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>

src/cmd/compile/internal/abi/abiutils.go

@@ -27,6 +27,8 @@ type ABIParamResultInfo struct {
 	outparams         []ABIParamAssignment
 	offsetToSpillArea int64
 	spillAreaSize     int64
+	inRegistersUsed   int
+	outRegistersUsed  int
 	config            *ABIConfig // to enable String() method
 }
 
@@ -42,6 +44,14 @@ func (a *ABIParamResultInfo) OutParams() []ABIParamAssignment {
 	return a.outparams
 }
 
+func (a *ABIParamResultInfo) InRegistersUsed() int {
+	return a.inRegistersUsed
+}
+
+func (a *ABIParamResultInfo) OutRegistersUsed() int {
+	return a.outRegistersUsed
+}
+
 func (a *ABIParamResultInfo) InParam(i int) ABIParamAssignment {
 	return a.inparams[i]
 }
@@ -164,6 +174,55 @@ func (a *ABIConfig) NumParamRegs(t *types.Type) int {
 	return n
 }
 
+// preAllocateParams gets the slice sizes right for inputs and outputs.
+func (a *ABIParamResultInfo) preAllocateParams(hasRcvr bool, nIns, nOuts int) {
+	if hasRcvr {
+		nIns++
+	}
+	a.inparams = make([]ABIParamAssignment, 0, nIns)
+	a.outparams = make([]ABIParamAssignment, 0, nOuts)
+}
+
+// ABIAnalyzeTypes takes an optional receiver type, arrays of ins and outs, and returns an ABIParamResultInfo,
+// based on the given configuration.  This is the same result computed by config.ABIAnalyze applied to the
+// corresponding method/function type, except that all the embedded parameter names are nil.
+// This is intended for use by ssagen/ssa.go:(*state).rtcall, for runtime functions that lack a parsed function type.
+func (config *ABIConfig) ABIAnalyzeTypes(rcvr *types.Type, ins, outs []*types.Type) *ABIParamResultInfo {
+	setup()
+	s := assignState{
+		rTotal: config.regAmounts,
+	}
+	result := &ABIParamResultInfo{config: config}
+	result.preAllocateParams(rcvr != nil, len(ins), len(outs))
+
+	// Receiver
+	if rcvr != nil {
+		result.inparams = append(result.inparams,
+			s.assignParamOrReturn(rcvr, nil, false))
+	}
+
+	// Inputs
+	for _, t := range ins {
+		result.inparams = append(result.inparams,
+			s.assignParamOrReturn(t, nil, false))
+	}
+	s.stackOffset = types.Rnd(s.stackOffset, int64(types.RegSize))
+	result.inRegistersUsed = s.rUsed.intRegs + s.rUsed.floatRegs
+
+	// Outputs
+	s.rUsed = RegAmounts{}
+	for _, t := range outs {
+		result.outparams = append(result.outparams, s.assignParamOrReturn(t, nil, true))
+	}
+	// The spill area is at a register-aligned offset and its size is rounded up to a register alignment.
+	// TODO in theory could align offset only to minimum required by spilled data types.
+	result.offsetToSpillArea = alignTo(s.stackOffset, types.RegSize)
+	result.spillAreaSize = alignTo(s.spillOffset, types.RegSize)
+	result.outRegistersUsed = s.rUsed.intRegs + s.rUsed.floatRegs
+
+	return result
+}
+
 // ABIAnalyze takes a function type 't' and an ABI rules description
 // 'config' and analyzes the function to determine how its parameters
 // and results will be passed (in registers or on the stack), returning
@@ -174,33 +233,37 @@ func (config *ABIConfig) ABIAnalyze(t *types.Type) *ABIParamResultInfo {
 		rTotal: config.regAmounts,
 	}
 	result := &ABIParamResultInfo{config: config}
+	ft := t.FuncType()
+	result.preAllocateParams(t.NumRecvs() != 0, ft.Params.NumFields(), ft.Results.NumFields())
 
 	// Receiver
-	ft := t.FuncType()
+	// TODO(register args) ? seems like "struct" and "fields" is not right anymore for describing function parameters
 	if t.NumRecvs() != 0 {
-		rfsl := ft.Receiver.FieldSlice()
+		r := ft.Receiver.FieldSlice()[0]
 		result.inparams = append(result.inparams,
-			s.assignParamOrReturn(rfsl[0], false))
+			s.assignParamOrReturn(r.Type, r.Nname, false))
 	}
 
 	// Inputs
 	ifsl := ft.Params.FieldSlice()
 	for _, f := range ifsl {
 		result.inparams = append(result.inparams,
-			s.assignParamOrReturn(f, false))
+			s.assignParamOrReturn(f.Type, f.Nname, false))
 	}
 	s.stackOffset = types.Rnd(s.stackOffset, int64(types.RegSize))
+	result.inRegistersUsed = s.rUsed.intRegs + s.rUsed.floatRegs
 
 	// Outputs
 	s.rUsed = RegAmounts{}
 	ofsl := ft.Results.FieldSlice()
 	for _, f := range ofsl {
-		result.outparams = append(result.outparams, s.assignParamOrReturn(f, true))
+		result.outparams = append(result.outparams, s.assignParamOrReturn(f.Type, f.Nname, true))
 	}
 	// The spill area is at a register-aligned offset and its size is rounded up to a register alignment.
 	// TODO in theory could align offset only to minimum required by spilled data types.
 	result.offsetToSpillArea = alignTo(s.stackOffset, types.RegSize)
 	result.spillAreaSize = alignTo(s.spillOffset, types.RegSize)
+	result.outRegistersUsed = s.rUsed.intRegs + s.rUsed.floatRegs
 
 	return result
 }
@@ -460,17 +523,15 @@ func (state *assignState) regassign(pt *types.Type) bool {
 // of field f to determine whether it can be register assigned.
 // The result of the analysis is recorded in the result
 // ABIParamResultInfo held in 'state'.
-func (state *assignState) assignParamOrReturn(f *types.Field, isReturn bool) ABIParamAssignment {
-	// TODO(register args) ? seems like "struct" and "fields" is not right anymore for describing function parameters
-	pt := f.Type
+func (state *assignState) assignParamOrReturn(pt *types.Type, n types.Object, isReturn bool) ABIParamAssignment {
 	state.pUsed = RegAmounts{}
 	if pt.Width == types.BADWIDTH {
 		panic("should never happen")
 	} else if pt.Width == 0 {
-		return state.stackAllocate(pt, f.Nname)
+		return state.stackAllocate(pt, n)
 	} else if state.regassign(pt) {
-		return state.regAllocate(pt, f.Nname, isReturn)
+		return state.regAllocate(pt, n, isReturn)
 	} else {
-		return state.stackAllocate(pt, f.Nname)
+		return state.stackAllocate(pt, n)
 	}
 }