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don't strdup tokens in the lexer

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every stringy token the lexer returns is turned into a Symbol and not
used further, so we don't have to strdup. using a string_view is
sufficient, but due to limitations of the current parser we have to use
a POD type that holds the same information.

gives ~2% on system build, 6% on search, 8% on parsing alone

 # before

Benchmark 1: nix search --offline nixpkgs hello
  Time (mean ± σ):     610.6 ms ±   2.4 ms    [User: 602.5 ms, System: 7.8 ms]
  Range (min … max):   606.6 ms … 617.3 ms    50 runs

Benchmark 2: nix eval -f hackage-packages.nix
  Time (mean ± σ):     430.1 ms ±   1.4 ms    [User: 393.1 ms, System: 36.7 ms]
  Range (min … max):   428.2 ms … 434.2 ms    50 runs

Benchmark 3: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
  Time (mean ± σ):      3.032 s ±  0.005 s    [User: 2.808 s, System: 0.223 s]
  Range (min … max):    3.023 s …  3.041 s    50 runs

 # after

Benchmark 1: nix search --offline nixpkgs hello
  Time (mean ± σ):     574.7 ms ±   2.8 ms    [User: 566.3 ms, System: 8.0 ms]
  Range (min … max):   569.2 ms … 580.7 ms    50 runs

Benchmark 2: nix eval -f hackage-packages.nix
  Time (mean ± σ):     394.4 ms ±   0.8 ms    [User: 361.8 ms, System: 32.3 ms]
  Range (min … max):   392.7 ms … 395.7 ms    50 runs

Benchmark 3: nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
  Time (mean ± σ):      2.976 s ±  0.005 s    [User: 2.757 s, System: 0.218 s]
  Range (min … max):    2.966 s …  2.990 s    50 runs
This commit is contained in:
pennae 2021-12-21 09:17:31 +01:00
parent de273bbff2
commit 61a9d16d5c
2 changed files with 23 additions and 16 deletions
Download patch file Download diff file Expand all files Collapse all files

14
src/libexpr/lexer.l
View file

@ -139,7 +139,7 @@ or { return OR_KW; }
\/\/ { return UPDATE; }
\+\+ { return CONCAT; }
{ID} { yylval->id = strdup(yytext); return ID; }
{ID} { yylval->id = {yytext, (size_t) yyleng}; return ID; }
{INT} { errno = 0;
try {
yylval->n = boost::lexical_cast<int64_t>(yytext);
@ -221,14 +221,14 @@ or { return OR_KW; }
<PATH_START>{PATH_SEG} {
POP_STATE();
PUSH_STATE(INPATH_SLASH);
yylval->path = strdup(yytext);
yylval->path = {yytext, (size_t) yyleng};
return PATH;
}
<PATH_START>{HPATH_START} {
POP_STATE();
PUSH_STATE(INPATH_SLASH);
yylval->path = strdup(yytext);
yylval->path = {yytext, (size_t) yyleng};
return HPATH;
}
@ -237,7 +237,7 @@ or { return OR_KW; }
PUSH_STATE(INPATH_SLASH);
else
PUSH_STATE(INPATH);
yylval->path = strdup(yytext);
yylval->path = {yytext, (size_t) yyleng};
return PATH;
}
{HPATH} {
@ -245,7 +245,7 @@ or { return OR_KW; }
PUSH_STATE(INPATH_SLASH);
else
PUSH_STATE(INPATH);
yylval->path = strdup(yytext);
yylval->path = {yytext, (size_t) yyleng};
return HPATH;
}
@ -280,8 +280,8 @@ or { return OR_KW; }
throw ParseError("path has a trailing slash");
}
{SPATH} { yylval->path = strdup(yytext); return SPATH; }
{URI} { yylval->uri = strdup(yytext); return URI; }
{SPATH} { yylval->path = {yytext, (size_t) yyleng}; return SPATH; }
{URI} { yylval->uri = {yytext, (size_t) yyleng}; return URI; }
[ \t\r\n]+ /* eat up whitespace */
\#[^\r\n]* /* single-line comments */