         config_state.post_update(ctx, jobs, &self.state);
-        diff_state.post_update(ctx, jobs, &self.state);
+        diff_state.post_update(action, ctx, jobs, &self.state);
 
         let Ok(mut state) = self.state.write() else {
             return;
         };
         let state = &mut *state;
 
-        if let Some(info) = &state.project_config_info {
+        let mut mod_check = false;
-            if file_modified(&info.path, info.timestamp) {
+        if state.last_mod_check.elapsed().as_millis() >= 500 {
-                state.config_change = true;
+            state.last_mod_check = Instant::now();
+            mod_check = true;
+        }
+
+        if mod_check {
+            if let Some(info) = &state.project_config_info {
+                if let Some(last_ts) = info.timestamp {
+                    if file_modified(&info.path, last_ts) {
+                        state.config_change = true;
+                    }
+                }
             }
         }
 
         if state.config_change {
             state.config_change = false;
             match load_project_config(state) {
-                Ok(()) => config_state.load_error = None,
+                Ok(()) => state.config_error = None,
                 Err(e) => {
                     log::error!("Failed to load project config: {e}");
-                    config_state.load_error = Some(format!("{e}"));
+                    state.config_error = Some(format!("{e}"));
                 }
             }
         }
@@ -409,8 +595,7 @@ impl App {
         }
 
         if let Some(result) = &diff_state.build {
-            if state.last_mod_check.elapsed().as_millis() >= 500 {
+            if mod_check {
-                state.last_mod_check = Instant::now();
                 if let Some((obj, _)) = &result.first_obj {
                     if let (Some(path), Some(timestamp)) = (&obj.path, obj.timestamp) {
                         if file_modified(path, timestamp) {
@@ -434,11 +619,11 @@ impl App {
             && state.config.selected_obj.is_some()
             && !jobs.is_running(Job::ObjDiff)
         {
-            jobs.push(start_build(ctx, ObjDiffConfig::from_config(&state.config)));
+            jobs.push(start_build(ctx, ObjDiffConfig::from_state(state)));
             state.queue_build = false;
             state.queue_reload = false;
         } else if state.queue_reload && !jobs.is_running(Job::ObjDiff) {
-            let mut diff_config = ObjDiffConfig::from_config(&state.config);
+            let mut diff_config = ObjDiffConfig::from_state(state);
             // Don't build, just reload the current files
             diff_config.build_base = false;
             diff_config.build_target = false;
@@ -485,12 +670,26 @@ impl eframe::App for App {
             show_debug,
             show_graphics,
             show_jobs,
+            show_side_panel,
         } = view_state;
 
         frame_history.on_new_frame(ctx.input(|i| i.time), frame.info().cpu_usage);
 
+        let side_panel_available = diff_state.current_view == View::SymbolDiff;
+
         egui::TopBottomPanel::top("top_panel").show(ctx, |ui| {
             egui::menu::bar(ui, |ui| {
+                if ui
+                    .add_enabled(
+                        side_panel_available,
+                        egui::Button::new(if *show_side_panel { "⏴" } else { "⏵" }),
+                    )
+                    .on_hover_text("Toggle side panel")
+                    .clicked()
+                {
+                    *show_side_panel = !*show_side_panel;
+                }
+                ui.separator();
                 ui.menu_button("File", |ui| {
                     #[cfg(debug_assertions)]
                     if ui.button("Debug…").clicked() {
@@ -599,6 +798,11 @@ impl eframe::App for App {
                     {
                         state.queue_reload = true;
                     }
+                    if ui.button("Clear custom symbol mappings").clicked() {
+                        state.clear_mappings();
+                        diff_state.post_build_nav = Some(DiffViewNavigation::symbol_diff());
+                        state.queue_reload = true;
+                    }
                 });
                 ui.separator();
                 if jobs_menu_ui(ui, jobs, appearance) {
@@ -607,31 +811,28 @@ impl eframe::App for App {
             });
         });
 
