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Skip label symbols when inferring symbol sizes

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COFF objects in particular don't contain the size of
symbols. We infer the size of these symbols by
extending them to the next symbol. If a tool emits
symbols for branch targets, this causes the inferred
size to be too small.

This checks if a symbol starts with a certain prefix
(right now, just .L or LAB_), and skips over it
during symbol size inference.

Resolves #174
This commit is contained in:
Luke Street
2025-05-13 22:36:02 -06:00
parent e865f3d598
commit 8e8ab6bef8
6 changed files with 204 additions and 22 deletions
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9
objdiff-core/tests/arch_x86.rs
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@@ -68,3 +68,12 @@ fn read_x86_jumptable() {
let output = common::display_diff(&obj, &diff, symbol_idx, &diff_config);
insta::assert_snapshot!(output);
}
// Inferred size of functions should ignore symbols with specific prefixes
#[test]
#[cfg(feature = "x86")]
fn read_x86_local_labels() {
let diff_config = diff::DiffObjConfig::default();
let obj = obj::read::parse(include_object!("data/x86/local_labels.obj"), &diff_config).unwrap();
insta::assert_debug_snapshot!(obj);
}

BIN
objdiff-core/tests/data/x86/local_labels.obj Normal file
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163
objdiff-core/tests/snapshots/arch_x86__read_x86_local_labels.snap Normal file
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@@ -0,0 +1,163 @@
---
source: objdiff-core/tests/arch_x86.rs
expression: obj
---
Object {
arch: ArchX86 {
arch: X86,
endianness: Little,
},
endianness: Little,
symbols: [
Symbol {
name: "42b830_convertToUppercaseShiftJIS.obj",
demangled_name: None,
address: 0,
size: 0,
kind: Unknown,
section: None,
flags: FlagSet(Local),
align: None,
virtual_address: None,
},
Symbol {
name: "[.text]",
demangled_name: None,
address: 0,
size: 0,
kind: Section,
section: Some(
0,
),
flags: FlagSet(Local),
align: None,
virtual_address: None,
},
Symbol {
name: "LAB_0042b850",
demangled_name: None,
address: 32,
size: 0,
kind: Object,
section: Some(
0,
),
flags: FlagSet(Local),
align: None,
virtual_address: None,
},
Symbol {
name: "LAB_0042b883",
demangled_name: None,
address: 83,
size: 0,
kind: Object,
section: Some(
0,
),
flags: FlagSet(Local),
align: None,
virtual_address: None,
},
Symbol {
name: "LAB_0042b87c",
demangled_name: None,
address: 76,
size: 0,
kind: Object,
section: Some(
0,
),
flags: FlagSet(Local),
align: None,
virtual_address: None,
},
Symbol {
name: "LAB_0042b884",
demangled_name: None,
address: 84,
size: 0,
kind: Object,
section: Some(
0,
),
flags: FlagSet(Local),
align: None,
virtual_address: None,
},
Symbol {
name: "LAB_0042b889",
demangled_name: None,
address: 89,
size: 0,
kind: Object,
section: Some(
0,
),
flags: FlagSet(Local),
align: None,
virtual_address: None,
},
Symbol {
name: "LAB_0042b845",
demangled_name: None,
address: 21,
size: 0,
kind: Object,
section: Some(
0,
),
flags: FlagSet(Local),
align: None,
virtual_address: None,
},
Symbol {
name: "LAB_0042b869",
demangled_name: None,
address: 57,
size: 0,
kind: Object,
section: Some(
0,
),
flags: FlagSet(Local),
align: None,
virtual_address: None,
},
Symbol {
name: "ConvertToUppercaseShiftJIS",
demangled_name: None,
address: 0,
size: 92,
kind: Function,
section: Some(
0,
),
flags: FlagSet(Global | SizeInferred),
align: None,
virtual_address: None,
},
],
sections: [
Section {
id: ".text-0",
name: ".text",
address: 0,
size: 92,
kind: Code,
data: SectionData(
92,
),
flags: FlagSet(),
align: Some(
16,
),
relocations: [],
line_info: {},
virtual_address: None,
},
],
split_meta: None,
path: None,
timestamp: None,
}