[dev.typeparams] cmd/compile: optimize wrapping of constant arguments
When wrapping a go/defer statement like:
go f(g(), "x", 42)
we were wrapping it like:
_0, _1, _2, _3 := f, g(), "x", 42
go func() { _0(_1, _2, _3) }()
This is simple and general (and often necessary), but suboptimal in
some cases, such as this. Instead of evaluating the constant arguments
at the go/defer statement, and storing them into the closure context,
we can just keep them in the wrapped call expression.
This CL changes the code to instead generate (assuming f is a declared
function, not a function-typed variable):
_0 := g()
go func() { f(_0, "x", 42) }()
Change-Id: I2bdd4951e7ee93363e1656ecf9b5bd69a121c38a
Reviewed-on: https://go-review.googlesource.com/c/go/+/330332
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
diff --git a/src/cmd/compile/internal/escape/call.go b/src/cmd/compile/internal/escape/call.go
index 850b9cb..b8e28cd 100644
--- a/src/cmd/compile/internal/escape/call.go
+++ b/src/cmd/compile/internal/escape/call.go
@@ -293,6 +293,18 @@
}
visit := func(pos src.XPos, argp *ir.Node) {
+ // Optimize a few common constant expressions. By leaving these
+ // untouched in the call expression, we let the wrapper handle
+ // evaluating them, rather than taking up closure context space.
+ switch arg := *argp; arg.Op() {
+ case ir.OLITERAL, ir.ONIL, ir.OMETHEXPR:
+ return
+ case ir.ONAME:
+ if arg.(*ir.Name).Class == ir.PFUNC {
+ return
+ }
+ }
+
if unsafeUintptr(*argp) {
return
}
