AArch64: Add backend intrinsic for rbit.

Define an intrinsic for the frontend to use and pattern match it to
the RBIT instruction.

rdar://9283021

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211058 91177308-0d34-0410-b5e6-96231b3b80d8

Author: Jim Grosbach

include/llvm/IR/IntrinsicsAArch64.td

@@ -31,6 +31,13 @@ def int_aarch64_sdiv : Intrinsic<[llvm_anyint_ty], [LLVMMatchType<0>,
                                 LLVMMatchType<0>], [IntrNoMem]>;
 def int_aarch64_udiv : Intrinsic<[llvm_anyint_ty], [LLVMMatchType<0>,
                                 LLVMMatchType<0>], [IntrNoMem]>;
+
+//===----------------------------------------------------------------------===//
+// RBIT
+
+def int_aarch64_rbit : Intrinsic<[llvm_anyint_ty], [LLVMMatchType<0>],
+                                 [IntrNoMem]>;
+
 }
 
 //===----------------------------------------------------------------------===//

lib/Target/AArch64/AArch64InstrInfo.td

@@ -737,6 +737,10 @@ def : Pat<(not GPR64:$Xm), (ORNXrr XZR, GPR64:$Xm)>;
 defm CLS    : OneOperandData<0b101, "cls">;
 defm CLZ    : OneOperandData<0b100, "clz", ctlz>;
 defm RBIT   : OneOperandData<0b000, "rbit">;
+
+def : Pat<(int_aarch64_rbit GPR32:$Rn), (RBITWr $Rn)>;
+def : Pat<(int_aarch64_rbit GPR64:$Rn), (RBITXr $Rn)>;
+
 def  REV16Wr : OneWRegData<0b001, "rev16",
                                   UnOpFrag<(rotr (bswap node:$LHS), (i64 16))>>;
 def  REV16Xr : OneXRegData<0b001, "rev16", null_frag>;