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WIP timer thread safety:

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CAS functions now implemented directly in external asm files (avoids
wrapper functions)
reinstated cpu_CAS64 (checking ARCH_IA32 at every call site is onerous)
(temporarily disable timer monotonicity check)

This was SVN commit r8515.
This commit is contained in:
janwas 2010-11-01 09:54:03 +00:00
parent 2b9774aa05
commit 657ec9aa45
10 changed files with 63 additions and 101 deletions
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31
source/lib/sysdep/arch/amd64/amd64.cpp
View File

@ -25,12 +25,8 @@
#if ARCH_AMD64
#include "lib/sysdep/arch/amd64/amd64.h"
#include "lib/sysdep/arch/amd64/amd64_asm.h"
#include "lib/sysdep/cpu.h"
#if MSC_VERSION
#include <intrin.h>
#endif
void cpu_ConfigureFloatingPoint()
{
@ -43,31 +39,4 @@ void* cpu_memcpy(void* RESTRICT dst, const void* RESTRICT src, size_t size)
return memcpy(dst, src, size);
}
#if MSC_VERSION
bool cpu_CAS(volatile intptr_t* location, intptr_t expected, intptr_t newValue)
{
const intptr_t initial = _InterlockedCompareExchange64((volatile __int64*)location, newValue, expected);
return initial == expected;
}
intptr_t cpu_AtomicAdd(volatile intptr_t* location, intptr_t increment)
{
return _InterlockedExchangeAdd64(location, increment);
}
#elif GCC_VERSION
intptr_t cpu_AtomicAdd(volatile intptr_t* location, intptr_t increment)
{
return amd64_AtomicAdd(location, increment);
}
bool cpu_CAS(volatile intptr_t* location, intptr_t expected, intptr_t newValue)
{
return amd64_CAS(location, expected, newValue) ? true : false;
}
#endif
#endif // ARCH_AMD64

25
source/lib/sysdep/arch/amd64/amd64_asm.asm
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@ -46,18 +46,23 @@ sym(amd64_asm_cpuid):
ret
ALIGN 8
; extern "C" intptr_t amd64_CAS(volatile uintptr_t *location, uintptr_t expected, uintptr_t newValue);
global sym(amd64_CAS)
sym(amd64_CAS):
; extern "C" intptr_t cpu_AtomicAdd(intptr_t* location, intptr_t increment);
global sym(cpu_AtomicAdd)
sym(cpu_AtomicAdd):
lock xadd [arg0], arg1
mov rax, arg1
ret
; extern "C" bool amd64_CAS(volatile intptr_t* location, intptr_t expected, intptr_t newValue);
; extern "C" bool amd64_CAS64(volatile i64* location, i64 expected, i64 newValue);
global sym(cpu_CAS)
global sym(cpu_CAS64)
sym(cpu_CAS):
sym(cpu_CAS64):
mov rax, arg1 ; expected -> rax
lock cmpxchg [arg0], arg2
sete al
movzx rax, al
ret
; extern "C" intptr_t amd64_AtomicAdd(intptr_t *location, intptr_t increment);
global sym(amd64_AtomicAdd)
sym(amd64_AtomicAdd):
lock xadd [arg0], arg1
mov rax, arg1
ret

4
source/lib/sysdep/arch/amd64/amd64_asm.h
View File

@ -34,9 +34,7 @@ extern "C" {
struct x86_x64_CpuidRegs;
extern void CALL_CONV amd64_asm_cpuid(x86_x64_CpuidRegs* reg);
extern intptr_t CALL_CONV amd64_CAS(volatile intptr_t *location, intptr_t expected, intptr_t newValue);
extern intptr_t CALL_CONV amd64_AtomicAdd(volatile intptr_t *location, intptr_t increment);
// also implements cpu_AtomicAdd, cpu_CAS and cpu_CAS64 from "sysdep/cpu.h"
#ifdef __cplusplus
}

12
source/lib/sysdep/arch/ia32/ia32.cpp
View File

@ -147,18 +147,6 @@ void cpu_ConfigureFloatingPoint()
}
intptr_t cpu_AtomicAdd(volatile intptr_t* location, intptr_t increment)
{
return ia32_asm_AtomicAdd(location, increment);
}
bool cpu_CAS(volatile intptr_t* location, intptr_t expected, intptr_t new_value)
{
return ia32_asm_CAS(location, expected, new_value);
}
void* cpu_memcpy(void* RESTRICT dst, const void* RESTRICT src, size_t size)
{
return memcpy(dst, src, size);

