[dev.regabi] cmd/compile: added limited //go:registerparams pragma for new ABI dev

This only works for functions; if you try it with a method, it will
fail.  It does work for both local package and imports.  For now,
it tells you when it thinks it sees either a declaration or a call of
such a function (this will normally be silent since no existing
code uses this pragma).

Note: it appears to be really darn hard to figure out if this
pragma was set for a method, and the method's call site.  Better
ir.Node wranglers than I might be able to make headway, but it
seemed unnecessary for this experiment.

Change-Id: I601c2ddd124457bf6d62f714d7ac871705743c0a
Reviewed-on: https://go-review.googlesource.com/c/go/+/279521
Trust: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>

4 files changed, 70 insertions, 0 deletions

diff --git a/test/abi/regabipragma.dir/main.go b/test/abi/regabipragma.dir/main.go
new file mode 100644
index 0000000000..d663337a10
--- /dev/null
+++ b/test/abi/regabipragma.dir/main.go
@@ -0,0 +1,36 @@
+// Copyright 2021 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 main
+
+import (
+	"fmt"
+	"regabipragma.dir/tmp"
+)
+
+type S string
+
+//go:noinline
+func (s S) ff(t string) string {
+	return string(s) + " " + t
+}
+
+//go:noinline
+//go:registerparams
+func f(s,t string) string { // ERROR "Declared function f has register params"
+	return s + " " + t
+}
+
+func check(s string) {
+	if s != "Hello world!" {
+		fmt.Printf("FAIL, wanted 'Hello world!' but got '%s'\n", s)
+	}
+}
+
+func main() {
+	check(f("Hello", "world!"))   // ERROR "Called function ...f has register params"
+	check(tmp.F("Hello", "world!"))  // ERROR "Called function regabipragma.dir/tmp.F has register params"
+	check(S("Hello").ff("world!"))
+	check(tmp.S("Hello").FF("world!"))
+}
diff --git a/test/abi/regabipragma.dir/tmp/foo.go b/test/abi/regabipragma.dir/tmp/foo.go
new file mode 100644
index 0000000000..cff989bbcd
--- /dev/null
+++ b/test/abi/regabipragma.dir/tmp/foo.go
@@ -0,0 +1,19 @@
+// Copyright 2021 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 tmp
+
+
+type S string
+
+//go:noinline
+func (s S) FF(t string) string {
+        return string(s) + " " + t
+}
+
+//go:noinline
+//go:registerparams
+func F(s,t string) string {
+        return s + " " + t
+}
diff --git a/test/abi/regabipragma.go b/test/abi/regabipragma.go
new file mode 100644
index 0000000000..93cdb6abbb
--- /dev/null
+++ b/test/abi/regabipragma.go
@@ -0,0 +1,9 @@
+// runindir
+
+// Copyright 2021 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.
+
+// TODO May delete or adapt this test once regabi is the default
+
+package ignore
diff --git a/test/abi/regabipragma.out b/test/abi/regabipragma.out
new file mode 100644
index 0000000000..7803613351
--- /dev/null
+++ b/test/abi/regabipragma.out
@@ -0,0 +1,6 @@
+# regabipragma.dir/tmp
+tmp/foo.go:17:6: Declared function F has register params
+# regabipragma.dir
+./main.go:21:6: Declared function f has register params
+./main.go:32:9: Called function "".f has register params
+./main.go:33:13: Called function regabipragma.dir/tmp.F has register params