From 11d22ae7c572ce35923ced63415e95f0a2ab8361 Mon Sep 17 00:00:00 2001 From: Nicholas Nethercote Date: Mon, 30 May 2022 15:59:45 +1000 Subject: [PATCH] Lazify `SourceFile::lines`. `SourceFile::lines` is a big part of metadata. It's stored in a compressed form (a difference list) to save disk space. Decoding it is a big fraction of compile time for very small crates/programs. This commit introduces a new type `SourceFileLines` which has a `Lines` form and a `Diffs` form. The latter is used when the metadata is first read, and it is only decoded into the `Lines` form when line data is actually needed. This avoids the decoding cost for many files, especially in `std`. It's a performance win of up to 15% for tiny crates/programs where metadata decoding is a high part of compilation costs. A `Lock` is needed because the methods that access lines data (which can trigger decoding) take `&self` rather than `&mut self`. To allow for this, `SourceFile::lines` now takes a `FnMut` that operates on the lines slice rather than returning the lines slice. --- .../src/undocumented_unsafe_blocks.rs | 36 +++++++++++-------- clippy_utils/src/diagnostics.rs | 4 +-- clippy_utils/src/lib.rs | 2 +- 3 files changed, 24 insertions(+), 18 deletions(-) diff --git a/clippy_lints/src/undocumented_unsafe_blocks.rs b/clippy_lints/src/undocumented_unsafe_blocks.rs index 5a8677f90be..025dd57e83a 100644 --- a/clippy_lints/src/undocumented_unsafe_blocks.rs +++ b/clippy_lints/src/undocumented_unsafe_blocks.rs @@ -187,11 +187,13 @@ fn item_has_safety_comment(cx: &LateContext<'_>, item: &hir::Item<'_>) -> bool { && Lrc::ptr_eq(&unsafe_line.sf, &comment_start_line.sf) && let Some(src) = unsafe_line.sf.src.as_deref() { - comment_start_line.line < unsafe_line.line && text_has_safety_comment( - src, - &unsafe_line.sf.lines[comment_start_line.line + 1..=unsafe_line.line], - unsafe_line.sf.start_pos.to_usize(), - ) + unsafe_line.sf.lines(|lines| { + comment_start_line.line < unsafe_line.line && text_has_safety_comment( + src, + &lines[comment_start_line.line + 1..=unsafe_line.line], + unsafe_line.sf.start_pos.to_usize(), + ) + }) } else { // Problem getting source text. Pretend a comment was found. true @@ -249,11 +251,13 @@ fn span_from_macro_expansion_has_safety_comment(cx: &LateContext<'_>, span: Span && Lrc::ptr_eq(&unsafe_line.sf, ¯o_line.sf) && let Some(src) = unsafe_line.sf.src.as_deref() { - macro_line.line < unsafe_line.line && text_has_safety_comment( - src, - &unsafe_line.sf.lines[macro_line.line + 1..=unsafe_line.line], - unsafe_line.sf.start_pos.to_usize(), - ) + unsafe_line.sf.lines(|lines| { + macro_line.line < unsafe_line.line && text_has_safety_comment( + src, + &lines[macro_line.line + 1..=unsafe_line.line], + unsafe_line.sf.start_pos.to_usize(), + ) + }) } else { // Problem getting source text. Pretend a comment was found. true @@ -276,11 +280,13 @@ fn span_in_body_has_safety_comment(cx: &LateContext<'_>, span: Span) -> bool { // Get the text from the start of function body to the unsafe block. // fn foo() { some_stuff; unsafe { stuff }; other_stuff; } // ^-------------^ - body_line.line < unsafe_line.line && text_has_safety_comment( - src, - &unsafe_line.sf.lines[body_line.line + 1..=unsafe_line.line], - unsafe_line.sf.start_pos.to_usize(), - ) + unsafe_line.sf.lines(|lines| { + body_line.line < unsafe_line.line && text_has_safety_comment( + src, + &lines[body_line.line + 1..=unsafe_line.line], + unsafe_line.sf.start_pos.to_usize(), + ) + }) } else { // Problem getting source text. Pretend a comment was found. true diff --git a/clippy_utils/src/diagnostics.rs b/clippy_utils/src/diagnostics.rs index 4e037d88494..39595f589c7 100644 --- a/clippy_utils/src/diagnostics.rs +++ b/clippy_utils/src/diagnostics.rs @@ -283,10 +283,10 @@ pub fn span_lint_and_sugg_for_edges( { let split_idx = MAX_SUGGESTION_HIGHLIGHT_LINES / 2; let span_upper = sm.span_until_char( - sp.with_hi(line_upper.sf.lines[line_upper.line + split_idx]), + sp.with_hi(line_upper.sf.lines(|lines| lines[line_upper.line + split_idx])), '\n', ); - let span_bottom = sp.with_lo(line_bottom.sf.lines[line_bottom.line - split_idx]); + let span_bottom = sp.with_lo(line_bottom.sf.lines(|lines| lines[line_bottom.line - split_idx])); let sugg_lines_vec = sugg.lines().collect::>(); let sugg_upper = sugg_lines_vec[..split_idx].join("\n"); diff --git a/clippy_utils/src/lib.rs b/clippy_utils/src/lib.rs index adb37cc9d75..833f8cde63a 100644 --- a/clippy_utils/src/lib.rs +++ b/clippy_utils/src/lib.rs @@ -1149,7 +1149,7 @@ fn line_span(cx: &T, span: Span) -> Span { let span = original_sp(span, DUMMY_SP); let source_map_and_line = cx.sess().source_map().lookup_line(span.lo()).unwrap(); let line_no = source_map_and_line.line; - let line_start = source_map_and_line.sf.lines[line_no]; + let line_start = source_map_and_line.sf.lines(|lines| lines[line_no]); span.with_lo(line_start) }