Revert "[TailDuplicator] Do not restrict the computed gotos (#114990)"

This reverts commit dd21aac.

Author: alexfh

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

llvm/lib/CodeGen/TailDuplicator.cpp

@@ -601,11 +601,8 @@ bool TailDuplicator::shouldTailDuplicate(bool IsSimple,
   // that rearrange the predecessors of the indirect branch.
 
   bool HasIndirectbr = false;
-  bool HasComputedGoto = false;
-  if (!TailBB.empty()) {
+  if (!TailBB.empty())
     HasIndirectbr = TailBB.back().isIndirectBranch();
-    HasComputedGoto = TailBB.back().isComputedGoto();
-  }
 
   if (HasIndirectbr && PreRegAlloc)
     MaxDuplicateCount = TailDupIndirectBranchSize;
@@ -663,12 +660,7 @@ bool TailDuplicator::shouldTailDuplicate(bool IsSimple,
   // Duplicating a BB which has both multiple predecessors and successors will
   // may cause huge amount of PHI nodes. If we want to remove this limitation,
   // we have to address https://github.com/llvm/llvm-project/issues/78578.
-  // NB. This basically unfactors computed gotos that were factored early on in
-  // the compilation process to speed up edge based data flow. If we do not
-  // unfactor them again, it can seriously pessimize code with many computed
-  // jumps in the source code, such as interpreters. Therefore we do not
-  // restrict the computed gotos.
-  if (!HasComputedGoto && TailBB.pred_size() > TailDupPredSize &&
+  if (TailBB.pred_size() > TailDupPredSize &&
       TailBB.succ_size() > TailDupSuccSize) {
     // If TailBB or any of its successors contains a phi, we may have to add a
     // large number of additional phis with additional incoming values.