[llvm-commits] CVS: llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
Chris Lattner
lattner at cs.uiuc.edu
Thu Jan 6 23:48:22 PST 2005
Changes in directory llvm/lib/CodeGen/SelectionDAG:
LegalizeDAG.cpp added (r1.1)
---
Log message:
Initial implementation of the DAG legalization. This still has a long way
to go, but it does work for some non-trivial cases now.
---
Diffs of the changes: (+703 -0)
Index: llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
diff -c /dev/null llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp:1.1
*** /dev/null Fri Jan 7 01:48:20 2005
--- llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp Fri Jan 7 01:47:09 2005
***************
*** 0 ****
--- 1,703 ----
+ //===-- LegalizeDAG.cpp - Implement SelectionDAG::Legalize ----------------===//
+ //
+ // 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 file implements the SelectionDAG::Legalize method.
+ //
+ //===----------------------------------------------------------------------===//
+
+ #include "llvm/CodeGen/SelectionDAG.h"
+ #include "llvm/CodeGen/MachineConstantPool.h"
+ #include "llvm/CodeGen/MachineFunction.h"
+ #include "llvm/Target/TargetLowering.h"
+ #include "llvm/Constants.h"
+ #include <iostream>
+ using namespace llvm;
+
+ //===----------------------------------------------------------------------===//
+ /// SelectionDAGLegalize - This takes an arbitrary SelectionDAG as input and
+ /// hacks on it until the target machine can handle it. This involves
+ /// eliminating value sizes the machine cannot handle (promoting small sizes to
+ /// large sizes or splitting up large values into small values) as well as
+ /// eliminating operations the machine cannot handle.
+ ///
+ /// This code also does a small amount of optimization and recognition of idioms
+ /// as part of its processing. For example, if a target does not support a
+ /// 'setcc' instruction efficiently, but does support 'brcc' instruction, this
+ /// will attempt merge setcc and brc instructions into brcc's.
+ ///
+ namespace {
+ class SelectionDAGLegalize {
+ TargetLowering &TLI;
+ SelectionDAG &DAG;
+
+ /// LegalizeAction - This enum indicates what action we should take for each
+ /// value type the can occur in the program.
+ enum LegalizeAction {
+ Legal, // The target natively supports this value type.
+ Promote, // This should be promoted to the next larger type.
+ Expand, // This integer type should be broken into smaller pieces.
+ };
+
+ /// TransformToType - For any value types we are promoting or expanding, this
+ /// contains the value type that we are changing to. For Expanded types, this
+ /// contains one step of the expand (e.g. i64 -> i32), even if there are
+ /// multiple steps required (e.g. i64 -> i16)
+ MVT::ValueType TransformToType[MVT::LAST_VALUETYPE];
+
+ /// ValueTypeActions - This is a bitvector that contains two bits for each
+ /// value type, where the two bits correspond to the LegalizeAction enum.
+ /// This can be queried with "getTypeAction(VT)".
+ unsigned ValueTypeActions;
+
+ /// NeedsAnotherIteration - This is set when we expand a large integer
+ /// operation into smaller integer operations, but the smaller operations are
+ /// not set. This occurs only rarely in practice, for targets that don't have
+ /// 32-bit or larger integer registers.
+ bool NeedsAnotherIteration;
+
+ /// LegalizedNodes - For nodes that are of legal width, and that have more
+ /// than one use, this map indicates what regularized operand to use. This
+ /// allows us to avoid legalizing the same thing more than once.
+ std::map<SDOperand, SDOperand> LegalizedNodes;
+
+ /// ExpandedNodes - For nodes that need to be expanded, and which have more
+ /// than one use, this map indicates which which operands are the expanded
+ /// version of the input. This allows us to avoid expanding the same node
+ /// more than once.
+ std::map<SDOperand, std::pair<SDOperand, SDOperand> > ExpandedNodes;
+
+ /// setValueTypeAction - Set the action for a particular value type. This
+ /// assumes an action has not already been set for this value type.
