model: Update encoder cache to use multimodal input processing handler

The encoder cache needs to know the position of images in the input
stream so that it knows when to delete them. Previously images didn't
have a position, so we implied one by breaking batches before an
image and then assuming the image was in the first position. However,
multimodal objects are now given explicit positions in the input
stream, so we can use that instead.

Breaking batches was also a way to simulate a cross attention mask
for mllama. However, given that it only supports a single sequence
and a single image, this mask doesn't serve any real purpose.
Removing the batch break does not appear to affect the quality of
the output.

Most of this is simply moving the input data structures to a new
package to avoid import cycles.

kvcache/cache.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 
 	"github.com/ollama/ollama/ml"
+	"github.com/ollama/ollama/model/input"
 )
 
 var (
@@ -51,7 +52,7 @@ type Cache interface {
 	// StartForward is called before the start of the model's forward pass.
 	// For each token in the coming batch, there must be a corresponding
 	// entry in positions and seqs.
-	StartForward(ctx ml.Context, positions []int32, seqs []int) error
+	StartForward(ctx ml.Context, opts input.Options) error
 
 	// CopyPrefix copies tokens in the range [0, len) from srcSeq to dstSeq
 	CopyPrefix(srcSeq, dstSeq int, len int32)

kvcache/causal.go

@@ -8,6 +8,7 @@ import (
 	"slices"
 
 	"github.com/ollama/ollama/ml"
+	"github.com/ollama/ollama/model/input"
 )
 
 type shiftFn func(ctx ml.Context, layer int, key, shift ml.Tensor) (ml.Tensor, error)
@@ -140,10 +141,10 @@ func (c *Causal) Close() {
 	}
 }
 
-func (c *Causal) StartForward(ctx ml.Context, positions []int32, seqs []int) error {
-	c.curBatchSize = len(positions)
-	c.curSequences = seqs
-	c.curPositions = positions
+func (c *Causal) StartForward(ctx ml.Context, opts input.Options) error {
+	c.curBatchSize = len(opts.Positions)
+	c.curSequences = opts.Sequences
+	c.curPositions = opts.Positions
 
 	var err error
 	c.curLoc, err = c.findStartLoc()
@@ -156,8 +157,8 @@ func (c *Causal) StartForward(ctx ml.Context, positions []int32, seqs []int) err
 	}
 
 	c.curCellRange = newRange()
-	for i, pos := range positions {
-		seq := seqs[i]
+	for i, pos := range opts.Positions {
+		seq := opts.Sequences[i]
 
 		c.cells[c.curLoc+i] = cacheCell{pos: pos, sequences: []int{seq}}
 

kvcache/causal_test.go

@@ -6,6 +6,7 @@ import (
 	"testing"
 
 	"github.com/ollama/ollama/ml"
+	"github.com/ollama/ollama/model/input"
 )
 
 type testCase struct {
@@ -269,7 +270,7 @@ func testCache(t *testing.T, backend ml.Backend, cache Cache, tests []testCase)
 			context := backend.NewContext()
 			defer context.Close()
 
-			err := cache.StartForward(context, test.pos, test.seqs)
+			err := cache.StartForward(context, input.Options{Positions: test.pos, Sequences: test.seqs})
 			if err != nil {
 				panic(err)
 			}

kvcache/encoder.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 
 	"github.com/ollama/ollama/ml"
+	"github.com/ollama/ollama/model/input"
 )
 
 // Encoder cache stores K and V tensors that are position independent
@@ -78,9 +79,11 @@ func (c *EncoderCache) Close() {
 	}
 }
 
-func (c *EncoderCache) StartForward(ctx ml.Context, positions []int32, seqs []int) error {
-	// The image is always in the first position
-	c.curPos = positions[0]
+func (c *EncoderCache) StartForward(ctx ml.Context, opts input.Options) error {
+	// We work with the most recent image
+	if len(opts.Multimodal) > 0 {
+		c.curPos = opts.Positions[opts.Multimodal[len(opts.Multimodal)-1].Index]
+	}
 
 	return nil
 }

kvcache/wrapper.go

@@ -4,6 +4,7 @@ import (
 	"math"
 
 	"github.com/ollama/ollama/ml"
+	"github.com/ollama/ollama/model/input"
 )
 
 // Wrapper cache is a container for multiple types of caches,
@@ -40,14 +41,14 @@ func (c *WrapperCache) Close() {
 	}
 }
 
-func (c *WrapperCache) StartForward(ctx ml.Context, positions []int32, seqs []int) error {
+func (c *WrapperCache) StartForward(ctx ml.Context, opts input.Options) error {
 	for i, cache := range c.caches {
-		err := cache.StartForward(ctx, positions, seqs)
+		err := cache.StartForward(ctx, opts)
 		if err != nil {
 			// unwind on error - Remove with endIndex set to math.MaxInt32 does not fail
 			for j := i - 1; j >= 0; j-- {
-				for k := range positions {
-					_ = c.caches[j].Remove(seqs[k], positions[k], math.MaxInt32)
+				for k := range opts.Positions {
+					_ = c.caches[j].Remove(opts.Sequences[k], opts.Positions[k], math.MaxInt32)
 				}
 			}
 			return err