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feat: allocate tmp variable for pointer to vmlinux struct field access.

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varun-r-mallya
2025-11-27 14:02:00 +05:30
parent d43d3ad637
commit a8595ff1d2
3 changed files with 48 additions and 16 deletions
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20
pythonbpf/allocation_pass.py
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@ -384,6 +384,7 @@ def _allocate_for_attribute(builder, var_name, rval, local_sym_tab, structs_sym_
f"Could not determine size for ctypes field {field_name}: {e}"
)
actual_ir_type = ir.IntType(64)
field_size_bits = 64
# Check if it's a nested vmlinux struct or complex type
elif field.type.__module__ == "vmlinux":
@ -392,23 +393,34 @@ def _allocate_for_attribute(builder, var_name, rval, local_sym_tab, structs_sym_
field.ctype_complex_type, ctypes._Pointer
):
actual_ir_type = ir.IntType(64) # Pointer is always 64-bit
field_size_bits = 64
# For embedded structs, this is more complex - might need different handling
else:
logger.warning(
f"Field {field_name} is a nested vmlinux struct, using i64 for now"
)
actual_ir_type = ir.IntType(64)
field_size_bits = 64
else:
logger.warning(
f"Unknown field type module {field.type.__module__} for {field_name}"
)
actual_ir_type = ir.IntType(64)
field_size_bits = 64
# Allocate with the actual IR type
# Pre-allocate the tmp storage used by load_struct_field (so we don't alloca inside handler)
tmp_name = f"{struct_var}_{field_name}_tmp"
tmp_ir_type = ir.IntType(field_size_bits)
tmp_var = builder.alloca(tmp_ir_type, name=tmp_name)
tmp_var.align = tmp_ir_type.width // 8
local_sym_tab[tmp_name] = LocalSymbol(tmp_var, tmp_ir_type)
logger.info(
f"Pre-allocated temp {tmp_name} (i{field_size_bits}) for vmlinux field read {vmlinux_struct_name}.{field_name}"
)
# Allocate with the actual IR type for the destination var
var = _allocate_with_type(builder, var_name, actual_ir_type)
local_sym_tab[var_name] = LocalSymbol(
var, actual_ir_type, field
) # <-- Store Field metadata
local_sym_tab[var_name] = LocalSymbol(var, actual_ir_type, field)
logger.info(
f"Pre-allocated {var_name} as {actual_ir_type} from vmlinux struct {vmlinux_struct_name}.{field_name}"