+ void setValueTypeAction(MVT::ValueType VT, LegalizeAction A) {
+ ValueTypeActions |= A << (VT*2);
+ if (A == Promote) {
+ MVT::ValueType PromoteTo;
+ if (VT == MVT::f32)
+ PromoteTo = MVT::f64;
+ else {
+ unsigned LargerReg = VT+1;
+ while (!TLI.hasNativeSupportFor((MVT::ValueType)LargerReg)) {
+ ++LargerReg;
+ assert(MVT::isInteger((MVT::ValueType)LargerReg) &&
+ "Nothing to promote to??");
+ }
+ PromoteTo = (MVT::ValueType)LargerReg;
+ }
+
+ assert(MVT::isInteger(VT) == MVT::isInteger(PromoteTo) &&
+ MVT::isFloatingPoint(VT) == MVT::isFloatingPoint(PromoteTo) &&
+ "Can only promote from int->int or fp->fp!");
+ assert(VT < PromoteTo && "Must promote to a larger type!");
+ TransformToType[VT] = PromoteTo;
+ } else if (A == Expand) {
+ assert(MVT::isInteger(VT) && VT > MVT::i8 &&
+ "Cannot expand this type: target must support SOME integer reg!");
+ // Expand to the next smaller integer type!
+ TransformToType[VT] = (MVT::ValueType)(VT-1);
+ }
+ }
+
+ public:
+
+ SelectionDAGLegalize(TargetLowering &TLI, SelectionDAG &DAG);
+
+ /// Run - While there is still lowering to do, perform a pass over the DAG.
+ /// Most regularization can be done in a single pass, but targets that require
+ /// large values to be split into registers multiple times (e.g. i64 -> 4x
+ /// i16) require iteration for these values (the first iteration will demote
+ /// to i32, the second will demote to i16).
+ void Run() {
+ do {
+ NeedsAnotherIteration = false;
+ LegalizeDAG();
+ } while (NeedsAnotherIteration);
+ }
+
+ /// getTypeAction - Return how we should legalize values of this type, either
+ /// it is already legal or we need to expand it into multiple registers of
+ /// smaller integer type, or we need to promote it to a larger type.
+ LegalizeAction getTypeAction(MVT::ValueType VT) const {
+ return (LegalizeAction)((ValueTypeActions >> (2*VT)) & 3);
+ }
+
+ /// isTypeLegal - Return true if this type is legal on this target.
+ ///
+ bool isTypeLegal(MVT::ValueType VT) const {
+ return getTypeAction(VT) == Legal;
+ }
+
+ private:
+ void LegalizeDAG();
+
+ SDOperand LegalizeOp(SDOperand O);
+ void ExpandOp(SDOperand O, SDOperand &Lo, SDOperand &Hi);
+
+ SDOperand getIntPtrConstant(uint64_t Val) {
+ return DAG.getConstant(Val, TLI.getPointerTy());
+ }
+ };
+ }
+
+
+ SelectionDAGLegalize::SelectionDAGLegalize(TargetLowering &tli,
+ SelectionDAG &dag)
+ : TLI(tli), DAG(dag), ValueTypeActions(0) {
+
+ assert(MVT::LAST_VALUETYPE <= 16 &&
+ "Too many value types for ValueTypeActions to hold!");
+
+ // Inspect all of the ValueType's possible, deciding how to process them.
+ for (unsigned IntReg = MVT::i1; IntReg <= MVT::i128; ++IntReg)
+ // If TLI says we are expanding this type, expand it!
+ if (TLI.getNumElements((MVT::ValueType)IntReg) != 1)
+ setValueTypeAction((MVT::ValueType)IntReg, Expand);
+ else if (!TLI.hasNativeSupportFor((MVT::ValueType)IntReg))
+ // Otherwise, if we don't have native support, we must promote to a
+ // larger type.
+ setValueTypeAction((MVT::ValueType)IntReg, Promote);
+
+ // If the target does not have native support for F32, promote it to F64.
+ if (!TLI.hasNativeSupportFor(MVT::f32))
+ setValueTypeAction(MVT::f32, Promote);
+ }
+
+
+ void SelectionDAGLegalize::LegalizeDAG() {
+ SDOperand OldRoot = DAG.getRoot();
+ SDOperand NewRoot = LegalizeOp(OldRoot);
+ DAG.setRoot(NewRoot);
+
+ ExpandedNodes.clear();
+ LegalizedNodes.clear();
+
+ // Remove dead nodes now.
