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[dev.simd] cmd/compile: enhance inlining for closure-of-SIMD

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We noticed some hand-translated code that used
nested functions as the translation of asm macros,
and they were too big to inline, and the resulting
performance was underwhelming.  Any such closures
really need to be inlined.

Because Gerrit removed votes from a previous patch
set, and because in offline discussion we realized
that this was actually a hard-to-abuse inlining hack,
I decided to turn it up some more, and also add a
"this one goes to 11" joke.  The number is utterly
unprincipled, only "simd is supposed to go fast,
and this is a natural use of closures, and we don't
want there to be issues where it doesn't go fast."

The test verifies that the inlining occurs for a
function that exceeds the current inlining threshold.
Inspection of the generated code shows that it has
the desired effect.

Change-Id: I7a8b57c07d6482e6d98cedaf9622c960f956834d
Reviewed-on: https://go-review.googlesource.com/c/go/+/715740
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Junyang Shao <shaojunyang@google.com>
This commit is contained in:
David Chase 2025-10-28 13:32:56 -04:00
parent ca1264ac50
commit e452f4ac7d
2 changed files with 52 additions and 1 deletions
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11
src/cmd/compile/internal/inline/inl.go
View file

@ -183,9 +183,18 @@ func simdCreditMultiplier(fn *ir.Func) int32 {
for _, field := range fn.Type().RecvParamsResults() {
if field.Type.IsSIMD() {
return 3
break
}
}
// Sometimes code uses closures, that do not take simd
// parameters, to perform repetitive SIMD operations.
// fn. These really need to be inlined, or the anticipated
// awesome SIMD performance will be missed.
for _, v := range fn.ClosureVars {
if v.Type().IsSIMD() {
return 11 // 11 ought to be enough.
}
}
return 1
}

42
test/simd_inline.go Normal file
View file

@ -0,0 +1,42 @@
// errorcheck -0 -m
//go:build goexperiment.simd && amd64
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package foo
import "simd"
func hasClosure(a, b, c, d simd.Int64x4) (w, x, y, z simd.Int64x4) {
shuf := func() { // ERROR "can inline hasClosure.func1"
w = z.RotateAllLeft(1).Xor(a)
x = w.RotateAllLeft(3).Xor(b)
y = x.RotateAllLeft(5).Xor(c)
z = y.RotateAllLeft(7).Xor(d)
a, b, c, d = b.RotateAllLeft(1).Xor(a.RotateAllLeft(23)), c.RotateAllLeft(1).Xor(b.RotateAllLeft(23)), d.RotateAllLeft(1).Xor(c.RotateAllLeft(23)), a.RotateAllLeft(1).Xor(d.RotateAllLeft(23))
w = z.RotateAllLeft(1).Xor(a)
x = w.RotateAllLeft(3).Xor(b)
y = x.RotateAllLeft(5).Xor(c)
z = y.RotateAllLeft(7).Xor(d)
a, b, c, d = b.RotateAllLeft(1).Xor(a.RotateAllLeft(23)), c.RotateAllLeft(1).Xor(b.RotateAllLeft(23)), d.RotateAllLeft(1).Xor(c.RotateAllLeft(23)), a.RotateAllLeft(1).Xor(d.RotateAllLeft(23))
w = z.RotateAllLeft(1).Xor(a)
x = w.RotateAllLeft(3).Xor(b)
y = x.RotateAllLeft(5).Xor(c)
z = y.RotateAllLeft(7).Xor(d)
a, b, c, d = b.RotateAllLeft(1).Xor(a.RotateAllLeft(23)), c.RotateAllLeft(1).Xor(b.RotateAllLeft(23)), d.RotateAllLeft(1).Xor(c.RotateAllLeft(23)), a.RotateAllLeft(1).Xor(d.RotateAllLeft(23))
}
shuf() // ERROR "inlining call to hasClosure.func1"
shuf() // ERROR "inlining call to hasClosure.func1"
shuf() // ERROR "inlining call to hasClosure.func1"
shuf() // ERROR "inlining call to hasClosure.func1"
shuf() // ERROR "inlining call to hasClosure.func1"
shuf() // ERROR "inlining call to hasClosure.func1"
shuf() // ERROR "inlining call to hasClosure.func1"
shuf() // ERROR "inlining call to hasClosure.func1"
shuf() // ERROR "inlining call to hasClosure.func1"
return
}