[llvm] [SelectionDAG] add cli option to write SelectionDAG graphviz to file (PR #161979)

[Matt Arsenault via llvm-commits]

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@@ -175,16 +175,21 @@ static cl::opt<bool>
 ViewISelDAGs("view-isel-dags", cl::Hidden,
           cl::desc("Pop up a window to show isel dags as they are selected"));
 static cl::opt<bool>
-ViewSchedDAGs("view-sched-dags", cl::Hidden,
-          cl::desc("Pop up a window to show sched dags as they are processed"));
+    WriteDAGsToFile("write-dags-to-file", cl::Hidden,
+                    cl::desc("Write dags as they are selected to DOT files "
+                             "instead of opening viewer"));
+static cl::opt<bool> ViewSchedDAGs(
+    "view-sched-dags", cl::Hidden,
+    cl::desc("Pop up a window to show sched dags as they are processed"));
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arsenm wrote:

Yes, something like that. It doesn't really matter if the existing flags are changed 

https://github.com/llvm/llvm-project/pull/161979