[llvm] [AMDGPU] Remove blocks that only branch to other blocks (PR #184908)

[via llvm-commits]

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@@ -763,6 +765,72 @@ MachineInstrBuilder SIPreEmitPeephole::createUnpackedMI(MachineInstr &I,
   return NewMI;
 }
 
+// Remove blocks that only have an unconditional branch.
+bool SIPreEmitPeephole::removeUnconditionalBranchBlocks(MachineFunction &MF) {
+  SIMachineFunctionInfo *FuncInfo = MF.getInfo<SIMachineFunctionInfo>();
+  SmallVector<MachineBasicBlock *, 2> ToRemoveMBB;
+  bool Changed = false;
+
+  for (MachineBasicBlock &MBB : MF) {
+    MachineBasicBlock *Succ = *MBB.succ_begin();
+    // Cannot remove entry block
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LU-JOHN wrote:

This would require blocks to be re-ordered.  

https://github.com/llvm/llvm-project/pull/184908