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refactor: carry planned value sizes #156

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Merged
swananan merged 1 commit into from
May 5, 2026
Merged

refactor: carry planned value sizes #156

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69 changes: 13 additions & 56 deletions ghostscope-compiler/src/ebpf/dwarf_bridge.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -66,24 +66,21 @@ impl<'ctx, 'dw> EbpfContext<'ctx, 'dw> {
fn planned_value_to_llvm_value(
&mut self,
value: &ghostscope_dwarf::PlannedValue,
dwarf_type: &TypeInfo,
var_name: &str,
_pc_address: u64,
status_ptr: Option<PointerValue<'ctx>>,
) -> Result<BasicValueEnum<'ctx>> {
let pt_regs_ptr = self.get_pt_regs_parameter()?;
let result_size = MemoryAccessSize::from_size(Self::get_dwarf_type_size(dwarf_type));
match value {
ghostscope_dwarf::PlannedValue::Constant(value) => Ok(self
ghostscope_dwarf::PlannedValue::Constant { value, .. } => Ok(self
.context
.i64_type()
.const_int(*value as u64, true)
.into()),
ghostscope_dwarf::PlannedValue::RegisterValue { dwarf_reg } => {
ghostscope_dwarf::PlannedValue::RegisterValue { dwarf_reg, .. } => {
debug!("Generating register value: {dwarf_reg}");
self.load_register_value(*dwarf_reg, pt_regs_ptr)
}
ghostscope_dwarf::PlannedValue::ComputedValue { steps } => {
ghostscope_dwarf::PlannedValue::ComputedValue { steps, result_size } => {
debug!("Generating computed value: {} steps", steps.len());
let runtime_status_ptr = if self.condition_context_active {
Some(self.get_or_create_cond_error_global())
Expand All @@ -93,7 +90,7 @@ impl<'ctx, 'dw> EbpfContext<'ctx, 'dw> {
self.generate_compute_steps(
steps,
pt_regs_ptr,
Some(result_size),
Some(*result_size),
runtime_status_ptr,
None,
)
Expand All @@ -106,7 +103,7 @@ impl<'ctx, 'dw> EbpfContext<'ctx, 'dw> {
}
Ok(self.context.i64_type().const_int(value, false).into())
}
ghostscope_dwarf::PlannedValue::AddressValue { address } => {
ghostscope_dwarf::PlannedValue::AddressValue { address, .. } => {
debug!("Generating address direct value for variable: {var_name}");
let runtime_status_ptr = if self.condition_context_active {
Some(self.get_or_create_cond_error_global())
Expand Down Expand Up @@ -302,14 +299,7 @@ impl<'ctx, 'dw> EbpfContext<'ctx, 'dw> {

/// Convert DWARF type size to MemoryAccessSize
fn dwarf_type_to_memory_access_size(&self, dwarf_type: &TypeInfo) -> MemoryAccessSize {
let size = Self::get_dwarf_type_size(dwarf_type);
match size {
1 => MemoryAccessSize::U8,
2 => MemoryAccessSize::U16,
4 => MemoryAccessSize::U32,
8 => MemoryAccessSize::U64,
_ => MemoryAccessSize::U64, // Default to U64 for unknown sizes
}
MemoryAccessSize::from_size(dwarf_type.size())
}

fn is_signed_integer_type(dwarf_type: &TypeInfo) -> bool {
Expand Down Expand Up @@ -377,7 +367,12 @@ impl<'ctx, 'dw> EbpfContext<'ctx, 'dw> {
));
}

if materialization.availability != Availability::OptimizedOut {
if materialization.availability != Availability::OptimizedOut
&& matches!(
materialization.materialization,
ghostscope_dwarf::VariableMaterialization::UserMemoryRead { .. }
)
{
materialization.dwarf_type.as_ref().ok_or_else(|| {
CodeGenError::DwarfError("Expression has no DWARF type information".to_string())
})?;
Expand All @@ -394,18 +389,7 @@ impl<'ctx, 'dw> EbpfContext<'ctx, 'dw> {
) -> Result<BasicValueEnum<'ctx>> {
match &materialization.materialization {
ghostscope_dwarf::VariableMaterialization::DirectValue { value } => {
let dwarf_type = materialization.dwarf_type.as_ref().ok_or_else(|| {
CodeGenError::DwarfError(
"Expression has no DWARF type information".to_string(),
)
})?;
self.planned_value_to_llvm_value(
value,
dwarf_type,
&materialization.name,
pc_address,
status_ptr,
)
self.planned_value_to_llvm_value(value, &materialization.name, status_ptr)
}
ghostscope_dwarf::VariableMaterialization::UserMemoryRead { address } => {
let dwarf_type = materialization.dwarf_type.as_ref().ok_or_else(|| {
Expand Down Expand Up @@ -1399,33 +1383,6 @@ impl<'ctx, 'dw> EbpfContext<'ctx, 'dw> {
Ok(Some((base, VariableAccessPath::new(segments))))
}

/// Get DWARF type size in bytes
pub fn get_dwarf_type_size(dwarf_type: &TypeInfo) -> u64 {
match dwarf_type {
TypeInfo::BaseType { size, .. } => *size,
TypeInfo::PointerType { size, .. } => *size,
TypeInfo::ArrayType { total_size, .. } => total_size.unwrap_or(0),
TypeInfo::StructType { size, .. } => *size,
TypeInfo::UnionType { size, .. } => *size,
TypeInfo::EnumType { size, .. } => *size,
TypeInfo::BitfieldType {
underlying_type, ..
} => {
// Read size equals the storage type size
Self::get_dwarf_type_size(underlying_type)
}
TypeInfo::TypedefType {
underlying_type, ..
} => Self::get_dwarf_type_size(underlying_type),
TypeInfo::QualifiedType {
underlying_type, ..
} => Self::get_dwarf_type_size(underlying_type),
TypeInfo::FunctionType { .. } => 8, // Function pointer size
TypeInfo::UnknownType { .. } => 0,
TypeInfo::OptimizedOut { .. } => 0, // Optimized out has no size
}
}

