[dev.regabi] cmd/compile: modify abiutils for recently updated ABI

Discovered difficluties posed by earlier design, these modifications
should work better.  Updated tests, also added some helper functions
for use in call lowering.

Change-Id: I459f0f71ad8a6730c571244925c3f395e1df28de
Reviewed-on: https://go-review.googlesource.com/c/go/+/285392
Trust: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>

3 files changed, 244 insertions, 134 deletions

diff --git a/src/cmd/compile/internal/abi/abiutils.go b/src/cmd/compile/internal/abi/abiutils.go
index 3ac59e6f75..e935821802 100644
--- a/src/cmd/compile/internal/abi/abiutils.go
+++ b/src/cmd/compile/internal/abi/abiutils.go
@@ -25,9 +25,8 @@ import (
 type ABIParamResultInfo struct {
 	inparams          []ABIParamAssignment // Includes receiver for method calls.  Does NOT include hidden closure pointer.
 	outparams         []ABIParamAssignment
-	intSpillSlots     int
-	floatSpillSlots   int
 	offsetToSpillArea int64
+	spillAreaSize     int64
 	config            *ABIConfig // to enable String() method
 }
 
@@ -47,18 +46,14 @@ func (a *ABIParamResultInfo) OutParam(i int) ABIParamAssignment {
 	return a.outparams[i]
 }
 
-func (a *ABIParamResultInfo) IntSpillCount() int {
-	return a.intSpillSlots
-}
-
-func (a *ABIParamResultInfo) FloatSpillCount() int {
-	return a.floatSpillSlots
-}
-
 func (a *ABIParamResultInfo) SpillAreaOffset() int64 {
 	return a.offsetToSpillArea
 }
 
+func (a *ABIParamResultInfo) SpillAreaSize() int64 {
+	return a.spillAreaSize
+}
+
 // RegIndex stores the index into the set of machine registers used by
 // the ABI on a specific architecture for parameter passing.  RegIndex
 // values 0 through N-1 (where N is the number of integer registers
@@ -78,7 +73,27 @@ type RegIndex uint8
 type ABIParamAssignment struct {
 	Type      *types.Type
 	Registers []RegIndex
-	Offset    int32
+	offset    int32
+}
+
+// Offset returns the stack offset for addressing the parameter that "a" describes.
+// This will panic if "a" describes a register-allocated parameter.
+func (a *ABIParamAssignment) Offset() int32 {
+	if len(a.Registers) > 0 {
+		panic("Register allocated parameters have no offset")
+	}
+	return a.offset
+}
+
+// SpillOffset returns the offset *within the spill area* for the parameter that "a" describes.
+// Registers will be spilled here; if a memory home is needed (for a pointer method e.g.)
+// then that will be the address.
+// This will panic if "a" describes a stack-allocated parameter.
+func (a *ABIParamAssignment) SpillOffset() int32 {
+	if len(a.Registers) == 0 {
+		panic("Stack-allocated parameters have no spill offset")
+	}
+	return a.offset
 }
 
 // RegAmounts holds a specified number of integer/float registers.
@@ -91,20 +106,58 @@ type RegAmounts struct {
 // by the ABI rules for parameter passing and result returning.
 type ABIConfig struct {
 	// Do we need anything more than this?
-	regAmounts RegAmounts
+	regAmounts       RegAmounts
+	regsForTypeCache map[*types.Type]int
 }
 
 // NewABIConfig returns a new ABI configuration for an architecture with
 // iRegsCount integer/pointer registers and fRegsCount floating point registers.
 func NewABIConfig(iRegsCount, fRegsCount int) *ABIConfig {
-	return &ABIConfig{RegAmounts{iRegsCount, fRegsCount}}
+	return &ABIConfig{regAmounts: RegAmounts{iRegsCount, fRegsCount}, regsForTypeCache: make(map[*types.Type]int)}
+}
+
+// NumParamRegs returns the number of parameter registers used for a given type,
+// without regard for the number available.
+func (a *ABIConfig) NumParamRegs(t *types.Type) int {
+	if n, ok := a.regsForTypeCache[t]; ok {
+		return n
+	}
+
+	if t.IsScalar() || t.IsPtrShaped() {
+		var n int
+		if t.IsComplex() {
+			n = 2
+		} else {
+			n = (int(t.Size()) + types.RegSize - 1) / types.RegSize
+		}
+		a.regsForTypeCache[t] = n
+		return n
+	}
+	typ := t.Kind()
+	n := 0
+	switch typ {
+	case types.TARRAY:
+		n = a.NumParamRegs(t.Elem()) * int(t.NumElem())
+	case types.TSTRUCT:
+		for _, f := range t.FieldSlice() {
+			n += a.NumParamRegs(f.Type)
+		}
+	case types.TSLICE:
+		n = a.NumParamRegs(synthSlice)
+	case types.TSTRING:
+		n = a.NumParamRegs(synthString)
+	case types.TINTER:
+		n = a.NumParamRegs(synthIface)
+	}
+	a.regsForTypeCache[t] = n
+	return n
 }
 
 // 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
 // an ABIParamResultInfo object that holds the results of the analysis.
-func ABIAnalyze(t *types.Type, config *ABIConfig) ABIParamResultInfo {
+func (config *ABIConfig) ABIAnalyze(t *types.Type) ABIParamResultInfo {
 	setup()
 	s := assignState{
 		rTotal: config.regAmounts,
@@ -116,28 +169,27 @@ func ABIAnalyze(t *types.Type, config *ABIConfig) ABIParamResultInfo {
 	if t.NumRecvs() != 0 {
 		rfsl := ft.Receiver.FieldSlice()
 		result.inparams = append(result.inparams,
-			s.assignParamOrReturn(rfsl[0].Type))
+			s.assignParamOrReturn(rfsl[0].Type, false))
 	}
 
 	// Inputs
 	ifsl := ft.Params.FieldSlice()
 	for _, f := range ifsl {
 		result.inparams = append(result.inparams,
-			s.assignParamOrReturn(f.Type))
+			s.assignParamOrReturn(f.Type, false))
 	}
 	s.stackOffset = types.Rnd(s.stackOffset, int64(types.RegSize))
 
-	// Record number of spill slots needed.
-	result.intSpillSlots = s.rUsed.intRegs
-	result.floatSpillSlots = s.rUsed.floatRegs
-
 	// Outputs
 	s.rUsed = RegAmounts{}
 	ofsl := ft.Results.FieldSlice()
 	for _, f := range ofsl {
-		result.outparams = append(result.outparams, s.assignParamOrReturn(f.Type))
+		result.outparams = append(result.outparams, s.assignParamOrReturn(f.Type, true))
 	}
-	result.offsetToSpillArea = s.stackOffset
+	// 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)
 
 	return result
 }
@@ -160,10 +212,14 @@ func (c *RegAmounts) regString(r RegIndex) string {
 // form, suitable for debugging or unit testing.
 func (ri *ABIParamAssignment) toString(config *ABIConfig) string {
 	regs := "R{"
+	offname := "spilloffset" // offset is for spill for register(s)
+	if len(ri.Registers) == 0 {
+		offname = "offset" // offset is for memory arg
+	}
 	for _, r := range ri.Registers {
 		regs += " " + config.regAmounts.regString(r)
 	}
-	return fmt.Sprintf("%s } offset: %d typ: %v", regs, ri.Offset, ri.Type)
+	return fmt.Sprintf("%s } %s: %d typ: %v", regs, offname, ri.offset, ri.Type)
 }
 
 // toString method renders an ABIParamResultInfo in human-readable
@@ -176,8 +232,8 @@ func (ri *ABIParamResultInfo) String() string {
 	for k, r := range ri.outparams {
 		res += fmt.Sprintf("OUT %d: %s\n", k, r.toString(ri.config))
 	}
-	res += fmt.Sprintf("intspill: %d floatspill: %d offsetToSpillArea: %d",
-		ri.intSpillSlots, ri.floatSpillSlots, ri.offsetToSpillArea)
+	res += fmt.Sprintf("offsetToSpillArea: %d spillAreaSize: %d",
+		ri.offsetToSpillArea, ri.spillAreaSize)
 	return res
 }
 
@@ -188,16 +244,27 @@ type assignState struct {
 	rUsed       RegAmounts // regs used by params completely assigned so far
 	pUsed       RegAmounts // regs used by the current param (or pieces therein)
 	stackOffset int64      // current stack offset
+	spillOffset int64      // current spill offset
+}
+
+// align returns a rounded up to t's alignment
+func align(a int64, t *types.Type) int64 {
+	return alignTo(a, int(t.Align))
+}
+
+// alignTo returns a rounded up to t, where t must be 0 or a power of 2.
+func alignTo(a int64, t int) int64 {
+	if t == 0 {
+		return a
+	}
+	return types.Rnd(a, int64(t))
 }
 
 // stackSlot returns a stack offset for a param or result of the
 // specified type.
 func (state *assignState) stackSlot(t *types.Type) int64 {
-	if t.Align > 0 {
-		state.stackOffset = types.Rnd(state.stackOffset, int64(t.Align))
-	}
-	rv := state.stackOffset
-	state.stackOffset += t.Width
+	rv := align(state.stackOffset, t)
+	state.stackOffset = rv + t.Width
 	return rv
 }
 
@@ -225,11 +292,17 @@ func (state *assignState) allocateRegs() []RegIndex {
 // regAllocate creates a register ABIParamAssignment object for a param
 // or result with the specified type, as a final step (this assumes
 // that all of the safety/suitability analysis is complete).
-func (state *assignState) regAllocate(t *types.Type) ABIParamAssignment {
+func (state *assignState) regAllocate(t *types.Type, isReturn bool) ABIParamAssignment {
+	spillLoc := int64(-1)
+	if !isReturn {
+		// Spill for register-resident t must be aligned for storage of a t.
+		spillLoc = align(state.spillOffset, t)
+		state.spillOffset = spillLoc + t.Size()
+	}
 	return ABIParamAssignment{
 		Type:      t,
 		Registers: state.allocateRegs(),
-		Offset:    -1,
+		offset:    int32(spillLoc),
 	}
 }
 
@@ -239,7 +312,7 @@ func (state *assignState) regAllocate(t *types.Type) ABIParamAssignment {
 func (state *assignState) stackAllocate(t *types.Type) ABIParamAssignment {
 	return ABIParamAssignment{
 		Type:   t,
-		Offset: int32(state.stackSlot(t)),
+		offset: int32(state.stackSlot(t)),
 	}
 }
 
@@ -261,6 +334,9 @@ func (state *assignState) floatUsed() int {
 // accordingly).
 func (state *assignState) regassignIntegral(t *types.Type) bool {
 	regsNeeded := int(types.Rnd(t.Width, int64(types.PtrSize)) / int64(types.PtrSize))
+	if t.IsComplex() {
+		regsNeeded = 2
+	}
 
 	// Floating point and complex.
 	if t.IsFloat() || t.IsComplex() {
@@ -371,14 +447,14 @@ func (state *assignState) regassign(pt *types.Type) bool {
 // of type 'pt' 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(pt *types.Type) ABIParamAssignment {
+func (state *assignState) assignParamOrReturn(pt *types.Type, isReturn bool) ABIParamAssignment {
 	state.pUsed = RegAmounts{}
 	if pt.Width == types.BADWIDTH {
 		panic("should never happen")
 	} else if pt.Width == 0 {
 		return state.stackAllocate(pt)
 	} else if state.regassign(pt) {
-		return state.regAllocate(pt)
+		return state.regAllocate(pt, isReturn)
 	} else {
 		return state.stackAllocate(pt)
 	}
diff --git a/src/cmd/compile/internal/test/abiutils_test.go b/src/cmd/compile/internal/test/abiutils_test.go
index ae7d484062..decc29667e 100644
--- a/src/cmd/compile/internal/test/abiutils_test.go
+++ b/src/cmd/compile/internal/test/abiutils_test.go
@@ -21,7 +21,7 @@ import (
 // AMD64 registers available:
 // - integer: RAX, RBX, RCX, RDI, RSI, R8, R9, r10, R11
 // - floating point: X0 - X14
-var configAMD64 = abi.NewABIConfig(9,15)
+var configAMD64 = abi.NewABIConfig(9, 15)
 
 func TestMain(m *testing.M) {
 	ssagen.Arch.LinkArch = &x86.Linkamd64
@@ -46,9 +46,9 @@ func TestABIUtilsBasic1(t *testing.T) {
 
 	// expected results
 	exp := makeExpectedDump(`
-		IN 0: R{ I0 } offset: -1 typ: int32
-		OUT 0: R{ I0 } offset: -1 typ: int32
-		intspill: 1 floatspill: 0 offsetToSpillArea: 0
+        IN 0: R{ I0 } spilloffset: 0 typ: int32
+        OUT 0: R{ I0 } spilloffset: -1 typ: int32
+        offsetToSpillArea: 0 spillAreaSize: 8
 `)
 
 	abitest(t, ft, exp)
@@ -75,39 +75,39 @@ func TestABIUtilsBasic2(t *testing.T) {
 			i8, i16, i32, i64},
 		[]*types.Type{i32, f64, f64})
 	exp := makeExpectedDump(`
-		IN 0: R{ I0 } offset: -1 typ: int8
-		IN 1: R{ I1 } offset: -1 typ: int16
-		IN 2: R{ I2 } offset: -1 typ: int32
-		IN 3: R{ I3 } offset: -1 typ: int64
-		IN 4: R{ F0 } offset: -1 typ: float32
-		IN 5: R{ F1 } offset: -1 typ: float32
-		IN 6: R{ F2 } offset: -1 typ: float64
-		IN 7: R{ F3 } offset: -1 typ: float64
-		IN 8: R{ I4 } offset: -1 typ: int8
-		IN 9: R{ I5 } offset: -1 typ: int16
-		IN 10: R{ I6 } offset: -1 typ: int32
-		IN 11: R{ I7 } offset: -1 typ: int64
-		IN 12: R{ F4 } offset: -1 typ: float32
-		IN 13: R{ F5 } offset: -1 typ: float32
-		IN 14: R{ F6 } offset: -1 typ: float64
-		IN 15: R{ F7 } offset: -1 typ: float64
-		IN 16: R{ F8 F9 } offset: -1 typ: complex128
-		IN 17: R{ F10 F11 } offset: -1 typ: complex128
-		IN 18: R{ F12 F13 } offset: -1 typ: complex128
-		IN 19: R{ } offset: 0 typ: complex128
-		IN 20: R{ F14 } offset: -1 typ: complex64
-		IN 21: R{ I8 } offset: -1 typ: int8
-		IN 22: R{ } offset: 16 typ: int16
-		IN 23: R{ } offset: 20 typ: int32
-		IN 24: R{ } offset: 24 typ: int64
-		IN 25: R{ } offset: 32 typ: int8
-		IN 26: R{ } offset: 34 typ: int16
-		IN 27: R{ } offset: 36 typ: int32
-		IN 28: R{ } offset: 40 typ: int64
-		OUT 0: R{ I0 } offset: -1 typ: int32
-		OUT 1: R{ F0 } offset: -1 typ: float64
-		OUT 2: R{ F1 } offset: -1 typ: float64
-		intspill: 9 floatspill: 15 offsetToSpillArea: 48
+        IN 0: R{ I0 } spilloffset: 0 typ: int8
+        IN 1: R{ I1 } spilloffset: 2 typ: int16
+        IN 2: R{ I2 } spilloffset: 4 typ: int32
+        IN 3: R{ I3 } spilloffset: 8 typ: int64
+        IN 4: R{ F0 } spilloffset: 16 typ: float32
+        IN 5: R{ F1 } spilloffset: 20 typ: float32
+        IN 6: R{ F2 } spilloffset: 24 typ: float64
+        IN 7: R{ F3 } spilloffset: 32 typ: float64
+        IN 8: R{ I4 } spilloffset: 40 typ: int8
+        IN 9: R{ I5 } spilloffset: 42 typ: int16
+        IN 10: R{ I6 } spilloffset: 44 typ: int32
+        IN 11: R{ I7 } spilloffset: 48 typ: int64
+        IN 12: R{ F4 } spilloffset: 56 typ: float32
+        IN 13: R{ F5 } spilloffset: 60 typ: float32
+        IN 14: R{ F6 } spilloffset: 64 typ: float64
+        IN 15: R{ F7 } spilloffset: 72 typ: float64
+        IN 16: R{ F8 F9 } spilloffset: 80 typ: complex128
+        IN 17: R{ F10 F11 } spilloffset: 96 typ: complex128
+        IN 18: R{ F12 F13 } spilloffset: 112 typ: complex128
+        IN 19: R{ } offset: 0 typ: complex128
+        IN 20: R{ } offset: 16 typ: complex64
+        IN 21: R{ I8 } spilloffset: 128 typ: int8
+        IN 22: R{ } offset: 24 typ: int16
+        IN 23: R{ } offset: 28 typ: int32
+        IN 24: R{ } offset: 32 typ: int64
+        IN 25: R{ } offset: 40 typ: int8
+        IN 26: R{ } offset: 42 typ: int16
+        IN 27: R{ } offset: 44 typ: int32
+        IN 28: R{ } offset: 48 typ: int64
+        OUT 0: R{ I0 } spilloffset: -1 typ: int32
+        OUT 1: R{ F0 } spilloffset: -1 typ: float64
+        OUT 2: R{ F1 } spilloffset: -1 typ: float64
+        offsetToSpillArea: 56 spillAreaSize: 136
 `)
 
 	abitest(t, ft, exp)
@@ -123,15 +123,15 @@ func TestABIUtilsArrays(t *testing.T) {
 		[]*types.Type{a2, a1, ae, aa1})
 
 	exp := makeExpectedDump(`
-		IN 0: R{ I0 } offset: -1 typ: [1]int32
-		IN 1: R{ } offset: 0 typ: [0]int32
-		IN 2: R{ I1 } offset: -1 typ: [1][1]int32
-		IN 3: R{ } offset: 0 typ: [2]int32
-		OUT 0: R{ } offset: 8 typ: [2]int32
-		OUT 1: R{ I0 } offset: -1 typ: [1]int32
-		OUT 2: R{ } offset: 16 typ: [0]int32
-		OUT 3: R{ I1 } offset: -1 typ: [1][1]int32
-		intspill: 2 floatspill: 0 offsetToSpillArea: 16
+        IN 0: R{ I0 } spilloffset: 0 typ: [1]int32
+        IN 1: R{ } offset: 0 typ: [0]int32
+        IN 2: R{ I1 } spilloffset: 4 typ: [1][1]int32
+        IN 3: R{ } offset: 0 typ: [2]int32
+        OUT 0: R{ } offset: 8 typ: [2]int32
+        OUT 1: R{ I0 } spilloffset: -1 typ: [1]int32
+        OUT 2: R{ } offset: 16 typ: [0]int32
+        OUT 3: R{ I1 } spilloffset: -1 typ: [1][1]int32
+        offsetToSpillArea: 16 spillAreaSize: 8
 `)
 
 	abitest(t, ft, exp)
@@ -147,13 +147,13 @@ func TestABIUtilsStruct1(t *testing.T) {
 		[]*types.Type{s, i8, i32})
 
 	exp := makeExpectedDump(`
-		IN 0: R{ I0 } offset: -1 typ: int8
-		IN 1: R{ I1 I2 I3 I4 } offset: -1 typ: struct { int8; int8; struct {}; int8; int16 }
-		IN 2: R{ I5 } offset: -1 typ: int64
-		OUT 0: R{ I0 I1 I2 I3 } offset: -1 typ: struct { int8; int8; struct {}; int8; int16 }
-		OUT 1: R{ I4 } offset: -1 typ: int8
-		OUT 2: R{ I5 } offset: -1 typ: int32
-		intspill: 6 floatspill: 0 offsetToSpillArea: 0
+        IN 0: R{ I0 } spilloffset: 0 typ: int8
+        IN 1: R{ I1 I2 I3 I4 } spilloffset: 2 typ: struct { int8; int8; struct {}; int8; int16 }
+        IN 2: R{ I5 } spilloffset: 8 typ: int64
+        OUT 0: R{ I0 I1 I2 I3 } spilloffset: -1 typ: struct { int8; int8; struct {}; int8; int16 }
+        OUT 1: R{ I4 } spilloffset: -1 typ: int8
+        OUT 2: R{ I5 } spilloffset: -1 typ: int32
+        offsetToSpillArea: 0 spillAreaSize: 16
 `)
 
 	abitest(t, ft, exp)
@@ -168,12 +168,12 @@ func TestABIUtilsStruct2(t *testing.T) {
 		[]*types.Type{fs, fs})
 
 	exp := makeExpectedDump(`
-		IN 0: R{ I0 } offset: -1 typ: struct { int64; struct {} }
-		IN 1: R{ I1 } offset: -1 typ: struct { int64; struct {} }
-		IN 2: R{ I2 F0 } offset: -1 typ: struct { float64; struct { int64; struct {} }; struct {} }
-		OUT 0: R{ I0 F0 } offset: -1 typ: struct { float64; struct { int64; struct {} }; struct {} }
-		OUT 1: R{ I1 F1 } offset: -1 typ: struct { float64; struct { int64; struct {} }; struct {} }
-		intspill: 3 floatspill: 1 offsetToSpillArea: 0
+        IN 0: R{ I0 } spilloffset: 0 typ: struct { int64; struct {} }
+        IN 1: R{ I1 } spilloffset: 16 typ: struct { int64; struct {} }
+        IN 2: R{ I2 F0 } spilloffset: 32 typ: struct { float64; struct { int64; struct {} }; struct {} }
+        OUT 0: R{ I0 F0 } spilloffset: -1 typ: struct { float64; struct { int64; struct {} }; struct {} }
+        OUT 1: R{ I1 F1 } spilloffset: -1 typ: struct { float64; struct { int64; struct {} }; struct {} }
+        offsetToSpillArea: 0 spillAreaSize: 64
 `)
 
 	abitest(t, ft, exp)
@@ -189,19 +189,19 @@ func TestABIUtilsSliceString(t *testing.T) {
 		[]*types.Type{str, i64, str, sli32})
 
 	exp := makeExpectedDump(`
-		IN 0: R{ I0 I1 I2 } offset: -1 typ: []int32
-		IN 1: R{ I3 } offset: -1 typ: int8
-		IN 2: R{ I4 I5 I6 } offset: -1 typ: []int32
-		IN 3: R{ I7 } offset: -1 typ: int8
-		IN 4: R{ } offset: 0 typ: string
-		IN 5: R{ I8 } offset: -1 typ: int8
-		IN 6: R{ } offset: 16 typ: int64
-		IN 7: R{ } offset: 24 typ: []int32
-		OUT 0: R{ I0 I1 } offset: -1 typ: string
-		OUT 1: R{ I2 } offset: -1 typ: int64
-		OUT 2: R{ I3 I4 } offset: -1 typ: string
-		OUT 3: R{ I5 I6 I7 } offset: -1 typ: []int32
-		intspill: 9 floatspill: 0 offsetToSpillArea: 48
+        IN 0: R{ I0 I1 I2 } spilloffset: 0 typ: []int32
+        IN 1: R{ I3 } spilloffset: 24 typ: int8
+        IN 2: R{ I4 I5 I6 } spilloffset: 32 typ: []int32
+        IN 3: R{ I7 } spilloffset: 56 typ: int8
+        IN 4: R{ } offset: 0 typ: string
+        IN 5: R{ I8 } spilloffset: 57 typ: int8
+        IN 6: R{ } offset: 16 typ: int64
+        IN 7: R{ } offset: 24 typ: []int32
+        OUT 0: R{ I0 I1 } spilloffset: -1 typ: string
+        OUT 1: R{ I2 } spilloffset: -1 typ: int64
+        OUT 2: R{ I3 I4 } spilloffset: -1 typ: string
+        OUT 3: R{ I5 I6 I7 } spilloffset: -1 typ: []int32
+        offsetToSpillArea: 48 spillAreaSize: 64
 `)
 
 	abitest(t, ft, exp)
@@ -219,17 +219,17 @@ func TestABIUtilsMethod(t *testing.T) {
 		[]*types.Type{a7, f64, i64})
 
 	exp := makeExpectedDump(`
-		IN 0: R{ I0 I1 I2 } offset: -1 typ: struct { int16; int16; int16 }
-		IN 1: R{ I3 } offset: -1 typ: *struct { int16; int16; int16 }
-		IN 2: R{ } offset: 0 typ: [7]*struct { int16; int16; int16 }
-		IN 3: R{ F0 } offset: -1 typ: float64
-		IN 4: R{ I4 } offset: -1 typ: int16
-		IN 5: R{ I5 } offset: -1 typ: int16
-		IN 6: R{ I6 } offset: -1 typ: int16
-		OUT 0: R{ } offset: 56 typ: [7]*struct { int16; int16; int16 }
-		OUT 1: R{ F0 } offset: -1 typ: float64
-		OUT 2: R{ I0 } offset: -1 typ: int64
-		intspill: 7 floatspill: 1 offsetToSpillArea: 112
+        IN 0: R{ I0 I1 I2 } spilloffset: 0 typ: struct { int16; int16; int16 }
+        IN 1: R{ I3 } spilloffset: 8 typ: *struct { int16; int16; int16 }
+        IN 2: R{ } offset: 0 typ: [7]*struct { int16; int16; int16 }
+        IN 3: R{ F0 } spilloffset: 16 typ: float64
+        IN 4: R{ I4 } spilloffset: 24 typ: int16
+        IN 5: R{ I5 } spilloffset: 26 typ: int16
+        IN 6: R{ I6 } spilloffset: 28 typ: int16
+        OUT 0: R{ } offset: 56 typ: [7]*struct { int16; int16; int16 }
+        OUT 1: R{ F0 } spilloffset: -1 typ: float64
+        OUT 2: R{ I0 } spilloffset: -1 typ: int64
+        offsetToSpillArea: 112 spillAreaSize: 32
 `)
 
 	abitest(t, ft, exp)
@@ -252,18 +252,44 @@ func TestABIUtilsInterfaces(t *testing.T) {
 		[]*types.Type{ei, nei, pei})
 
 	exp := makeExpectedDump(`
-		IN 0: R{ I0 I1 I2 } offset: -1 typ: struct { int16; int16; bool }
-		IN 1: R{ I3 I4 } offset: -1 typ: interface {}
-		IN 2: R{ I5 I6 } offset: -1 typ: interface {}
-		IN 3: R{ I7 I8 } offset: -1 typ: interface { () untyped string }
-		IN 4: R{ } offset: 0 typ: *interface {}
-		IN 5: R{ } offset: 8 typ: interface { () untyped string }
-		IN 6: R{ } offset: 24 typ: int16
-		OUT 0: R{ I0 I1 } offset: -1 typ: interface {}
-		OUT 1: R{ I2 I3 } offset: -1 typ: interface { () untyped string }
-		OUT 2: R{ I4 } offset: -1 typ: *interface {}
-		intspill: 9 floatspill: 0 offsetToSpillArea: 32
+        IN 0: R{ I0 I1 I2 } spilloffset: 0 typ: struct { int16; int16; bool }
+        IN 1: R{ I3 I4 } spilloffset: 8 typ: interface {}
+        IN 2: R{ I5 I6 } spilloffset: 24 typ: interface {}
+        IN 3: R{ I7 I8 } spilloffset: 40 typ: interface { () untyped string }
+        IN 4: R{ } offset: 0 typ: *interface {}
+        IN 5: R{ } offset: 8 typ: interface { () untyped string }
+        IN 6: R{ } offset: 24 typ: int16
+        OUT 0: R{ I0 I1 } spilloffset: -1 typ: interface {}
+        OUT 1: R{ I2 I3 } spilloffset: -1 typ: interface { () untyped string }
+        OUT 2: R{ I4 } spilloffset: -1 typ: *interface {}
+        offsetToSpillArea: 32 spillAreaSize: 56
 `)
 
 	abitest(t, ft, exp)
 }
+
+func TestABINumParamRegs(t *testing.T) {
+	i8 := types.Types[types.TINT8]
+	i16 := types.Types[types.TINT16]
+	i32 := types.Types[types.TINT32]
+	i64 := types.Types[types.TINT64]
+	f32 := types.Types[types.TFLOAT32]
+	f64 := types.Types[types.TFLOAT64]
+	c64 := types.Types[types.TCOMPLEX64]
+	c128 := types.Types[types.TCOMPLEX128]
+
+	s := mkstruct([]*types.Type{i8, i8, mkstruct([]*types.Type{}), i8, i16})
+	a := types.NewArray(s, 3)
+
+	nrtest(t, i8, 1)
+	nrtest(t, i16, 1)
+	nrtest(t, i32, 1)
+	nrtest(t, i64, 1)
+	nrtest(t, f32, 1)
+	nrtest(t, f64, 1)
+	nrtest(t, c64, 2)
+	nrtest(t, c128, 2)
+	nrtest(t, s, 4)
+	nrtest(t, a, 12)
+
+}
\ No newline at end of file
diff --git a/src/cmd/compile/internal/test/abiutilsaux_test.go b/src/cmd/compile/internal/test/abiutilsaux_test.go
index 10fb668745..19dd3a51fd 100644
--- a/src/cmd/compile/internal/test/abiutilsaux_test.go
+++ b/src/cmd/compile/internal/test/abiutilsaux_test.go
@@ -78,9 +78,9 @@ func tokenize(src string) []string {
 
 func verifyParamResultOffset(t *testing.T, f *types.Field, r abi.ABIParamAssignment, which string, idx int) int {
 	n := ir.AsNode(f.Nname).(*ir.Name)
-	if n.FrameOffset() != int64(r.Offset) {
+	if n.FrameOffset() != int64(r.Offset()) {
 		t.Errorf("%s %d: got offset %d wanted %d t=%v",
-			which, idx, r.Offset, n.Offset_, f.Type)
+			which, idx, r.Offset(), n.Offset_, f.Type)
 		return 1
 	}
 	return 0
@@ -106,12 +106,20 @@ func difftokens(atoks []string, etoks []string) string {
 	return ""
 }
 
+func nrtest(t *testing.T, ft *types.Type, expected int) {
+	types.CalcSize(ft)
+	got := configAMD64.NumParamRegs(ft)
+	if got != expected {
+		t.Errorf("]\nexpected num regs = %d, got %d, type %v", expected, got, ft)
+	}
+}
+
 func abitest(t *testing.T, ft *types.Type, exp expectedDump) {
 
 	types.CalcSize(ft)
 
 	// Analyze with full set of registers.
-	regRes := abi.ABIAnalyze(ft, configAMD64)
+	regRes := configAMD64.ABIAnalyze(ft)
 	regResString := strings.TrimSpace(regRes.String())
 
 	// Check results.
@@ -122,8 +130,8 @@ func abitest(t *testing.T, ft *types.Type, exp expectedDump) {
 	}
 
 	// Analyze again with empty register set.
-	empty := &abi.ABIConfig{}
-	emptyRes := abi.ABIAnalyze(ft, empty)
+	empty := abi.NewABIConfig(0, 0)
+	emptyRes := empty.ABIAnalyze(ft)
 	emptyResString := emptyRes.String()
 
 	// Walk the results and make sure the offsets assigned match