Kernel: Decrease number of captured variables for lambda

This decreases the number of bytes necessary to capture the variables
for this lambda. The next step will be to remove dynamic allocations
from AK::Function which depends on this change to keep the size of
AK::Function objects reasonable.

1 files changed, 36 insertions, 31 deletions

diff --git a/Kernel/Arch/x86/Time/APICTimer.cpp b/Kernel/Arch/x86/Time/APICTimer.cpp
index 25381238c0..d7543a8c7c 100644
--- a/Kernel/Arch/x86/Time/APICTimer.cpp
+++ b/Kernel/Arch/x86/Time/APICTimer.cpp
@@ -36,40 +36,45 @@ UNMAP_AFTER_INIT bool APICTimer::calibrate(HardwareTimerBase& calibration_source
 
     dmesgln("APICTimer: Using {} as calibration source", calibration_source.model());
 
-    auto& apic = APIC::the();
+    struct {
 #ifdef APIC_TIMER_MEASURE_CPU_CLOCK
-    bool supports_tsc = Processor::current().has_feature(CPUFeature::TSC);
+        bool supports_tsc { Processor::current().has_feature(CPUFeature::TSC) };
 #endif
-
-    // temporarily replace the timer callbacks
-    const size_t ticks_in_100ms = calibration_source.ticks_per_second() / 10;
-    Atomic<size_t, AK::memory_order_relaxed> calibration_ticks = 0;
+        APIC& apic { APIC::the() };
+        size_t ticks_in_100ms { 0 };
+        Atomic<size_t, AK::memory_order_relaxed> calibration_ticks { 0 };
 #ifdef APIC_TIMER_MEASURE_CPU_CLOCK
-    volatile u64 start_tsc = 0, end_tsc = 0;
+        volatile u64 start_tsc { 0 }, end_tsc { 0 };
 #endif
-    volatile u64 start_reference = 0, end_reference = 0;
-    volatile u32 start_apic_count = 0, end_apic_count = 0;
-    bool query_reference = calibration_source.can_query_raw();
-    auto original_source_callback = calibration_source.set_callback([&](RegisterState const&) {
-        u32 current_timer_count = apic.get_timer_current_count();
+        volatile u64 start_reference { 0 }, end_reference { 0 };
+        volatile u32 start_apic_count { 0 }, end_apic_count { 0 };
+        bool query_reference { false };
+    } state;
+
+    state.ticks_in_100ms = calibration_source.ticks_per_second() / 10;
+    state.query_reference = calibration_source.can_query_raw();
+
+    // temporarily replace the timer callbacks
+    auto original_source_callback = calibration_source.set_callback([&state, &calibration_source](RegisterState const&) {
+        u32 current_timer_count = state.apic.get_timer_current_count();
 #ifdef APIC_TIMER_MEASURE_CPU_CLOCK
-        u64 current_tsc = supports_tsc ? read_tsc() : 0;
+        u64 current_tsc = state.supports_tsc ? read_tsc() : 0;
 #endif
-        u64 current_reference = query_reference ? calibration_source.current_raw() : 0;
+        u64 current_reference = state.query_reference ? calibration_source.current_raw() : 0;
 
-        auto prev_tick = calibration_ticks.fetch_add(1);
+        auto prev_tick = state.calibration_ticks.fetch_add(1);
         if (prev_tick == 0) {
 #ifdef APIC_TIMER_MEASURE_CPU_CLOCK
-            start_tsc = current_tsc;
+            state.start_tsc = current_tsc;
 #endif
-            start_apic_count = current_timer_count;
-            start_reference = current_reference;
-        } else if (prev_tick + 1 == ticks_in_100ms + 1) {
+            state.start_apic_count = current_timer_count;
+            state.start_reference = current_reference;
+        } else if (prev_tick + 1 == state.ticks_in_100ms + 1) {
 #ifdef APIC_TIMER_MEASURE_CPU_CLOCK
-            end_tsc = current_tsc;
+            state.end_tsc = current_tsc;
 #endif
-            end_apic_count = current_timer_count;
-            end_reference = current_reference;
+            state.end_apic_count = current_timer_count;
+            state.end_reference = current_reference;
         }
     });
 
@@ -81,11 +86,11 @@ UNMAP_AFTER_INIT bool APICTimer::calibrate(HardwareTimerBase& calibration_source
         // TODO: How should we handle this?
         PANIC("APICTimer: Timer fired during calibration!");
     });
-    apic.setup_local_timer(0xffffffff, APIC::TimerMode::Periodic, true);
+    state.apic.setup_local_timer(0xffffffff, APIC::TimerMode::Periodic, true);
 
     sti();
     // Loop for about 100 ms
-    while (calibration_ticks.load() <= ticks_in_100ms)
+    while (state.calibration_ticks.load() <= state.ticks_in_100ms)
         ;
     cli();
 
@@ -95,8 +100,8 @@ UNMAP_AFTER_INIT bool APICTimer::calibrate(HardwareTimerBase& calibration_source
 
     disable_local_timer();
 
-    if (query_reference) {
-        u64 one_tick_ns = calibration_source.raw_to_ns((end_reference - start_reference) / ticks_in_100ms);
+    if (state.query_reference) {
+        u64 one_tick_ns = calibration_source.raw_to_ns((state.end_reference - state.start_reference) / state.ticks_in_100ms);
         m_frequency = (u32)(1000000000ull / one_tick_ns);
         dmesgln("APICTimer: Ticks per second: {} ({}.{}ms)", m_frequency, one_tick_ns / 1000000, one_tick_ns % 1000000);
     } else {
@@ -105,10 +110,10 @@ UNMAP_AFTER_INIT bool APICTimer::calibrate(HardwareTimerBase& calibration_source
         dmesgln("APICTimer: Ticks per second: {} (assume same frequency as reference clock)", m_frequency);
     }
 
-    auto delta_apic_count = start_apic_count - end_apic_count; // The APIC current count register decrements!
-    m_timer_period = (delta_apic_count * apic.get_timer_divisor()) / ticks_in_100ms;
+    auto delta_apic_count = state.start_apic_count - state.end_apic_count; // The APIC current count register decrements!
+    m_timer_period = (delta_apic_count * state.apic.get_timer_divisor()) / state.ticks_in_100ms;
 
-    u64 apic_freq = delta_apic_count * apic.get_timer_divisor() * 10;
+    u64 apic_freq = delta_apic_count * state.apic.get_timer_divisor() * 10;
     dmesgln("APICTimer: Bus clock speed: {}.{} MHz", apic_freq / 1000000, apic_freq % 1000000);
     if (apic_freq < 1000000) {
         dmesgln("APICTimer: Frequency too slow!");
@@ -116,8 +121,8 @@ UNMAP_AFTER_INIT bool APICTimer::calibrate(HardwareTimerBase& calibration_source
     }
 
 #ifdef APIC_TIMER_MEASURE_CPU_CLOCK
-    if (supports_tsc) {
-        auto delta_tsc = (end_tsc - start_tsc) * 10;
+    if (state.supports_tsc) {
+        auto delta_tsc = (state.end_tsc - state.start_tsc) * 10;
         dmesgln("APICTimer: CPU clock speed: {}.{} MHz", delta_tsc / 1000000, delta_tsc % 1000000);
     }
 #endif