lix/local.mk
jade 94ea517dbe 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
2024-03-27 23:54:04 -07:00

18 lines
842 B
Makefile

# 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