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write: implement expressions
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Expressions are now are Vec of operations, instead of raw bytecode.
This is required to support addresses and references within the
expression.
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@philipc
philipc committed Apr 27, 2020
1 parent f92b2b6 commit ea2e758
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Showing 9 changed files with 1,907 additions and 184 deletions.
36 changes: 36 additions & 0 deletions src/read/op.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -885,6 +885,42 @@ impl<R: Reader> Expression<R> {
pub fn evaluation(self, encoding: Encoding) -> Evaluation<R> {
Evaluation::new(self.0, encoding)
}

/// Return an iterator for the operations in the expression.
pub fn operations(self, encoding: Encoding) -> OperationIter<R> {
OperationIter {
input: self.0,
encoding,
}
}
}

/// An iterator for the operations in an expression.
#[derive(Debug, Clone, Copy)]
pub struct OperationIter<R: Reader> {
input: R,
encoding: Encoding,
}

impl<R: Reader> OperationIter<R> {
/// Read the next operation in an expression.
pub fn next(&mut self) -> Result<Option<Operation<R>>> {
if self.input.is_empty() {
return Ok(None);
}
match Operation::parse(&mut self.input, self.encoding) {
Ok(op) => Ok(Some(op)),
Err(e) => {
self.input.empty();
Err(e)
}
}
}

/// Return the current byte offset of the iterator.
pub fn offset_from(&self, expression: &Expression<R>) -> R::Offset {
self.input.offset_from(&expression.0)
}
}

/// A DWARF expression evaluator.
Expand Down
69 changes: 38 additions & 31 deletions src/write/cfi.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -251,7 +251,7 @@ impl CommonInformationEntry {
}

for instruction in &self.instructions {
instruction.write(w, self)?;
instruction.write(w, encoding, self)?;
}

write_nop(
Expand Down Expand Up @@ -357,7 +357,7 @@ impl FrameDescriptionEntry {
for (offset, instruction) in &self.instructions {
write_advance_loc(w, cie.code_alignment_factor, prev_offset, *offset)?;
prev_offset = *offset;
instruction.write(w, cie)?;
instruction.write(w, encoding, cie)?;
}

write_nop(
Expand Down Expand Up @@ -413,7 +413,12 @@ pub enum CallFrameInstruction {
}

impl CallFrameInstruction {
fn write<W: Writer>(&self, w: &mut W, cie: &CommonInformationEntry) -> Result<()> {
fn write<W: Writer>(
&self,
w: &mut W,
encoding: Encoding,
cie: &CommonInformationEntry,
) -> Result<()> {
match *self {
CallFrameInstruction::Cfa(register, offset) => {
if offset < 0 {
Expand Down Expand Up @@ -445,8 +450,8 @@ impl CallFrameInstruction {
}
CallFrameInstruction::CfaExpression(ref expression) => {
w.write_u8(constants::DW_CFA_def_cfa_expression.0)?;
w.write_uleb128(expression.0.len() as u64)?;
w.write(&expression.0)?;
w.write_uleb128(expression.size(encoding, None) as u64)?;
expression.write(w, None, encoding, None)?;
}
CallFrameInstruction::Restore(register) => {
if register.0 < 0x40 {
Expand Down Expand Up @@ -499,14 +504,14 @@ impl CallFrameInstruction {
CallFrameInstruction::Expression(register, ref expression) => {
w.write_u8(constants::DW_CFA_expression.0)?;
w.write_uleb128(register.0.into())?;
w.write_uleb128(expression.0.len() as u64)?;
w.write(&expression.0)?;
w.write_uleb128(expression.size(encoding, None) as u64)?;
expression.write(w, None, encoding, None)?;
}
CallFrameInstruction::ValExpression(register, ref expression) => {
w.write_u8(constants::DW_CFA_val_expression.0)?;
w.write_uleb128(register.0.into())?;
w.write_uleb128(expression.0.len() as u64)?;
w.write(&expression.0)?;
w.write_uleb128(expression.size(encoding, None) as u64)?;
expression.write(w, None, encoding, None)?;
}
CallFrameInstruction::RememberState => {
w.write_u8(constants::DW_CFA_remember_state.0)?;
Expand Down Expand Up @@ -675,9 +680,12 @@ pub(crate) mod convert {
let mut offset = 0;
let mut from_instructions = from_cie.instructions(frame, bases);
while let Some(from_instruction) = from_instructions.next()? {
if let Some(instruction) =
CallFrameInstruction::from(from_instruction, from_cie, &mut offset)?
{
if let Some(instruction) = CallFrameInstruction::from(
from_instruction,
from_cie,
convert_address,
&mut offset,
)? {
cie.instructions.push(instruction);
}
}
Expand Down Expand Up @@ -716,9 +724,12 @@ pub(crate) mod convert {
let mut offset = 0;
let mut from_instructions = from_fde.instructions(frame, bases);
while let Some(from_instruction) = from_instructions.next()? {
if let Some(instruction) =
CallFrameInstruction::from(from_instruction, from_cie, &mut offset)?
{
if let Some(instruction) = CallFrameInstruction::from(
from_instruction,
from_cie,
convert_address,
&mut offset,
)? {
fde.instructions.push((offset, instruction));
}
}
Expand All @@ -731,8 +742,11 @@ pub(crate) mod convert {
fn from<R: Reader<Offset = usize>>(
from_instruction: read::CallFrameInstruction<R>,
from_cie: &read::CommonInformationEntry<R>,
convert_address: &dyn Fn(u64) -> Option<Address>,
offset: &mut u32,
) -> ConvertResult<Option<CallFrameInstruction>> {
let convert_expression =
|x| Expression::from(x, from_cie.encoding(), None, None, None, convert_address);
// TODO: validate integer type conversions
Ok(Some(match from_instruction {
read::CallFrameInstruction::SetLoc { .. } => {
Expand Down Expand Up @@ -764,8 +778,7 @@ pub(crate) mod convert {
CallFrameInstruction::CfaOffset(offset as i32)
}
read::CallFrameInstruction::DefCfaExpression { expression } => {
let expression = Expression(expression.0.to_slice()?.into());
CallFrameInstruction::CfaExpression(expression)
CallFrameInstruction::CfaExpression(convert_expression(expression)?)
}
read::CallFrameInstruction::Undefined { register } => {
CallFrameInstruction::Undefined(register)
Expand Down Expand Up @@ -808,17 +821,11 @@ pub(crate) mod convert {
read::CallFrameInstruction::Expression {
register,
expression,
} => {
let expression = Expression(expression.0.to_slice()?.into());
CallFrameInstruction::Expression(register, expression)
}
} => CallFrameInstruction::Expression(register, convert_expression(expression)?),
read::CallFrameInstruction::ValExpression {
register,
expression,
} => {
let expression = Expression(expression.0.to_slice()?.into());
CallFrameInstruction::ValExpression(register, expression)
}
} => CallFrameInstruction::ValExpression(register, convert_expression(expression)?),
read::CallFrameInstruction::Restore { register } => {
CallFrameInstruction::Restore(register)
}
Expand Down Expand Up @@ -922,6 +929,9 @@ mod tests {

