tree 61b896d88767ecfd863ded2b4761f2755237ac07
parent 3287064c24cbf0c50776cdb87a720d29130b4363
author Ian Lance Taylor <iant@golang.org> 1519831677 -0800
committer Ian Lance Taylor <iant@golang.org> 1520433017 +0000

runtime: use a fence instruction before rdtsc

This implements the same choices made in the gc runtime, except that
for 32-bit x86 we only use the fence instruction if the processor
supports SSE2.

The code here is hacked up for speed; the gc runtime uses straight
assembler.

Change-Id: I853679cfdf732395ce0f947b45a7e3844427e1f8
Reviewed-on: https://go-review.googlesource.com/97715
Reviewed-by: Than McIntosh <thanm@google.com>