[llvm] [llvm-mca][FeatureRequest] Itimeline graph, note source of delay for each instruction (PR #136423)

[Matt Arsenault via llvm-commits]

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@@ -256,6 +265,13 @@ void TimelineView::printTimelineViewEntry(formatted_raw_ostream &OS,
 
 static void printTimelineHeader(formatted_raw_ostream &OS, unsigned Cycles) {
   OS << "\n\nTimeline view:\n";
+  OS << "D: Instruction Dispatched\n";
+  OS << "e: Instruction Executingn\n";
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arsenm wrote:

This can all be a print of one big literal instead of multiple OS << statements 

https://github.com/llvm/llvm-project/pull/136423