[llvm] [SandboxIR] Add more Instruction member functions (PR #98588)

[via llvm-commits]

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@@ -262,6 +262,113 @@ const char *Instruction::getOpcodeName(Opcode Opc) {
   llvm_unreachable("Unknown Opcode");
 }
 
+llvm::Instruction *Instruction::getTopmostLLVMInstruction() const {
+  Instruction *Prev = getPrevNode();
+  if (Prev == nullptr) {
+    // If at top of the BB, return the first BB instruction.
+    return &*cast<llvm::BasicBlock>(getParent()->Val)->begin();
+  }
+  // Else get the Previous sandbox IR instruction's bottom IR instruction and
+  // return its successor.
+  llvm::Instruction *PrevBotI = cast<llvm::Instruction>(Prev->Val);
+  return PrevBotI->getNextNode();
+}
+
+BBIterator Instruction::getIterator() const {
+  auto *I = cast<llvm::Instruction>(Val);
+  return BasicBlock::iterator(I->getParent(), I->getIterator(), &Ctx);
+}
+
+Instruction *Instruction::getNextNode() const {
+  assert(getParent() != nullptr && "Detached!");
+  assert(getIterator() != getParent()->end() && "Already at end!");
+  auto *LLVMI = cast<llvm::Instruction>(Val);
+  assert(LLVMI->getParent() != nullptr && "LLVM IR instr is detached!");
+  auto *NextLLVMI = LLVMI->getNextNode();
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vporpo wrote:

So here is how this works: `NextLLVMI` is an LLVM instruction that belongs to the next SandboxIR instruction, whether it's a single-Instruction or multi-Instruction. If it's a multi-Instruction, then `NextLLVMI` will be the topmost LLVM instruction. In either case `Ctxt.getValue(NextLLVMI)` returns the correct SandboxIR Instruction that maps to `NextLLVMI`. Does this make sense?

https://github.com/llvm/llvm-project/pull/98588