Replace TargetLowering::isIntImmLegal() with

ScalarTargetTransformInfo::getIntImmCost() instead. "Legal" is a poorly defined
term for something like integer immediate materialization. It is always possible
to materialize an integer immediate. Whether to use it for memcpy expansion is
more a "cost" conceern.

llvm-svn: 169929

include/llvm/Target/TargetLowering.h

@@ -371,16 +371,6 @@ public:
     return false;
   }
 
-  /// isIntImmLegal - Returns true if the target can instruction select the
-  /// specified integer immediate natively (that is, it's materialized with one
-  /// instruction). The current *assumption* in isel is all of integer
-  /// immediates are "legal" and only the memcpy / memset expansion code is
-  /// making use of this. The rest of isel doesn't have proper cost model for
-  /// immediate materialization.
-  virtual bool isIntImmLegal(const APInt &/*Imm*/, EVT /*VT*/) const {
-    return true;
-  }
-
   /// isShuffleMaskLegal - Targets can use this to indicate that they only
   /// support *some* VECTOR_SHUFFLE operations, those with specific masks.
   /// By default, if a target supports the VECTOR_SHUFFLE node, all mask values

include/llvm/TargetTransformInfo.h

@@ -140,6 +140,13 @@ public:
   virtual PopcntHwSupport getPopcntHwSupport(unsigned IntTyWidthInBit) const {
     return None;
   }
+
+  /// getIntImmCost - Return the expected cost of materializing the given
+  /// integer immediate of the specified type.
+  virtual unsigned getIntImmCost(const APInt&, Type*) const {
+    // Default assumption is immediate is cheap.
+    return 1;
+  }
 };
 
 /// VectorTargetTransformInfo - This interface is used by the vectorizers

lib/CodeGen/SelectionDAG/SelectionDAG.cpp

@@ -41,6 +41,7 @@
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/Mutex.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/TargetTransformInfo.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetIntrinsicInfo.h"
 #include "llvm/Target/TargetLowering.h"
@@ -3382,7 +3383,10 @@ static SDValue getMemsetStringVal(EVT VT, DebugLoc dl, SelectionDAG &DAG,
       Val |= (uint64_t)(unsigned char)Str[i] << (NumVTBytes-i-1)*8;
   }
 
-  if (TLI.isIntImmLegal(Val, VT))
+  // If the "cost" of materializing the integer immediate is 1 or free, then
+  // it is cost effective to turn the load into the immediate.
+  if (DAG.getTarget().getScalarTargetTransformInfo()->
+      getIntImmCost(Val, VT.getTypeForEVT(*DAG.getContext())) < 2)
     return DAG.getConstant(Val, VT);
   return SDValue(0, 0);
 }

lib/Target/ARM/ARMISelLowering.cpp

@@ -10260,24 +10260,6 @@ bool ARMTargetLowering::isFPImmLegal(const APFloat &Imm, EVT VT) const {
   return false;
 }
 
-bool ARMTargetLowering::isIntImmLegal(const APInt &Imm, EVT VT) const {
-  if (VT.getSizeInBits() > 32)
-    return false;
-
-  int32_t ImmVal = Imm.getSExtValue();
-  if (!Subtarget->isThumb()) {
-    return (ImmVal >= 0 && ImmVal < 65536) ||
-      (ARM_AM::getSOImmVal(ImmVal) != -1) ||
-      (ARM_AM::getSOImmVal(~ImmVal) != -1);
-  } else if (Subtarget->isThumb2()) {
-    return (ImmVal >= 0 && ImmVal < 65536) ||
-      (ARM_AM::getT2SOImmVal(ImmVal) != -1) ||
-      (ARM_AM::getT2SOImmVal(~ImmVal) != -1);
-  } else /*Thumb1*/ {
-    return (ImmVal >= 0 && ImmVal < 256);
-  }
-}
-
 /// getTgtMemIntrinsic - Represent NEON load and store intrinsics as
 /// MemIntrinsicNodes.  The associated MachineMemOperands record the alignment
 /// specified in the intrinsic calls.
@@ -10359,3 +10341,36 @@ bool ARMTargetLowering::getTgtMemIntrinsic(IntrinsicInfo &Info,
 