+ if (OldRoot != NewRoot)
+ // Delete all of these efficiently first.
+ ;
+
+ // Then scan AllNodes.
+ }
+
+ SDOperand SelectionDAGLegalize::LegalizeOp(SDOperand Op) {
+ // If this operation defines any values that cannot be represented in a
+ // register on this target, make sure to expand it.
+ if (Op.Val->getNumValues() == 1) {// Fast path == assertion only
+ assert(getTypeAction(Op.Val->getValueType(0)) == Legal &&
+ "For a single use value, caller should check for legality!");
+ } else {
+ for (unsigned i = 0, e = Op.Val->getNumValues(); i != e; ++i)
+ switch (getTypeAction(Op.Val->getValueType(i))) {
+ case Legal: break; // Nothing to do.
+ case Expand: {
+ SDOperand T1, T2;
+ ExpandOp(Op.getValue(i), T1, T2);
+ assert(LegalizedNodes.count(Op) &&
+ "Expansion didn't add legal operands!");
+ return LegalizedNodes[Op];
+ }
+ case Promote:
+ // FIXME: Implement promotion!
+ assert(0 && "Promotion not implemented at all yet!");
+ }
+ }
+
+ // If there is more than one use of this, see if we already legalized it.
+ // There is no use remembering values that only have a single use, as the map
+ // entries will never be reused.
+ if (!Op.Val->hasOneUse()) {
+ std::map<SDOperand, SDOperand>::iterator I = LegalizedNodes.find(Op);
+ if (I != LegalizedNodes.end()) return I->second;
+ }
+
+ SDOperand Tmp1, Tmp2;
+
+ SDOperand Result = Op;
+ SDNode *Node = Op.Val;
+ LegalizeAction Action;
+
+ switch (Node->getOpcode()) {
+ default:
+ std::cerr << "NODE: "; Node->dump(); std::cerr << "\n";
+ assert(0 && "Do not know how to legalize this operator!");
+ abort();
+ case ISD::EntryToken:
+ case ISD::FrameIndex:
+ case ISD::GlobalAddress:
+ case ISD::ConstantPool:
+ case ISD::CopyFromReg: // Nothing to do.
+ assert(getTypeAction(Node->getValueType(0)) == Legal &&
+ "This must be legal!");
+ break;
+ case ISD::Constant:
+ // We know we don't need to expand constants here, constants only have one
+ // value and we check that it is fine above.
+
+ // FIXME: Maybe we should handle things like targets that don't support full
+ // 32-bit immediates?
+ break;
+ case ISD::ConstantFP: {
+ // Spill FP immediates to the constant pool if the target cannot directly
+ // codegen them. Targets often have some immediate values that can be
+ // efficiently generated into an FP register without a load. We explicitly
+ // leave these constants as ConstantFP nodes for the target to deal with.
+
+ ConstantFPSDNode *CFP = cast<ConstantFPSDNode>(Node);
+
+ // Check to see if this FP immediate is already legal.
+ bool isLegal = false;
+ for (TargetLowering::legal_fpimm_iterator I = TLI.legal_fpimm_begin(),
+ E = TLI.legal_fpimm_end(); I != E; ++I)
+ if (CFP->isExactlyValue(*I)) {
+ isLegal = true;
+ break;
+ }
+
+ if (!isLegal) {
+ // Otherwise we need to spill the constant to memory.
+ MachineConstantPool *CP = DAG.getMachineFunction().getConstantPool();
+
+ bool Extend = false;
+
+ // If a FP immediate is precise when represented as a float, we put it
+ // into the constant pool as a float, even if it's is statically typed
+ // as a double.
