3 files changed, 41 insertions, 0 deletions
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 891d401..9902ed7 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -2322,6 +2322,27 @@ TargetLowering::SimplifySetCC(EVT VT, SDValue N0, SDValue N1,
           }
         }
       }
+
+    if (!isLegalICmpImmediate(C1.getSExtValue())) {
+      // (X & -256) == 256 -> (X >> 8) == 1
+      if ((Cond == ISD::SETEQ || Cond == ISD::SETNE) &&
+          N0.getOpcode() == ISD::AND && N0.hasOneUse()) {
+        if (ConstantSDNode *AndRHS =
+            dyn_cast<ConstantSDNode>(N0.getOperand(1))) {
+          const APInt &AndRHSC = AndRHS->getAPIntValue();
+          if ((-AndRHSC).isPowerOf2() && (AndRHSC & C1) == C1) {
+            unsigned ShiftBits = AndRHSC.countTrailingZeros();
+            EVT ShiftTy = DCI.isBeforeLegalize() ?
+              getPointerTy() : getShiftAmountTy(N0.getValueType());
+            EVT CmpTy = N0.getValueType();
+            SDValue Shift = DAG.getNode(ISD::SRL, dl, CmpTy, N0.getOperand(0),
+                                        DAG.getConstant(ShiftBits, ShiftTy));
+            SDValue CmpRHS = DAG.getConstant(C1.lshr(ShiftBits), CmpTy);
+            return DAG.getSetCC(dl, VT, Shift, CmpRHS, Cond);
+          }
+        }
+      }
+    }
   }
 
   if (isa<ConstantFPSDNode>(N0.getNode())) {
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 1d72aad..347f197 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -11384,6 +11384,14 @@ bool X86TargetLowering::isTruncateFree(Type *Ty1, Type *Ty2) const {
   return true;
 }
 
+bool X86TargetLowering::isLegalICmpImmediate(int64_t Imm) const {
+  return Imm == (int32_t)Imm;
+}
+
+bool X86TargetLowering::isLegalAddImmediate(int64_t Imm) const {
+  return Imm == (int32_t)Imm;
+}
+
 bool X86TargetLowering::isTruncateFree(EVT VT1, EVT VT2) const {
   if (!VT1.isInteger() || !VT2.isInteger())
     return false;
diff --git a/lib/Target/X86/X86ISelLowering.h b/lib/Target/X86/X86ISelLowering.h
index 41bdd06..1afe68a 100644
--- a/lib/Target/X86/X86ISelLowering.h
+++ b/lib/Target/X86/X86ISelLowering.h
@@ -568,6 +568,18 @@ namespace llvm {
     /// by AM is legal for this target, for a load/store of the specified type.
     virtual bool isLegalAddressingMode(const AddrMode &AM, Type *Ty)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(int64_t Imm) const;
+
+    /// isLegalAddImmediate - Return true if the specified immediate is legal
+    /// add immediate, that is the target has add instructions which can
+    /// add a register and the immediate without having to materialize
+    /// the immediate into a register.
+    virtual bool isLegalAddImmediate(int64_t Imm) const;
+
     /// isTruncateFree - Return true if it's free to truncate a value of
     /// type Ty1 to type Ty2. e.g. On x86 it's free to truncate a i32 value in
     /// register EAX to i16 by referencing its sub-register AX.