|
Currently the following source code:
u64 NanoTime() {
kernel_timeval tv = {};
internal_syscall(__NR_gettimeofday, &tv, 0);
return (u64)tv.tv_sec * 1000*1000*1000 + tv.tv_usec * 1000;
}
generates the following assembly:
Dump of assembler code for function __sanitizer::NanoTime():
=> 0x00007ff30657d380 <+0>: lea -0x10(%rsp),%rdi
0x00007ff30657d385 <+5>: xor %esi,%esi
0x00007ff30657d387 <+7>: mov $0x60,%eax
0x00007ff30657d38c <+12>: syscall
0x00007ff30657d38e <+14>: mov $0,%eax
0x00007ff30657d393 <+19>: retq
with this change:
Dump of assembler code for function __sanitizer::NanoTime():
=> 0x00007faab834f380 <+0>: movq $0x0,-0x10(%rsp)
0x00007faab834f389 <+9>: movq $0x0,-0x8(%rsp)
0x00007faab834f392 <+18>: lea -0x10(%rsp),%rdi
0x00007faab834f397 <+23>: xor %esi,%esi
0x00007faab834f399 <+25>: mov $0x60,%eax
0x00007faab834f39e <+30>: syscall
0x00007faab834f3a0 <+32>: mov -0x8(%rsp),%rax
0x00007faab834f3a5 <+37>: mov -0x10(%rsp),%rcx
0x00007faab834f3aa <+42>: imul $0x3e8,%rax,%rdx
0x00007faab834f3b1 <+49>: imul $0x3b9aca00,%rcx,%rax
0x00007faab834f3b8 <+56>: add %rdx,%rax
0x00007faab834f3bb <+59>: retq
git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@191908 91177308-0d34-0410-b5e6-96231b3b80d8
|