CodeGen: Use a single SlotTracker in MachineFunction::print()

Expose enough of the IR-level `SlotTracker` so that
`MachineFunction::print()` can use a single one for printing
`BasicBlock`s.  Next step would be to lift this through a few more APIs
so that we can make other print methods faster.

Fixes PR23865, changing the runtime of `llc -print-machineinstrs` from
many minutes (killed after 3 minutes, but it wasn't very close) to
13 seconds for a 502185 line dump.

llvm-svn: 240842

1 files changed, 4 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/MachineFunction.cpp b/llvm/lib/CodeGen/MachineFunction.cpp
index 960e06a..800d1b5 100644
--- a/llvm/lib/CodeGen/MachineFunction.cpp
+++ b/llvm/lib/CodeGen/MachineFunction.cpp
@@ -29,6 +29,7 @@
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/DebugInfo.h"
 #include "llvm/IR/Function.h"
+#include "llvm/IR/ModuleSlotTracker.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/Support/Debug.h"
@@ -361,9 +362,11 @@ void MachineFunction::print(raw_ostream &OS, SlotIndexes *Indexes) const {
     OS << '\n';
   }
 
+  ModuleSlotTracker MST(getFunction()->getParent());
+  MST.incorporateFunction(*getFunction());
   for (const auto &BB : *this) {
     OS << '\n';
-    BB.print(OS, Indexes);
+    BB.print(OS, MST, Indexes);
   }
 
   OS << "\n# End machine code for function " << getName() << ".\n\n";