Merge pull request #243 from Consensys/193-support-fieldarray

Support `FrArray`

pkg/cmd/check.go

@@ -162,6 +162,7 @@ func checkTraceWithLoweringDefault(tr trace.Trace, hirSchema *hir.Schema, cfg ch
 }
 
 func checkTrace(tr trace.Trace, schema sc.Schema, cfg checkConfig) (trace.Trace, error) {
+	//
 	if cfg.expand {
 		// Clone to prevent interefence with subsequent checks
 		tr = tr.Clone()
@@ -186,12 +187,10 @@ func checkTrace(tr trace.Trace, schema sc.Schema, cfg checkConfig) (trace.Trace,
 			return tr, err
 		}
 	}
-
 	// Perform Alignment
 	if err := performAlignment(false, tr, schema, cfg); err != nil {
 		return tr, err
 	}
-
 	// Apply padding (as necessary)
 	for n := cfg.padding.Left; n <= cfg.padding.Right; n++ {
 		if ptr, err := padAndCheckTrace(n, tr, schema); err != nil {

pkg/cmd/trace.go

@@ -6,7 +6,6 @@ import (
 	"os"
 	"strings"
 
-	"github.com/consensys/gnark-crypto/ecc/bls12-377/fr"
 	"github.com/consensys/go-corset/pkg/trace"
 	"github.com/consensys/go-corset/pkg/util"
 
@@ -80,12 +79,7 @@ func filterColumns(tr trace.Trace, prefix string) trace.Trace {
 		if strings.HasPrefix(qName, prefix) {
 			ith := tr.Columns().Get(i)
 			// Copy column data
-			data := make([]*fr.Element, ith.Height())
-			//
-			for j := 0; j < int(ith.Height()); j++ {
-				data[j] = ith.Get(j)
-			}
-
+			data := ith.Data().Clone()
 			err := builder.Add(qName, ith.Padding(), data)
 			// Sanity check
 			if err != nil {
@@ -102,9 +96,9 @@ func listColumns(tr trace.Trace) {
 	tbl := util.NewTablePrinter(3, n)
 
 	for i := uint(0); i < n; i++ {
-		ith := tr.Columns().Get(i)
-		elems := fmt.Sprintf("%d rows", ith.Height())
-		bytes := fmt.Sprintf("%d bytes", ith.Width()*ith.Height())
+		ith := tr.Columns().Get(i).Data()
+		elems := fmt.Sprintf("%d rows", ith.Len())
+		bytes := fmt.Sprintf("(%d*%d) = %d bytes", ith.Len(), ith.ByteWidth(), ith.ByteWidth()*ith.Len())
 		tbl.SetRow(i, QualifiedColumnName(i, tr), elems, bytes)
 	}
 

pkg/schema/assignment/byte_decomposition.go

@@ -69,24 +69,25 @@ func (p *ByteDecomposition) ExpandTrace(tr trace.Trace) error {
 	// Identify source column
 	source := columns.Get(p.source)
 	// Construct byte column data
-	cols := make([][]*fr.Element, n)
+	cols := make([]util.FrArray, n)
 	// Initialise columns
 	for i := 0; i < n; i++ {
-		cols[i] = make([]*fr.Element, source.Height())
+		// Construct a byte column for ith byte
+		cols[i] = util.NewFrArray(source.Height(), 1)
 	}
 	// Decompose each row of each column
-	for i := 0; i < int(source.Height()); i = i + 1 {
-		ith := decomposeIntoBytes(source.Get(i), n)
+	for i := uint(0); i < source.Height(); i = i + 1 {
+		ith := decomposeIntoBytes(source.Get(int(i)), n)
 		for j := 0; j < n; j++ {
-			cols[j][i] = ith[j]
+			cols[j].Set(i, ith[j])
 		}
 	}
 	// Determine padding values
 	padding := decomposeIntoBytes(source.Padding(), n)
 	// Finally, add byte columns to trace
 	for i := 0; i < n; i++ {
 		ith := p.targets[i]
-		columns.Add(trace.NewFieldColumn(ith.Context(), ith.Name(), cols[i], padding[i]))
+		columns.Add(ith.Context(), ith.Name(), cols[i], padding[i])
 	}
 	// Done
 	return nil

