Check relocation addends when diffing functions (#158)

* Check relocation addends when diffing functions

* Also highlight addend when reloc differs

objdiff-cli/src/views/function_diff.rs

@@ -1,3 +1,5 @@
+use std::cmp::Ordering;
+
 use anyhow::{bail, Result};
 use crossterm::event::{Event, KeyCode, KeyEventKind, KeyModifiers, MouseButton, MouseEventKind};
 use objdiff_core::{
@@ -563,6 +565,18 @@ impl FunctionDiffUi {
                             base_color = Color::White;
                         }
                     }
+                    DiffText::Addend(addend, diff) => {
+                        label_text = match addend.cmp(&0i64) {
+                            Ordering::Greater => format!("+{:#x}", addend),
+                            Ordering::Less => format!("-{:#x}", -addend),
+                            _ => "".to_string(),
+                        };
+                        if let Some(diff) = diff {
+                            base_color = COLOR_ROTATION[diff.idx % COLOR_ROTATION.len()]
+                        } else {
+                            base_color = Color::White;
+                        }
+                    }
                     DiffText::Spacing(n) => {
                         line.spans.push(Span::raw(" ".repeat(n)));
                         sx += n as u16;

objdiff-core/src/diff/code.rs

@@ -192,8 +192,18 @@ fn resolve_branches(vec: &mut [ObjInsDiff]) {
     }
 }
 
-fn address_eq(left: &ObjReloc, right: &ObjReloc) -> bool {
-    left.target.address as i64 + left.addend == right.target.address as i64 + right.addend
+pub fn address_eq(left: &ObjReloc, right: &ObjReloc) -> bool {
+    if right.target.size == 0 && left.target.size != 0 {
+        // The base relocation is against a pool but the target relocation isn't.
+        // This can happen in rare cases where the compiler will generate a pool+addend relocation
+        // in the base's data, but the one detected in the target is direct with no addend.
+        // Just check that the final address is the same so these count as a match.
+        left.target.address as i64 + left.addend == right.target.address as i64 + right.addend
+    } else {
+        // But otherwise, if the compiler isn't using a pool, we're more strict and check that the
+        // target symbol address and relocation addend both match exactly.
+        left.target.address == right.target.address && left.addend == right.addend
+    }
 }
 
 pub fn section_name_eq(
@@ -235,13 +245,14 @@ fn reloc_eq(
         return true;
     }
 
-    let symbol_name_matches = left.target.name == right.target.name;
+    let symbol_name_addend_matches =
+        left.target.name == right.target.name && left.addend == right.addend;
     match (&left.target.orig_section_index, &right.target.orig_section_index) {
         (Some(sl), Some(sr)) => {
-            // Match if section and name or address match
+            // Match if section and name+addend or address match
             section_name_eq(left_obj, right_obj, *sl, *sr)
                 && (config.function_reloc_diffs == FunctionRelocDiffs::DataValue
-                    || symbol_name_matches
+                    || symbol_name_addend_matches
                     || address_eq(left, right))
                 && (config.function_reloc_diffs == FunctionRelocDiffs::NameAddress
                     || left.target.kind != ObjSymbolKind::Object
@@ -251,9 +262,9 @@ fn reloc_eq(
         (Some(_), None) => false,
         (None, Some(_)) => {
             // Match if possibly stripped weak symbol
-            symbol_name_matches && right.target.flags.0.contains(ObjSymbolFlags::Weak)
+            symbol_name_addend_matches && right.target.flags.0.contains(ObjSymbolFlags::Weak)
         }
-        (None, None) => symbol_name_matches,
+        (None, None) => symbol_name_addend_matches,
     }
 }
 

objdiff-core/src/diff/data.rs

@@ -6,7 +6,7 @@ use std::{
 use anyhow::{anyhow, Result};
 use similar::{capture_diff_slices_deadline, get_diff_ratio, Algorithm};
 
-use super::code::section_name_eq;
+use super::code::{address_eq, section_name_eq};
 use crate::{
     diff::{ObjDataDiff, ObjDataDiffKind, ObjDataRelocDiff, ObjSectionDiff, ObjSymbolDiff},
     obj::{ObjInfo, ObjReloc, ObjSection, ObjSymbolFlags, SymbolRef},
@@ -41,39 +41,25 @@ pub fn no_diff_symbol(_obj: &ObjInfo, symbol_ref: SymbolRef) -> ObjSymbolDiff {
     ObjSymbolDiff { symbol_ref, target_symbol: None, instructions: vec![], match_percent: None }
 }
 
