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Merge pull request #2594 from nspcc-dev/compiler-inline-return
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compiler: allow to use multiple returns in inlined functions
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@roman-khimov
roman-khimov committed Jul 12, 2022
2 parents 9414538 + 17329ee commit 71b721c
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Showing 5 changed files with 141 additions and 67 deletions.
99 changes: 52 additions & 47 deletions pkg/compiler/codegen.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -62,9 +62,8 @@ type codegen struct {
labels map[labelWithType]uint16
// A list of nested label names together with evaluation stack depth.
labelList []labelWithStackSize
// inlineLabelOffsets contains size of labelList at the start of inline call processing.
// For such calls, we need to drop only the newly created part of stack.
inlineLabelOffsets []int
// inlineContext contains info about inlined function calls.
inlineContext []inlineContextSingle
// globalInlineCount contains the amount of auxiliary variables introduced by
// function inlining during global variables initialization.
globalInlineCount int
Expand Down Expand Up @@ -146,6 +145,14 @@ type nameWithLocals struct {
count int
}

type inlineContextSingle struct {
// labelOffset contains size of labelList at the start of inline call processing.
// For such calls, we need to drop only the newly created part of stack.
labelOffset int
// returnLabel contains label ID pointing to the first instruction right after the call.
returnLabel uint16
}

type varType int

const (
Expand Down Expand Up @@ -680,8 +687,8 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {

cnt := 0
start := 0
if len(c.inlineLabelOffsets) > 0 {
start = c.inlineLabelOffsets[len(c.inlineLabelOffsets)-1]
if len(c.inlineContext) > 0 {
start = c.inlineContext[len(c.inlineContext)-1].labelOffset
}
for i := start; i < len(c.labelList); i++ {
cnt += c.labelList[i].sz
Expand Down Expand Up @@ -711,6 +718,8 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
c.saveSequencePoint(n)
if len(c.pkgInfoInline) == 0 {
emit.Opcodes(c.prog.BinWriter, opcode.RET)
} else {
emit.Jmp(c.prog.BinWriter, opcode.JMPL, c.inlineContext[len(c.inlineContext)-1].returnLabel)
}
return nil

Expand Down Expand Up @@ -2211,7 +2220,7 @@ func (c *codegen) resolveFuncDecls(f *ast.File, pkg *types.Package) {

func (c *codegen) writeJumps(b []byte) ([]byte, error) {
ctx := vm.NewContext(b)
var offsets []int
var nopOffsets []int
for op, param, err := ctx.Next(); err == nil && ctx.IP() < len(b); op, param, err = ctx.Next() {
switch op {
case opcode.JMP, opcode.JMPIFNOT, opcode.JMPIF, opcode.CALL,
Expand All @@ -2235,13 +2244,20 @@ func (c *codegen) writeJumps(b []byte) ([]byte, error) {
return nil, err
}
if op != opcode.PUSHA && math.MinInt8 <= offset && offset <= math.MaxInt8 {
offsets = append(offsets, ctx.IP())
if op == opcode.JMPL && offset == 5 {
copy(b[ctx.IP():], []byte{byte(opcode.NOP), byte(opcode.NOP), byte(opcode.NOP), byte(opcode.NOP), byte(opcode.NOP)})
nopOffsets = append(nopOffsets, ctx.IP(), ctx.IP()+1, ctx.IP()+2, ctx.IP()+3, ctx.IP()+4)
} else {
copy(b[ctx.IP():], []byte{byte(toShortForm(op)), byte(offset), byte(opcode.NOP), byte(opcode.NOP), byte(opcode.NOP)})
nopOffsets = append(nopOffsets, ctx.IP()+2, ctx.IP()+3, ctx.IP()+4)
}
}
case opcode.INITSLOT:
nextIP := ctx.NextIP()
info := c.reverseOffsetMap[ctx.IP()]
if argCount := b[nextIP-1]; info.count == 0 && argCount == 0 {
offsets = append(offsets, ctx.IP())
copy(b[ctx.IP():], []byte{byte(opcode.NOP), byte(opcode.NOP), byte(opcode.NOP)})
nopOffsets = append(nopOffsets, ctx.IP(), ctx.IP()+1, ctx.IP()+2)
continue
}

