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Kernel/LibC: Use builtin functions over inline asm

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Getting flags and saving/restoring sse state and reading TSC can be done
using compiler builtins
This commit is contained in:
Bananymous
2026-01-09 15:19:19 +02:00
parent a9ceab0415
commit 74f70ae4bd
5 changed files with 14 additions and 39 deletions
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9
userspace/libraries/LibC/time.cpp
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@@ -38,13 +38,6 @@ int clock_gettime(clockid_t clock_id, struct timespec* tp)
return cpu;
};
const auto read_tsc =
[]() -> uint64_t {
uint32_t high, low;
asm volatile("lfence; rdtsc" : "=d"(high), "=a"(low));
return (static_cast<uint64_t>(high) << 32) | low;
};
for (;;)
{
const auto cpu = get_cpu();
@@ -56,7 +49,7 @@ int clock_gettime(clockid_t clock_id, struct timespec* tp)
if (old_seq & 1)
continue;
const auto monotonic_ns = lgettime.last_ns + (((read_tsc() - lgettime.last_tsc) * sgettime.mult) >> sgettime.shift);
const auto monotonic_ns = lgettime.last_ns + (((__builtin_ia32_rdtsc() - lgettime.last_tsc) * sgettime.mult) >> sgettime.shift);
if (old_seq != lgettime.seq || cpu != get_cpu())
continue;