-        let build_success = matches!(&diff_state.build, Some(b) if b.first_status.success && b.second_status.success);
+        if side_panel_available {
-        if diff_state.current_view == View::FunctionDiff && build_success {
+            egui::SidePanel::left("side_panel").show_animated(ctx, *show_side_panel, |ui| {
-            egui::CentralPanel::default().show(ctx, |ui| {
-                function_diff_ui(ui, diff_state, appearance);
-            });
-        } else if diff_state.current_view == View::DataDiff && build_success {
-            egui::CentralPanel::default().show(ctx, |ui| {
-                data_diff_ui(ui, diff_state, appearance);
-            });
-        } else if diff_state.current_view == View::ExtabDiff && build_success {
-            egui::CentralPanel::default().show(ctx, |ui| {
-                extab_diff_ui(ui, diff_state, appearance);
-            });
-        } else {
-            egui::SidePanel::left("side_panel").show(ctx, |ui| {
                 egui::ScrollArea::both().show(ui, |ui| {
                     config_ui(ui, state, show_project_config, config_state, appearance);
                 });
             });
-
-            egui::CentralPanel::default().show(ctx, |ui| {
-                symbol_diff_ui(ui, diff_state, appearance);
-            });
         }
 
+        let mut action = None;
+        egui::CentralPanel::default().show(ctx, |ui| {
+            let build_success = matches!(&diff_state.build, Some(b) if b.first_status.success && b.second_status.success);
+            action = if diff_state.current_view == View::FunctionDiff && build_success {
+                function_diff_ui(ui, diff_state, appearance)
+            } else if diff_state.current_view == View::DataDiff && build_success {
+                data_diff_ui(ui, diff_state, appearance)
+            } else if diff_state.current_view == View::ExtabDiff && build_success {
+                extab_diff_ui(ui, diff_state, appearance)
+            } else {
+                symbol_diff_ui(ui, diff_state, appearance)
+            };
+        });
+
         project_window(ctx, state, show_project_config, config_state, appearance);
         appearance_window(ctx, show_appearance_config, appearance);
         demangle_window(ctx, show_demangle, demangle_state, appearance);
@@ -641,10 +842,10 @@ impl eframe::App for App {
         graphics_window(ctx, show_graphics, frame_history, graphics_state, appearance);
         jobs_window(ctx, show_jobs, jobs, appearance);
 
-        self.post_update(ctx);
+        self.post_update(ctx, action);
     }
 
-    /// Called by the frame work to save state before shutdown.
+    /// Called by the framework to save state before shutdown.
     fn save(&mut self, storage: &mut dyn eframe::Storage) {
         if let Ok(state) = self.state.read() {
             eframe::set_value(storage, CONFIG_KEY, &state.config);

objdiff-gui/src/app_config.rs

@@ -2,6 +2,10 @@ use std::path::PathBuf;
 
 use eframe::Storage;
 use globset::Glob;
+use objdiff_core::{
+    config::ScratchConfig,
+    diff::{ArmArchVersion, ArmR9Usage, DiffObjConfig, MipsAbi, MipsInstrCategory, X86Formatter},
+};
 
 use crate::app::{AppConfig, ObjectConfig, CONFIG_KEY};
 
@@ -11,7 +15,7 @@ pub struct AppConfigVersion {
 }
 
 impl Default for AppConfigVersion {
-    fn default() -> Self { Self { version: 1 } }
+    fn default() -> Self { Self { version: 2 } }
 }
 
 /// Deserialize the AppConfig from storage, handling upgrades from older versions.
@@ -19,7 +23,8 @@ pub fn deserialize_config(storage: &dyn Storage) -> Option<AppConfig> {
     let str = storage.get_string(CONFIG_KEY)?;
     match ron::from_str::<AppConfigVersion>(&str) {
         Ok(version) => match version.version {
-            1 => from_str::<AppConfig>(&str),
+            2 => from_str::<AppConfig>(&str),
+            1 => from_str::<AppConfigV1>(&str).map(|c| c.into_config()),
             _ => {
                 log::warn!("Unknown config version: {}", version.version);
                 None
@@ -44,6 +49,180 @@ where T: serde::de::DeserializeOwned {
     }
 }
 
