Add support for the convergent flag at the MC and MachineInstr levels.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238450 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/MachineInstr.h

@@ -483,6 +483,13 @@ public:
     return hasProperty(MCID::NotDuplicable, Type);
   }
 
+  /// Return true if this instruction is convergent.
+  /// Convergent instructions can only be moved to locations that are
+  /// control-equivalent to their initial position.
+  bool isConvergent(QueryType Type = AnyInBundle) const {
+    return hasProperty(MCID::Convergent, Type);
+  }
+
   /// Returns true if the specified instruction has a delay slot
   /// which must be filled by the code generator.
   bool hasDelaySlot(QueryType Type = AnyInBundle) const {

include/llvm/MC/MCInstrDesc.h

@@ -125,7 +125,8 @@ enum Flag {
   ExtraDefRegAllocReq,
   RegSequence,
   ExtractSubreg,
-  InsertSubreg
+  InsertSubreg,
+  Convergent
 };
 }
 
@@ -331,6 +332,13 @@ public:
   /// override accordingly.
   bool isInsertSubregLike() const { return Flags & (1 << MCID::InsertSubreg); }
 
+
+  /// \brief Return true if this instruction is convergent.
+  ///
+  /// Convergent instructions may only be moved to locations that are
+  /// control-equivalent to their original positions.
+  bool isConvergent() const { return Flags & (1 << MCID::Convergent); }
+
   //===--------------------------------------------------------------------===//
   // Side Effect Analysis
   //===--------------------------------------------------------------------===//

include/llvm/Target/Target.td

@@ -381,6 +381,7 @@ class Instruction {
   bit hasPostISelHook = 0;  // To be *adjusted* after isel by target hook.
   bit hasCtrlDep   = 0;     // Does this instruction r/w ctrl-flow chains?
   bit isNotDuplicable = 0;  // Is it unsafe to duplicate this instruction?
+  bit isConvergent = 0;     // Is this instruction convergent?
   bit isAsCheapAsAMove = 0; // As cheap (or cheaper) than a move instruction.
   bit hasExtraSrcRegAllocReq = 0; // Sources have special regalloc requirement?
   bit hasExtraDefRegAllocReq = 0; // Defs have special regalloc requirement?