Add Constant Hoisting Pass

Retry commit r200022 with a fix for the build bot errors. Constant expressions
have (unlike instructions) module scope use lists and therefore may have users
in different functions. The fix is to simply ignore these out-of-function uses.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200034 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 33 insertions, 10 deletions

diff --git a/include/llvm/Analysis/TargetTransformInfo.h b/include/llvm/Analysis/TargetTransformInfo.h
index a8975b7a4f..f2613e35c5 100644
--- a/include/llvm/Analysis/TargetTransformInfo.h
+++ b/include/llvm/Analysis/TargetTransformInfo.h
@@ -92,6 +92,7 @@ public:
   enum TargetCostConstants {
     TCC_Free = 0,       ///< Expected to fold away in lowering.
     TCC_Basic = 1,      ///< The cost of a typical 'add' instruction.
+    TCC_Load = 3,
     TCC_Expensive = 4   ///< The cost of a 'div' instruction on x86.
   };
 
@@ -299,6 +300,13 @@ public:
   /// immediate of the specified type.
   virtual unsigned getIntImmCost(const APInt &Imm, Type *Ty) const;
 
+  /// \brief Return the expected cost of materialization for the given integer
+  /// immediate of the specified type for a given instruction. The cost can be
+  /// zero if the immediate can be folded into the specified instruction.
+  virtual unsigned getIntImmCost(unsigned Opcode, const APInt &Imm,
+                                 Type *Ty) const;
+  virtual unsigned getIntImmCost(Intrinsic::ID IID, const APInt &Imm,
+                                 Type *Ty) const;
   /// @}
 
   /// \name Vector Target Information
diff --git a/include/llvm/CodeGen/SelectionDAG.h b/include/llvm/CodeGen/SelectionDAG.h
index 82becca315..523c81337c 100644
--- a/include/llvm/CodeGen/SelectionDAG.h
+++ b/include/llvm/CodeGen/SelectionDAG.h
@@ -401,18 +401,22 @@ public:
   //===--------------------------------------------------------------------===//
   // Node creation methods.
   //
-  SDValue getConstant(uint64_t Val, EVT VT, bool isTarget = false);
-  SDValue getConstant(const APInt &Val, EVT VT, bool isTarget = false);
-  SDValue getConstant(const ConstantInt &Val, EVT VT, bool isTarget = false);
+  SDValue getConstant(uint64_t Val, EVT VT, bool isTarget = false,
+                      bool isOpaque = false);
+  SDValue getConstant(const APInt &Val, EVT VT, bool isTarget = false,
+                      bool isOpaque = false);
+  SDValue getConstant(const ConstantInt &Val, EVT VT, bool isTarget = false,
+                      bool isOpaque = false);
   SDValue getIntPtrConstant(uint64_t Val, bool isTarget = false);
-  SDValue getTargetConstant(uint64_t Val, EVT VT) {
-    return getConstant(Val, VT, true);
+  SDValue getTargetConstant(uint64_t Val, EVT VT, bool isOpaque = false) {
+    return getConstant(Val, VT, true, isOpaque);
   }
-  SDValue getTargetConstant(const APInt &Val, EVT VT) {
-    return getConstant(Val, VT, true);
+  SDValue getTargetConstant(const APInt &Val, EVT VT, bool isOpaque = false) {
+    return getConstant(Val, VT, true, isOpaque);
   }
-  SDValue getTargetConstant(const ConstantInt &Val, EVT VT) {
-    return getConstant(Val, VT, true);
+  SDValue getTargetConstant(const ConstantInt &Val, EVT VT,
+                            bool isOpaque = false) {
+    return getConstant(Val, VT, true, isOpaque);
   }
   // The forms below that take a double should only be used for simple
   // constants that can be exactly represented in VT.  No checks are made.
diff --git a/include/llvm/CodeGen/SelectionDAGNodes.h b/include/llvm/CodeGen/SelectionDAGNodes.h
index 00773b3e66..976d212ce3 100644
--- a/include/llvm/CodeGen/SelectionDAGNodes.h
+++ b/include/llvm/CodeGen/SelectionDAGNodes.h
@@ -1250,9 +1250,10 @@ public:
 class ConstantSDNode : public SDNode {
   const ConstantInt *Value;
   friend class SelectionDAG;
-  ConstantSDNode(bool isTarget, const ConstantInt *val, EVT VT)
+  ConstantSDNode(bool isTarget, bool isOpaque, const ConstantInt *val, EVT VT)
     : SDNode(isTarget ? ISD::TargetConstant : ISD::Constant,
              0, DebugLoc(), getSDVTList(VT)), Value(val) {
+    SubclassData |= isOpaque;
   }
 public:
 
@@ -1265,6 +1266,8 @@ public:
   bool isNullValue() const { return Value->isNullValue(); }
   bool isAllOnesValue() const { return Value->isAllOnesValue(); }
 
+  bool isOpaque() const { return SubclassData & 1; }
+
   static bool classof(const SDNode *N) {
     return N->getOpcode() == ISD::Constant ||
            N->getOpcode() == ISD::TargetConstant;
diff --git a/include/llvm/InitializePasses.h b/include/llvm/InitializePasses.h
index 36efee570b..923571ea4b 100644
--- a/include/llvm/InitializePasses.h
+++ b/include/llvm/InitializePasses.h
@@ -90,6 +90,7 @@ void initializeCFGSimplifyPassPass(PassRegistry&);
 void initializeFlattenCFGPassPass(PassRegistry&);
 void initializeStructurizeCFGPass(PassRegistry&);
 void initializeCFGViewerPass(PassRegistry&);
+void initializeConstantHoistingPass(PassRegistry&);
 void initializeCodeGenPreparePass(PassRegistry&);
 void initializeConstantMergePass(PassRegistry&);
 void initializeConstantPropagationPass(PassRegistry&);
diff --git a/include/llvm/LinkAllPasses.h b/include/llvm/LinkAllPasses.h
index e1d788e6e0..16032504cb 100644
--- a/include/llvm/LinkAllPasses.h
+++ b/include/llvm/LinkAllPasses.h
@@ -129,6 +129,7 @@ namespace {
       (void) llvm::createJumpThreadingPass();
       (void) llvm::createUnifyFunctionExitNodesPass();
       (void) llvm::createInstCountPass();
+      (void) llvm::createConstantHoistingPass();
       (void) llvm::createCodeGenPreparePass();
       (void) llvm::createEarlyCSEPass();
       (void) llvm::createGVNPass();
diff --git a/include/llvm/Transforms/Scalar.h b/include/llvm/Transforms/Scalar.h
index 6f9e1245e5..e1890f6803 100644
--- a/include/llvm/Transforms/Scalar.h
+++ b/include/llvm/Transforms/Scalar.h
@@ -312,6 +312,12 @@ Pass *createLoopDeletionPass();
   
 //===----------------------------------------------------------------------===//
 //
+// ConstantHoisting - This pass prepares a function for expensive constants.
+//
+FunctionPass *createConstantHoistingPass();
+
+//===----------------------------------------------------------------------===//
+//
 // CodeGenPrepare - This pass prepares a function for instruction selection.
 //
 FunctionPass *createCodeGenPreparePass(const TargetMachine *TM = 0);