[opt-viewer] Don't except when debug info is not available.

For records without DebugLoc we simply skip the caller location in
map_remarks.

Fixes PR33764.

Patch by Simon Whittaker!

llvm-svn: 307880

llvm/tools/opt-viewer/opt-viewer.py

@@ -178,7 +178,10 @@ def map_remarks(all_remarks):
             for arg in remark.Args:
                 caller = arg.get('Caller')
                 if caller:
-                    context.caller_loc[caller] = arg['DebugLoc']
+                    try:
+                        context.caller_loc[caller] = arg['DebugLoc']
+                    except KeyError:
+                        pass
 
 
 def generate_report(all_remarks,