Add a flag to indicate that an instruction is as cheap (or cheaper) than a move

instruction to execute. This can be used for transformations (like two-address
conversion) to remat an instruction instead of generating a "move"
instruction. The idea is to decrease the live ranges and register pressure and
all that jazz.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51660 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 19 insertions, 14 deletions

diff --git a/utils/TableGen/CodeGenInstruction.cpp b/utils/TableGen/CodeGenInstruction.cpp
index 53daf9d944..37c2069ec7 100644
--- a/utils/TableGen/CodeGenInstruction.cpp
+++ b/utils/TableGen/CodeGenInstruction.cpp
@@ -99,6 +99,7 @@ CodeGenInstruction::CodeGenInstruction(Record *R, const std::string &AsmStr)
   hasSideEffects = R->getValueAsBit("hasSideEffects");
   mayHaveSideEffects = R->getValueAsBit("mayHaveSideEffects");
   neverHasSideEffects = R->getValueAsBit("neverHasSideEffects");
+  isAsCheapAsAMove = R->getValueAsBit("isAsCheapAsAMove");
   hasOptionalDef = false;
   isVariadic = false;
 
diff --git a/utils/TableGen/CodeGenInstruction.h b/utils/TableGen/CodeGenInstruction.h
index 9bfd4323f9..0727e38c53 100644
--- a/utils/TableGen/CodeGenInstruction.h
+++ b/utils/TableGen/CodeGenInstruction.h
@@ -102,7 +102,10 @@ namespace llvm {
     bool hasCtrlDep;
     bool isNotDuplicable;
     bool hasOptionalDef;
-    bool hasSideEffects, mayHaveSideEffects, neverHasSideEffects;
+    bool hasSideEffects;
+    bool mayHaveSideEffects;
+    bool neverHasSideEffects;
+    bool isAsCheapAsAMove;
     
     /// ParseOperandName - Parse an operand name like "$foo" or "$foo.bar",
     /// where $foo is a whole operand and $foo.bar refers to a suboperand.
diff --git a/utils/TableGen/InstrInfoEmitter.cpp b/utils/TableGen/InstrInfoEmitter.cpp
index 57d72b436e..028fbeb88b 100644
--- a/utils/TableGen/InstrInfoEmitter.cpp
+++ b/utils/TableGen/InstrInfoEmitter.cpp
@@ -208,26 +208,27 @@ void InstrInfoEmitter::emitRecord(const CodeGenInstruction &Inst, unsigned Num,
      << ",\t\"" << Inst.TheDef->getName() << "\", 0";
 
   // Emit all of the target indepedent flags...
-  if (Inst.isReturn)     OS << "|(1<<TID::Return)";
-  if (Inst.isBranch)     OS << "|(1<<TID::Branch)";
-  if (Inst.isIndirectBranch) OS << "|(1<<TID::IndirectBranch)";
-  if (Inst.isBarrier)    OS << "|(1<<TID::Barrier)";
-  if (Inst.hasDelaySlot) OS << "|(1<<TID::DelaySlot)";
-  if (Inst.isCall)       OS << "|(1<<TID::Call)";
-  if (Inst.isSimpleLoad) OS << "|(1<<TID::SimpleLoad)";
-  if (Inst.mayLoad)      OS << "|(1<<TID::MayLoad)";
-  if (Inst.mayStore)     OS << "|(1<<TID::MayStore)";
-  if (Inst.isPredicable) OS << "|(1<<TID::Predicable)";
+  if (Inst.isReturn)           OS << "|(1<<TID::Return)";
+  if (Inst.isBranch)           OS << "|(1<<TID::Branch)";
+  if (Inst.isIndirectBranch)   OS << "|(1<<TID::IndirectBranch)";
+  if (Inst.isBarrier)          OS << "|(1<<TID::Barrier)";
+  if (Inst.hasDelaySlot)       OS << "|(1<<TID::DelaySlot)";
+  if (Inst.isCall)             OS << "|(1<<TID::Call)";
+  if (Inst.isSimpleLoad)       OS << "|(1<<TID::SimpleLoad)";
+  if (Inst.mayLoad)            OS << "|(1<<TID::MayLoad)";
+  if (Inst.mayStore)           OS << "|(1<<TID::MayStore)";
+  if (Inst.isPredicable)       OS << "|(1<<TID::Predicable)";
   if (Inst.isConvertibleToThreeAddress) OS << "|(1<<TID::ConvertibleTo3Addr)";
-  if (Inst.isCommutable) OS << "|(1<<TID::Commutable)";
-  if (Inst.isTerminator) OS << "|(1<<TID::Terminator)";
+  if (Inst.isCommutable)       OS << "|(1<<TID::Commutable)";
+  if (Inst.isTerminator)       OS << "|(1<<TID::Terminator)";
   if (Inst.isReMaterializable) OS << "|(1<<TID::Rematerializable)";
   if (Inst.isNotDuplicable)    OS << "|(1<<TID::NotDuplicable)";
   if (Inst.hasOptionalDef)     OS << "|(1<<TID::HasOptionalDef)";
   if (Inst.usesCustomDAGSchedInserter)
     OS << "|(1<<TID::UsesCustomDAGSchedInserter)";
   if (Inst.isVariadic)         OS << "|(1<<TID::Variadic)";
-  if (Inst.hasSideEffects)          OS << "|(1<<TID::UnmodeledSideEffects)";
+  if (Inst.hasSideEffects)     OS << "|(1<<TID::UnmodeledSideEffects)";
+  if (Inst.isAsCheapAsAMove)   OS << "|(1<<TID::CheapAsAMove)";
   OS << ", 0";
 
   // Emit all of the target-specific flags...