/// Compute a typed pointed-to location for expressions like `ptr +/- K` where K is an element index.
/// Returns a computed location along with the pointed-to DWARF type.
/// The offset is scaled by the element size of the pointer/array target type.
Expand Down
87 changes: 75 additions & 12 deletions ghostscope-dwarf/src/semantics/variable_plan.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -83,11 +83,23 @@ pub enum PlannedAddressKind {

#[derive(Debug, Clone, PartialEq)]
pub enum PlannedValue {
Constant(i64),
RegisterValue { dwarf_reg: u16 },
ComputedValue { steps: Vec<ComputeStep> },
Constant {
value: i64,
size: MemoryAccessSize,
},
RegisterValue {
dwarf_reg: u16,
size: MemoryAccessSize,
},
ComputedValue {
steps: Vec<ComputeStep>,
result_size: MemoryAccessSize,
},
ImplicitBytes(Vec<u8>),
AddressValue { address: PlannedAddress },
AddressValue {
address: PlannedAddress,
size: MemoryAccessSize,
},
}

#[derive(Debug, Clone, PartialEq)]
Expand Down Expand Up @@ -297,7 +309,8 @@ impl VariableReadPlan {
} else {
match lowering.kind {
VariableLoweringKind::DirectValue => {
match PlannedValue::from_location(self.location.clone()) {
let size = planned_value_size(self.dwarf_type.as_ref());
match PlannedValue::from_location(self.location.clone(), size) {
Some(value) => VariableMaterialization::DirectValue { value },
None => VariableMaterialization::Unavailable {
availability: Availability::Unsupported(
Expand Down Expand Up @@ -470,22 +483,28 @@ impl VariableReadPlan {
}

impl PlannedValue {
pub fn from_location(location: VariableLocation) -> Option<Self> {
pub fn from_location(location: VariableLocation, size: MemoryAccessSize) -> Option<Self> {
match location {
VariableLocation::RegisterValue { dwarf_reg } => {
Some(Self::RegisterValue { dwarf_reg })
Some(Self::RegisterValue { dwarf_reg, size })
}
VariableLocation::ComputedValue(steps) => {
if let [ComputeStep::PushConstant(value)] = steps.as_slice() {
Some(Self::Constant(*value))
Some(Self::Constant {
value: *value,
size,
})
} else {
Some(Self::ComputedValue { steps })
Some(Self::ComputedValue {
steps,
result_size: size,
})
}
}
VariableLocation::ImplicitValue(bytes) => Some(Self::ImplicitBytes(bytes)),
VariableLocation::AbsoluteAddressValue(expr) => {
PlannedAddress::from_location(VariableLocation::AbsoluteAddressValue(expr))
.map(|address| Self::AddressValue { address })
.map(|address| Self::AddressValue { address, size })
}
VariableLocation::Address(_)
| VariableLocation::RegisterAddress { .. }
Expand Down Expand Up @@ -573,6 +592,12 @@ impl RuntimeCapabilities {
}
}

fn planned_value_size(dwarf_type: Option<&TypeInfo>) -> MemoryAccessSize {
dwarf_type
.map(|ty| MemoryAccessSize::from_size(ty.size()))
.unwrap_or(MemoryAccessSize::U64)
}

fn address_origin_for_steps(steps: &[ComputeStep]) -> AddressOrigin {
if fold_constant_steps(steps).is_some() {
return AddressOrigin::LinkTime;
Expand Down Expand Up @@ -1231,6 +1256,7 @@ mod tests {
kind: PlannedAddressKind::Constant { address: 0x2000 },
..
},
size: MemoryAccessSize::U64,
},
} => {}
VariableMaterialization::DirectValue { value } => {
Expand All @@ -1249,7 +1275,40 @@ mod tests {

match materialized.materialization {
VariableMaterialization::DirectValue {
value: PlannedValue::Constant(42),
value:
PlannedValue::Constant {
value: 42,
size: MemoryAccessSize::U64,
},
} => {}
other => panic!("unexpected materialization: {other:?}"),
}
}

#[test]
fn materialization_plan_records_direct_value_size_from_type() {
let byte_type = TypeInfo::BaseType {
name: "uint8_t".to_string(),
size: 1,
encoding: gimli::constants::DW_ATE_unsigned.0 as u16,
};
let plan = typed_read_plan(
VariableLocation::ComputedValue(vec![
ComputeStep::LoadRegister(0),
ComputeStep::PushConstant(1),
ComputeStep::Add,
]),
byte_type,
);
let materialized = plan.materialization_plan(&capabilities(false));

match materialized.materialization {
VariableMaterialization::DirectValue {
value:
PlannedValue::ComputedValue {
result_size: MemoryAccessSize::U8,
..
},
} => {}
other => panic!("unexpected materialization: {other:?}"),
}
Expand All @@ -1262,7 +1321,11 @@ mod tests {

match materialized.materialization {
VariableMaterialization::DirectValue {
value: PlannedValue::RegisterValue { dwarf_reg: 6 },
value:
PlannedValue::RegisterValue {
dwarf_reg: 6,
size: MemoryAccessSize::U64,
},
} => {}
other => panic!("unexpected materialization: {other:?}"),
}
Expand Down
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