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| author | Jason A. Donenfeld <Jason@zx2c4.com> | 2021-11-03 18:19:04 +0100 |
|---|---|---|
| committer | Jason A. Donenfeld <Jason@zx2c4.com> | 2021-11-03 18:37:22 +0000 |
| commit | cfd016df1fba2a2a104f4cca705aa4357777986b (patch) | |
| tree | a0704332a5565aa06525c733d7e935dab7eb2451 /src/runtime/time_windows_arm64.s | |
| parent | d4e0e8e4a41e5e1e7d0359287a1015791ce778ed (diff) | |
| download | go-cfd016df1fba2a2a104f4cca705aa4357777986b.tar.xz | |
runtime: on windows, read nanotime with one instruction or issue barrier
On 64-bit, this is more efficient, and on ARM64, this prevents the time
from moving backwards due to the weaker memory model. On ARM32 due to
the weaker memory model, we issue a memory barrier.
Updates #48072.
Change-Id: If4695716c3039d8af14e14808af217f5c99fc93a
Reviewed-on: https://go-review.googlesource.com/c/go/+/361057
Trust: Jason A. Donenfeld <Jason@zx2c4.com>
Run-TryBot: Jason A. Donenfeld <Jason@zx2c4.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Diffstat (limited to 'src/runtime/time_windows_arm64.s')
| -rw-r--r-- | src/runtime/time_windows_arm64.s | 22 |
1 files changed, 3 insertions, 19 deletions
diff --git a/src/runtime/time_windows_arm64.s b/src/runtime/time_windows_arm64.s index ef52ce4c99..e8a0eb2f93 100644 --- a/src/runtime/time_windows_arm64.s +++ b/src/runtime/time_windows_arm64.s @@ -13,34 +13,18 @@ TEXT time·now(SB),NOSPLIT|NOFRAME,$0-24 MOVB runtime·useQPCTime(SB), R0 CMP $0, R0 BNE useQPC - MOVD $_INTERRUPT_TIME, R3 -loop: - MOVWU time_hi1(R3), R1 - MOVWU time_lo(R3), R0 - MOVWU time_hi2(R3), R2 - CMP R1, R2 - BNE loop - // wintime = R1:R0, multiply by 100 - ORR R1<<32, R0 + MOVD $_INTERRUPT_TIME, R3 + MOVD time_lo(R3), R0 MOVD $100, R1 MUL R1, R0 MOVD R0, mono+16(FP) MOVD $_SYSTEM_TIME, R3 -wall: - MOVWU time_hi1(R3), R1 - MOVWU time_lo(R3), R0 - MOVWU time_hi2(R3), R2 - CMP R1, R2 - BNE wall - - // w = R1:R0 in 100ns units + MOVD time_lo(R3), R0 // convert to Unix epoch (but still 100ns units) #define delta 116444736000000000 - ORR R1<<32, R0 SUB $delta, R0 - // Convert to nSec MOVD $100, R1 MUL R1, R0 |