pkg/schema/assignment/computed_column.go

@@ -87,23 +87,23 @@ func (p *ComputedColumn[E]) ExpandTrace(tr trace.Trace) error {
 	// Determine multiplied height
 	height := tr.Modules().Get(p.target.Context().Module()).Height() * multiplier
 	// Make space for computed data
-	data := make([]*fr.Element, height)
+	data := util.NewFrArray(height, 32)
 	// Expand the trace
-	for i := 0; i < len(data); i++ {
-		val := p.expr.EvalAt(i, tr)
+	for i := uint(0); i < data.Len(); i++ {
+		val := p.expr.EvalAt(int(i), tr)
 		if val != nil {
-			data[i] = val
+			data.Set(i, val)
 		} else {
 			zero := fr.NewElement(0)
-			data[i] = &zero
+			data.Set(i, &zero)
 		}
 	}
 	// Determine padding value.  A negative row index is used here to ensure
 	// that all columns return their padding value which is then used to compute
 	// the padding value for *this* column.
 	padding := p.expr.EvalAt(-1, tr)
 	// Colunm needs to be expanded.
-	columns.Add(trace.NewFieldColumn(p.target.Context(), p.Name(), data, padding))
+	columns.Add(p.target.Context(), p.Name(), data, padding)
 	// Done
 	return nil
 }

pkg/schema/assignment/interleave.go

@@ -3,9 +3,7 @@ package assignment
 import (
 	"fmt"
 
-	"github.com/consensys/gnark-crypto/ecc/bls12-377/fr"
 	"github.com/consensys/go-corset/pkg/schema"
-	"github.com/consensys/go-corset/pkg/trace"
 	tr "github.com/consensys/go-corset/pkg/trace"
 	"github.com/consensys/go-corset/pkg/util"
 )
@@ -73,12 +71,16 @@ func (p *Interleaving) RequiredSpillage() uint {
 func (p *Interleaving) ExpandTrace(tr tr.Trace) error {
 	columns := tr.Columns()
 	ctx := p.target.Context()
+	// Byte width records the largest width of any column.
+	byte_width := uint(0)
 	// Ensure target column doesn't exist
 	for i := p.Columns(); i.HasNext(); {
-		name := i.Next().Name()
+		ith := i.Next()
+		// Update byte width
+		byte_width = max(byte_width, ith.Type().ByteWidth())
 		// Sanity check no column already exists with this name.
-		if _, ok := columns.IndexOf(ctx.Module(), name); ok {
-			return fmt.Errorf("interleaved column already exists ({%s})", name)
+		if _, ok := columns.IndexOf(ctx.Module(), ith.Name()); ok {
+			return fmt.Errorf("interleaved column already exists ({%s})", ith.Name())
 		}
 	}
 	// Determine interleaving width
@@ -90,7 +92,7 @@ func (p *Interleaving) ExpandTrace(tr tr.Trace) error {
 	// the interleaved column)
 	height := tr.Modules().Get(ctx.Module()).Height() * multiplier
 	// Construct empty array
-	data := make([]*fr.Element, height*width)
+	data := util.NewFrArray(height*width, byte_width)
 	// Offset just gives the column index
 	offset := uint(0)
 	// Copy interleaved data
@@ -99,7 +101,7 @@ func (p *Interleaving) ExpandTrace(tr tr.Trace) error {
 		col := tr.Columns().Get(p.sources[i])
 		// Copy over
 		for j := uint(0); j < height; j++ {
-			data[offset+(j*width)] = col.Get(int(j))
+			data.Set(offset+(j*width), col.Get(int(j)))
 		}
 