18
source/lib/sysdep/arch/ia32/ia32_asm.asm
View File

@ -60,9 +60,9 @@ sym(ia32_asm_cpuid):
; lock-free support routines
;-------------------------------------------------------------------------------
; extern "C" intptr_t __cdecl ia32_asm_AtomicAdd(volatile intptr_t* location, intptr_t increment);
global sym(ia32_asm_AtomicAdd)
sym(ia32_asm_AtomicAdd):
; extern "C" intptr_t __cdecl cpu_AtomicAdd(volatile intptr_t* location, intptr_t increment);
global sym(cpu_AtomicAdd)
sym(cpu_AtomicAdd):
mov edx, [esp+4] ; location
mov eax, [esp+8] ; increment
db 0xf0 ; LOCK prefix
@ -79,9 +79,9 @@ db 0xf0 ; LOCK prefix
; - nor do we bother skipping the LOCK prefix on single-processor systems.
; the branch may be well-predicted, but difference in performance still
; isn't expected to be enough to justify the effort.
; extern "C" bool __cdecl ia32_asm_CAS(volatile uintptr_t* location, uintptr_t expected, uintptr_t new_value);
global sym(ia32_asm_CAS)
sym(ia32_asm_CAS):
; extern "C" bool __cdecl cpu_CAS(volatile intptr_t* location, intptr_t expected, intptr_t new_value);
global sym(cpu_CAS)
sym(cpu_CAS):
mov edx, [esp+4] ; location
mov eax, [esp+8] ; expected
mov ecx, [esp+12] ; new_value
@ -92,9 +92,9 @@ db 0xf0 ; LOCK prefix
ret
; extern bool CALL_CONV ia32_asm_CAS64(volatile i64* location, i64 expected, i64 new_value);
global sym(ia32_asm_CAS64)
sym(ia32_asm_CAS64):
; extern bool CALL_CONV cpu_CAS64(volatile i64* location, i64 expected, i64 new_value);
global sym(cpu_CAS64)
sym(cpu_CAS64):
push ebx
push esi
mov esi, [esp+8+4] ; location

4
source/lib/sysdep/arch/ia32/ia32_asm.h
View File

@ -34,9 +34,7 @@ extern "C" {
struct x86_x64_CpuidRegs;
extern void CALL_CONV ia32_asm_cpuid(x86_x64_CpuidRegs* regs);
extern intptr_t CALL_CONV ia32_asm_AtomicAdd(volatile intptr_t* location, intptr_t increment);
extern bool CALL_CONV ia32_asm_CAS(volatile intptr_t* location, intptr_t expected, intptr_t new_value);
extern bool CALL_CONV ia32_asm_CAS64(volatile i64* location, i64 expected, i64 new_value);
// also implements cpu_AtomicAdd, cpu_CAS and cpu_CAS64 from "sysdep/cpu.h"
/// control87
// FPU control word

8
source/lib/sysdep/cpu.cpp
View File

@ -27,10 +27,6 @@
#include "precompiled.h"
#include "lib/sysdep/cpu.h"
#if ARCH_IA32
# include "lib/sysdep/arch/ia32/ia32_asm.h" // ia32_asm_CAS64
#endif
ERROR_ASSOCIATE(ERR::CPU_FEATURE_MISSING, L"This CPU doesn't support a required feature", -1);
ERROR_ASSOCIATE(ERR::CPU_UNKNOWN_OPCODE, L"Disassembly failed", -1);
ERROR_ASSOCIATE(ERR::CPU_UNKNOWN_VENDOR, L"CPU vendor unknown", -1);
@ -51,11 +47,9 @@ cassert(sizeof(void*) == sizeof(intptr_t));
static void TestCAS64()
{
#if ARCH_IA32
volatile i64 var = 1;
ia32_asm_CAS64(&var, 1ull, 2ull);
cpu_CAS64(&var, 1ull, 2ull);
debug_assert(var == 2ull);
#endif
}
static void TestAtomicAdd()