   return false;
 }
+
+unsigned
+ARMScalarTargetTransformImpl::getIntImmCost(const APInt &Imm, Type *Ty) const {
+  assert(Ty->isIntegerTy());
+
+  unsigned Bits = Ty->getPrimitiveSizeInBits();
+  if (Bits == 0 || Bits > 32)
+    return 4;
+
+  int32_t SImmVal = Imm.getSExtValue();
+  uint32_t ZImmVal = Imm.getZExtValue();
+  if (!Subtarget->isThumb()) {
+    if ((SImmVal >= 0 && SImmVal < 65536) ||
+        (ARM_AM::getSOImmVal(ZImmVal) != -1) ||
+        (ARM_AM::getSOImmVal(~ZImmVal) != -1))
+      return 1;
+    return Subtarget->hasV6T2Ops() ? 2 : 3;
+  } else if (Subtarget->isThumb2()) {
+    if ((SImmVal >= 0 && SImmVal < 65536) ||
+        (ARM_AM::getT2SOImmVal(ZImmVal) != -1) ||
+        (ARM_AM::getT2SOImmVal(~ZImmVal) != -1))
+      return 1;
+    return Subtarget->hasV6T2Ops() ? 2 : 3;
+  } else /*Thumb1*/ {
+    if (SImmVal >= 0 && SImmVal < 256)
+      return 1;
+    if ((~ZImmVal < 256) || ARM_AM::isThumbImmShiftedVal(ZImmVal))
+      return 2;
+    // Load from constantpool.
+    return 3;
+  }
+  return 2;
+}

lib/Target/ARM/ARMISelLowering.h

@@ -22,6 +22,7 @@
 #include "llvm/CodeGen/SelectionDAG.h"
 #include "llvm/Target/TargetLowering.h"
 #include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Target/TargetTransformImpl.h"
 #include <vector>
 
 namespace llvm {
@@ -387,8 +388,6 @@ namespace llvm {
     /// materialize the FP immediate as a load from a constant pool.
     virtual bool isFPImmLegal(const APFloat &Imm, EVT VT) const;
 
-    virtual bool isIntImmLegal(const APInt &Imm, EVT VT) const;
-
     virtual bool getTgtMemIntrinsic(IntrinsicInfo &Info,
                                     const CallInst &I,
                                     unsigned Intrinsic) const;
@@ -575,6 +574,16 @@ namespace llvm {
     FastISel *createFastISel(FunctionLoweringInfo &funcInfo,
                              const TargetLibraryInfo *libInfo);
   }
+
+  class ARMScalarTargetTransformImpl : public ScalarTargetTransformImpl {
+    const ARMSubtarget *Subtarget;
+  public:
+    explicit ARMScalarTargetTransformImpl(const TargetLowering *TL) :
+      ScalarTargetTransformImpl(TL),
+      Subtarget(&TL->getTargetMachine().getSubtarget<ARMSubtarget>()) {};
+
+    virtual unsigned getIntImmCost(const APInt &Imm, Type *Ty) const;
+  };
 }
 
 #endif  // ARMISELLOWERING_H

lib/Target/ARM/ARMTargetMachine.h

@@ -66,7 +66,7 @@ class ARMTargetMachine : public ARMBaseTargetMachine {
   ARMTargetLowering   TLInfo;
   ARMSelectionDAGInfo TSInfo;
   ARMFrameLowering    FrameLowering;
-  ScalarTargetTransformImpl STTI;
+  ARMScalarTargetTransformImpl STTI;
   VectorTargetTransformImpl VTTI;
  public:
   ARMTargetMachine(const Target &T, StringRef TT,
@@ -112,7 +112,7 @@ class ThumbTargetMachine : public ARMBaseTargetMachine {
   ARMSelectionDAGInfo TSInfo;
   // Either Thumb1FrameLowering or ARMFrameLowering.
   OwningPtr<ARMFrameLowering> FrameLowering;
-  ScalarTargetTransformImpl STTI;
+  ARMScalarTargetTransformImpl STTI;
   VectorTargetTransformImpl VTTI;
 public:
   ThumbTargetMachine(const Target &T, StringRef TT,