+ MVT::ValueType VT = CFP->getValueType(0);
+ bool isDouble = VT == MVT::f64;
+ ConstantFP *LLVMC = ConstantFP::get(isDouble ? Type::DoubleTy :
+ Type::FloatTy, CFP->getValue());
+ if (isDouble && CFP->isExactlyValue((float)CFP->getValue())) {
+ LLVMC = cast<ConstantFP>(ConstantExpr::getCast(LLVMC, Type::FloatTy));
+ VT = MVT::f32;
+ Extend = true;
+ }
+
+ SDOperand CPIdx = DAG.getConstantPool(CP->getConstantPoolIndex(LLVMC),
+ TLI.getPointerTy());
+ Result = DAG.getLoad(VT, DAG.getEntryNode(), CPIdx);
+
+ if (Extend) Result = DAG.getNode(ISD::FP_EXTEND, MVT::f64, Result);
+ }
+ break;
+ }
+ case ISD::ADJCALLSTACKDOWN:
+ case ISD::ADJCALLSTACKUP:
+ Tmp1 = LegalizeOp(Node->getOperand(0)); // Legalize the chain.
+ // There is no need to legalize the size argument (Operand #1)
+ if (Tmp1 != Node->getOperand(0))
+ Result = DAG.getNode(Node->getOpcode(), MVT::Other, Tmp1,
+ Node->getOperand(1));
+ break;
+ case ISD::CALL:
+ Tmp1 = LegalizeOp(Node->getOperand(0)); // Legalize the chain.
+ Tmp2 = LegalizeOp(Node->getOperand(1)); // Legalize the callee.
+ if (Tmp2 != Node->getOperand(0) || Tmp2 != Node->getOperand(1)) {
+ std::vector<MVT::ValueType> RetTyVTs;
+ RetTyVTs.reserve(Node->getNumValues());
+ for (unsigned i = 0, e = Node->getNumValues(); i != e; ++i)
+ RetTyVTs.push_back(Node->getValueType(0));
+ Result = SDOperand(DAG.getCall(RetTyVTs, Tmp1, Tmp2), Op.ResNo);
+ }
+ break;
+
+ case ISD::LOAD:
+ Tmp1 = LegalizeOp(Node->getOperand(0)); // Legalize the chain.
+ Tmp2 = LegalizeOp(Node->getOperand(1)); // Legalize the pointer.
+ if (Tmp1 != Node->getOperand(0) ||
+ Tmp2 != Node->getOperand(1))
+ Result = DAG.getLoad(Node->getValueType(0), Tmp1, Tmp2);
+ break;
+
+ case ISD::EXTRACT_ELEMENT:
+ // Get both the low and high parts.
+ ExpandOp(Node->getOperand(0), Tmp1, Tmp2);
+ if (cast<ConstantSDNode>(Node->getOperand(1))->getValue())
+ Result = Tmp2; // 1 -> Hi
+ else
+ Result = Tmp1; // 0 -> Lo
+ break;
+
+ case ISD::CopyToReg:
+ Tmp1 = LegalizeOp(Node->getOperand(0)); // Legalize the chain.
+
+ switch (getTypeAction(Node->getOperand(1).getValueType())) {
+ case Legal:
+ // Legalize the incoming value (must be legal).
+ Tmp2 = LegalizeOp(Node->getOperand(1));
+ if (Tmp1 != Node->getOperand(0) || Tmp2 != Node->getOperand(1))
+ Result = DAG.getCopyToReg(Tmp1, Tmp2,
+ cast<CopyRegSDNode>(Node)->getReg());
+ break;
+ case Expand: {
+ SDOperand Lo, Hi;
+ ExpandOp(Node->getOperand(1), Lo, Hi);
+ unsigned Reg = cast<CopyRegSDNode>(Node)->getReg();
+ Result = DAG.getCopyToReg(Tmp1, Lo, Reg);
+ Result = DAG.getCopyToReg(Result, Hi, Reg+1);
+ assert(isTypeLegal(Result.getValueType()) &&
+ "Cannot expand multiple times yet (i64 -> i16)");
+ break;
+ }
+ case Promote:
+ assert(0 && "Don't know what it means to promote this!");
+ abort();
+ }
+ break;
+
+ case ISD::RET:
+ Tmp1 = LegalizeOp(Node->getOperand(0)); // Legalize the chain.
