[llvm] [CodeGen] Fix lpad padding at section start after empty block (PR #112595)

[via llvm-commits]

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@@ -383,13 +383,28 @@ void MachineFunction::RenumberBlocks(MachineBasicBlock *MBB) {
 /// and the SectionID's are assigned to MBBs.
 void MachineFunction::assignBeginEndSections() {
   front().setIsBeginSection();
+  front().setIsFirstNonEmptyBBInSection();
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WenleiHe wrote:

Is this line intentional? I thought you want to check before setting this flag (i.e. line 392). 

https://github.com/llvm/llvm-project/pull/112595