[TailDuplicator] Determine if computed gotos using blockaddress (#132536)

Using `blockaddress` should be more reliable than determining if an
operand comes from a jump table index.

Alternative: Add the `MachineInstr::MIFlag::ComputedGoto` flag when
lowering `indirectbr`. But I don't think this approach is suitable to
backport.

Author: dianqk

llvm/include/llvm/CodeGen/MachineBasicBlock.h

@@ -313,6 +313,15 @@ class MachineBasicBlock
   const MachineFunction *getParent() const { return xParent; }
   MachineFunction *getParent() { return xParent; }
 
+  /// Returns true if the original IR terminator is an `indirectbr`. This
+  /// typically corresponds to a `goto` in C, rather than jump tables.
+  bool terminatorIsComputedGoto() const {
+    return back().isIndirectBranch() &&
+           llvm::all_of(successors(), [](const MachineBasicBlock *Succ) {
+             return Succ->isIRBlockAddressTaken();
+           });
+  }
+
   using instr_iterator = Instructions::iterator;
   using const_instr_iterator = Instructions::const_iterator;
   using reverse_instr_iterator = Instructions::reverse_iterator;

llvm/include/llvm/CodeGen/MachineInstr.h

@@ -994,17 +994,8 @@ class MachineInstr
 
   /// Return true if this is an indirect branch, such as a
   /// branch through a register.
-  bool isIndirectBranch(QueryType Type = AnyInBundle,
-                        bool IncludeJumpTable = true) const {
-    return hasProperty(MCID::IndirectBranch, Type) &&
-           (IncludeJumpTable || !llvm::any_of(operands(), [](const auto &Op) {
-              return Op.isJTI();
-            }));
-  }
-
-  bool isComputedGoto(QueryType Type = AnyInBundle) const {
-    // Jump tables are not considered computed gotos.
-    return isIndirectBranch(Type, /*IncludeJumpTable=*/false);
+  bool isIndirectBranch(QueryType Type = AnyInBundle) const {
+    return hasProperty(MCID::IndirectBranch, Type);
   }
 
   /// Return true if this is a branch which may fall
@@ -2088,6 +2079,9 @@ class MachineInstr
                     MCSymbol *PreInstrSymbol, MCSymbol *PostInstrSymbol,
                     MDNode *HeapAllocMarker, MDNode *PCSections,
                     uint32_t CFIType, MDNode *MMRAs);
+
+  /// Returns true if all successors are IRBlockAddressTaken.
+  bool jumpToIRBlockAddressTaken() const;
 };
 
 /// Special DenseMapInfo traits to compare MachineInstr* by *value* of the

llvm/lib/CodeGen/TailDuplicator.cpp

@@ -604,7 +604,7 @@ bool TailDuplicator::shouldTailDuplicate(bool IsSimple,
   bool HasComputedGoto = false;
   if (!TailBB.empty()) {
     HasIndirectbr = TailBB.back().isIndirectBranch();
-    HasComputedGoto = TailBB.back().isComputedGoto();
+    HasComputedGoto = TailBB.terminatorIsComputedGoto();
   }
 
   if (HasIndirectbr && PreRegAlloc)