cmd/compile: spill output parameters passed in registers as autos

ALSO:
found evidence that stack maps for bodyless methods are wrong.
gofmt in test/abi
removed never-executed code in types/size.go

Updates #44816.

Change-Id: I658c33f049337fb6f1e625f0c55430d25bfa877e
Reviewed-on: https://go-review.googlesource.com/c/go/+/300749
Trust: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

6 files changed, 179 insertions, 7 deletions

diff --git a/test/abi/fibish2.go b/test/abi/fibish2.go
index 14f3f9ada7..388aabc8b0 100644
--- a/test/abi/fibish2.go
+++ b/test/abi/fibish2.go
@@ -13,12 +13,12 @@ import "fmt"
 
 // Test that register results are correctly returned (and passed)
 
-type MagicLastTypeNameForTestingRegisterABI func(int,MagicLastTypeNameForTestingRegisterABI) int
+type MagicLastTypeNameForTestingRegisterABI func(int, MagicLastTypeNameForTestingRegisterABI) int
 
 //go:registerparams
 //go:noinline
 func minus(decrement int) MagicLastTypeNameForTestingRegisterABI {
-	return MagicLastTypeNameForTestingRegisterABI( func(x int, _ MagicLastTypeNameForTestingRegisterABI) int { return x-decrement} )
+	return MagicLastTypeNameForTestingRegisterABI(func(x int, _ MagicLastTypeNameForTestingRegisterABI) int { return x - decrement })
 }
 
 //go:noinline
diff --git a/test/abi/leaf.go b/test/abi/leaf.go
new file mode 100644
index 0000000000..f893f5dddb
--- /dev/null
+++ b/test/abi/leaf.go
@@ -0,0 +1,36 @@
+// run
+
+//go:build !wasm
+// +build !wasm
+
+// 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.
+
+// wasm is excluded because the compiler chatter about register abi pragma ends up
+// on stdout, and causes the expected output to not match.
+
+package main
+
+import "fmt"
+
+type i5f5 struct {
+	a, b          int16
+	c, d, e       int32
+	r, s, t, u, v float32
+}
+
+//go:registerparams
+//go:noinline
+func F(x i5f5) i5f5 {
+	return x
+}
+
+func main() {
+	x := i5f5{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
+	y := x
+	z := F(x)
+	if y != z {
+		fmt.Printf("y=%v, z=%v\n", y, z)
+	}
+}
diff --git a/test/abi/leaf2.go b/test/abi/leaf2.go
new file mode 100644
index 0000000000..d2018d5313
--- /dev/null
+++ b/test/abi/leaf2.go
@@ -0,0 +1,43 @@
+// run
+
+//go:build !wasm
+// +build !wasm
+
+// 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.
+
+// wasm is excluded because the compiler chatter about register abi pragma ends up
+// on stdout, and causes the expected output to not match.
+
+package main
+
+import "fmt"
+
+type i4 struct {
+	a, b, c, d int
+}
+
+//go:registerparams
+//go:noinline
+func F(x i4) i4 {
+	ab := x.a + x.b
+	bc := x.b + x.c
+	cd := x.c + x.d
+	ad := x.a + x.d
+	ba := x.a - x.b
+	cb := x.b - x.c
+	dc := x.c - x.d
+	da := x.a - x.d
+
+	return i4{ab*bc + da, cd*ad + cb, ba*cb + ad, dc*da + bc}
+}
+
+func main() {
+	x := i4{1, 2, 3, 4}
+	y := x
+	z := F(x)
+	if (i4{12, 34, 6, 8}) != z {
+		fmt.Printf("y=%v, z=%v\n", y, z)
+	}
+}
diff --git a/test/abi/methods.go b/test/abi/methods.go
index 9ecae9833e..3dcd3e327a 100644
--- a/test/abi/methods.go
+++ b/test/abi/methods.go
@@ -14,7 +14,7 @@ import (
 )
 
 type toobig struct {
-	a,b,c string
+	a, b, c string
 }
 
 //go:registerparams
@@ -29,8 +29,8 @@ type AnInterface interface {
 
 //go:registerparams
 //go:noinline
-func I(a,b,c string) toobig {
-	return toobig{a,b,c}
+func I(a, b, c string) toobig {
+	return toobig{a, b, c}
 }
 
 // AnIid prevents the compiler from figuring out what the interface really is.
@@ -40,12 +40,13 @@ func AnIid(x AnInterface) AnInterface {
 }
 
 var tmp toobig
+
 func main() {
 	x := I("Ahoy", "1,", "2")
 	y := I("3", "there,", "4")
 	z := I("5", "6,", "Matey")
-	tmp = x.MagicMethodNameForTestingRegisterABI(y,z)
+	tmp = x.MagicMethodNameForTestingRegisterABI(y, z)
 	fmt.Println(tmp.a, tmp.b, tmp.c)
-	tmp = AnIid(&x).MagicMethodNameForTestingRegisterABI(y,z)
+	tmp = AnIid(&x).MagicMethodNameForTestingRegisterABI(y, z)
 	fmt.Println(tmp.a, tmp.b, tmp.c)
 }
diff --git a/test/abi/spills3.go b/test/abi/spills3.go
new file mode 100644
index 0000000000..247828437b
--- /dev/null
+++ b/test/abi/spills3.go
@@ -0,0 +1,48 @@
+// run
+
+//go:build !wasm
+// +build !wasm
+
+// 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.
+
+// wasm is excluded because the compiler chatter about register abi pragma ends up
+// on stdout, and causes the expected output to not match.
+
+package main
+
+import "fmt"
+
+type i4 struct {
+	a, b, c, d int
+}
+
+//go:noinline
+func spills(px *i4) {
+}
+
+//go:registerparams
+//go:noinline
+func F(x i4) i4 {
+	ab := x.a + x.b
+	bc := x.b + x.c
+	cd := x.c + x.d
+	ad := x.a + x.d
+	ba := x.a - x.b
+	cb := x.b - x.c
+	dc := x.c - x.d
+	da := x.a - x.d
+	i := i4{ab*bc + da, cd*ad + cb, ba*cb + ad, dc*da + bc}
+	spills(&i)
+	return i
+}
+
+func main() {
+	x := i4{1, 2, 3, 4}
+	y := x
+	z := F(x)
+	if z != (i4{12, 34, 6, 8}) {
+		fmt.Printf("y=%v, z=%v\n", y, z)
+	}
+}
diff --git a/test/abi/spills4.go b/test/abi/spills4.go
new file mode 100644
index 0000000000..205f5a64c0
--- /dev/null
+++ b/test/abi/spills4.go
@@ -0,0 +1,44 @@
+// run
+
+//go:build !wasm
+// +build !wasm
+
+// 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.
+
+// wasm is excluded because the compiler chatter about register abi pragma ends up
+// on stdout, and causes the expected output to not match.
+
+package main
+
+import "fmt"
+
+type i5f5 struct {
+	a, b          int16
+	c, d, e       int32
+	r, s, t, u, v float32
+}
+
+//go:noinline
+func spills(_ *float32) {
+
+}
+
+//go:registerparams
+//go:noinline
+func F(x i5f5) i5f5 {
+	y := x.v
+	spills(&y)
+	x.r = y
+	return x
+}
+
+func main() {
+	x := i5f5{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
+	y := x
+	z := F(x)
+	if (i5f5{1, 2, 3, 4, 5, 10, 7, 8, 9, 10}) != z {
+		fmt.Printf("y=%v, z=%v\n", y, z)
+	}
+}