#[test]
fn test_frame_instruction() {
let mut expression = Expression::new();
expression.op_constu(0);

let cie_instructions = [
CallFrameInstruction::Cfa(X86_64::RSP, 8),
CallFrameInstruction::Offset(X86_64::RA, -8),
Expand All @@ -934,10 +944,7 @@ mod tests {
(4, CallFrameInstruction::CfaOffset(8)),
(4, CallFrameInstruction::CfaOffset(0)),
(4, CallFrameInstruction::CfaOffset(-8)),
(
6,
CallFrameInstruction::CfaExpression(Expression(vec![1, 2, 3])),
),
(6, CallFrameInstruction::CfaExpression(expression.clone())),
(8, CallFrameInstruction::Restore(Register(1))),
(8, CallFrameInstruction::Restore(Register(101))),
(10, CallFrameInstruction::Undefined(Register(2))),
Expand All @@ -949,11 +956,11 @@ mod tests {
(18, CallFrameInstruction::Register(Register(6), Register(7))),
(
20,
CallFrameInstruction::Expression(Register(8), Expression(vec![2, 3, 4])),
CallFrameInstruction::Expression(Register(8), expression.clone()),
),
(
22,
CallFrameInstruction::ValExpression(Register(9), Expression(vec![3, 4, 5])),
CallFrameInstruction::ValExpression(Register(9), expression.clone()),
),
(24 + 0x80, CallFrameInstruction::RememberState),
(26 + 0x280, CallFrameInstruction::RestoreState),
Expand Down
6 changes: 3 additions & 3 deletions src/write/dwarf.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -87,17 +87,17 @@ impl DwarfUnit {
let abbrev_offset = sections.debug_abbrev.offset();
let mut abbrevs = AbbreviationTable::default();

let mut debug_info_refs = Vec::new();
self.unit.write(
sections,
abbrev_offset,
&mut abbrevs,
&line_strings,
&strings,
&mut debug_info_refs,
)?;
// None should exist because we didn't give out any UnitId.
assert!(debug_info_refs.is_empty());
assert!(sections.debug_info_refs.is_empty());
assert!(sections.debug_loc_refs.is_empty());
assert!(sections.debug_loclists_refs.is_empty());

abbrevs.write(&mut sections.debug_abbrev)?;
Ok(())
Expand Down
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