[PATCH] Add new debug kind LocTrackingOnly.

[David Blaikie]

================
Comment at: lib/CodeGen/CGDebugInfo.cpp:378
@@ -377,2 +377,3 @@
       CGM.getCodeGenOpts().DwarfDebugFlags, RuntimeVers, SplitDwarfFilename,
-      DebugKind == CodeGenOptions::DebugLineTablesOnly
+      (DebugKind == CodeGenOptions::DebugLineTablesOnly ||
+       DebugKind == CodeGenOptions::LocTrackingOnly)
----------------
I'd use <= here, though it doesn't really matter since this metadata should never end up being read/used in the LocTrackingOnly situation.

================
Comment at: lib/Frontend/CompilerInvocation.cpp:571
@@ +570,3 @@
+      Opts.setDebugInfo(CodeGenOptions::LocTrackingOnly);
+      Opts.DebugColumnInfo = true;
+    }
----------------
You only want to track column info if the user didn't request debug info? That seems like a strange limitation - the diagnostic quality will improve/change in non-debug builds?

================
Comment at: test/Frontend/optimization-remark.c:11
@@ +10,3 @@
+// -Rpass should produce source location annotations.
+// CHECK: , !dbg !
+//
----------------
You should be able to test for the absence of any type information, for example (at a guess: CHECK-NOT: DW_TAG_basic_type) now that you've changed those couple of == GMLT to <= GMLT. If you undo those changes, add the CHECK-NOT I mentioned, verify the test fails, then reapply the changes, that'd be great.

http://reviews.llvm.org/D4235