-fn address_eq(left: &ObjReloc, right: &ObjReloc) -> bool {
-    if right.target.size == 0 && left.target.size != 0 {
-        // The base relocation is against a pool but the target relocation isn't.
-        // This can happen in rare cases where the compiler will generate a pool+addend relocation
-        // in the base, but the one detected in the target is direct with no addend.
-        // Just check that the final address is the same so these count as a match.
-        left.target.address as i64 + left.addend == right.target.address as i64 + right.addend
-    } else {
-        // But otherwise, if the compiler isn't using a pool, we're more strict and check that the
-        // target symbol address and relocation addend both match exactly.
-        left.target.address == right.target.address && left.addend == right.addend
-    }
-}
-
 fn reloc_eq(left_obj: &ObjInfo, right_obj: &ObjInfo, left: &ObjReloc, right: &ObjReloc) -> bool {
     if left.flags != right.flags {
         return false;
     }
 
-    let symbol_name_matches = left.target.name == right.target.name;
+    let symbol_name_addend_matches =
+        left.target.name == right.target.name && left.addend == right.addend;
     match (&left.target.orig_section_index, &right.target.orig_section_index) {
         (Some(sl), Some(sr)) => {
             // Match if section and name+addend or address match
             section_name_eq(left_obj, right_obj, *sl, *sr)
-                && ((symbol_name_matches && left.addend == right.addend) || address_eq(left, right))
+                && (symbol_name_addend_matches || address_eq(left, right))
         }
         (Some(_), None) => false,
         (None, Some(_)) => {
             // Match if possibly stripped weak symbol
-            (symbol_name_matches && left.addend == right.addend)
-                && right.target.flags.0.contains(ObjSymbolFlags::Weak)
+            symbol_name_addend_matches && right.target.flags.0.contains(ObjSymbolFlags::Weak)
         }
-        (None, None) => symbol_name_matches,
+        (None, None) => symbol_name_addend_matches,
     }
 }
 

objdiff-core/src/diff/display.rs

@@ -1,5 +1,3 @@
-use std::cmp::Ordering;
-
 use crate::{
     diff::{ObjInsArgDiff, ObjInsDiff},
     obj::{ObjInsArg, ObjInsArgValue, ObjReloc, ObjSymbol},
@@ -23,6 +21,8 @@ pub enum DiffText<'a> {
     BranchDest(u64, Option<&'a ObjInsArgDiff>),
     /// Symbol name
     Symbol(&'a ObjSymbol, Option<&'a ObjInsArgDiff>),
+    /// Relocation addend
+    Addend(i64, Option<&'a ObjInsArgDiff>),
     /// Number of spaces
     Spacing(usize),
     /// End of line
@@ -99,11 +99,7 @@ fn display_reloc_name<E>(
     diff: Option<&ObjInsArgDiff>,
 ) -> Result<(), E> {
     cb(DiffText::Symbol(&reloc.target, diff))?;
-    match reloc.addend.cmp(&0i64) {
-        Ordering::Greater => cb(DiffText::Basic(&format!("+{:#x}", reloc.addend))),
-        Ordering::Less => cb(DiffText::Basic(&format!("-{:#x}", -reloc.addend))),
-        _ => Ok(()),
-    }
+    cb(DiffText::Addend(reloc.addend, diff))
 }
 
 impl PartialEq<DiffText<'_>> for HighlightKind {

objdiff-gui/src/views/function_diff.rs

@@ -324,6 +324,18 @@ fn diff_text_ui(
                 base_color = appearance.emphasized_text_color;
             }
         }
+        DiffText::Addend(addend, diff) => {
+            label_text = match addend.cmp(&0i64) {
+                Ordering::Greater => format!("+{:#x}", addend),
+                Ordering::Less => format!("-{:#x}", -addend),
+                _ => "".to_string(),
+            };
+            if let Some(diff) = diff {
+                base_color = appearance.diff_colors[diff.idx % appearance.diff_colors.len()]
+            } else {
+                base_color = appearance.emphasized_text_color;
+            }
+        }
         DiffText::Spacing(n) => {
             ui.add_space(n as f32 * space_width);
             return ret;