First draft of new Target interface

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19324 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/SelectionDAG/TargetLowering.cpp

@@ -0,0 +1,48 @@
+//===-- TargetLowering.cpp - Implement the TargetLowering class -----------===//
+// 
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// 
+//===----------------------------------------------------------------------===//
+//
+// This implements the TargetLowering class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Target/TargetLowering.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/CodeGen/SelectionDAG.h"
+using namespace llvm;
+
+TargetLowering::TargetLowering(TargetMachine &tm)
+  : TM(tm), TD(TM.getTargetData()) {
+  assert(ISD::BUILTIN_OP_END <= 128 &&
+         "Fixed size array in TargetLowering is not large enough!");
+
+  IsLittleEndian = TD.isLittleEndian();
+  PointerTy = getValueType(TD.getIntPtrType());
+  memset(UnsupportedOps, 0, ISD::BUILTIN_OP_END*sizeof(short));
+  memset(RegClassForVT, 0,MVT::LAST_VALUETYPE*sizeof(TargetRegisterClass*));
+}
+
+/// computeRegisterProperties - Once all of the register classes are added,
+/// this allows us to compute derived properties we expose.
+void TargetLowering::computeRegisterProperties() {
+  // Everything defaults to one.
+  for (unsigned i = 0; i != MVT::LAST_VALUETYPE; ++i)
+    NumElementsForVT[i] = 1;
+  
+  // Find the largest integer register class.
+  unsigned LargestIntReg = MVT::i128;
+  for (; RegClassForVT[LargestIntReg] == 0; --LargestIntReg)
+    assert(LargestIntReg != MVT::i1 && "No integer registers defined!");
+
+  // Every integer value type larger than this largest register takes twice as
+  // many registers to represent as the previous ValueType.
+  unsigned ExpandedReg = LargestIntReg; ++LargestIntReg;
+  for (++ExpandedReg; MVT::isInteger((MVT::ValueType)ExpandedReg);++ExpandedReg)
+    NumElementsForVT[ExpandedReg] = 2*NumElementsForVT[ExpandedReg-1];
+}
+