+#[derive(serde::Deserialize, serde::Serialize)]
+pub struct ScratchConfigV1 {
+    #[serde(default)]
+    pub platform: Option<String>,
+    #[serde(default)]
+    pub compiler: Option<String>,
+    #[serde(default)]
+    pub c_flags: Option<String>,
+    #[serde(default)]
+    pub ctx_path: Option<PathBuf>,
+    #[serde(default)]
+    pub build_ctx: bool,
+}
+
+impl ScratchConfigV1 {
+    fn into_config(self) -> ScratchConfig {
+        ScratchConfig {
+            platform: self.platform,
+            compiler: self.compiler,
+            c_flags: self.c_flags,
+            ctx_path: self.ctx_path,
+            build_ctx: self.build_ctx.then_some(true),
+        }
+    }
+}
+
+#[derive(serde::Deserialize, serde::Serialize)]
+pub struct ObjectConfigV1 {
+    pub name: String,
+    pub target_path: Option<PathBuf>,
+    pub base_path: Option<PathBuf>,
+    pub reverse_fn_order: Option<bool>,
+    pub complete: Option<bool>,
+    pub scratch: Option<ScratchConfigV1>,
+    pub source_path: Option<String>,
+}
+
+impl ObjectConfigV1 {
+    fn into_config(self) -> ObjectConfig {
+        ObjectConfig {
+            name: self.name,
+            target_path: self.target_path,
+            base_path: self.base_path,
+            reverse_fn_order: self.reverse_fn_order,
+            complete: self.complete,
+            scratch: self.scratch.map(|scratch| scratch.into_config()),
+            source_path: self.source_path,
+            ..Default::default()
+        }
+    }
+}
+
+#[derive(serde::Deserialize, serde::Serialize)]
+#[serde(default)]
+pub struct DiffObjConfigV1 {
+    pub relax_reloc_diffs: bool,
+    #[serde(default = "bool_true")]
+    pub space_between_args: bool,
+    pub combine_data_sections: bool,
+    // x86
+    pub x86_formatter: X86Formatter,
+    // MIPS
+    pub mips_abi: MipsAbi,
+    pub mips_instr_category: MipsInstrCategory,
+    // ARM
+    pub arm_arch_version: ArmArchVersion,
+    pub arm_unified_syntax: bool,
+    pub arm_av_registers: bool,
+    pub arm_r9_usage: ArmR9Usage,
+    pub arm_sl_usage: bool,
+    pub arm_fp_usage: bool,
+    pub arm_ip_usage: bool,
+}
+
+impl Default for DiffObjConfigV1 {
+    fn default() -> Self {
+        Self {
+            relax_reloc_diffs: false,
+            space_between_args: true,
+            combine_data_sections: false,
+            x86_formatter: Default::default(),
+            mips_abi: Default::default(),
+            mips_instr_category: Default::default(),
+            arm_arch_version: Default::default(),
+            arm_unified_syntax: true,
+            arm_av_registers: false,
+            arm_r9_usage: Default::default(),
+            arm_sl_usage: false,
+            arm_fp_usage: false,
+            arm_ip_usage: false,
+        }
+    }
+}
+
+impl DiffObjConfigV1 {
+    fn into_config(self) -> DiffObjConfig {
+        DiffObjConfig {
+            relax_reloc_diffs: self.relax_reloc_diffs,
+            space_between_args: self.space_between_args,
+            combine_data_sections: self.combine_data_sections,
+            x86_formatter: self.x86_formatter,
+            mips_abi: self.mips_abi,
+            mips_instr_category: self.mips_instr_category,
+            arm_arch_version: self.arm_arch_version,
+            arm_unified_syntax: self.arm_unified_syntax,
+            arm_av_registers: self.arm_av_registers,
+            arm_r9_usage: self.arm_r9_usage,
+            arm_sl_usage: self.arm_sl_usage,
+            arm_fp_usage: self.arm_fp_usage,
+            arm_ip_usage: self.arm_ip_usage,
+            ..Default::default()
+        }
+    }
+}
+
+#[inline]
+fn bool_true() -> bool { true }
+
+#[derive(serde::Deserialize, serde::Serialize)]
+pub struct AppConfigV1 {
+    pub version: u32,
+    #[serde(default)]
+    pub custom_make: Option<String>,
+    #[serde(default)]
+    pub custom_args: Option<Vec<String>>,
+    #[serde(default)]
+    pub selected_wsl_distro: Option<String>,
+    #[serde(default)]
+    pub project_dir: Option<PathBuf>,
+    #[serde(default)]
+    pub target_obj_dir: Option<PathBuf>,
+    #[serde(default)]
+    pub base_obj_dir: Option<PathBuf>,
+    #[serde(default)]
+    pub selected_obj: Option<ObjectConfigV1>,
+    #[serde(default = "bool_true")]
+    pub build_base: bool,
+    #[serde(default)]
+    pub build_target: bool,
+    #[serde(default = "bool_true")]
+    pub rebuild_on_changes: bool,
+    #[serde(default)]
+    pub auto_update_check: bool,
+    #[serde(default)]
+    pub watch_patterns: Vec<Glob>,
+    #[serde(default)]
+    pub recent_projects: Vec<PathBuf>,
+    #[serde(default)]
+    pub diff_obj_config: DiffObjConfigV1,
+}
+
+impl AppConfigV1 {
+    fn into_config(self) -> AppConfig {
+        log::info!("Upgrading configuration from v1");
+        AppConfig {
+            custom_make: self.custom_make,
+            custom_args: self.custom_args,
+            selected_wsl_distro: self.selected_wsl_distro,
+            project_dir: self.project_dir,
+            target_obj_dir: self.target_obj_dir,
+            base_obj_dir: self.base_obj_dir,
+            selected_obj: self.selected_obj.map(|obj| obj.into_config()),
+            build_base: self.build_base,
+            build_target: self.build_target,
+            rebuild_on_changes: self.rebuild_on_changes,
+            auto_update_check: self.auto_update_check,
+            watch_patterns: self.watch_patterns,
+            recent_projects: self.recent_projects,
+            diff_obj_config: self.diff_obj_config.into_config(),
+            ..Default::default()
+        }
+    }
+}
+
 #[derive(serde::Deserialize, serde::Serialize)]
 pub struct ObjectConfigV0 {
     pub name: String,
@@ -59,9 +238,7 @@ impl ObjectConfigV0 {
             target_path: Some(self.target_path),
             base_path: Some(self.base_path),
             reverse_fn_order: self.reverse_fn_order,
-            complete: None,
+            ..Default::default()
-            scratch: None,
-            source_path: None,
         }
     }
 }

