Enum gimli::read::Operation

pub enum Operation<R, Offset = <R as Reader>::Offset>
where
    R: Reader<Offset = Offset>,
    Offset: ReaderOffset,
{
    Deref {
        base_type: UnitOffset<Offset>,
        size: u8,
        space: bool,
    },
    Drop,
    Pick {
        index: u8,
    },
    Swap,
    Rot,
    Abs,
    And,
    Div,
    Minus,
    Mod,
    Mul,
    Neg,
    Not,
    Or,
    Plus,
    PlusConstant {
        value: u64,
    },
    Shl,
    Shr,
    Shra,
    Xor,
    Bra {
        target: i16,
    },
    Eq,
    Ge,
    Gt,
    Le,
    Lt,
    Ne,
    Skip {
        target: i16,
    },
    UnsignedConstant {
        value: u64,
    },
    SignedConstant {
        value: i64,
    },
    Register {
        register: Register,
    },
    RegisterOffset {
        register: Register,
        offset: i64,
        base_type: UnitOffset<Offset>,
    },
    FrameOffset {
        offset: i64,
    },
    Nop,
    PushObjectAddress,
    Call {
        offset: DieReference<Offset>,
    },
    TLS,
    CallFrameCFA,
    Piece {
        size_in_bits: u64,
        bit_offset: Option<u64>,
    },
    ImplicitValue {
        data: R,
    },
    StackValue,
    ImplicitPointer {
        value: DebugInfoOffset<Offset>,
        byte_offset: i64,
    },
    EntryValue {
        expression: R,
    },
    ParameterRef {
        offset: UnitOffset<Offset>,
    },
    Address {
        address: u64,
    },
    AddressIndex {
        index: DebugAddrIndex<Offset>,
    },
    ConstantIndex {
        index: DebugAddrIndex<Offset>,
    },
    TypedLiteral {
        base_type: UnitOffset<Offset>,
        value: R,
    },
    Convert {
        base_type: UnitOffset<Offset>,
    },
    Reinterpret {
        base_type: UnitOffset<Offset>,
    },
    WasmLocal {
        index: u32,
    },
    WasmGlobal {
        index: u32,
    },
    WasmStack {
        index: u32,
    },
}

A single decoded DWARF expression operation.

DWARF expression evaluation is done in two parts: first the raw bytes of the next part of the expression are decoded; and then the decoded operation is evaluated. This approach lets other consumers inspect the DWARF expression without reimplementing the decoding operation.

Multiple DWARF opcodes may decode into a single Operation. For example, both DW_OP_deref and DW_OP_xderef are represented using Operation::Deref.

Variants

Deref

Fields

base_type: UnitOffset<Offset>

The DIE of the base type or 0 to indicate the generic type

size: u8

The size of the data to dereference.

space: bool

True if the dereference operation takes an address space argument from the stack; false otherwise.

Dereference the topmost value of the stack.

Drop

Drop an item from the stack.

Pick

Fields

index: u8

The index, from the top of the stack, of the item to copy.

Pick an item from the stack and push it on top of the stack. This operation handles DW_OP_pick, DW_OP_dup, and DW_OP_over.

Swap

Swap the top two stack items.

Rot

Rotate the top three stack items.

Abs

Take the absolute value of the top of the stack.

And

Bitwise and of the top two values on the stack.

Div

Divide the top two values on the stack.

Minus

Subtract the top two values on the stack.

Mod

Modulus of the top two values on the stack.

Mul

Multiply the top two values on the stack.

Neg

Negate the top of the stack.

Not

Bitwise not of the top of the stack.

Or

Bitwise or of the top two values on the stack.

Plus

Add the top two values on the stack.

PlusConstant

Fields

value: u64

The value to add.

Add a constant to the topmost value on the stack.

Shl

Logical left shift of the 2nd value on the stack by the number of bits given by the topmost value on the stack.

Shr

Right shift of the 2nd value on the stack by the number of bits given by the topmost value on the stack.

Shra

Arithmetic left shift of the 2nd value on the stack by the number of bits given by the topmost value on the stack.

Xor

Bitwise xor of the top two values on the stack.

Bra

Fields

target: i16

The relative offset to the target bytecode.

Branch to the target location if the top of stack is nonzero.

Eq

Compare the top two stack values for equality.

Ge

Compare the top two stack values using >=.

Gt

Compare the top two stack values using >.

Le

Compare the top two stack values using <=.

Lt

Compare the top two stack values using <.

Ne

Compare the top two stack values using !=.

Skip

Fields

target: i16

The relative offset to the target bytecode.

Unconditional branch to the target location.

UnsignedConstant

Fields

value: u64

The value to push.

Push an unsigned constant value on the stack. This handles multiple DWARF opcodes.

SignedConstant

Fields

value: i64

The value to push.

Push a signed constant value on the stack. This handles multiple DWARF opcodes.

Register

Fields

register: Register

The register number.

Indicate that this piece’s location is in the given register.

Completes the piece or expression.

RegisterOffset

Fields

register: Register

The register number.

offset: i64

The offset to add.

base_type: UnitOffset<Offset>

The DIE of the base type or 0 to indicate the generic type

Find the value of the given register, add the offset, and then push the resulting sum on the stack.

FrameOffset

Fields

offset: i64

The offset to add.

