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Make function size inference logic arch-specific

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For MIPS, account for delay slot nops. For x86,
check for trailing nops (0x90). For PPC, check
for 4-byte 0x00 padding.

Resolves #229
This commit is contained in:
Luke Street
2025-08-02 10:56:26 -06:00
parent 1205e8ceb4
commit 1e62d4664c
12 changed files with 131 additions and 146 deletions
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22
objdiff-core/src/obj/read.rs
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@@ -122,7 +122,7 @@ fn map_symbols(
}
// Infer symbol sizes for 0-size symbols
infer_symbol_sizes(&mut symbols, sections);
infer_symbol_sizes(arch, &mut symbols, sections)?;
Ok((symbols, symbol_indices))
}
@@ -136,7 +136,7 @@ fn is_local_label(symbol: &Symbol) -> bool {
&& LABEL_PREFIXES.iter().any(|p| symbol.name.starts_with(p))
}
fn infer_symbol_sizes(symbols: &mut [Symbol], sections: &[Section]) {
fn infer_symbol_sizes(arch: &dyn Arch, symbols: &mut [Symbol], sections: &[Section]) -> Result<()> {
// Create a sorted list of symbol indices by section
let mut symbols_with_section = Vec::<usize>::with_capacity(symbols.len());
for (i, symbol) in symbols.iter().enumerate() {
@@ -206,18 +206,13 @@ fn infer_symbol_sizes(symbols: &mut [Symbol], sections: &[Section]) {
iter_idx += 1;
};
let section = &sections[section_idx];
let mut next_address =
let next_address =
next_symbol.map(|s| s.address).unwrap_or_else(|| section.address + section.size);
if section.kind == SectionKind::Code {
// For functions, trim any trailing 4-byte zeroes from the end (padding, nops)
while next_address > symbol.address + 4
&& let Some(data) = section.data_range(next_address - 4, 4)
&& data == [0u8; 4]
{
next_address -= 4;
}
}
let new_size = next_address.saturating_sub(symbol.address);
let new_size = if section.kind == SectionKind::Code {
arch.infer_function_size(symbol, section, next_address)?
} else {
next_address.saturating_sub(symbol.address)
};
if new_size > 0 {
let symbol = &mut symbols[symbol_idx];
symbol.size = new_size;
@@ -234,6 +229,7 @@ fn infer_symbol_sizes(symbols: &mut [Symbol], sections: &[Section]) {
}
}
}
Ok(())
}
fn map_sections(