From c3200c3bb54b94bafb0731adeffd2128f1d6cdd3 Mon Sep 17 00:00:00 2001 From: Nicholas Nethercote Date: Tue, 24 Jun 2025 08:42:14 +1000 Subject: [PATCH] Tweak `-Zmacro-stats` measurement. It currently reports net size, i.e. size(output) - size(input). After some use I think this is sub-optimal, and it's better to just report size(output). Because for derive macros the input size is always 1, and for attribute macros it's almost always 1. --- compiler/rustc_expand/src/stats.rs | 28 +++++-------- compiler/rustc_interface/src/passes.rs | 4 +- .../src/compiler-flags/macro-stats.md | 6 +-- tests/ui/stats/macro-stats.stderr | 40 +++++++++---------- 4 files changed, 35 insertions(+), 43 deletions(-) diff --git a/compiler/rustc_expand/src/stats.rs b/compiler/rustc_expand/src/stats.rs index 6b2ad30dffd06..b4c4eac028fe5 100644 --- a/compiler/rustc_expand/src/stats.rs +++ b/compiler/rustc_expand/src/stats.rs @@ -15,15 +15,11 @@ pub struct MacroStat { /// Number of uses of the macro. pub uses: usize, - /// Net increase in number of lines of code (when pretty-printed), i.e. - /// `lines(output) - lines(invocation)`. Can be negative because a macro - /// output may be smaller than the invocation. - pub lines: isize, - - /// Net increase in number of lines of code (when pretty-printed), i.e. - /// `bytes(output) - bytes(invocation)`. Can be negative because a macro - /// output may be smaller than the invocation. - pub bytes: isize, + /// Number of lines of code (when pretty-printed). + pub lines: usize, + + /// Number of bytes of code (when pretty-printed). + pub bytes: usize, } pub(crate) fn elems_to_string(elems: &SmallVec<[T; 1]>, f: impl Fn(&T) -> String) -> String { @@ -131,16 +127,12 @@ pub(crate) fn update_macro_stats( input: &str, fragment: &AstFragment, ) { - fn lines_and_bytes(s: &str) -> (usize, usize) { - (s.trim_end().split('\n').count(), s.len()) - } - // Measure the size of the output by pretty-printing it and counting // the lines and bytes. let name = Symbol::intern(&pprust::path_to_string(path)); let output = fragment.to_string(); - let (in_l, in_b) = lines_and_bytes(input); - let (out_l, out_b) = lines_and_bytes(&output); + let num_lines = output.trim_end().split('\n').count(); + let num_bytes = output.len(); // This code is useful for debugging `-Zmacro-stats`. For every // invocation it prints the full input and output. @@ -157,7 +149,7 @@ pub(crate) fn update_macro_stats( {name}: [{crate_name}] ({fragment_kind:?}) {span}\n\ -------------------------------\n\ {input}\n\ - -- ({in_l} lines, {in_b} bytes) --> ({out_l} lines, {out_b} bytes) --\n\ + -- {num_lines} lines, {num_bytes} bytes --\n\ {output}\n\ " ); @@ -166,6 +158,6 @@ pub(crate) fn update_macro_stats( // The recorded size is the difference between the input and the output. let entry = ecx.macro_stats.entry((name, macro_kind)).or_insert(MacroStat::default()); entry.uses += 1; - entry.lines += out_l as isize - in_l as isize; - entry.bytes += out_b as isize - in_b as isize; + entry.lines += num_lines; + entry.bytes += num_bytes; } diff --git a/compiler/rustc_interface/src/passes.rs b/compiler/rustc_interface/src/passes.rs index 201b7e2b940c8..bba56281edde6 100644 --- a/compiler/rustc_interface/src/passes.rs +++ b/compiler/rustc_interface/src/passes.rs @@ -354,9 +354,9 @@ fn print_macro_stats(ecx: &ExtCtxt<'_>) { "{prefix} {:uses_w$}{:>lines_w$}{:>avg_lines_w$}{:>bytes_w$}{:>avg_bytes_w$}", name, thousands::usize_with_underscores(uses), - thousands::isize_with_underscores(lines), + thousands::usize_with_underscores(lines), thousands::f64p1_with_underscores(avg_lines), - thousands::isize_with_underscores(bytes), + thousands::usize_with_underscores(bytes), thousands::f64p1_with_underscores(avg_bytes), ); } diff --git a/src/doc/unstable-book/src/compiler-flags/macro-stats.md b/src/doc/unstable-book/src/compiler-flags/macro-stats.md index b2622cff0570a..f3fa69058a719 100644 --- a/src/doc/unstable-book/src/compiler-flags/macro-stats.md +++ b/src/doc/unstable-book/src/compiler-flags/macro-stats.md @@ -10,12 +10,12 @@ generated code is normally invisible to the programmer. This flag helps identify such cases. When enabled, the compiler measures the effect on code size of all used macros and prints a table summarizing that -effect. For each distinct macro, it counts how many times it is used, and the -net effect on code size (in terms of lines of code, and bytes of code). The +effect. For each distinct macro, it counts how many times it is used, and how +much code it produces when expanded (in lines of code, and bytes of code). The code size evaluation uses the compiler's internal pretty-printing, and so will be independent of the formatting in the original code. -Note that the net effect of a macro may be negative. E.g. the `cfg!` and +Note that the output size of a macro may be zero. E.g. the `cfg!` and `#[test]` macros often strip out code. If a macro is identified as causing a large increase in code size, it is worth diff --git a/tests/ui/stats/macro-stats.stderr b/tests/ui/stats/macro-stats.stderr index f87e34622b92c..00c6b55c6a23e 100644 --- a/tests/ui/stats/macro-stats.stderr +++ b/tests/ui/stats/macro-stats.stderr @@ -2,25 +2,25 @@ macro-stats ==================================================================== macro-stats MACRO EXPANSION STATS: macro_stats macro-stats Macro Name Uses Lines Avg Lines Bytes Avg Bytes macro-stats ----------------------------------------------------------------------------------- -macro-stats #[derive(Clone)] 8 56 7.0 1_660 207.5 -macro-stats #[derive(PartialOrd)] 1 16 16.0 654 654.0 -macro-stats #[derive(Hash)] 2 15 7.5 547 273.5 -macro-stats #[derive(Ord)] 1 14 14.0 489 489.0 -macro-stats q! 1 24 24.0 435 435.0 -macro-stats #[derive(Default)] 2 14 7.0 367 183.5 -macro-stats #[derive(Eq)] 1 10 10.0 312 312.0 -macro-stats #[derive(Debug)] 1 7 7.0 261 261.0 -macro-stats #[derive(PartialEq)] 1 8 8.0 247 247.0 -macro-stats #[derive(Copy)] 1 1 1.0 46 46.0 -macro-stats p! 1 2 2.0 28 28.0 -macro-stats trait_impl_tys! 1 1 1.0 11 11.0 -macro-stats foreign_item! 1 0 0.0 6 6.0 -macro-stats impl_const! 1 0 0.0 4 4.0 -macro-stats trait_tys! 1 1 1.0 3 3.0 -macro-stats u32! 1 0 0.0 -3 -3.0 -macro-stats none! 1 0 0.0 -3 -3.0 -macro-stats n99! 2 0 0.0 -8 -4.0 +macro-stats #[derive(Clone)] 8 64 8.0 1_788 223.5 +macro-stats #[derive(PartialOrd)] 1 17 17.0 675 675.0 +macro-stats #[derive(Hash)] 2 17 8.5 577 288.5 +macro-stats q! 1 26 26.0 519 519.0 +macro-stats #[derive(Ord)] 1 15 15.0 503 503.0 +macro-stats #[derive(Default)] 2 16 8.0 403 201.5 +macro-stats #[derive(Eq)] 1 11 11.0 325 325.0 +macro-stats #[derive(Debug)] 1 8 8.0 277 277.0 +macro-stats #[derive(PartialEq)] 1 9 9.0 267 267.0 +macro-stats #[derive(Copy)] 1 2 2.0 61 61.0 +macro-stats p! 1 3 3.0 32 32.0 +macro-stats trait_impl_tys! 1 2 2.0 28 28.0 +macro-stats foreign_item! 1 1 1.0 21 21.0 macro-stats this_is_a_really_really_long_macro_name! -macro-stats 1 0 0.0 -30 -30.0 -macro-stats #[test] 1 -6 -6.0 -158 -158.0 +macro-stats 1 1 1.0 18 18.0 +macro-stats impl_const! 1 1 1.0 17 17.0 +macro-stats trait_tys! 1 2 2.0 15 15.0 +macro-stats n99! 2 2 1.0 4 2.0 +macro-stats none! 1 1 1.0 4 4.0 +macro-stats u32! 1 1 1.0 3 3.0 +macro-stats #[test] 1 1 1.0 0 0.0 macro-stats ===================================================================================