Expand All @@ -2253,20 +2269,20 @@ func (c *codegen) writeJumps(b []byte) ([]byte, error) {
}

if c.deployEndOffset >= 0 {
_, end := correctRange(uint16(c.initEndOffset+1), uint16(c.deployEndOffset), offsets)
_, end := correctRange(uint16(c.initEndOffset+1), uint16(c.deployEndOffset), nopOffsets)
c.deployEndOffset = int(end)
}
if c.initEndOffset > 0 {
_, end := correctRange(0, uint16(c.initEndOffset), offsets)
_, end := correctRange(0, uint16(c.initEndOffset), nopOffsets)
c.initEndOffset = int(end)
}

// Correct function ip range.
// Note: indices are sorted in increasing order.
for _, f := range c.funcs {
f.rng.Start, f.rng.End = correctRange(f.rng.Start, f.rng.End, offsets)
f.rng.Start, f.rng.End = correctRange(f.rng.Start, f.rng.End, nopOffsets)
}
return shortenJumps(b, offsets), nil
return removeNOPs(b, nopOffsets), nil
}

func correctRange(start, end uint16, offsets []int) (uint16, uint16) {
Expand All @@ -2277,10 +2293,10 @@ loop:
case ind > int(end):
break loop
case ind < int(start):
newStart -= longToShortRemoveCount
newEnd -= longToShortRemoveCount
newStart--
newEnd--
case ind >= int(start):
newEnd -= longToShortRemoveCount
newEnd--
}
}
return newStart, newEnd
Expand All @@ -2303,21 +2319,22 @@ func (c *codegen) replaceLabelWithOffset(ip int, arg []byte) (int, error) {
return offset, nil
}

// longToShortRemoveCount is a difference between short and long instruction sizes in bytes.
// By pure coincidence, this is also the size of `INITSLOT` instruction.
const longToShortRemoveCount = 3

// shortenJumps converts b to a program where all long JMP*/CALL* specified by absolute offsets
// removeNOPs converts b to a program where all long JMP*/CALL* specified by absolute offsets
// are replaced with their corresponding short counterparts. It panics if either b or offsets are invalid.
// This is done in 2 passes:
// 1. Alter jump offsets taking into account parts to be removed.
// 2. Perform actual removal of jump targets.
// Note: after jump offsets altering, there can appear new candidates for conversion.
// These are ignored for now.
func shortenJumps(b []byte, offsets []int) []byte {
if len(offsets) == 0 {
func removeNOPs(b []byte, nopOffsets []int) []byte {
if len(nopOffsets) == 0 {
return b
}
for i := range nopOffsets {
if b[nopOffsets[i]] != byte(opcode.NOP) {
panic("NOP offset is invalid")
}
}

// 1. Alter existing jump offsets.
ctx := vm.NewContext(b)
Expand All @@ -2330,57 +2347,46 @@ func shortenJumps(b []byte, offsets []int) []byte {
opcode.JMPEQ, opcode.JMPNE,
opcode.JMPGT, opcode.JMPGE, opcode.JMPLE, opcode.JMPLT, opcode.ENDTRY:
offset := int(int8(b[nextIP-1]))
offset += calcOffsetCorrection(ip, ip+offset, offsets)
offset += calcOffsetCorrection(ip, ip+offset, nopOffsets)
b[nextIP-1] = byte(offset)
case opcode.TRY:
catchOffset := int(int8(b[nextIP-2]))
catchOffset += calcOffsetCorrection(ip, ip+catchOffset, offsets)
catchOffset += calcOffsetCorrection(ip, ip+catchOffset, nopOffsets)
b[nextIP-1] = byte(catchOffset)
finallyOffset := int(int8(b[nextIP-1]))
finallyOffset += calcOffsetCorrection(ip, ip+finallyOffset, offsets)
finallyOffset += calcOffsetCorrection(ip, ip+finallyOffset, nopOffsets)
b[nextIP-1] = byte(finallyOffset)
case opcode.JMPL, opcode.JMPIFL, opcode.JMPIFNOTL,
opcode.JMPEQL, opcode.JMPNEL,
opcode.JMPGTL, opcode.JMPGEL, opcode.JMPLEL, opcode.JMPLTL,
opcode.CALLL, opcode.PUSHA, opcode.ENDTRYL:
arg := b[nextIP-4:]
offset := int(int32(binary.LittleEndian.Uint32(arg)))
offset += calcOffsetCorrection(ip, ip+offset, offsets)
offset += calcOffsetCorrection(ip, ip+offset, nopOffsets)
binary.LittleEndian.PutUint32(arg, uint32(offset))
case opcode.TRYL:
arg := b[nextIP-8:]
catchOffset := int(int32(binary.LittleEndian.Uint32(arg)))
catchOffset += calcOffsetCorrection(ip, ip+catchOffset, offsets)
catchOffset += calcOffsetCorrection(ip, ip+catchOffset, nopOffsets)
binary.LittleEndian.PutUint32(arg, uint32(catchOffset))
arg = b[nextIP-4:]
finallyOffset := int(int32(binary.LittleEndian.Uint32(arg)))
finallyOffset += calcOffsetCorrection(ip, ip+finallyOffset, offsets)
finallyOffset += calcOffsetCorrection(ip, ip+finallyOffset, nopOffsets)
binary.LittleEndian.PutUint32(arg, uint32(finallyOffset))
}
}

