cmd/compile: allow non-pointer writes in the middle of a write barrier

This lets us combine more write barriers, getting rid of some of the
test+branch and gcWriteBarrier* calls.
With the new write barriers, it's easy to add a few non-pointer writes
to the set of values written.

We allow up to 2 non-pointer writes between pointer writes. This is enough
for, for example, adjacent slice fields.

Fixes #62126

Change-Id: I872d0fa9cc4eb855e270ffc0223b39fde1723c4b
Reviewed-on: https://go-review.googlesource.com/c/go/+/521498
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Keith Randall <khr@google.com>

1 files changed, 55 insertions, 0 deletions

diff --git a/test/codegen/writebarrier.go b/test/codegen/writebarrier.go
new file mode 100644
index 0000000000..cfcfe15a40
--- /dev/null
+++ b/test/codegen/writebarrier.go
@@ -0,0 +1,55 @@
+// asmcheck
+
+// Copyright 2023 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 codegen
+
+func combine2string(p *[2]string, a, b string) {
+	// amd64:`.*runtime[.]gcWriteBarrier4\(SB\)`
+	// arm64:`.*runtime[.]gcWriteBarrier4\(SB\)`
+	p[0] = a
+	// amd64:-`.*runtime[.]gcWriteBarrier`
+	// arm64:-`.*runtime[.]gcWriteBarrier`
+	p[1] = b
+}
+
+func combine4string(p *[4]string, a, b, c, d string) {
+	// amd64:`.*runtime[.]gcWriteBarrier8\(SB\)`
+	// arm64:`.*runtime[.]gcWriteBarrier8\(SB\)`
+	p[0] = a
+	// amd64:-`.*runtime[.]gcWriteBarrier`
+	// arm64:-`.*runtime[.]gcWriteBarrier`
+	p[1] = b
+	// amd64:-`.*runtime[.]gcWriteBarrier`
+	// arm64:-`.*runtime[.]gcWriteBarrier`
+	p[2] = c
+	// amd64:-`.*runtime[.]gcWriteBarrier`
+	// arm64:-`.*runtime[.]gcWriteBarrier`
+	p[3] = d
+}
+
+func combine2slice(p *[2][]byte, a, b []byte) {
+	// amd64:`.*runtime[.]gcWriteBarrier4\(SB\)`
+	// arm64:`.*runtime[.]gcWriteBarrier4\(SB\)`
+	p[0] = a
+	// amd64:-`.*runtime[.]gcWriteBarrier`
+	// arm64:-`.*runtime[.]gcWriteBarrier`
+	p[1] = b
+}
+
+func combine4slice(p *[4][]byte, a, b, c, d []byte) {
+	// amd64:`.*runtime[.]gcWriteBarrier8\(SB\)`
+	// arm64:`.*runtime[.]gcWriteBarrier8\(SB\)`
+	p[0] = a
+	// amd64:-`.*runtime[.]gcWriteBarrier`
+	// arm64:-`.*runtime[.]gcWriteBarrier`
+	p[1] = b
+	// amd64:-`.*runtime[.]gcWriteBarrier`
+	// arm64:-`.*runtime[.]gcWriteBarrier`
+	p[2] = c
+	// amd64:-`.*runtime[.]gcWriteBarrier`
+	// arm64:-`.*runtime[.]gcWriteBarrier`
+	p[3] = d
+}