[llvm] [RISCV] Emit lpad for function with returns-twice attribute (PR #170520)

[Craig Topper via llvm-commits]

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@@ -100,5 +110,21 @@ bool RISCVIndirectBranchTracking::runOnMachineFunction(MachineFunction &MF) {
     }
   }
 
+  // Check for calls to functions with ReturnsTwice attribute and insert
+  // LPAD after such calls
+  for (MachineBasicBlock &MBB : MF) {
+    for (MachineBasicBlock::iterator I = MBB.begin(); I != MBB.end(); ++I) {
+      if (I->isCall() && I->getNumOperands() > 0) {
+        if (IsCallReturnTwice(I->getOperand(0))) {
+          auto NextI = std::next(I);
+          BuildMI(MBB, NextI, MBB.findDebugLoc(NextI), TII->get(RISCV::AUIPC),
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topperc wrote:

Can we use `emitLpad` here by making it take a `MachineBasicBlock::iterator` instead of a MachineBasicBlock?

https://github.com/llvm/llvm-project/pull/170520