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

[Pierre van Houtryve 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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Pierre-vh wrote:

The main downside I see is that this will be redundant with `-print-before-all`
Maybe don't print it if it's the first iteration?

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