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use std::tie() for macro-generated operators

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as written the comparisons generate copies, even though it looks as
though they shouldn't.

before:

  Time (mean ± σ):      4.396 s ±  0.002 s    [User: 3.894 s, System: 0.501 s]
  Range (min … max):    4.393 s …  4.399 s    10 runs

after:

  Time (mean ± σ):      4.260 s ±  0.003 s    [User: 3.754 s, System: 0.505 s]
  Range (min … max):    4.257 s …  4.266 s    10 runs
This commit is contained in:
pennae 2023-12-10 09:49:38 +01:00
parent 74c134914c
commit cc4038d541
3 changed files with 6 additions and 10 deletions
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4
src/libcmd/built-path.cc
View file

@ -12,9 +12,9 @@ namespace nix {
bool MY_TYPE ::operator COMPARATOR (const MY_TYPE & other) const \
{ \
const MY_TYPE* me = this; \
auto fields1 = std::make_tuple<const CHILD_TYPE &, const FIELD_TYPE &>(*me->drvPath, me->FIELD); \
auto fields1 = std::tie(*me->drvPath, me->FIELD); \
me = &other; \
auto fields2 = std::make_tuple<const CHILD_TYPE &, const FIELD_TYPE &>(*me->drvPath, me->FIELD); \
auto fields2 = std::tie(*me->drvPath, me->FIELD); \
return fields1 COMPARATOR fields2; \
}
#define CMP(CHILD_TYPE, MY_TYPE, FIELD) \

8
src/libstore/derived-path.cc
View file

@ -12,9 +12,9 @@ namespace nix {
bool MY_TYPE ::operator COMPARATOR (const MY_TYPE & other) const \
{ \
const MY_TYPE* me = this; \
auto fields1 = std::make_tuple<const CHILD_TYPE &, const FIELD_TYPE &>(*me->drvPath, me->FIELD); \
auto fields1 = std::tie(*me->drvPath, me->FIELD); \
me = &other; \
auto fields2 = std::make_tuple<const CHILD_TYPE &, const FIELD_TYPE &>(*me->drvPath, me->FIELD); \
auto fields2 = std::tie(*me->drvPath, me->FIELD); \
return fields1 COMPARATOR fields2; \
}
#define CMP(CHILD_TYPE, MY_TYPE, FIELD) \
@ -22,13 +22,9 @@ namespace nix {
CMP_ONE(CHILD_TYPE, MY_TYPE, FIELD, !=) \
CMP_ONE(CHILD_TYPE, MY_TYPE, FIELD, <)
#define FIELD_TYPE std::string
CMP(SingleDerivedPath, SingleDerivedPathBuilt, output)
#undef FIELD_TYPE
#define FIELD_TYPE OutputsSpec
CMP(SingleDerivedPath, DerivedPathBuilt, outputs)
#undef FIELD_TYPE
#undef CMP
#undef CMP_ONE

4
src/libutil/comparator.hh
View file

@ -13,9 +13,9 @@
#define GENERATE_ONE_CMP(PRE, QUAL, COMPARATOR, MY_TYPE, ...) \
PRE bool QUAL operator COMPARATOR(const MY_TYPE & other) const { \
__VA_OPT__(const MY_TYPE * me = this;) \
auto fields1 = std::make_tuple( __VA_ARGS__ ); \
auto fields1 = std::tie( __VA_ARGS__ ); \
__VA_OPT__(me = &other;) \
auto fields2 = std::make_tuple( __VA_ARGS__ ); \
auto fields2 = std::tie( __VA_ARGS__ ); \
return fields1 COMPARATOR fields2; \
}
#define GENERATE_EQUAL(prefix, qualification, my_type, args...) \