Lower byte swap intrinsic.

src/IceTargetLoweringX8632.cpp

 //===- subzero/src/IceTargetLoweringX8632.cpp - x86-32 lowering -----------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the TargetLoweringX8632 class, which
@@ skipping 2578 matching lines @@
       OperandX8632Mem *Addr = FormMemoryOperand(Ptr, IceType_f64);
       _storeq(T, Addr);
       _mfence();
       return;
     }
     InstStore *Store = InstStore::create(Func, Value, Ptr);
     lowerStore(Store);
     _mfence();
     return;
   }
-  case Intrinsics::Bswap:
-    Func->setError("Unhandled intrinsic");
+  case Intrinsics::Bswap: {
+    Variable *Dest = Instr->getDest();
+    Operand *Val = Instr->getArg(0);
+    // In 32-bit mode, bswap only works on 32-bit arguments, and the
+    // argument must be a register. Use rotate left for 16-bit bswap.
+    if (Val->getType() == IceType_i64) {
+      Variable *T_Lo = legalizeToVar(loOperand(Val));
+      Variable *T_Hi = legalizeToVar(hiOperand(Val));
+      Variable *DestLo = llvm::cast<Variable>(loOperand(Dest));
+      Variable *DestHi = llvm::cast<Variable>(hiOperand(Dest));
+      _bswap(T_Lo);
+      _bswap(T_Hi);
+      _mov(DestLo, T_Hi);
+      _mov(DestHi, T_Lo);
+    } else if (Val->getType() == IceType_i32) {
+      Variable *T = legalizeToVar(Val);
+      _bswap(T);
+      _mov(Dest, T);
+    } else {
+      assert(Val->getType() == IceType_i16);
+      Val = legalize(Val);
+      Constant *Eight = Ctx->getConstantInt(IceType_i16, 8);
+      Variable *T = NULL;
+      _mov(T, Val);
+      _rol(T, Eight);
+      _mov(Dest, T);
+    }
     return;
+  }
   case Intrinsics::Ctpop: {
     Variable *Dest = Instr->getDest();
     Operand *Val = Instr->getArg(0);
     InstCall *Call = makeHelperCall(Val->getType() == IceType_i64 ?
         "__popcountdi2" : "__popcountsi2", Dest, 1);
     Call->addArg(Val);
     lowerCall(Call);
     // The popcount helpers always return 32-bit values, while the intrinsic's
     // signature matches the native POPCNT instruction and fills a 64-bit reg
     // (in 64-bit mode). Thus, clear the upper bits of the dest just in case
@@ skipping 1105 matching lines @@
     for (SizeT i = 0; i < Size; ++i) {
       Str << "\t.byte\t" << (((unsigned)Data[i]) & 0xff) << "\n";
     }
     Str << "\t.size\t" << MangledName << ", " << Size << "\n";
   }
   Str << "\t" << (IsInternal ? ".local" : ".global") << "\t" << MangledName
       << "\n";
 }
 
 } // end of namespace Ice