Add constant check (maybe broken) and also a globals pass

pythonbpf/constants_pass.py

@@ -0,0 +1,46 @@
+from llvmlite import ir
+import ast
+
+def emit_constants(module: ir.Module, constant_str: str, name: str):
+    constant_bytes = constant_str.encode("utf8") + b"\x00"
+    elems = [ir.Constant(ir.IntType(8), b) for b in constant_bytes]
+    ty = ir.ArrayType(ir.IntType(8), len(elems))
+
+    gvar = ir.GlobalVariable(module, ty, name=name)
+
+    gvar.initializer = ir.Constant(ty, elems)  # type: ignore
+
+    gvar.align = 1                      # type: ignore
+    gvar.linkage = "internal"           # type: ignore
+    gvar.global_constant = True
+
+    return gvar
+
+def constants_processing(tree, module):
+    """Process string constants in the given AST tree and emit them to rodata"""
+    constant_count = 0
+    current_function = None
+
+    class ConstantVisitor(ast.NodeVisitor):
+        def visit_FunctionDef(self, node):
+            nonlocal current_function
+            old_function = current_function
+            current_function = node.name
+            self.generic_visit(node)
+            current_function = old_function
+
+        def visit_Constant(self, node):
+            nonlocal constant_count
+            if isinstance(node.value, str) and current_function is not None:
+                if constant_count == 0:
+                    constant_name = f"{current_function}.____fmt"
+                else:
+                    constant_name = f"{current_function}.____fmt.{constant_count}"
+                emit_constants(module, node.value, constant_name)
+                constant_count += 1
+            self.generic_visit(node)
+
+    visitor = ConstantVisitor()
+    visitor.visit(tree)
+
+    return constant_count