[go] simd: for 1.27, make ARM64 Reduce* methods return scalar

0 views

Skip to first unread message

David Chase (Gerrit)

unread,

Jun 5, 2026, 4:56:14 PM (2 days ago) Jun 5

to goph...@pubsubhelper.golang.org, golang-...@googlegroups.com, golang...@luci-project-accounts.iam.gserviceaccount.com, Cherry Mui, Gopher Robot, golang-co...@googlegroups.com

David Chase submitted the change with unreviewed changes

Unreviewed changes

1 is the latest approved patch-set.
The change was submitted with unreviewed changes in the following files:

```
The name of the file: src/simd/archsimd/_gen/tmplgen/main.go
Insertions: 6, Deletions: 0.

@@ -1284,6 +1284,8 @@
 
 var reduceSumTemplateArm64 = shapedTemplateOf(arm64ReduceIntegerShapes, "arm64_ReduceSum methods", `
 // ReduceSum reduces x by summing all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x {{.VType}}) ReduceSum() {{.Etype}} {
 	return x.reduceSum().GetElem(0)
 }
@@ -1291,11 +1293,15 @@
 
 var reduceMinMaxTemplateArm64 = shapedTemplateOf(arm64ReduceAllShapes, "arm64_ReduceMax/Min methods", `
 // ReduceMax reduces x by taking the maximum of all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x {{.VType}}) ReduceMax() {{.Etype}} {
 	return x.reduceMax().GetElem(0)
 }
 
 // ReduceMin reduces x by taking the minimum of all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x {{.VType}}) ReduceMin() {{.Etype}} {
 	return x.reduceMin().GetElem(0)
 }
```
```
The name of the file: src/simd/archsimd/other_gen_arm64.go
Insertions: 40, Deletions: 0.

@@ -379,101 +379,141 @@
 }
 
 // ReduceSum reduces x by summing all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x Int8x16) ReduceSum() int8 {
 	return x.reduceSum().GetElem(0)
 }
 
 // ReduceSum reduces x by summing all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x Int16x8) ReduceSum() int16 {
 	return x.reduceSum().GetElem(0)
 }
 
 // ReduceSum reduces x by summing all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x Int32x4) ReduceSum() int32 {
 	return x.reduceSum().GetElem(0)
 }
 
 // ReduceSum reduces x by summing all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x Uint8x16) ReduceSum() uint8 {
 	return x.reduceSum().GetElem(0)
 }
 
 // ReduceSum reduces x by summing all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x Uint16x8) ReduceSum() uint16 {
 	return x.reduceSum().GetElem(0)
 }
 
 // ReduceSum reduces x by summing all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x Uint32x4) ReduceSum() uint32 {
 	return x.reduceSum().GetElem(0)
 }
 
 // ReduceMax reduces x by taking the maximum of all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x Int8x16) ReduceMax() int8 {
 	return x.reduceMax().GetElem(0)
 }
 
 // ReduceMin reduces x by taking the minimum of all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x Int8x16) ReduceMin() int8 {
 	return x.reduceMin().GetElem(0)
 }
 
 // ReduceMax reduces x by taking the maximum of all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x Int16x8) ReduceMax() int16 {
 	return x.reduceMax().GetElem(0)
 }
 
 // ReduceMin reduces x by taking the minimum of all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x Int16x8) ReduceMin() int16 {
 	return x.reduceMin().GetElem(0)
 }
 
 // ReduceMax reduces x by taking the maximum of all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x Int32x4) ReduceMax() int32 {
 	return x.reduceMax().GetElem(0)
 }
 
 // ReduceMin reduces x by taking the minimum of all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x Int32x4) ReduceMin() int32 {
 	return x.reduceMin().GetElem(0)
 }
 
 // ReduceMax reduces x by taking the maximum of all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x Uint8x16) ReduceMax() uint8 {
 	return x.reduceMax().GetElem(0)
 }
 
 // ReduceMin reduces x by taking the minimum of all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x Uint8x16) ReduceMin() uint8 {
 	return x.reduceMin().GetElem(0)
 }
 
 // ReduceMax reduces x by taking the maximum of all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x Uint16x8) ReduceMax() uint16 {
 	return x.reduceMax().GetElem(0)
 }
 
 // ReduceMin reduces x by taking the minimum of all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x Uint16x8) ReduceMin() uint16 {
 	return x.reduceMin().GetElem(0)
 }
 
 // ReduceMax reduces x by taking the maximum of all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x Uint32x4) ReduceMax() uint32 {
 	return x.reduceMax().GetElem(0)
 }
 
 // ReduceMin reduces x by taking the minimum of all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x Uint32x4) ReduceMin() uint32 {
 	return x.reduceMin().GetElem(0)
 }
 
 // ReduceMax reduces x by taking the maximum of all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x Float32x4) ReduceMax() float32 {
 	return x.reduceMax().GetElem(0)
 }
 
 // ReduceMin reduces x by taking the minimum of all elements.
+//
+// Emulated, CPU Feature: NEON
 func (x Float32x4) ReduceMin() float32 {
 	return x.reduceMin().GetElem(0)
 }
```

Change information

Commit message:

simd: for 1.27, make ARM64 Reduce* methods return scalar

This is a cherry pick of Alexander Musman's CL 784800,
done this way to help with 1.27 release deadlines and
a minor amount of merging friction.

ReduceSum/ReduceMax/ReduceMin on all types now return scalar (e.g. int32)
instead of vector. Internally, the intrinsics are unexported (lowercase)
and return a vector with the result in lane 0. The exported wrappers
call GetElem(0) to extract the scalar, generated by tmplgen.

A follow-up CL will add peephole rules to elide the GetElem(0)
when the result feeds directly into another SIMD operation.

Former-Change-Id: I630cec6a26d54ed9ed1412a37076e20df9e51038

Change-Id: Id8ff6e07083bc62de4ca595dea3c9884b75ec517

Reviewed-on: https://go-review.googlesource.com/c/go/+/787560

LUCI-TryBot-Result: golang...@luci-project-accounts.iam.gserviceaccount.com <golang...@luci-project-accounts.iam.gserviceaccount.com>

Reviewed-by: Cherry Mui <cher...@google.com>

Files: