pass,printer: display required ISA features (#120)

Fixes #119

examples/args/args.s

@@ -63,12 +63,14 @@ TEXT ·FieldUint64(SB), NOSPLIT, $0-184
 	RET
 
 // func FieldFloat32(s Struct) float32
+// Requires: SSE
 TEXT ·FieldFloat32(SB), NOSPLIT, $0-180
 	MOVSS s_Float32+16(FP), X0
 	MOVSS X0, ret+176(FP)
 	RET
 
 // func FieldFloat64(s Struct) float64
+// Requires: SSE2
 TEXT ·FieldFloat64(SB), NOSPLIT, $0-184
 	MOVSD s_Float64+24(FP), X0
 	MOVSD X0, ret+176(FP)
@@ -99,18 +101,21 @@ TEXT ·FieldArrayOneC(SB), NOSPLIT, $0-178
 	RET
 
 // func FieldComplex64Imag(s Struct) float32
+// Requires: SSE
 TEXT ·FieldComplex64Imag(SB), NOSPLIT, $0-180
 	MOVSS s_Complex64_imag+156(FP), X0
 	MOVSS X0, ret+176(FP)
 	RET
 
 // func FieldComplex128Real(s Struct) float64
+// Requires: SSE2
 TEXT ·FieldComplex128Real(SB), NOSPLIT, $0-184
 	MOVSD s_Complex128_real+160(FP), X0
 	MOVSD X0, ret+176(FP)
 	RET
 
 // func DereferenceFloat32(s *Struct) float32
+// Requires: SSE
 TEXT ·DereferenceFloat32(SB), NOSPLIT, $0-12
 	MOVQ  s+0(FP), AX
 	MOVSS 16(AX), X0

