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cmd/compile: reduce inline cost of OCONVOP

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OCONVOP doesn't have effect in the compiled code so, it can be safely
excluded from inline cost calculation.

Also make sequence ODEREF OCONVNOP* OADDR cost 1. This is rather common
conversion, such as *(*uint32)(unsafe.Pointer(&x)).

Fixes #42788

Change-Id: I5001f7e89d985c198b6405694cdd5b819cf3f47a
Reviewed-on: https://go-review.googlesource.com/c/go/+/281232
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Elias Naur <mail@eliasnaur.com>
This commit is contained in:
Egon Elbre 2021-01-02 16:28:11 +02:00 committed by Josh Bleecher Snyder
parent 27684ea195
commit adb467ffd2
2 changed files with 39 additions and 0 deletions
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16
src/cmd/compile/internal/inline/inl.go
View File

@ -384,6 +384,22 @@ func (v *hairyVisitor) doNode(n ir.Node) bool {
case ir.OAPPEND:
v.budget -= inlineExtraAppendCost
case ir.ODEREF:
// *(*X)(unsafe.Pointer(&x)) is low-cost
n := n.(*ir.StarExpr)
ptr := n.X
for ptr.Op() == ir.OCONVNOP {
ptr = ptr.(*ir.ConvExpr).X
}
if ptr.Op() == ir.OADDR {
v.budget += 1 // undo half of default cost of ir.ODEREF+ir.OADDR
}
case ir.OCONVNOP:
// This doesn't produce code, but the children might.
v.budget++ // undo default cost
case ir.ODCLCONST, ir.OFALL:
// These nodes don't produce code; omit from inlining budget.
return false

23
test/inline.go
View File

@ -10,6 +10,7 @@
package foo
import (
"math"
"runtime"
"unsafe"
)
@ -262,3 +263,25 @@ func gd2() int { // ERROR "can inline gd2"
func gd3() func() { // ERROR "can inline gd3"
return ii
}
// Issue #42788 - ensure ODEREF OCONVNOP* OADDR is low cost.
func EncodeQuad(d []uint32, x [6]float32) { // ERROR "can inline EncodeQuad" "d does not escape"
_ = d[:6]
d[0] = math.Float32bits(x[0]) // ERROR "inlining call to math.Float32bits"
d[1] = math.Float32bits(x[1]) // ERROR "inlining call to math.Float32bits"
d[2] = math.Float32bits(x[2]) // ERROR "inlining call to math.Float32bits"
d[3] = math.Float32bits(x[3]) // ERROR "inlining call to math.Float32bits"
d[4] = math.Float32bits(x[4]) // ERROR "inlining call to math.Float32bits"
d[5] = math.Float32bits(x[5]) // ERROR "inlining call to math.Float32bits"
}
// Ensure OCONVNOP is zero cost.
func Conv(v uint64) uint64 { // ERROR "can inline Conv"
return conv2(conv2(conv2(v))) // ERROR "inlining call to (conv1|conv2)"
}
func conv2(v uint64) uint64 { // ERROR "can inline conv2"
return conv1(conv1(conv1(conv1(v)))) // ERROR "inlining call to conv1"
}
func conv1(v uint64) uint64 { // ERROR "can inline conv1"
return uint64(uint64(uint64(uint64(uint64(uint64(uint64(uint64(uint64(uint64(uint64(v)))))))))))
}