Compute the frame base (using DW_AT_frame_base), add the given offset, and then push the resulting sum on the stack.

Nop

No operation.

PushObjectAddress

Push the object address on the stack.

Call

Fields

offset: DieReference<Offset>

The DIE to use.

Evaluate a DWARF expression as a subroutine. The expression comes from the DW_AT_location attribute of the indicated DIE.

TLS

Compute the address of a thread-local variable and push it on the stack.

CallFrameCFA

Compute the call frame CFA and push it on the stack.

Piece

Fields

size_in_bits: u64

The size of this piece in bits.

bit_offset: Option<u64>

The bit offset of this piece. If None, then this piece was specified using DW_OP_piece and should start at the next byte boundary.

Terminate a piece.

ImplicitValue

Fields

data: R

The implicit value to use.

The object has no location, but has a known constant value.

Represents DW_OP_implicit_value. Completes the piece or expression.

StackValue

The object has no location, but its value is at the top of the stack.

Represents DW_OP_stack_value. Completes the piece or expression.

ImplicitPointer

Fields

value: DebugInfoOffset<Offset>

The .debug_info offset of the value that this is an implicit pointer into.

byte_offset: i64

The byte offset into the value that the implicit pointer points to.

The object is a pointer to a value which has no actual location, such as an implicit value or a stack value.

Represents DW_OP_implicit_pointer. Completes the piece or expression.

EntryValue

Fields

expression: R

The expression to be evaluated.

Evaluate an expression at the entry to the current subprogram, and push it on the stack.

Represents DW_OP_entry_value.

ParameterRef

Fields

offset: UnitOffset<Offset>

The DIE to use.

This represents a parameter that was optimized out.

The offset points to the definition of the parameter, and is matched to the DW_TAG_GNU_call_site_parameter in the caller that also points to the same definition of the parameter.

Represents DW_OP_GNU_parameter_ref.

Address

Fields

address: u64

The offset to add.

Relocate the address if needed, and push it on the stack.

Represents DW_OP_addr.

AddressIndex

Fields

index: DebugAddrIndex<Offset>

The index of the address in .debug_addr.

Read the address at the given index in `.debug_addr, relocate the address if needed, and push it on the stack.

Represents DW_OP_addrx.

ConstantIndex

Fields

index: DebugAddrIndex<Offset>

The index of the address in .debug_addr.

Read the address at the given index in `.debug_addr, and push it on the stack. Do not relocate the address.

Represents DW_OP_constx.

TypedLiteral

Fields

base_type: UnitOffset<Offset>

The DIE of the base type.

value: R

The value bytes.

Interpret the value bytes as a constant of a given type, and push it on the stack.

Represents DW_OP_const_type.

Convert

Fields

base_type: UnitOffset<Offset>

The DIE of the base type.

Pop the top stack entry, convert it to a different type, and push it on the stack.

Represents DW_OP_convert.

Reinterpret

Fields

base_type: UnitOffset<Offset>

The DIE of the base type.

Pop the top stack entry, reinterpret the bits in its value as a different type, and push it on the stack.

Represents DW_OP_reinterpret.

WasmLocal

Fields

index: u32

The index of the local.

The index of a local in the currently executing function.

Represents DW_OP_WASM_location 0x00. Completes the piece or expression.

WasmGlobal

Fields

index: u32

The index of the global.

The index of a global.

Represents DW_OP_WASM_location 0x01 or DW_OP_WASM_location 0x03. Completes the piece or expression.

WasmStack

Fields

index: u32

The index of the stack item. 0 is the bottom of the operand stack.

The index of an item on the operand stack.

Represents DW_OP_WASM_location 0x02. Completes the piece or expression.

Implementations

impl<R, Offset> Operation<R, Offset>

where R: Reader<Offset = Offset>, Offset: ReaderOffset,

pub fn parse(bytes: &mut R, encoding: Encoding) -> Result<Operation<R, Offset>>

Parse a single DWARF expression operation.

This is useful when examining a DWARF expression for reasons other than direct evaluation.

bytes points to a the operation to decode. It should point into the same array as bytecode, which should be the entire expression.

Trait Implementations

impl<R, Offset> Clone for Operation<R, Offset>

where R: Reader<Offset = Offset> + Clone, Offset: ReaderOffset + Clone,

fn clone(&self) -> Operation<R, Offset>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<R, Offset> Debug for Operation<R, Offset>

where R: Reader<Offset = Offset> + Debug, Offset: ReaderOffset + Debug,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<R, Offset> PartialEq for Operation<R, Offset>

where R: Reader<Offset = Offset> + PartialEq, Offset: ReaderOffset + PartialEq,

fn eq(&self, other: &Operation<R, Offset>) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<R, Offset> Copy for Operation<R, Offset>

where R: Reader<Offset = Offset> + Copy, Offset: ReaderOffset + Copy,

impl<R, Offset> Eq for Operation<R, Offset>

where R: Reader<Offset = Offset> + Eq, Offset: ReaderOffset + Eq,

impl<R, Offset> StructuralEq for Operation<R, Offset>

where R: Reader<Offset = Offset>, Offset: ReaderOffset,

impl<R, Offset> StructuralPartialEq for Operation<R, Offset>

where R: Reader<Offset = Offset>, Offset: ReaderOffset,