+ switch (Node->getNumOperands()) {
+ case 2: // ret val
+ switch (getTypeAction(Node->getOperand(1).getValueType())) {
+ case Legal:
+ Tmp2 = LegalizeOp(Node->getOperand(1));
+ if (Tmp2 != Node->getOperand(1))
+ Result = DAG.getNode(ISD::RET, MVT::Other, Tmp1, Tmp2);
+ break;
+ case Expand: {
+ SDOperand Lo, Hi;
+ ExpandOp(Node->getOperand(1), Lo, Hi);
+ Result = DAG.getNode(ISD::RET, MVT::Other, Tmp1, Lo, Hi);
+ break;
+ }
+ case Promote:
+ assert(0 && "Can't promote return value!");
+ }
+ break;
+ case 1: // ret void
+ if (Tmp1 != Node->getOperand(0))
+ Result = DAG.getNode(ISD::RET, MVT::Other, Tmp1);
+ break;
+ default: { // ret <values>
+ std::vector<SDOperand> NewValues;
+ NewValues.push_back(Tmp1);
+ for (unsigned i = 1, e = Node->getNumOperands(); i != e; ++i)
+ switch (getTypeAction(Node->getOperand(i).getValueType())) {
+ case Legal:
+ NewValues.push_back(LegalizeOp(Node->getOperand(1)));
+ break;
+ case Expand: {
+ SDOperand Lo, Hi;
+ ExpandOp(Node->getOperand(i), Lo, Hi);
+ NewValues.push_back(Lo);
+ NewValues.push_back(Hi);
+ break;
+ }
+ case Promote:
+ assert(0 && "Can't promote return value!");
+ }
+ Result = DAG.getNode(ISD::RET, MVT::Other, NewValues);
+ break;
+ }
+ }
+ break;
+ case ISD::STORE:
+ Tmp1 = LegalizeOp(Node->getOperand(0)); // Legalize the chain.
+ Tmp2 = LegalizeOp(Node->getOperand(2)); // Legalize the pointer.
+
+ switch (getTypeAction(Node->getOperand(1).getValueType())) {
+ case Legal: {
+ SDOperand Val = LegalizeOp(Node->getOperand(1));
+ if (Val != Node->getOperand(1) || Tmp1 != Node->getOperand(0) ||
+ Tmp2 != Node->getOperand(2))
+ Result = DAG.getNode(ISD::STORE, MVT::Other, Tmp1, Val, Tmp2);
+ break;
+ }
+ case Promote:
+ assert(0 && "FIXME: promote for stores not implemented!");
+ case Expand:
+ SDOperand Lo, Hi;
+ ExpandOp(Node->getOperand(1), Lo, Hi);
+
+ if (!TLI.isLittleEndian())
+ std::swap(Lo, Hi);
+
+ // FIXME: These two stores are independent of each other!
+ Result = DAG.getNode(ISD::STORE, MVT::Other, Tmp1, Lo, Tmp2);
+
+ unsigned IncrementSize;
+ switch (Lo.getValueType()) {
+ default: assert(0 && "Unknown ValueType to expand to!");
+ case MVT::i32: IncrementSize = 4; break;
+ case MVT::i16: IncrementSize = 2; break;
+ case MVT::i8: IncrementSize = 1; break;
+ }
+ Tmp2 = DAG.getNode(ISD::ADD, Tmp2.getValueType(), Tmp2,
+ getIntPtrConstant(IncrementSize));
+ assert(isTypeLegal(Tmp2.getValueType()) &&
+ "Pointers must be legal!");
+ Result = DAG.getNode(ISD::STORE, MVT::Other, Result, Hi, Tmp2);
+ }
+ break;
+ case ISD::SELECT: {
+ // FIXME: BOOLS MAY REQUIRE PROMOTION!
