lix/local.mk

# 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.
DEFAULT_SANITIZE_FLAGS = -fsanitize=signed-integer-overflow -fsanitize-undefined-trap-on-error
GLOBAL_CXXFLAGS += -Wno-deprecated-declarations -Werror=switch $(DEFAULT_SANITIZE_FLAGS)
GLOBAL_LDFLAGS += $(DEFAULT_SANITIZE_FLAGS)
# Allow switch-enum to be overridden for files that do not support it, usually because of dependency headers.
ERROR_SWITCH_ENUM = -Werror=switch-enum

$(foreach i, config.h $(wildcard src/lib*/*.hh), \
  $(eval $(call install-file-in, $(i), $(includedir)/nix, 0644)))

$(GCH): src/libutil/util.hh config.h

GCH_CXXFLAGS = -I src/libutil
Build with traps on signed overflow This is UB, we should not be doing it, and we can cheaply turn it into crashes reliably. We would much rather have crashes than the program doing something silly. Benchmarks, but i wonder if they are nonsense because they get identical times across compilers?! \| Command \| Mean [ms] \| Min [ms] \| Max [ms] \| Relative \| \|:---\|---:\|---:\|---:\|---:\| \| `result-clang/bin/nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix` \| 375.5 ± 24.0 \| 353.8 \| 408.8 \| 1.00 \| \| `result-gcc/bin/nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix` \| 407.9 ± 26.0 \| 385.1 \| 449.5 \| 1.09 ± 0.10 \| \| `result-clangsan/bin/nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix` \| 382.2 ± 26.6 \| 354.9 \| 419.0 \| 1.02 ± 0.10 \| \| `result-gccsan/bin/nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix` \| 408.6 ± 24.6 \| 384.5 \| 441.9 \| 1.09 ± 0.10 \| \| Command \| Mean [s] \| Min [s] \| Max [s] \| Relative \| \|:---\|---:\|---:\|---:\|---:\| \| `result-clang/bin/nix search --no-eval-cache github:nixos/nixpkgs/e1fa12d4f6c6fe19ccb59cac54b5b3f25e160870 hello` \| 17.199 ± 0.167 \| 16.930 \| 17.499 \| 1.01 ± 0.01 \| \| `result-gcc/bin/nix search --no-eval-cache github:nixos/nixpkgs/e1fa12d4f6c6fe19ccb59cac54b5b3f25e160870 hello` \| 17.409 ± 0.126 \| 17.242 \| 17.633 \| 1.02 ± 0.01 \| \| `result-clangsan/bin/nix search --no-eval-cache github:nixos/nixpkgs/e1fa12d4f6c6fe19ccb59cac54b5b3f25e160870 hello` \| 17.080 ± 0.137 \| 16.879 \| 17.350 \| 1.00 \| \| `result-gccsan/bin/nix search --no-eval-cache github:nixos/nixpkgs/e1fa12d4f6c6fe19ccb59cac54b5b3f25e160870 hello` \| 17.396 ± 0.160 \| 17.131 \| 17.660 \| 1.02 ± 0.01 \| \| Command \| Mean [s] \| Min [s] \| Max [s] \| Relative \| \|:---\|---:\|---:\|---:\|---:\| \| `result-clang/bin/nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'` \| 6.267 ± 0.069 \| 6.197 \| 6.415 \| 1.02 ± 0.01 \| \| `result-gcc/bin/nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'` \| 6.232 ± 0.045 \| 6.180 \| 6.311 \| 1.01 ± 0.01 \| \| `result-clangsan/bin/nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'` \| 6.162 ± 0.020 \| 6.133 \| 6.196 \| 1.00 \| \| `result-gccsan/bin/nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'` \| 6.229 ± 0.031 \| 6.199 \| 6.289 \| 1.01 ± 0.01 \| \| Command \| Mean [s] \| Min [s] \| Max [s] \| Relative \| \|:---\|---:\|---:\|---:\|---:\| \| `GC_INITIAL_HEAP_SIZE=10g result-clang/bin/nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'` \| 4.683 ± 0.044 \| 4.630 \| 4.761 \| 1.00 \| \| `GC_INITIAL_HEAP_SIZE=10g result-gcc/bin/nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'` \| 4.750 ± 0.041 \| 4.680 \| 4.812 \| 1.01 ± 0.01 \| \| `GC_INITIAL_HEAP_SIZE=10g result-clangsan/bin/nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'` \| 4.703 ± 0.040 \| 4.640 \| 4.760 \| 1.00 ± 0.01 \| \| `GC_INITIAL_HEAP_SIZE=10g result-gccsan/bin/nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'` \| 4.766 ± 0.037 \| 4.727 \| 4.844 \| 1.02 ± 0.01 \| Change-Id: I616ca3eab670317587d47b41870d8ac963c019ae 2024-03-25 07:45:25 +01:00			`# 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.`
			`DEFAULT_SANITIZE_FLAGS = -fsanitize=signed-integer-overflow -fsanitize-undefined-trap-on-error`
			`GLOBAL_CXXFLAGS += -Wno-deprecated-declarations -Werror=switch $(DEFAULT_SANITIZE_FLAGS)`
			`GLOBAL_LDFLAGS += $(DEFAULT_SANITIZE_FLAGS)`
Enable -Werror=switch-enum switch statements must now match all enum values or disable the warning. Explicit is good. This has helped us find two bugs, after solving another one by debugging. From now on, adding to an enum will raise errors where they are not explicitly handled, which is good for productivity, and helps us decide the correct behavior in all usages. Notably still excluded from this though are the cases where the warning is disabled by local pragmas. fromTOML.cc did not build despite a top-level pragma, so I've had to resort to a makefile solution for that. 2023-04-03 18:11:42 +02:00			`# Allow switch-enum to be overridden for files that do not support it, usually because of dependency headers.`
			`ERROR_SWITCH_ENUM = -Werror=switch-enum`
Install header files 2014-02-07 17:15:00 +01:00
Install headers in the correct location 2020-02-03 18:04:09 +01:00			`$(foreach i, config.h $(wildcard src/lib/.hh), \`
Install serve-protocol.hh 2015-06-09 11:14:36 +02:00			`$(eval $(call install-file-in, $(i), $(includedir)/nix, 0644)))`
Fix precompiled-headers generation It's now regenerated when util.hh changes, and is ordered after config.h to fix a race. 2019-12-05 20:26:24 +01:00
mk/precompiled-headers.mk: Remove special handling for clang 2020-10-06 13:27:09 +02:00			`$(GCH): src/libutil/util.hh config.h`
Remove global -I flags 2020-03-30 14:29:29 +02:00
			`GCH_CXXFLAGS = -I src/libutil`