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Unhardcode alignas cache line size #15213

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Merged
xokdvium merged 2 commits into from
Feb 12, 2026
Merged

Unhardcode alignas cache line size #15213

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df21c81
libexpr: Fix some typos in value.hh
xokdvium Feb 12, 2026
7352205
libexpr: Replace hardcoded cache line size with std::hardware_destruc…
xokdvium Feb 12, 2026
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1 change: 1 addition & 0 deletions nix-meson-build-support/common/meson.build
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Expand Up @@ -25,6 +25,7 @@ add_project_arguments(
'-Wignored-qualifiers',
'-Wimplicit-fallthrough',
'-Wno-deprecated-declarations',
'-Wno-interference-size', # Used for C++ ABI only. We don't provide any guarantees about different march tunings.
language : 'cpp',
)

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1 change: 0 additions & 1 deletion src/libexpr/eval.cc
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Expand Up @@ -318,7 +318,6 @@ EvalState::EvalState(
countCalls = getEnv("NIX_COUNT_CALLS").value_or("0") != "0";

static_assert(sizeof(Env) <= 16, "environment must be <= 16 bytes");
static_assert(sizeof(Counter) == 64, "counters must be 64 bytes");

/* Construct the Nix expression search path. */
assert(lookupPath.elements.empty());
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2 changes: 1 addition & 1 deletion src/libexpr/include/nix/expr/counter.hh
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Expand Up @@ -11,7 +11,7 @@ namespace nix {
* variable is set. This is to prevent contention on these counters
* when multi-threaded evaluation is enabled.
*/
struct alignas(64) Counter
struct alignas(std::hardware_destructive_interference_size) Counter
{
using value_type = uint64_t;

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4 changes: 2 additions & 2 deletions src/libexpr/include/nix/expr/value.hh
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Expand Up @@ -134,7 +134,7 @@ public:
virtual bool operator==(const ExternalValueBase & b) const noexcept;

/**
* Print the value as JSON. Defaults to unconvertable, i.e. throws an error
* Print the value as JSON. Defaults to unconvertible, i.e. throws an error
*/
virtual nlohmann::json
printValueAsJSON(EvalState & state, bool strict, NixStringContext & context, bool copyToStore = true) const;
Expand Down Expand Up @@ -587,7 +587,7 @@ class alignas(16)
enum PrimaryDiscriminator : int {
pdUninitialized = 0,
pdSingleDWord, //< layout: Single/zero field payload
/* The order of these enumations must be the same as in InternalType. */
/* The order of these enumerations must be the same as in InternalType. */
pdListN, //< layout: Single untaggable field.
pdString,
pdPath,
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