+ Tmp1 = LegalizeOp(Node->getOperand(0)); // Cond
+ Tmp2 = LegalizeOp(Node->getOperand(1)); // TrueVal
+ SDOperand Tmp3 = LegalizeOp(Node->getOperand(2)); // FalseVal
+
+ if (Tmp1 != Node->getOperand(0) ||
+ Tmp2 != Node->getOperand(1) ||
+ Tmp3 != Node->getOperand(2))
+ Result = DAG.getNode(ISD::SELECT, Node->getValueType(0), Tmp1, Tmp2,Tmp3);
+ break;
+ }
+ case ISD::SETCC:
+ switch (getTypeAction(Node->getOperand(0).getValueType())) {
+ case Legal:
+ Tmp1 = LegalizeOp(Node->getOperand(0)); // LHS
+ Tmp2 = LegalizeOp(Node->getOperand(1)); // RHS
+ if (Tmp1 != Node->getOperand(0) || Tmp2 != Node->getOperand(1))
+ Result = DAG.getSetCC(cast<SetCCSDNode>(Node)->getCondition(),
+ Tmp1, Tmp2);
+ break;
+ case Promote:
+ assert(0 && "Can't promote setcc operands yet!");
+ break;
+ case Expand:
+ SDOperand LHSLo, LHSHi, RHSLo, RHSHi;
+ ExpandOp(Node->getOperand(0), LHSLo, LHSHi);
+ ExpandOp(Node->getOperand(1), RHSLo, RHSHi);
+ switch (cast<SetCCSDNode>(Node)->getCondition()) {
+ case ISD::SETEQ:
+ case ISD::SETNE:
+ Tmp1 = DAG.getNode(ISD::XOR, LHSLo.getValueType(), LHSLo, RHSLo);
+ Tmp2 = DAG.getNode(ISD::XOR, LHSLo.getValueType(), LHSHi, RHSHi);
+ Tmp1 = DAG.getNode(ISD::OR, Tmp1.getValueType(), Tmp1, Tmp2);
+ Result = DAG.getSetCC(cast<SetCCSDNode>(Node)->getCondition(), Tmp1,
+ DAG.getConstant(0, Tmp1.getValueType()));
+ break;
+ default:
+ // FIXME: This generated code sucks.
+ ISD::CondCode LowCC;
+ switch (cast<SetCCSDNode>(Node)->getCondition()) {
+ default: assert(0 && "Unknown integer setcc!");
+ case ISD::SETLT:
+ case ISD::SETULT: LowCC = ISD::SETULT; break;
+ case ISD::SETGT:
+ case ISD::SETUGT: LowCC = ISD::SETUGT; break;
+ case ISD::SETLE:
+ case ISD::SETULE: LowCC = ISD::SETULE; break;
+ case ISD::SETGE:
+ case ISD::SETUGE: LowCC = ISD::SETUGE; break;
+ }
+
+ // Tmp1 = lo(op1) < lo(op2) // Always unsigned comparison
+ // Tmp2 = hi(op1) < hi(op2) // Signedness depends on operands
+ // dest = hi(op1) == hi(op2) ? Tmp1 : Tmp2;
+
+ // NOTE: on targets without efficient SELECT of bools, we can always use
+ // this identity: (B1 ? B2 : B3) --> (B1 & B2)|(!B1&B3)
+ Tmp1 = DAG.getSetCC(LowCC, LHSLo, RHSLo);
+ Tmp2 = DAG.getSetCC(cast<SetCCSDNode>(Node)->getCondition(),
+ LHSHi, RHSHi);
+ Result = DAG.getSetCC(ISD::SETEQ, LHSHi, RHSHi);
+ Result = DAG.getNode(ISD::SELECT, MVT::i1, Result, Tmp1, Tmp2);
+ break;
+ }
+ }
+ break;
+
+ case ISD::ADD:
+ case ISD::SUB:
+ case ISD::MUL:
+ case ISD::UDIV:
+ case ISD::SDIV:
+ case ISD::UREM:
+ case ISD::SREM:
+ case ISD::AND:
+ case ISD::OR:
+ case ISD::XOR:
+ Tmp1 = LegalizeOp(Node->getOperand(0)); // LHS
+ Tmp2 = LegalizeOp(Node->getOperand(1)); // RHS
+ if (Tmp1 != Node->getOperand(0) ||
+ Tmp2 != Node->getOperand(1))
+ Result = DAG.getNode(Node->getOpcode(), Node->getValueType(0), Tmp1,Tmp2);
+ break;
+ case ISD::ZERO_EXTEND:
+ case ISD::SIGN_EXTEND:
+ switch (getTypeAction(Node->getOperand(0).getValueType())) {
+ case Legal:
+ Tmp1 = LegalizeOp(Node->getOperand(0));
+ if (Tmp1 != Node->getOperand(0))
+ Result = DAG.getNode(Node->getOpcode(), Node->getValueType(0), Tmp1);
+ break;
+ default:
+ assert(0 && "Do not know how to expand or promote this yet!");
+ }
+ break;
+ }
+
+ if (!Op.Val->hasOneUse()) {
+ bool isNew = LegalizedNodes.insert(std::make_pair(Op, Result)).second;
+ assert(isNew && "Got into the map somehow?");
+ }
+
+ return Result;
+ }
+
+
+ /// ExpandOp - Expand the specified SDOperand into its two component pieces
+ /// Lo&Hi. Note that the Op MUST be an expanded type. As a result of this, the
+ /// LegalizeNodes map is filled in for any results that are not expanded, the
+ /// ExpandedNodes map is filled in for any results that are expanded, and the
+ /// Lo/Hi values are returned.