objdiff-gui/src/config.rs

@@ -4,11 +4,11 @@ use anyhow::Result;
 use globset::Glob;
 use objdiff_core::config::{try_project_config, ProjectObject, DEFAULT_WATCH_PATTERNS};
 
-use crate::app::AppState;
+use crate::app::{AppState, ObjectConfig};
 
 #[derive(Clone)]
 pub enum ProjectObjectNode {
-    File(String, Box<ProjectObject>),
+    Unit(String, usize),
     Dir(String, Vec<ProjectObjectNode>),
 }
 
@@ -33,17 +33,18 @@ fn find_dir<'a>(
 }
 
 fn build_nodes(
-    objects: &[ProjectObject],
+    units: &mut [ProjectObject],
     project_dir: &Path,
     target_obj_dir: Option<&Path>,
     base_obj_dir: Option<&Path>,
 ) -> Vec<ProjectObjectNode> {
     let mut nodes = vec![];
-    for object in objects {
+    for (idx, unit) in units.iter_mut().enumerate() {
+        unit.resolve_paths(project_dir, target_obj_dir, base_obj_dir);
         let mut out_nodes = &mut nodes;
-        let path = if let Some(name) = &object.name {
+        let path = if let Some(name) = &unit.name {
             Path::new(name)
-        } else if let Some(path) = &object.path {
+        } else if let Some(path) = &unit.path {
             path
         } else {
             continue;
@@ -56,10 +57,8 @@ fn build_nodes(
                 }
             }
         }
-        let mut object = Box::new(object.clone());
-        object.resolve_paths(project_dir, target_obj_dir, base_obj_dir);
         let filename = path.file_name().unwrap().to_str().unwrap().to_string();
-        out_nodes.push(ProjectObjectNode::File(filename, object));
+        out_nodes.push(ProjectObjectNode::Unit(filename, idx));
     }
     nodes
 }
@@ -70,24 +69,36 @@ pub fn load_project_config(state: &mut AppState) -> Result<()> {
     };
     if let Some((result, info)) = try_project_config(project_dir) {
         let project_config = result?;
-        state.config.custom_make = project_config.custom_make;
+        state.config.custom_make = project_config.custom_make.clone();
-        state.config.custom_args = project_config.custom_args;
+        state.config.custom_args = project_config.custom_args.clone();
-        state.config.target_obj_dir = project_config.target_dir.map(|p| project_dir.join(p));
+        state.config.target_obj_dir =
-        state.config.base_obj_dir = project_config.base_dir.map(|p| project_dir.join(p));
+            project_config.target_dir.as_deref().map(|p| project_dir.join(p));
-        state.config.build_base = project_config.build_base;
+        state.config.base_obj_dir = project_config.base_dir.as_deref().map(|p| project_dir.join(p));
-        state.config.build_target = project_config.build_target;
+        state.config.build_base = project_config.build_base.unwrap_or(true);
-        state.config.watch_patterns = project_config.watch_patterns.unwrap_or_else(|| {
+        state.config.build_target = project_config.build_target.unwrap_or(false);
+        state.config.watch_patterns = project_config.watch_patterns.clone().unwrap_or_else(|| {
             DEFAULT_WATCH_PATTERNS.iter().map(|s| Glob::new(s).unwrap()).collect()
         });
         state.watcher_change = true;
-        state.objects = project_config.objects;
+        state.objects = project_config.units.clone().unwrap_or_default();
         state.object_nodes = build_nodes(
-            &state.objects,
+            &mut state.objects,
             project_dir,
             state.config.target_obj_dir.as_deref(),
             state.config.base_obj_dir.as_deref(),
         );
+        state.current_project_config = Some(project_config);
         state.project_config_info = Some(info);
+
+        // Reload selected object
+        if let Some(selected_obj) = &state.config.selected_obj {
+            if let Some(obj) = state.objects.iter().find(|o| o.name() == selected_obj.name) {
+                let config = ObjectConfig::from(obj);
+                state.set_selected_obj(config);
+            } else {
+                state.clear_selected_obj();
+            }
+        }
     }
     Ok(())
 }

