bpf passthrough gen in codegen

Signed-off-by: varun-r-mallya <varunrmallya@gmail.com>

Author: varun-r-mallya

pythonbpf/codegen.py

@@ -36,6 +36,23 @@ def finalize_module(original_str):
     replacement = r'\1 "btf_ama"'
     return re.sub(pattern, replacement, original_str)
 
+def bpf_passthrough_gen(module):
+    i32_ty = ir.IntType(32)
+    ptr_ty = ir.PointerType(ir.IntType(8))
+    fnty = ir.FunctionType(ptr_ty, [i32_ty, ptr_ty])
+
+    # Declare the intrinsic
+    passthrough = ir.Function(module, fnty, "llvm.bpf.passthrough.p0.p0")
+
+    # Set function attributes
+    # TODO: the ones commented are supposed to be there but cannot be added due to llvmlite limitations at the moment
+    # passthrough.attributes.add("nofree")
+    # passthrough.attributes.add("nosync")
+    passthrough.attributes.add("nounwind")
+    # passthrough.attributes.add("memory(none)")
+
+    return passthrough
+
 
 def find_bpf_chunks(tree):
     """Find all functions decorated with @bpf in the AST."""
@@ -57,6 +74,8 @@ def processor(source_code, filename, module):
     for func_node in bpf_chunks:
         logger.info(f"Found BPF function/struct: {func_node.name}")
 
+    bpf_passthrough_gen(module)
+
     vmlinux_symtab = vmlinux_proc(tree, module)
     if vmlinux_symtab:
         handler = VmlinuxHandler.initialize(vmlinux_symtab)

pythonbpf/vmlinux_parser/import_detector.py

@@ -77,28 +77,9 @@ def detect_import_statement(tree: ast.AST) -> list[tuple[str, ast.ImportFrom]]:
     return vmlinux_imports
 
 
-def bpf_passthrough_gen(module):
-    i32_ty = ir.IntType(32)
-    ptr_ty = ir.PointerType(ir.IntType(8))
-    fnty = ir.FunctionType(ptr_ty, [i32_ty, ptr_ty])
-
-    # Declare the intrinsic
-    passthrough = ir.Function(module, fnty, "llvm.bpf.passthrough.p0.p0")
-
-    # Set function attributes
-    # TODO: the ones commented are supposed to be there but cannot be added due to llvmlite limitations at the moment
-    # passthrough.attributes.add("nofree")
-    # passthrough.attributes.add("nosync")
-    passthrough.attributes.add("nounwind")
-    # passthrough.attributes.add("memory(none)")
-
-    return passthrough
-
-
 def vmlinux_proc(tree: ast.AST, module):
     import_statements = detect_import_statement(tree)
 
-    bpf_passthrough_gen(module)
     # initialise dependency handler
     handler = DependencyHandler()
     # initialise assignment dictionary of name to type