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cmd/cgo: optimize cgoCheckPointer call

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Currently cgoCheckPointer is only used with one optional argument.
Using a slice for the optional arguments is quite expensive, hence
replace it with a single interface{}. This results in ~30% improvement.

When checking struct fields, they quite often end up being without
pointers. Check this before calling cgoCheckPointer, which results in
additional ~20% improvement.

Inline some p == nil checks from cgoIsGoPointer which gives
additional ~15% improvement.

All of this translates to:

name                             old time/op  new time/op  delta
CgoCall/add-int-32               46.9ns ± 1%  46.6ns ± 1%   -0.75%  (p=0.000 n=18+20)
CgoCall/one-pointer-32            143ns ± 1%    87ns ± 1%  -38.96%  (p=0.000 n=20+20)
CgoCall/eight-pointers-32         767ns ± 0%   327ns ± 1%  -57.30%  (p=0.000 n=18+16)
CgoCall/eight-pointers-nil-32     110ns ± 1%    89ns ± 2%  -19.10%  (p=0.000 n=19+19)
CgoCall/eight-pointers-array-32  5.09µs ± 1%  3.56µs ± 2%  -30.09%  (p=0.000 n=19+19)
CgoCall/eight-pointers-slice-32  3.92µs ± 0%  2.57µs ± 2%  -34.48%  (p=0.000 n=20+20)

Change-Id: I2aa9f5ae8962a9a41a7fb1db0c300893109d0d75
Reviewed-on: https://go-review.googlesource.com/c/go/+/198081
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Egon Elbre 2019-10-01 18:12:55 +03:00 • committed by Ian Lance Taylor
parent 30d7b64008
commit e85ffec784
4 changed files with 98 additions and 20 deletions
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6
src/cmd/cgo/gcc.go
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@ -816,7 +816,7 @@ func (p *Package) rewriteCall(f *File, call *Call) (string, bool) {
// Rewrite C.f(p) to
// func() {
// _cgo0 := p
// _cgoCheckPointer(_cgo0)
// _cgoCheckPointer(_cgo0, nil)
// C.f(_cgo0)
// }()
// Using a function literal like this lets us evaluate the
@ -834,7 +834,7 @@ func (p *Package) rewriteCall(f *File, call *Call) (string, bool) {
// defer func() func() {
// _cgo0 := p
// return func() {
// _cgoCheckPointer(_cgo0)
// _cgoCheckPointer(_cgo0, nil)
// C.f(_cgo0)
// }
// }()()
@ -921,7 +921,7 @@ func (p *Package) rewriteCall(f *File, call *Call) (string, bool) {
}
fmt.Fprintf(&sb, "_cgo%d := %s; ", i, gofmtPos(arg, origArg.Pos()))
fmt.Fprintf(&sbCheck, "_cgoCheckPointer(_cgo%d); ", i)
fmt.Fprintf(&sbCheck, "_cgoCheckPointer(_cgo%d, nil); ", i)
}
if call.Deferred {