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atomic: analyze further

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Ciro Santilli 六四事件 法轮功
2019-11-17 00:00:00 +00:00
parent d43ca360eb
commit 8244e0529b
2 changed files with 125 additions and 18 deletions
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25
userland/cpp/atomic/main.hpp
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@@ -28,23 +28,26 @@ void threadMain() {
#if LKMC_USERLAND_ATOMIC_X86_64_INC
__asm__ __volatile__ (
"incq %0;"
: "+g" (global)
: "+g" (global),
"+g" (i) // to prevent loop unrolling, and make results more comparable across methods,
// see also: https://cirosantilli.com/linux-kernel-module-cheat#infinite-busy-loop
:
:
);
#elif LKMC_USERLAND_ATOMIC_X86_64_LOCK_INC
// https://cirosantilli.com/linux-kernel-module-cheat#x86-lock-prefix
__asm__ __volatile__ (
"lock;"
"incq %0;"
: "+m" (global)
"lock incq %0;"
: "+m" (global),
"+g" (i) // to prevent loop unrolling
:
:
);
#elif LKMC_USERLAND_ATOMIC_AARCH64_ADD
__asm__ __volatile__ (
"add %0, %0, 1;"
: "+r" (global)
: "+r" (global),
"+g" (i) // to prevent loop unrolling
:
:
);
@@ -52,18 +55,24 @@ void threadMain() {
// https://cirosantilli.com/linux-kernel-module-cheat#arm-lse
__asm__ __volatile__ (
"ldadd %[inc], xzr, [%[addr]];"
: "=m" (global)
: "=m" (global),
"+g" (i) // to prevent loop unrolling
: [inc] "r" (1),
[addr] "r" (&global)
:
);
#else
__asm__ __volatile__ (
""
: "+g" (i) // to prevent he loop from being optimized to a single add
// see also: https://stackoverflow.com/questions/37786547/enforcing-statement-order-in-c/56865717#56865717
: "g" (global)
:
);
global++;
#endif
#if LKMC_USERLAND_ATOMIC_MUTEX
mutex.unlock();
#endif
#if 0
#endif
}
}