qemu: heuristics to get Qemu related directories using debug info only

Signed-off-by: Efimov Vasily <[email protected]>

qemu/dwarf_hacks.py

@@ -0,0 +1,58 @@
+__all__ = [
+    "qemu_build_dir_by_dwarf"
+  , "qemu_target_dir_by_dwarf"
+]
+
+from os.path import (
+    abspath,
+    dirname
+)
+from six import (
+    PY3
+)
+from common import (
+    bsep
+)
+
+
+def qemu_build_dir_by_dwarf(dia):
+    # Sometimes trace-root.h is included by its absolute path:
+    # /path/to/build/directory/./trace-root.h
+    for cu in dia.di.iter_CUs():
+        for f in dia.get_CU_files(cu):
+            #           v--- because of /./
+            if len(f) > 2 and f[-1] == b"trace-root.h":
+                break
+        else:
+            continue
+        break
+    else:
+        raise RuntimeError(
+            "Nothing includes trace-root.h by absolute path"
+        )
+
+    f = bsep.join(f)
+
+    if PY3:
+        # TODO: Is DWARF file name encoding always utf-8?
+        f = f.decode("utf-8")
+
+    return dirname(abspath(f))
+
+
+def qemu_target_dir_by_dwarf(dwarf_info):
+    # There is a convention that TCG frontend (qemu target) has
+    # translate.c file in its directory.
+    # Also, there is only one TCG frontend per qemu binary.
+    for cu in dwarf_info.iter_CUs():
+        src_file = cu.get_top_DIE().attributes["DW_AT_name"].value
+        if src_file.endswith(b"translate.c"):
+            break
+    else:
+        raise RuntimeError("No compile unit for translate.c found")
+
+    if PY3:
+        # TODO: Is DWARF file name encoding always utf-8?
+        src_file = src_file.decode("utf-8")
+
+    return dirname(abspath(src_file))