[llvm] [GlobalISel] Dump the machine function after each legalization iteration. NFC (PR #83401)

[Matt Arsenault via llvm-commits]

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@@ -223,6 +223,7 @@ Legalizer::legalizeMachineFunction(MachineFunction &MF, const LegalizerInfo &LI,
   SmallVector<MachineInstr *, 128> RetryList;
   do {
     LLVM_DEBUG(dbgs() << "=== New Iteration ===\n");
+    LLVM_DEBUG(MF.dump());
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arsenm wrote:

Worried this will be excessive printing when debugging anything other than the most trivial of cases 

https://github.com/llvm/llvm-project/pull/83401