Add TargetLowering::isLegalICmpImmediate. It tells LSR what immediate can be folded into target icmp instructions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86858 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Target/TargetLowering.h

@@ -1514,6 +1514,14 @@ public:
     return false;
   }
 
+  /// isLegalICmpImmediate - Return true if the specified immediate is legal
+  /// icmp immediate, that is the target has icmp instructions which can compare
+  /// a register against the immediate without having to materialize the
+  /// immediate into a register.
+  virtual bool isLegalICmpImmediate(uint64_t Imm) const {
+    return true;
+  }
+
   //===--------------------------------------------------------------------===//
   // Div utility functions
   //

lib/Target/ARM/ARMISelLowering.cpp

@@ -3706,6 +3706,18 @@ bool ARMTargetLowering::isLegalAddressingMode(const AddrMode &AM,
   return true;
 }
 
+/// isLegalICmpImmediate - Return true if the specified immediate is legal
+/// icmp immediate, that is the target has icmp instructions which can compare
+/// a register against the immediate without having to materialize the
+/// immediate into a register.
+bool ARMTargetLowering::isLegalICmpImmediate(uint64_t Imm) const {
+  if (!Subtarget->isThumb())
+    return ARM_AM::getSOImmVal(Imm) != -1;
+  if (Subtarget->isThumb2())
+    return ARM_AM::getT2SOImmVal(Imm) != -1; 
+  return Imm < 256;
+}
+
 static bool getARMIndexedAddressParts(SDNode *Ptr, EVT VT,
                                       bool isSEXTLoad, SDValue &Base,
                                       SDValue &Offset, bool &isInc,

lib/Target/ARM/ARMISelLowering.h

@@ -180,6 +180,12 @@ namespace llvm {
     virtual bool isLegalAddressingMode(const AddrMode &AM, const Type *Ty)const;
     bool isLegalT2ScaledAddressingMode(const AddrMode &AM, EVT VT) const;
 
+    /// isLegalICmpImmediate - Return true if the specified immediate is legal
+    /// icmp immediate, that is the target has icmp instructions which can compare
+    /// a register against the immediate without having to materialize the
+    /// immediate into a register.
+    virtual bool isLegalICmpImmediate(uint64_t Imm) const;
+
     /// getPreIndexedAddressParts - returns true by value, base pointer and
     /// offset pointer and addressing mode by reference if the node's address
     /// can be legally represented as pre-indexed load / store address.