cmd/compile: change StaticCall to return a "Results"

StaticLECall (multiple value in +mem, multiple value result +mem) ->
StaticCall (multiple ergister value in +mem,
   multiple register-sized-value result +mem) ->
ARCH CallStatic (multiple ergister value in +mem,
   multiple register-sized-value result +mem)

But the architecture-dependent stuff is indifferent to whether
it is mem->mem or (mem)->(mem) until Prog generation.

Deal with OpSelectN -> Prog in ssagen/ssa.go, others, as they
appear.

For #40724.

Change-Id: I1d0436f6371054f1881862641d8e7e418e4a6a16
Reviewed-on: https://go-review.googlesource.com/c/go/+/293391
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>

1 files changed, 17 insertions, 6 deletions

diff --git a/src/cmd/compile/internal/types/type.go b/src/cmd/compile/internal/types/type.go
index b6374e49a5..9fb6d68994 100644
--- a/src/cmd/compile/internal/types/type.go
+++ b/src/cmd/compile/internal/types/type.go
@@ -581,12 +581,19 @@ func NewTuple(t1, t2 *Type) *Type {
 	return t
 }
 
-func NewResults(types []*Type) *Type {
+func newResults(types []*Type) *Type {
 	t := New(TRESULTS)
 	t.Extra.(*Results).Types = types
 	return t
 }
 
+func NewResults(types []*Type) *Type {
+	if len(types) == 1 && types[0] == TypeMem {
+		return TypeResultMem
+	}
+	return newResults(types)
+}
+
 func newSSA(name string) *Type {
 	t := New(TSSA)
 	t.Extra = name
@@ -1407,6 +1414,9 @@ func (t *Type) PtrTo() *Type {
 }
 
 func (t *Type) NumFields() int {
+	if t.kind == TRESULTS {
+		return len(t.Extra.(*Results).Types)
+	}
 	return t.Fields().Len()
 }
 func (t *Type) FieldType(i int) *Type {
@@ -1597,11 +1607,12 @@ func FakeRecvType() *Type {
 
 var (
 	// TSSA types. HasPointers assumes these are pointer-free.
-	TypeInvalid = newSSA("invalid")
-	TypeMem     = newSSA("mem")
-	TypeFlags   = newSSA("flags")
-	TypeVoid    = newSSA("void")
-	TypeInt128  = newSSA("int128")
+	TypeInvalid   = newSSA("invalid")
+	TypeMem       = newSSA("mem")
+	TypeFlags     = newSSA("flags")
+	TypeVoid      = newSSA("void")
+	TypeInt128    = newSSA("int128")
+	TypeResultMem = newResults([]*Type{TypeMem})
 )
 
 // NewNamed returns a new named type for the given type name.