// 2. Convert instructions.
copyOffset := 0
l := len(offsets)
if op := opcode.Opcode(b[offsets[0]]); op != opcode.INITSLOT {
b[offsets[0]] = byte(toShortForm(op))
}
l := len(nopOffsets)
for i := 0; i < l; i++ {
start := offsets[i] + 2
if b[offsets[i]] == byte(opcode.INITSLOT) {
start = offsets[i]
}

start := nopOffsets[i]
end := len(b)
if i != l-1 {
end = offsets[i+1]
if op := opcode.Opcode(b[offsets[i+1]]); op != opcode.INITSLOT {
end += 2
b[offsets[i+1]] = byte(toShortForm(op))
}
end = nopOffsets[i+1]
}
copy(b[start-copyOffset:], b[start+3:end])
copyOffset += longToShortRemoveCount
copy(b[start-copyOffset:], b[start+1:end])
copyOffset++
}
return b[:len(b)-copyOffset]
}
Expand All @@ -2392,9 +2398,8 @@ func calcOffsetCorrection(ip, target int, offsets []int) int {
})
for i := start; i < len(offsets) && (offsets[i] < target || offsets[i] <= ip); i++ {
ind := offsets[i]
if ip <= ind && ind < target ||
ind != ip && target <= ind && ind <= ip {
cnt += longToShortRemoveCount
if ip <= ind && ind < target || target <= ind && ind < ip {
cnt++
}
}
if ip < target {
Expand Down
14 changes: 9 additions & 5 deletions pkg/compiler/inline.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -21,12 +21,15 @@ import (
// <inline body of f directly>
// }
func (c *codegen) inlineCall(f *funcScope, n *ast.CallExpr) {
labelSz := len(c.labelList)
offSz := len(c.inlineLabelOffsets)
c.inlineLabelOffsets = append(c.inlineLabelOffsets, labelSz)
offSz := len(c.inlineContext)
c.inlineContext = append(c.inlineContext, inlineContextSingle{
labelOffset: len(c.labelList),
returnLabel: c.newLabel(),
})

defer func() {
c.inlineLabelOffsets = c.inlineLabelOffsets[:offSz]
c.labelList = c.labelList[:labelSz]
c.labelList = c.labelList[:c.inlineContext[offSz].labelOffset]
c.inlineContext = c.inlineContext[:offSz]
}()

pkg := c.packageCache[f.pkg.Path()]
Expand Down Expand Up @@ -113,6 +116,7 @@ func (c *codegen) inlineCall(f *funcScope, n *ast.CallExpr) {
c.fillImportMap(f.file, pkg)
ast.Inspect(f.decl, c.scope.analyzeVoidCalls)
ast.Walk(c, f.decl.Body)
c.setLabel(c.inlineContext[offSz].returnLabel)
if c.scope.voidCalls[n] {
for i := 0; i < f.decl.Type.Results.NumFields(); i++ {
emit.Opcodes(c.prog.BinWriter, opcode.DROP)
Expand Down
43 changes: 43 additions & 0 deletions pkg/compiler/inline_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -374,3 +374,46 @@ func TestInlinedMethodWithPointer(t *testing.T) {
}`
eval(t, src, big.NewInt(100542))
}

func TestInlineConditionalReturn(t *testing.T) {
srcTmpl := `package foo
import "github.com/nspcc-dev/neo-go/pkg/compiler/testdata/inline/c"
func Main() int {
x := %d
if c.Is42(x) {
return 100
}
return 10
}`
t.Run("true", func(t *testing.T) {
eval(t, fmt.Sprintf(srcTmpl, 123), big.NewInt(10))
})
t.Run("false", func(t *testing.T) {
eval(t, fmt.Sprintf(srcTmpl, 42), big.NewInt(100))
})
}

func TestInlineDoubleConditionalReturn(t *testing.T) {
srcTmpl := `package foo
import "github.com/nspcc-dev/neo-go/pkg/compiler/testdata/inline/c"
func Main() int {
return c.Transform(%d, %d)
}`

