ARTIQException: tell linecache where to look for runtime sources.

Runtime sources can appear in the backtrace when
artiq_raise_from_c is used.

artiq/coredevice/runtime.py

@@ -0,0 +1,13 @@
+import os
+
+class SourceLoader:
+    def __init__(self, runtime_root):
+        self.runtime_root = runtime_root
+
+    def get_source(self, filename):
+        print(os.path.join(self.runtime_root, filename))
+        with open(os.path.join(self.runtime_root, filename)) as f:
+            return f.read()
+
+artiq_root = os.path.join(os.path.dirname(__file__), "..", "..")
+source_loader = SourceLoader(os.path.join(artiq_root, "soc", "runtime"))

artiq/language/core.py

@@ -6,6 +6,8 @@ import linecache, re
 from collections import namedtuple
 from functools import wraps
 
+# for runtime files in backtraces
+from artiq.coredevice.runtime import source_loader
 
 
 __all__ = ["int64", "round64",
@@ -312,7 +314,8 @@ class ARTIQException(Exception):
 
         lines.append("Core Device Traceback (most recent call last):")
         for (filename, line, column, function, address) in self.traceback:
-            source_line = linecache.getline(filename, line)
+            stub_globals = {"__name__": filename, "__loader__": source_loader}
+            source_line = linecache.getline(filename, line, stub_globals)
             indentation = re.search(r"^\s*", source_line).end()
 
             if address is None:

soc/runtime/artiq_personality.h

@@ -40,7 +40,8 @@ void __artiq_reraise(void)
             .param = { exnparam0, exnparam1, exnparam2 }, \
             .file = __FILE__, \
             .line = __LINE__, \
-            .column = 0 \
+            .column = -1, \
+            .function = __func__, \
           }; \
           __artiq_raise(&exn); \
         } while(0)