[compiler-rt] [compiler-rt] Fix frame numbering for unparsable frames. (PR #148278)

[David Justo via llvm-commits]

================
@@ -507,20 +507,29 @@ def symbolize_address(self, addr, binary, offset, arch):
         assert result
         return result
 
-    def get_symbolized_lines(self, symbolized_lines, inc_frame_counter=True):
+    def get_symbolized_lines(self, symbolized_lines):
         if not symbolized_lines:
-            if inc_frame_counter:
-                self.frame_no += 1
-            return [self.current_line]
-        else:
-            assert inc_frame_counter
-            result = []
-            for symbolized_frame in symbolized_lines:
-                result.append(
-                    "    #%s %s" % (str(self.frame_no), symbolized_frame.rstrip())
+            # If it is an unparsable frame, but contains a frame counter and address
+            # replace the frame counter so the stack is still consistent.
+            unknown_stack_frame_format = r"^( *#([0-9]+) +)(0x[0-9a-f]+) +.*"
+            match = re.match(unknown_stack_frame_format, self.current_line)
+            if match:
+                rewritten_line = (
+                    self.current_line[: match.start(2)]
+                    + str(self.frame_no)
+                    + self.current_line[match.end(2) :]
----------------
davidmrdavid wrote:

dismissible nit, I would recommend introducing a variable for `match.start(2)`, to help with readability. The expression is already a bit complex, _in my opinion_.

```python
           if match:
                # update the frame counter
                frame_no_index = match.start(2)
                rewritten_line= (
                    self.current_line[: frame_no_index ]
                    + str(self.frame_no)
                    + self.current_line[frame_no_index  :]
```

https://github.com/llvm/llvm-project/pull/148278