testCase := []struct {
name string
a, b, result int
}{
{"true, true, small", 42, 3, 6},
{"true, true, big", 42, 15, 15},
{"true, false", 42, 42, 42},
{"false, true", 3, 11, 6},
{"false, false", 3, 42, 6},
}

for _, tc := range testCase {
t.Run(tc.name, func(t *testing.T) {
eval(t, fmt.Sprintf(srcTmpl, tc.a, tc.b), big.NewInt(int64(tc.result)))
})
}
}
30 changes: 15 additions & 15 deletions pkg/compiler/jumps_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@ func testShortenJumps(t *testing.T, before, after []opcode.Opcode, indices []int
for i := range before {
prog[i] = byte(before[i])
}
raw := shortenJumps(prog, indices)
raw := removeNOPs(prog, indices)
actual := make([]opcode.Opcode, len(raw))
for i := range raw {
actual[i] = opcode.Opcode(raw[i])
Expand All @@ -36,53 +36,53 @@ func TestShortenJumps(t *testing.T) {
for op, sop := range testCases {
t.Run(op.String(), func(t *testing.T) {
before := []opcode.Opcode{
op, 6, 0, 0, 0, opcode.PUSH1, opcode.NOP, // <- first jump to here
sop, 6, opcode.NOP, opcode.NOP, opcode.NOP, opcode.PUSH1, opcode.NOP, // <- first jump to here
op, 9, 12, 0, 0, opcode.PUSH1, opcode.NOP, // <- last jump to here
op, 255, 0, 0, 0, op, 0xFF - 5, 0xFF, 0xFF, 0xFF,
sop, 249, opcode.NOP, opcode.NOP, opcode.NOP, sop, 0xFF - 5, opcode.NOP, opcode.NOP, opcode.NOP,
}
after := []opcode.Opcode{
sop, 3, opcode.PUSH1, opcode.NOP,
op, 3, 12, 0, 0, opcode.PUSH1, opcode.NOP,
sop, 249, sop, 0xFF - 2,
}
testShortenJumps(t, before, after, []int{0, 14, 19})
testShortenJumps(t, before, after, []int{2, 3, 4, 16, 17, 18, 21, 22, 23})
})
}
t.Run("NoReplace", func(t *testing.T) {
b := []byte{0, 1, 2, 3, 4, 5}
expected := []byte{0, 1, 2, 3, 4, 5}
require.Equal(t, expected, shortenJumps(b, nil))
require.Equal(t, expected, removeNOPs(b, nil))
})
t.Run("InvalidIndex", func(t *testing.T) {
before := []byte{byte(opcode.PUSH1), 0, 0, 0, 0}
require.Panics(t, func() {
shortenJumps(before, []int{0})
removeNOPs(before, []int{0})
})
})
t.Run("SideConditions", func(t *testing.T) {
t.Run("Forward", func(t *testing.T) {
before := []opcode.Opcode{
opcode.JMPL, 5, 0, 0, 0,
opcode.JMPL, 5, 0, 0, 0,
opcode.JMP, 5, opcode.NOP, opcode.NOP, opcode.NOP,
opcode.JMP, 5, opcode.NOP, opcode.NOP, opcode.NOP,
}
after := []opcode.Opcode{
opcode.JMP, 2,
opcode.JMP, 2,
}
testShortenJumps(t, before, after, []int{0, 5})
testShortenJumps(t, before, after, []int{2, 3, 4, 7, 8, 9})
})
t.Run("Backwards", func(t *testing.T) {
before := []opcode.Opcode{
opcode.JMPL, 5, 0, 0, 0,
opcode.JMPL, 0xFF - 4, 0xFF, 0xFF, 0xFF,
opcode.JMPL, 0xFF - 4, 0xFF, 0xFF, 0xFF,
opcode.JMP, 5, opcode.NOP, opcode.NOP, opcode.NOP,
opcode.JMP, 0xFF - 4, opcode.NOP, opcode.NOP, opcode.NOP,
opcode.JMP, 0xFF - 4, opcode.NOP, opcode.NOP, opcode.NOP,
}
after := []opcode.Opcode{
opcode.JMPL, 5, 0, 0, 0,
opcode.JMP, 0xFF - 4,
opcode.JMP, 2,
opcode.JMP, 0xFF - 1,
opcode.JMP, 0xFF - 1,
}
testShortenJumps(t, before, after, []int{5, 10})
testShortenJumps(t, before, after, []int{2, 3, 4, 7, 8, 9, 12, 13, 14})
})
})
}
Expand Down
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