cmd/gofmt: only resolve go/ast objects when needed
go/parser will by default resolve objects as per the go/ast.Object type,
which is then used by gofmt's rewrite and simplify flags.
However, none of that is needed if neither of the flags is set,
so we can avoid the work entirely for a nice speed-up.
benchcmd -n 8 GofmtSrcCmd gofmt -l ~/tip/src/cmd
name old time/op new time/op delta
GofmtSrcCmd 957ms ± 7% 908ms ± 7% -5.12% (p=0.028 n=8+8)
name old user-time/op new user-time/op delta
GofmtSrcCmd 11.2s ± 1% 10.4s ± 1% -7.23% (p=0.001 n=7+7)
name old sys-time/op new sys-time/op delta
GofmtSrcCmd 325ms ±29% 286ms ±22% ~ (p=0.065 n=8+8)
name old peak-RSS-bytes new peak-RSS-bytes delta
GofmtSrcCmd 295MB ±17% 276MB ±15% ~ (p=0.328 n=8+8)
See #46485.
Change-Id: Iad1ae294953710c233f7837d7eb02e23d11c6185
Reviewed-on: https://go-review.googlesource.com/c/go/+/401454
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Bryan Mills <bcmills@google.com> Reviewed-by: Ian Lance Taylor <iant@google.com>