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//! Line info generation (`.debug_line`)
use std::ffi::OsStr;
use std::path::{Component, Path};
use crate::prelude::*;
use rustc_span::{
FileName, Pos, SourceFile, SourceFileAndLine, SourceFileHash, SourceFileHashAlgorithm,
};
use cranelift_codegen::binemit::CodeOffset;
use cranelift_codegen::MachSrcLoc;
use gimli::write::{
Address, AttributeValue, FileId, FileInfo, LineProgram, LineString, LineStringTable,
UnitEntryId,
};
// OPTIMIZATION: It is cheaper to do this in one pass than using `.parent()` and `.file_name()`.
fn split_path_dir_and_file(path: &Path) -> (&Path, &OsStr) {
let mut iter = path.components();
let file_name = match iter.next_back() {
Some(Component::Normal(p)) => p,
component => {
panic!(
"Path component {:?} of path {} is an invalid filename",
component,
path.display()
);
}
};
let parent = iter.as_path();
(parent, file_name)
}
// OPTIMIZATION: Avoid UTF-8 validation on UNIX.
fn osstr_as_utf8_bytes(path: &OsStr) -> &[u8] {
#[cfg(unix)]
{
use std::os::unix::ffi::OsStrExt;
path.as_bytes()
}
#[cfg(not(unix))]
{
path.to_str().unwrap().as_bytes()
}
}
pub(crate) const MD5_LEN: usize = 16;
pub(crate) fn make_file_info(hash: SourceFileHash) -> Option<FileInfo> {
if hash.kind == SourceFileHashAlgorithm::Md5 {
let mut buf = [0u8; MD5_LEN];
buf.copy_from_slice(hash.hash_bytes());
Some(FileInfo { timestamp: 0, size: 0, md5: buf })
} else {
None
}
}
fn line_program_add_file(
line_program: &mut LineProgram,
line_strings: &mut LineStringTable,
file: &SourceFile,
) -> FileId {
match &file.name {
FileName::Real(path) => {
let (dir_path, file_name) = split_path_dir_and_file(path.remapped_path_if_available());
let dir_name = osstr_as_utf8_bytes(dir_path.as_os_str());
let file_name = osstr_as_utf8_bytes(file_name);
let dir_id = if !dir_name.is_empty() {
let dir_name = LineString::new(dir_name, line_program.encoding(), line_strings);
line_program.add_directory(dir_name)
} else {
line_program.default_directory()
};
let file_name = LineString::new(file_name, line_program.encoding(), line_strings);
let info = make_file_info(file.src_hash);
line_program.file_has_md5 &= info.is_some();
line_program.add_file(file_name, dir_id, info)
}
// FIXME give more appropriate file names
filename => {
let dir_id = line_program.default_directory();
let dummy_file_name = LineString::new(
filename.prefer_remapped().to_string().into_bytes(),
line_program.encoding(),
line_strings,
);
line_program.add_file(dummy_file_name, dir_id, None)
}
}
}
impl<'tcx> DebugContext<'tcx> {
pub(super) fn emit_location(&mut self, entry_id: UnitEntryId, span: Span) {
let loc = self.tcx.sess.source_map().lookup_char_pos(span.lo());
let file_id = line_program_add_file(
&mut self.dwarf.unit.line_program,
&mut self.dwarf.line_strings,
&loc.file,
);
let entry = self.dwarf.unit.get_mut(entry_id);
entry.set(gimli::DW_AT_decl_file, AttributeValue::FileIndex(Some(file_id)));
entry.set(gimli::DW_AT_decl_line, AttributeValue::Udata(loc.line as u64));
entry.set(gimli::DW_AT_decl_column, AttributeValue::Udata(loc.col.to_usize() as u64));
}
pub(super) fn create_debug_lines(
&mut self,
symbol: usize,
entry_id: UnitEntryId,
context: &Context,
function_span: Span,
source_info_set: &indexmap::IndexSet<SourceInfo>,
) -> CodeOffset {
let tcx = self.tcx;
let line_program = &mut self.dwarf.unit.line_program;
let line_strings = &mut self.dwarf.line_strings;
let mut last_span = None;
let mut last_file = None;
let mut create_row_for_span = |line_program: &mut LineProgram, span: Span| {
if let Some(last_span) = last_span {
if span == last_span {
line_program.generate_row();
return;
}
}
last_span = Some(span);
// Based on https://github.com/rust-lang/rust/blob/e369d87b015a84653343032833d65d0545fd3f26/src/librustc_codegen_ssa/mir/mod.rs#L116-L131
// In order to have a good line stepping behavior in debugger, we overwrite debug
// locations of macro expansions with that of the outermost expansion site
// (unless the crate is being compiled with `-Z debug-macros`).
let span = if !span.from_expansion() || tcx.sess.opts.unstable_opts.debug_macros {
span
} else {
// Walk up the macro expansion chain until we reach a non-expanded span.
// We also stop at the function body level because no line stepping can occur
// at the level above that.
rustc_span::hygiene::walk_chain(span, function_span.ctxt())
};
let (file, line, col) = match tcx.sess.source_map().lookup_line(span.lo()) {
Ok(SourceFileAndLine { sf: file, line }) => {
let line_pos = file.line_begin_pos(span.lo());
(
file,
u64::try_from(line).unwrap() + 1,
u64::from((span.lo() - line_pos).to_u32()) + 1,
)
}
Err(file) => (file, 0, 0),
};
// line_program_add_file is very slow.
// Optimize for the common case of the current file not being changed.
let current_file_changed = if let Some(last_file) = &last_file {
// If the allocations are not equal, then the files may still be equal, but that
// is not a problem, as this is just an optimization.
!rustc_data_structures::sync::Lrc::ptr_eq(last_file, &file)
} else {
true
};
if current_file_changed {
let file_id = line_program_add_file(line_program, line_strings, &file);
line_program.row().file = file_id;
last_file = Some(file);
}
line_program.row().line = line;
line_program.row().column = col;
line_program.generate_row();
};
line_program.begin_sequence(Some(Address::Symbol { symbol, addend: 0 }));
let mut func_end = 0;
let mcr = context.mach_compile_result.as_ref().unwrap();
for &MachSrcLoc { start, end, loc } in mcr.buffer.get_srclocs_sorted() {
line_program.row().address_offset = u64::from(start);
if !loc.is_default() {
let source_info = *source_info_set.get_index(loc.bits() as usize).unwrap();
create_row_for_span(line_program, source_info.span);
} else {
create_row_for_span(line_program, function_span);
}
func_end = end;
}
line_program.end_sequence(u64::from(func_end));
let func_end = mcr.buffer.total_size();
assert_ne!(func_end, 0);
let entry = self.dwarf.unit.get_mut(entry_id);
entry.set(
gimli::DW_AT_low_pc,
AttributeValue::Address(Address::Symbol { symbol, addend: 0 }),
);
entry.set(gimli::DW_AT_high_pc, AttributeValue::Udata(u64::from(func_end)));
self.emit_location(entry_id, function_span);
func_end
}
}
|