21
source/lib/sysdep/cpu.h
View File

@ -52,6 +52,16 @@ LIB_API const char* cpu_IdentifierString();
//-----------------------------------------------------------------------------
// lock-free support routines
extern "C" { // (assembly-language implementations)
/**
* add a signed value to a variable without the possibility of interference
* from other threads/CPUs.
*
* @return the previous value.
**/
LIB_API intptr_t cpu_AtomicAdd(volatile intptr_t* location, intptr_t increment);
/**
* atomic "compare and swap".
*
@ -62,6 +72,9 @@ LIB_API const char* cpu_IdentifierString();
* otherwise true (also overwriting the contents of location)
**/
LIB_API bool cpu_CAS(volatile intptr_t* location, intptr_t expected, intptr_t newValue);
LIB_API bool cpu_CAS64(volatile i64* location, i64 expected, i64 newValue);
} // extern "C"
/**
* specialization of cpu_CAS for pointer types. this avoids error-prone
@ -74,14 +87,6 @@ bool cpu_CAS(volatile T* location, T expected, T new_value)
}
/**
* add a signed value to a variable without the possibility of interference
* from other threads/CPUs.
*
* @return the previous value.
**/
LIB_API intptr_t cpu_AtomicAdd(volatile intptr_t* location, intptr_t increment);
LIB_API void cpu_Test();
/**

27
source/lib/timer.cpp
View File

@ -35,6 +35,7 @@
#include "lib/module_init.h"
#include "lib/posix/posix_time.h"
# include "lib/sysdep/cpu.h"
#if OS_WIN
# include "lib/sysdep/os/win/whrt/whrt.h"
#endif
@ -81,6 +82,25 @@ void timer_LatchStartTime()
}
static void EnsureMonotonic(double& t)
{
//retry:
// static i64 t_lastBits; // initially 0.0
// memcpy(&t_lastBits, &m_seconds, sizeof(t_lastBits));
//
// i64 tBits;
// memcpy(&tBits, &seconds, sizeof(tBits));
//
// if(!cpu_CAS64((volatile i64*)&m_seconds, t_lastBits, tBits))
// goto retry;
//
// static double t_last = 0.0;
// if(t < t_last)
// t = t_last;
// t_last = t;
}
double timer_Time()
{
double t;
@ -99,12 +119,7 @@ double timer_Time()
# error "timer_Time: add timer implementation for this platform!"
#endif
// make sure time is monotonic (never goes backwards)
static double t_last = 0.0;
if(t < t_last)
t = t_last+DBL_EPSILON;
t_last = t;
EnsureMonotonic(t);
return t;
}

14
source/lib/timer.h
View File

@ -32,9 +32,6 @@
#if ARCH_X86_X64 && CONFIG2_TIMER_ALLOW_RDTSC
# include "lib/sysdep/os_cpu.h" // os_cpu_ClockFrequency
# include "lib/sysdep/arch/x86_x64/x86_x64.h" // x86_x64_rdtsc
# if ARCH_IA32
# include "lib/sysdep/arch/ia32/ia32_asm.h" // ia32_asm_CAS64
# endif
#endif
@ -181,7 +178,7 @@ public:
cpu_AtomicAdd((volatile intptr_t*)&m_cycles, (intptr_t)delta);
#elif ARCH_IA32
retry:
if(!ia32_asm_CAS64(&m_cycles, m_cycles, m_cycles+delta))
if(!cpu_CAS64(&m_cycles, m_cycles, m_cycles+delta))
goto retry;
#else
# error "port"
@ -238,15 +235,8 @@ retry:
i64 newRepresentation;
memcpy(&newRepresentation, &seconds, sizeof(newRepresentation));
#if ARCH_AMD64
if(!cpu_CAS((volatile intptr_t*)&m_seconds, oldRepresentation, newRepresentation))
if(!cpu_CAS64((volatile i64*)&m_seconds, oldRepresentation, newRepresentation))
goto retry;
#elif ARCH_IA32
if(!ia32_asm_CAS64((volatile i64*)&m_seconds, oldRepresentation, newRepresentation))
goto retry;
#else
# error "port"
#endif
}
void Subtract(TimerUnit t)