examples/complex/README.md

@@ -24,6 +24,7 @@ Generated assembly:
 [embedmd]:# (complex.s s /.*func Norm/ /RET/)
 ```s
 // func Norm(z complex128) float64
+// Requires: SSE2
 TEXT ·Norm(SB), NOSPLIT, $0-24
 	MOVSD  z_real+0(FP), X0
 	MOVSD  z_imag+8(FP), X1

examples/complex/complex.s

@@ -3,18 +3,21 @@
 #include "textflag.h"
 
 // func Real(z complex128) float64
+// Requires: SSE2
 TEXT ·Real(SB), NOSPLIT, $0-24
 	MOVSD z_real+0(FP), X0
 	MOVSD X0, ret+16(FP)
 	RET
 
 // func Imag(z complex128) float64
+// Requires: SSE2
 TEXT ·Imag(SB), NOSPLIT, $0-24
 	MOVSD z_imag+8(FP), X0
 	MOVSD X0, ret+16(FP)
 	RET
 
 // func Norm(z complex128) float64
+// Requires: SSE2
 TEXT ·Norm(SB), NOSPLIT, $0-24
 	MOVSD  z_real+0(FP), X0
 	MOVSD  z_imag+8(FP), X1

examples/dot/dot.s

@@ -3,6 +3,7 @@
 #include "textflag.h"
 
 // func Dot(x []float32, y []float32) float32
+// Requires: AVX, FMA3, SSE
 TEXT ·Dot(SB), NOSPLIT, $0-52
 	MOVQ   x_base+0(FP), AX
 	MOVQ   y_base+24(FP), CX

examples/geohash/geohash.s

@@ -3,6 +3,7 @@
 #include "textflag.h"
 
 // func EncodeInt(lat float64, lng float64) uint64
+// Requires: BMI2, SSE2
 TEXT ·EncodeInt(SB), NOSPLIT, $0-24
 	MOVSD lat+0(FP), X0
 	MOVSD lng+8(FP), X1

examples/returns/returns.s

@@ -12,6 +12,7 @@ TEXT ·Interval(SB), NOSPLIT, $0-32
 	RET
 
 // func Butterfly(x0 float64, x1 float64) (y0 float64, y1 float64)
+// Requires: SSE2
 TEXT ·Butterfly(SB), NOSPLIT, $0-32
 	MOVSD x0+0(FP), X0
 	MOVSD x1+8(FP), X1
@@ -36,6 +37,7 @@ TEXT ·Septuple(SB), NOSPLIT, $0-15
 	RET
 
 // func CriticalLine(t float64) complex128
+// Requires: SSE2
 TEXT ·CriticalLine(SB), NOSPLIT, $0-24
 	MOVSD t+0(FP), X0
 	MOVSD half<>+0(SB), X1
@@ -47,6 +49,7 @@ DATA half<>+0(SB)/8, $(0.5)
 GLOBL half<>(SB), RODATA|NOPTR, $8
 
 // func NewStruct(w uint16, p [2]float64, q uint64) Struct
+// Requires: SSE2
 TEXT ·NewStruct(SB), NOSPLIT, $0-64
 	MOVW  w+0(FP), AX
 	MOVSD p_0+8(FP), X0

internal/gen/ctors.go

@@ -92,6 +92,11 @@ func construct(i inst.Instruction, f inst.Form, s signature) string {
 	fmt.Fprintf(buf, "\tInputs: %s,\n", operandsWithAction(f, inst.R, s))
 	fmt.Fprintf(buf, "\tOutputs: %s,\n", operandsWithAction(f, inst.W, s))
 
+	// ISAs.
+	if len(f.ISA) > 0 {
+		fmt.Fprintf(buf, "\tISA: %#v,\n", f.ISA)
+	}
+
 	// Branch variables.
 	if i.IsBranch() {
 		fmt.Fprintf(buf, "\tIsBranch: true,\n")

ir/ir.go

@@ -47,6 +47,9 @@ type Instruction struct {
 	IsConditional    bool
 	CancellingInputs bool
 
+	// ISA is the list of required instruction set extensions.
+	ISA []string
+
 	// CFG.
 	Pred []*Instruction
 	Succ []*Instruction
@@ -166,6 +169,9 @@ type Function struct {
 
 	// Register allocation.
 	Allocation reg.Allocation
+
+	// ISA is the list of required instruction set extensions.
+	ISA []string
 }
 
 func (f *Function) section() {}

pass/isa.go

@@ -0,0 +1,31 @@
+package pass
+
+import (
+	"sort"
+
+	"github.com/mmcloughlin/avo/ir"
+)
+
+// RequiredISAExtensions determines ISA extensions required for the given
+// function. Populates the ISA field.
+func RequiredISAExtensions(fn *ir.Function) error {
+	// Collect ISA set.
+	set := map[string]bool{}
+	for _, i := range fn.Instructions() {
+		for _, isa := range i.ISA {
+			set[isa] = true
+		}
+	}
+
+	if len(set) == 0 {
+		return nil
+	}
+
+	// Populate the function's ISA field with the unique sorted list.
+	for isa := range set {
+		fn.ISA = append(fn.ISA, isa)
+	}
+	sort.Strings(fn.ISA)
+
+	return nil
+}

pass/isa_test.go

@@ -0,0 +1,25 @@
+package pass
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/mmcloughlin/avo/ir"
+)
+
+func TestRequiredISAExtensions(t *testing.T) {
+	f := ir.NewFunction("ISAs")
+	f.AddInstruction(&ir.Instruction{ISA: nil})
+	f.AddInstruction(&ir.Instruction{ISA: []string{"B", "A"}})
+	f.AddInstruction(&ir.Instruction{ISA: []string{"A", "C"}})
+
+	err := RequiredISAExtensions(f)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expect := []string{"A", "B", "C"}
+	if !reflect.DeepEqual(f.ISA, expect) {
+		t.FailNow()
+	}
+}

pass/pass.go

@@ -21,6 +21,7 @@ var Compile = Concat(
 	FunctionPass(VerifyAllocation),
 	Func(IncludeTextFlagHeader),
 	FunctionPass(PruneSelfMoves),
+	FunctionPass(RequiredISAExtensions),
 )
 
 // Interface for a processing pass.

printer/goasm.go

@@ -63,6 +63,10 @@ func (p *goasm) function(f *ir.Function) {
 	p.NL()
 	p.Comment(f.Stub())
 
+	if len(f.ISA) > 0 {
+		p.Comment("Requires: " + strings.Join(f.ISA, ", "))
+	}
+
 	// Reference: https://github.com/golang/go/blob/b115207baf6c2decc3820ada4574ef4e5ad940ec/src/cmd/internal/obj/util.go#L166-L176
 	//
 	//		if p.As == ATEXT {

tests/fixedbugs/issue50/issue50.s

@@ -3,6 +3,7 @@
 #include "textflag.h"
 
 // func Issue50(x uint32) uint32
+// Requires: SSE2
 TEXT ·Issue50(SB), NOSPLIT, $0-12
 	MOVL x+0(FP), AX
 	MOVQ AX, X0