[llvm] [BranchRelaxation] Remove quadratic behavior in relaxation pass (PR #96250)

[Mingming Liu via llvm-commits]

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@@ -384,11 +391,17 @@ bool BranchRelaxation::fixupConditionalBranch(MachineInstr &MI) {
 
   auto finalizeBlockChanges = [&](MachineBasicBlock *MBB,
                                   MachineBasicBlock *NewBB) {
-    // Keep the block offsets up to date.
-    adjustBlockOffsets(*MBB);
+    if (NewBB == nullptr)
+      return;
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minglotus-6 wrote:

nit: now `MBB` is not used and `finalizeBlockChanges` processes block changes around `NewBB` (including its prev and next). Remove unused `MBB` parameter and optionally rename `finalizeBlockChanges` to something like `finalizeBlockChangesForNewBB` to make code around the call-site clearer.

https://github.com/llvm/llvm-project/pull/96250