[EVM] Fold Or Jumpi

Author: akiramenai

llvm/lib/Target/EVM/EVMLowerJumpUnless.cpp

@@ -82,10 +82,16 @@ static void lowerJumpUnless(MachineInstr &MI, const EVMInstrInfo *TII,
 /// Returns `true` if any fold was performed.
 static bool tryFoldJumpUnless(MachineInstr &MI, const EVMInstrInfo *TII) {
   auto I = MachineBasicBlock::iterator(&MI);
-  auto *PrevMI = I == MI.getParent()->begin() ? nullptr : &*std::prev(I);
-  bool CanFold = PrevMI && (PrevMI->getOpcode() == EVM::ISZERO_S ||
-                            PrevMI->getOpcode() == EVM::EQ_S ||
-                            PrevMI->getOpcode() == EVM::SUB_S);
+  if (I == MI.getParent()->begin())
+    return false;
+  auto PrevMI = std::prev(I);
+  while (PrevMI != MI.getParent()->begin() && PrevMI->getOpcode() == EVM::OR_S)
+    PrevMI = std::prev(PrevMI);
+  if (PrevMI == MI.getParent()->begin())
+    return false;
+  bool CanFold = PrevMI->getOpcode() == EVM::ISZERO_S ||
+                 PrevMI->getOpcode() == EVM::EQ_S ||
+                 PrevMI->getOpcode() == EVM::SUB_S;
 
   if (!CanFold)
     return false;