From 0d37b99a155a82ea629ffc533c8f33250f6a4dd9 Mon Sep 17 00:00:00 2001 From: Jade Lovelace Date: Sun, 7 Apr 2024 17:19:37 -0700 Subject: build: enable libstdc++ assertions MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Benchmarks say that it does not regress performance by more than 1% (which is where it gets really hard to measure accurately anyhow). Meson appears to be planning to do this for us without asking us in a release we will get in the future, and it seems good enough to ship today: https://mesonbuild.com/Release-notes-for-1-4-0.html#ndebug-setting-now-controls-c-stdlib-assertions Benchmarks: | Command | Mean [ms] | Min [ms] | Max [ms] | Relative | |:---|---:|---:|---:|---:| | `result-asserts/bin/nix --extra-experimental-features 'nix-command flakes' eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix` | 418.4 ± 25.0 | 396.9 | 451.2 | 1.01 ± 0.08 | | `result/bin/nix --extra-experimental-features 'nix-command flakes' eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix` | 416.1 ± 23.9 | 397.1 | 445.4 | 1.00 | | Command | Mean [s] | Min [s] | Max [s] | Relative | |:---|---:|---:|---:|---:| | `GC_INITIAL_HEAP_SIZE=10g result-asserts/bin/nix eval --extra-experimental-features 'nix-command flakes' --raw --impure --expr 'with import {}; system'` | 4.147 ± 0.021 | 4.123 | 4.195 | 1.00 | | `GC_INITIAL_HEAP_SIZE=10g result/bin/nix eval --extra-experimental-features 'nix-command flakes' --raw --impure --expr 'with import {}; system'` | 4.149 ± 0.027 | 4.126 | 4.215 | 1.00 ± 0.01 | | Command | Mean [s] | Min [s] | Max [s] | Relative | |:---|---:|---:|---:|---:| | `result-asserts/bin/nix --extra-experimental-features 'nix-command flakes' eval --raw --impure --expr 'with import {}; system'` | 5.838 ± 0.023 | 5.799 | 5.867 | 1.01 ± 0.01 | | `result/bin/nix --extra-experimental-features 'nix-command flakes' eval --raw --impure --expr 'with import {}; system'` | 5.788 ± 0.044 | 5.715 | 5.876 | 1.00 | | Command | Mean [s] | Min [s] | Max [s] | Relative | |:---|---:|---:|---:|---:| | `result-asserts/bin/nix --extra-experimental-features 'nix-command flakes' search --no-eval-cache github:nixos/nixpkgs/e1fa12d4f6c6fe19ccb59cac54b5b3f25e160870 hello` | 15.993 ± 0.081 | 15.829 | 16.096 | 1.01 ± 0.01 | | `result/bin/nix --extra-experimental-features 'nix-command flakes' search --no-eval-cache github:nixos/nixpkgs/e1fa12d4f6c6fe19ccb59cac54b5b3f25e160870 hello` | 15.897 ± 0.075 | 15.807 | 16.047 | 1.00 | Fixes: https://git.lix.systems/lix-project/lix/issues/4 Change-Id: Id3a6f38274ba94d5d10b09edd19dfd96bc3e7d5f --- meson.build | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'meson.build') diff --git a/meson.build b/meson.build index 2cedabad5..456be5aa2 100644 --- a/meson.build +++ b/meson.build @@ -344,6 +344,12 @@ add_project_arguments( '-Wimplicit-fallthrough', '-Werror=switch', '-Werror=switch-enum', + # Enable assertions in libstdc++ by default. Harmless on libc++. Benchmarked + # at ~1% overhead in `nix search`. + # + # FIXME: remove when we get meson 1.4.0 which will default this to on for us: + # https://mesonbuild.com/Release-notes-for-1-4-0.html#ndebug-setting-now-controls-c-stdlib-assertions + '-D_GLIBCXX_ASSERTIONS=1', language : 'cpp', ) @@ -351,8 +357,7 @@ if cxx.get_id() in ['gcc', 'clang'] # 2024-03-24: jade benchmarked the default sanitize reporting in clang and got # a regression of about 10% on hackage-packages.nix with clang. So we are trapping instead. # - # This has an overhead of 0-4% on gcc and unmeasurably little on clang, in - # Nix evaluation benchmarks. + # This has an unmeasurably low overhead in Nix evaluation benchmarks. # # N.B. Meson generates a completely nonsense warning here: # https://github.com/mesonbuild/meson/issues/9822 -- cgit v1.2.3