 		offset++
@@ -108,7 +110,7 @@ func (p *Interleaving) ExpandTrace(tr tr.Trace) error {
 	// column in the interleaving.
 	padding := columns.Get(0).Padding()
 	// Colunm needs to be expanded.
-	columns.Add(trace.NewFieldColumn(ctx, p.target.Name(), data, padding))
+	columns.Add(ctx, p.target.Name(), data, padding)
 	//
 	return nil
 }

pkg/schema/assignment/lexicographic_sort.go

@@ -80,48 +80,55 @@ func (p *LexicographicSort) ExpandTrace(tr trace.Trace) error {
 	// Determine how many rows to be constrained.
 	nrows := tr.Modules().Get(p.context.Module()).Height() * multiplier
 	// Initialise new data columns
-	delta := make([]*fr.Element, nrows)
-	bit := make([][]*fr.Element, ncols)
+	bit := make([]util.FrArray, ncols)
+	// Byte width records the largest width of any column.
+	byte_width := uint(0)
 
 	for i := 0; i < ncols; i++ {
-		bit[i] = make([]*fr.Element, nrows)
+		// TODO: following can be optimised to use a single bit per element,
+		// rather than an entire byte.
+		bit[i] = util.NewFrArray(nrows, 1)
+		ith := columns.Get(p.sources[i])
+		byte_width = max(byte_width, ith.Data().ByteWidth())
 	}
 
-	for i := 0; i < int(nrows); i++ {
+	delta := util.NewFrArray(nrows, byte_width)
+
+	for i := uint(0); i < nrows; i++ {
 		set := false
 		// Initialise delta to zero
-		delta[i] = &zero
+		delta.Set(i, &zero)
 		// Decide which row is the winner (if any)
 		for j := 0; j < ncols; j++ {
-			prev := columns.Get(p.sources[j]).Get(i - 1)
-			curr := columns.Get(p.sources[j]).Get(i)
+			prev := columns.Get(p.sources[j]).Get(int(i - 1))
+			curr := columns.Get(p.sources[j]).Get(int(i))
 
 			if !set && prev != nil && prev.Cmp(curr) != 0 {
 				var diff fr.Element
 
-				bit[j][i] = &one
+				bit[j].Set(i, &one)
 				// Compute curr - prev
 				if p.signs[j] {
 					diff.Set(curr)
-					delta[i] = diff.Sub(&diff, prev)
+					delta.Set(i, diff.Sub(&diff, prev))
 				} else {
 					diff.Set(prev)
-					delta[i] = diff.Sub(&diff, curr)
+					delta.Set(i, diff.Sub(&diff, curr))
 				}
 
 				set = true
 			} else {
-				bit[j][i] = &zero
+				bit[j].Set(i, &zero)
 			}
 		}
 	}
 	// Add delta column data
 	first := p.targets[0]
-	columns.Add(trace.NewFieldColumn(first.Context(), first.Name(), delta, &zero))
+	columns.Add(first.Context(), first.Name(), delta, &zero)
 	// Add bit column data
 	for i := 0; i < ncols; i++ {
 		ith := p.targets[1+i]
-		columns.Add(trace.NewFieldColumn(ith.Context(), ith.Name(), bit[i], &zero))
+		columns.Add(ith.Context(), ith.Name(), bit[i], &zero)
 	}
 	// Done.
 	return nil

pkg/schema/assignment/sorted_permutation.go

@@ -3,7 +3,6 @@ package assignment
 import (
 	"fmt"
 
-	"github.com/consensys/gnark-crypto/ecc/bls12-377/fr"
 	"github.com/consensys/go-corset/pkg/schema"
 	"github.com/consensys/go-corset/pkg/trace"
 	tr "github.com/consensys/go-corset/pkg/trace"
@@ -132,20 +131,14 @@ func (p *SortedPermutation) ExpandTrace(tr tr.Trace) error {
 		}
 	}
 