+ void SelectionDAGLegalize::ExpandOp(SDOperand Op, SDOperand &Lo, SDOperand &Hi){
+ MVT::ValueType VT = Op.getValueType();
+ MVT::ValueType NVT = TransformToType[VT];
+ SDNode *Node = Op.Val;
+ assert(getTypeAction(VT) == Expand && "Not an expanded type!");
+ assert(MVT::isInteger(VT) && "Cannot expand FP values!");
+ assert(MVT::isInteger(NVT) && NVT < VT &&
+ "Cannot expand to FP value or to larger int value!");
+
+ // If there is more than one use of this, see if we already expanded it.
+ // There is no use remembering values that only have a single use, as the map
+ // entries will never be reused.
+ if (!Node->hasOneUse()) {
+ std::map<SDOperand, std::pair<SDOperand, SDOperand> >::iterator I
+ = ExpandedNodes.find(Op);
+ if (I != ExpandedNodes.end()) {
+ Lo = I->second.first;
+ Hi = I->second.second;
+ return;
+ }
+ }
+
+ // If we are lowering to a type that the target doesn't support, we will have
+ // to iterate lowering.
+ if (!isTypeLegal(NVT))
+ NeedsAnotherIteration = true;
+
+ LegalizeAction Action;
+ switch (Node->getOpcode()) {
+ default:
+ std::cerr << "NODE: "; Node->dump(); std::cerr << "\n";
+ assert(0 && "Do not know how to expand this operator!");
+ abort();
+ case ISD::Constant: {
+ uint64_t Cst = cast<ConstantSDNode>(Node)->getValue();
+ Lo = DAG.getConstant(Cst, NVT);
+ Hi = DAG.getConstant(Cst >> MVT::getSizeInBits(NVT), NVT);
+ break;
+ }
+
+ case ISD::CopyFromReg: {
+ unsigned Reg = cast<CopyRegSDNode>(Node)->getReg();
+ // Aggregate register values are always in consequtive pairs.
+ Lo = DAG.getCopyFromReg(Reg, NVT);
+ Hi = DAG.getCopyFromReg(Reg+1, NVT);
+ assert(isTypeLegal(NVT) && "Cannot expand this multiple times yet!");
+ break;
+ }
+
+ case ISD::LOAD: {
+ SDOperand Ch = LegalizeOp(Node->getOperand(0)); // Legalize the chain.
+ SDOperand Ptr = LegalizeOp(Node->getOperand(1)); // Legalize the pointer.
+ Lo = DAG.getLoad(NVT, Ch, Ptr);
+
+ // Increment the pointer to the other half.
+ unsigned IncrementSize;
+ switch (Lo.getValueType()) {
+ default: assert(0 && "Unknown ValueType to expand to!");
+ case MVT::i32: IncrementSize = 4; break;
+ case MVT::i16: IncrementSize = 2; break;
+ case MVT::i8: IncrementSize = 1; break;
+ }
+ Ptr = DAG.getNode(ISD::ADD, Ptr.getValueType(), Ptr,
+ getIntPtrConstant(IncrementSize));
+ // FIXME: This load is independent of the first one.
