cmd/compile, etc: use tflag to optimize Name()==""
Improves JSON decoding benchmark:
name old time/op new time/op delta
CodeDecoder-8 41.3ms ± 6% 39.8ms ± 1% -3.61% (p=0.000 n=10+10)
name old speed new speed delta
CodeDecoder-8 47.0MB/s ± 6% 48.7MB/s ± 1% +3.66% (p=0.000 n=10+10)
Change-Id: I524ee05c432fad5252e79b29222ec635c1dee4b4
Reviewed-on: https://go-review.googlesource.com/24452 Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>