106 lines
3.3 KiB
Go
106 lines
3.3 KiB
Go
package binary
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import (
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"bytes"
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"fmt"
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"io"
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"github.com/tetratelabs/wazero/api"
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"github.com/tetratelabs/wazero/internal/ieee754"
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"github.com/tetratelabs/wazero/internal/leb128"
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"github.com/tetratelabs/wazero/internal/wasm"
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)
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func decodeConstantExpression(r *bytes.Reader, enabledFeatures api.CoreFeatures, ret *wasm.ConstantExpression) error {
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b, err := r.ReadByte()
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if err != nil {
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return fmt.Errorf("read opcode: %v", err)
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}
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remainingBeforeData := int64(r.Len())
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offsetAtData := r.Size() - remainingBeforeData
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opcode := b
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switch opcode {
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case wasm.OpcodeI32Const:
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// Treat constants as signed as their interpretation is not yet known per /RATIONALE.md
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_, _, err = leb128.DecodeInt32(r)
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case wasm.OpcodeI64Const:
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// Treat constants as signed as their interpretation is not yet known per /RATIONALE.md
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_, _, err = leb128.DecodeInt64(r)
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case wasm.OpcodeF32Const:
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buf := make([]byte, 4)
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if _, err := io.ReadFull(r, buf); err != nil {
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return fmt.Errorf("read f32 constant: %v", err)
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}
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_, err = ieee754.DecodeFloat32(buf)
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case wasm.OpcodeF64Const:
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buf := make([]byte, 8)
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if _, err := io.ReadFull(r, buf); err != nil {
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return fmt.Errorf("read f64 constant: %v", err)
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}
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_, err = ieee754.DecodeFloat64(buf)
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case wasm.OpcodeGlobalGet:
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_, _, err = leb128.DecodeUint32(r)
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case wasm.OpcodeRefNull:
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if err := enabledFeatures.RequireEnabled(api.CoreFeatureBulkMemoryOperations); err != nil {
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return fmt.Errorf("ref.null is not supported as %w", err)
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}
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reftype, err := r.ReadByte()
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if err != nil {
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return fmt.Errorf("read reference type for ref.null: %w", err)
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} else if reftype != wasm.RefTypeFuncref && reftype != wasm.RefTypeExternref {
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return fmt.Errorf("invalid type for ref.null: 0x%x", reftype)
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}
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case wasm.OpcodeRefFunc:
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if err := enabledFeatures.RequireEnabled(api.CoreFeatureBulkMemoryOperations); err != nil {
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return fmt.Errorf("ref.func is not supported as %w", err)
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}
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// Parsing index.
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_, _, err = leb128.DecodeUint32(r)
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case wasm.OpcodeVecPrefix:
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if err := enabledFeatures.RequireEnabled(api.CoreFeatureSIMD); err != nil {
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return fmt.Errorf("vector instructions are not supported as %w", err)
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}
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opcode, err = r.ReadByte()
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if err != nil {
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return fmt.Errorf("read vector instruction opcode suffix: %w", err)
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}
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if opcode != wasm.OpcodeVecV128Const {
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return fmt.Errorf("invalid vector opcode for const expression: %#x", opcode)
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}
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remainingBeforeData = int64(r.Len())
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offsetAtData = r.Size() - remainingBeforeData
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n, err := r.Read(make([]byte, 16))
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if err != nil {
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return fmt.Errorf("read vector const instruction immediates: %w", err)
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} else if n != 16 {
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return fmt.Errorf("read vector const instruction immediates: needs 16 bytes but was %d bytes", n)
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}
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default:
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return fmt.Errorf("%v for const expression opt code: %#x", ErrInvalidByte, b)
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}
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if err != nil {
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return fmt.Errorf("read value: %v", err)
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}
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if b, err = r.ReadByte(); err != nil {
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return fmt.Errorf("look for end opcode: %v", err)
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}
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if b != wasm.OpcodeEnd {
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return fmt.Errorf("constant expression has been not terminated")
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}
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ret.Data = make([]byte, remainingBeforeData-int64(r.Len())-1)
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if _, err = r.ReadAt(ret.Data, offsetAtData); err != nil {
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return fmt.Errorf("error re-buffering ConstantExpression.Data")
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}
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ret.Opcode = opcode
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return nil
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}
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