-	cols := make([][]*fr.Element, len(p.sources))
+	cols := make([]util.FrArray, len(p.sources))
 	// Construct target columns
 	for i := 0; i < len(p.sources); i++ {
 		src := p.sources[i]
-		// Read column data to initialise permutation.
-		col := columns.Get(src)
-		// Copy column data to initialise permutation.
-		copy := make([]*fr.Element, col.Height())
-		//
-		for j := 0; j < int(col.Height()); j++ {
-			copy[j] = col.Get(j)
-		}
-		// Copy over
-		cols[i] = copy
+		// Read column data
+		data := columns.Get(src).Data()
+		// Clone it to initialise permutation.
+		cols[i] = data.Clone()
 	}
 	// Sort target columns
 	util.PermutationSort(cols, p.signs)
@@ -156,7 +149,7 @@ func (p *SortedPermutation) ExpandTrace(tr tr.Trace) error {
 		ith := i.Next()
 		dstColName := ith.Name()
 		srcCol := tr.Columns().Get(p.sources[index])
-		columns.Add(trace.NewFieldColumn(ith.Context(), dstColName, cols[index], srcCol.Padding()))
+		columns.Add(ith.Context(), dstColName, cols[index], srcCol.Padding())
 	}
 	//
 	return nil

pkg/schema/constraint/permutation.go

@@ -4,7 +4,6 @@ import (
 	"errors"
 	"fmt"
 
-	"github.com/consensys/gnark-crypto/ecc/bls12-377/fr"
 	"github.com/consensys/go-corset/pkg/trace"
 	"github.com/consensys/go-corset/pkg/util"
 )
@@ -72,20 +71,14 @@ func (p *PermutationConstraint) String() string {
 	return fmt.Sprintf("(permutation (%s) (%s))", targets, sources)
 }
 
-func sliceColumns(columns []uint, tr trace.Trace) [][]*fr.Element {
+func sliceColumns(columns []uint, tr trace.Trace) []util.FrArray {
 	// Allocate return array
-	cols := make([][]*fr.Element, len(columns))
+	cols := make([]util.FrArray, len(columns))
 	// Slice out the data
 	for i, n := range columns {
 		nth := tr.Columns().Get(n)
-		// Copy column data to initialise permutation.
-		copy := make([]*fr.Element, nth.Height())
-		//
-		for j := 0; j < int(nth.Height()); j++ {
-			copy[j] = nth.Get(j)
-		}
 		// Copy over
-		cols[i] = copy
+		cols[i] = nth.Data()
 	}
 	// Done
 	return cols

pkg/schema/type.go

@@ -22,6 +22,9 @@ type Type interface {
 	// Accept checks whether a specific value is accepted by this type
 	Accept(*fr.Element) bool
 
+	// Return the number of bytes required represent any element of this type.
+	ByteWidth() uint
+
 	// Produce a string representation of this type.
 	String() string
 }
@@ -59,6 +62,19 @@ func (p *UintType) AsField() *FieldType {
 	return nil
 }
 
+// ByteWidth returns the number of bytes required represent any element of this
+// type.
+func (p *UintType) ByteWidth() uint {
+	m := p.nbits / 8
+	n := p.nbits % 8
+	// Check for even division
+	if n == 0 {
+		return m
+	}
+	//
+	return m + 1
+}
+
 // Accept determines whether a given value is an element of this type.  For
 // example, 123 is an element of the type u8 whilst 256 is not.
 func (p *UintType) Accept(val *fr.Element) bool {
@@ -104,6 +120,12 @@ func (p *FieldType) AsField() *FieldType {
 	return p
 }
 
+// ByteWidth returns the number of bytes required represent any element of this
+// type.
+func (p *FieldType) ByteWidth() uint {
+	return 32
+}
+
 // Accept determines whether a given value is an element of this type.  In
 // fact, all field elements are members of this type.
 func (p *FieldType) Accept(val *fr.Element) bool {