[NFC][AsmPrinter] Pass MJTI by const reference instead of const pointer (#122365)

The caller `AsmPrinter::emitJumpTableInfo` checks [1] `MJTI` is not a
null pointer before calling `emitJumpTableEntry` or
`emitJumpTableSizesSection`.

This patch updates callee function's signature to accept const
reference, this way it's explicit `MJTI` won't be nullptr inside the
callee.

[1]
https://github.com/llvm/llvm-project/blob/9d5299eb61a64cd4df5fefa0299b0cf8d917978f/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp#L2857

Author: mingmingl-llvm

llvm/include/llvm/CodeGen/AsmPrinter.h

@@ -892,10 +892,10 @@ class AsmPrinter : public MachineFunctionPass {
   // Internal Implementation Details
   //===------------------------------------------------------------------===//
 
-  void emitJumpTableEntry(const MachineJumpTableInfo *MJTI,
+  void emitJumpTableEntry(const MachineJumpTableInfo &MJTI,
                           const MachineBasicBlock *MBB, unsigned uid) const;
 
-  void emitJumpTableSizesSection(const MachineJumpTableInfo *MJTI,
+  void emitJumpTableSizesSection(const MachineJumpTableInfo &MJTI,
                                  const Function &F) const;
 
   void emitLLVMUsedList(const ConstantArray *InitList);

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -2922,19 +2922,19 @@ void AsmPrinter::emitJumpTableInfo() {
     // Defer MCAssembler based constant folding due to a performance issue. The
     // label differences will be evaluated at write time.
     for (const MachineBasicBlock *MBB : JTBBs)
-      emitJumpTableEntry(MJTI, MBB, JTI);
+      emitJumpTableEntry(*MJTI, MBB, JTI);
   }
 
   if (EmitJumpTableSizesSection)
-    emitJumpTableSizesSection(MJTI, F);
+    emitJumpTableSizesSection(*MJTI, F);
 
   if (!JTInDiffSection)
     OutStreamer->emitDataRegion(MCDR_DataRegionEnd);
 }
 
-void AsmPrinter::emitJumpTableSizesSection(const MachineJumpTableInfo *MJTI,
+void AsmPrinter::emitJumpTableSizesSection(const MachineJumpTableInfo &MJTI,
                                            const Function &F) const {
-  const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
+  const std::vector<MachineJumpTableEntry> &JT = MJTI.getJumpTables();
 
   if (JT.empty())
     return;
@@ -2982,17 +2982,17 @@ void AsmPrinter::emitJumpTableSizesSection(const MachineJumpTableInfo *MJTI,
 
 /// EmitJumpTableEntry - Emit a jump table entry for the specified MBB to the
 /// current stream.
-void AsmPrinter::emitJumpTableEntry(const MachineJumpTableInfo *MJTI,
+void AsmPrinter::emitJumpTableEntry(const MachineJumpTableInfo &MJTI,
                                     const MachineBasicBlock *MBB,
                                     unsigned UID) const {
   assert(MBB && MBB->getNumber() >= 0 && "Invalid basic block");
   const MCExpr *Value = nullptr;
-  switch (MJTI->getEntryKind()) {
+  switch (MJTI.getEntryKind()) {
   case MachineJumpTableInfo::EK_Inline:
     llvm_unreachable("Cannot emit EK_Inline jump table entry");
   case MachineJumpTableInfo::EK_Custom32:
     Value = MF->getSubtarget().getTargetLowering()->LowerCustomJumpTableEntry(
-        MJTI, MBB, UID, OutContext);
+        &MJTI, MBB, UID, OutContext);
     break;
   case MachineJumpTableInfo::EK_BlockAddress:
     // EK_BlockAddress - Each entry is a plain address of block, e.g.:
@@ -3026,7 +3026,7 @@ void AsmPrinter::emitJumpTableEntry(const MachineJumpTableInfo *MJTI,
     // If the .set directive avoids relocations, this is emitted as:
     //      .set L4_5_set_123, LBB123 - LJTI1_2
     //      .word L4_5_set_123
-    if (MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32 &&
+    if (MJTI.getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32 &&
         MAI->doesSetDirectiveSuppressReloc()) {
       Value = MCSymbolRefExpr::create(GetJTSetSymbol(UID, MBB->getNumber()),
                                       OutContext);
@@ -3042,7 +3042,7 @@ void AsmPrinter::emitJumpTableEntry(const MachineJumpTableInfo *MJTI,
 
   assert(Value && "Unknown entry kind!");
 
-  unsigned EntrySize = MJTI->getEntrySize(getDataLayout());
+  unsigned EntrySize = MJTI.getEntrySize(getDataLayout());
   OutStreamer->emitValue(Value, EntrySize);
 }