+ Hi = DAG.getLoad(NVT, Lo.getValue(1), Ptr);
+
+ // Remember that we legalized the chain.
+ bool isNew = LegalizedNodes.insert(std::make_pair(Op.getValue(1),
+ Hi.getValue(1))).second;
+ assert(isNew && "This node was already legalized!");
+ if (!TLI.isLittleEndian())
+ std::swap(Lo, Hi);
+ break;
+ }
+ case ISD::CALL: {
+ SDOperand Chain = LegalizeOp(Node->getOperand(0)); // Legalize the chain.
+ SDOperand Callee = LegalizeOp(Node->getOperand(1)); // Legalize the callee.
+
+ assert(Node->getNumValues() == 2 && Op.ResNo == 0 &&
+ "Can only expand a call once so far, not i64 -> i16!");
+
+ std::vector<MVT::ValueType> RetTyVTs;
+ RetTyVTs.reserve(3);
+ RetTyVTs.push_back(NVT);
+ RetTyVTs.push_back(NVT);
+ RetTyVTs.push_back(MVT::Other);
+ SDNode *NC = DAG.getCall(RetTyVTs, Chain, Callee);
+ Lo = SDOperand(NC, 0);
+ Hi = SDOperand(NC, 1);
+
+ // Insert the new chain mapping.
+ bool isNew = LegalizedNodes.insert(std::make_pair(Op.getValue(1),
+ Hi.getValue(2))).second;
+ assert(isNew && "This node was already legalized!");
+ break;
+ }
+ case ISD::AND:
+ case ISD::OR:
+ case ISD::XOR: { // Simple logical operators -> two trivial pieces.
+ SDOperand LL, LH, RL, RH;
+ ExpandOp(Node->getOperand(0), LL, LH);
+ ExpandOp(Node->getOperand(1), RL, RH);
+ Lo = DAG.getNode(Node->getOpcode(), NVT, LL, RL);
+ Hi = DAG.getNode(Node->getOpcode(), NVT, LH, RH);
+ break;
+ }
+ case ISD::SELECT: {
+ SDOperand C, LL, LH, RL, RH;
+ // FIXME: BOOLS MAY REQUIRE PROMOTION!
+ C = LegalizeOp(Node->getOperand(0));
+ ExpandOp(Node->getOperand(1), LL, LH);
+ ExpandOp(Node->getOperand(2), RL, RH);
+ Lo = DAG.getNode(ISD::SELECT, NVT, C, LL, RL);
+ Hi = DAG.getNode(ISD::SELECT, NVT, C, LH, RH);
+ break;
+ }
+ case ISD::SIGN_EXTEND: {
+ // The low part is just a sign extension of the input (which degenerates to
+ // a copy).
+ Lo = DAG.getNode(ISD::SIGN_EXTEND, NVT, LegalizeOp(Node->getOperand(0)));
+
+ // The high part is obtained by SRA'ing all but one of the bits of the lo
+ // part.
+ unsigned SrcSize = MVT::getSizeInBits(Node->getOperand(0).getValueType());
+ Hi = DAG.getNode(ISD::SRA, NVT, Lo, DAG.getConstant(SrcSize-1, MVT::i8));
+ break;
+ }
+ case ISD::ZERO_EXTEND:
+ // The low part is just a zero extension of the input (which degenerates to
+ // a copy).
+ Lo = DAG.getNode(ISD::ZERO_EXTEND, NVT, LegalizeOp(Node->getOperand(0)));
+
+ // The high part is just a zero.
+ Hi = DAG.getConstant(0, NVT);
+ break;
+ }
+
+ // Remember in a map if the values will be reused later.
+ if (!Node->hasOneUse()) {
+ bool isNew = ExpandedNodes.insert(std::make_pair(Op,
+ std::make_pair(Lo, Hi))).second;
+ assert(isNew && "Value already expanded?!?");
+ }
+ }
+
+
+ // SelectionDAG::Legalize - This is the entry point for the file.
+ //
+ void SelectionDAG::Legalize(TargetLowering &TLI) {
+ /// run - This is the main entry point to this class.
+ ///
+ SelectionDAGLegalize(TLI, *this).Run();
+ }
+
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