objdiff-gui/src/jobs/create_scratch.rs

@@ -39,7 +39,7 @@ impl CreateScratchConfig {
         Ok(Self {
             build_config: BuildConfig::from_config(config),
             context_path: scratch_config.ctx_path.clone(),
-            build_context: scratch_config.build_ctx,
+            build_context: scratch_config.build_ctx.unwrap_or(false),
             compiler: scratch_config.compiler.clone().unwrap_or_default(),
             platform: scratch_config.platform.clone().unwrap_or_default(),
             compiler_flags: scratch_config.c_flags.clone().unwrap_or_default(),

objdiff-gui/src/jobs/mod.rs

@@ -53,7 +53,7 @@ impl JobQueue {
     }
 
     /// Returns whether any job is running.
-    #[allow(dead_code)]
+    #[expect(dead_code)]
     pub fn any_running(&self) -> bool {
         self.jobs.iter().any(|job| {
             if let Some(handle) = &job.handle {

objdiff-gui/src/jobs/objdiff.rs

@@ -6,13 +6,13 @@ use std::{
 
 use anyhow::{anyhow, Error, Result};
 use objdiff_core::{
-    diff::{diff_objs, DiffObjConfig, ObjDiff},
+    diff::{diff_objs, DiffObjConfig, MappingConfig, ObjDiff},
     obj::{read, ObjInfo},
 };
 use time::OffsetDateTime;
 
 use crate::{
-    app::{AppConfig, ObjectConfig},
+    app::{AppConfig, AppState, ObjectConfig},
     jobs::{start_job, update_status, Job, JobContext, JobResult, JobState},
 };
 
@@ -60,16 +60,20 @@ pub struct ObjDiffConfig {
     pub build_target: bool,
     pub selected_obj: Option<ObjectConfig>,
     pub diff_obj_config: DiffObjConfig,
+    pub selecting_left: Option<String>,
+    pub selecting_right: Option<String>,
 }
 
 impl ObjDiffConfig {
-    pub(crate) fn from_config(config: &AppConfig) -> Self {
+    pub(crate) fn from_state(state: &AppState) -> Self {
         Self {
-            build_config: BuildConfig::from_config(config),
+            build_config: BuildConfig::from_config(&state.config),
-            build_base: config.build_base,
+            build_base: state.config.build_base,
-            build_target: config.build_target,
+            build_target: state.config.build_target,
-            selected_obj: config.selected_obj.clone(),
+            selected_obj: state.config.selected_obj.clone(),
-            diff_obj_config: config.diff_obj_config.clone(),
+            diff_obj_config: state.config.diff_obj_config.clone(),
+            selecting_left: state.selecting_left.clone(),
+            selecting_right: state.selecting_right.clone(),
         }
     }
 }
@@ -158,9 +162,16 @@ pub(crate) fn run_make(config: &BuildConfig, arg: &Path) -> BuildStatus {
 fn run_build(
     context: &JobContext,
     cancel: Receiver<()>,
-    config: ObjDiffConfig,
+    mut config: ObjDiffConfig,
 ) -> Result<Box<ObjDiffResult>> {
-    let obj_config = config.selected_obj.as_ref().ok_or_else(|| Error::msg("Missing obj path"))?;
+    let obj_config = config.selected_obj.ok_or_else(|| Error::msg("Missing obj path"))?;
+    // Use the per-object symbol mappings, we don't set mappings globally
+    config.diff_obj_config.symbol_mappings = MappingConfig {
+        mappings: obj_config.symbol_mappings,
+        selecting_left: config.selecting_left,
+        selecting_right: config.selecting_right,
+    };
+
     let project_dir = config
         .build_config
         .project_dir