The last pieces needed for loading arbitrary
precision integers. This won't actually work
(and most of the code is dead) unless the new
legalization machinery is turned on. While
there, I rationalized the handling of i1, and
removed some bogus (and unused) sextload patterns.
For i1, this could result in microscopically
better code for some architectures (not X86).
It might also result in worse code if annotating
with AssertZExt nodes turns out to be more harmful
than helpful.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46280 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index 70dd97d..54cfad6 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -1820,76 +1820,188 @@
return Op.ResNo ? Tmp4 : Tmp3;
} else {
MVT::ValueType SrcVT = LD->getLoadedVT();
- switch (TLI.getLoadXAction(ExtType, SrcVT)) {
- default: assert(0 && "This action is not supported yet!");
- case TargetLowering::Promote:
- assert(SrcVT == MVT::i1 &&
- "Can only promote extending LOAD from i1 -> i8!");
- Result = DAG.getExtLoad(ExtType, Node->getValueType(0), Tmp1, Tmp2,
- LD->getSrcValue(), LD->getSrcValueOffset(),
- MVT::i8, LD->isVolatile(), LD->getAlignment());
- Tmp1 = Result.getValue(0);
- Tmp2 = Result.getValue(1);
- break;
- case TargetLowering::Custom:
- isCustom = true;
- // FALLTHROUGH
- case TargetLowering::Legal:
- Result = DAG.UpdateNodeOperands(Result, Tmp1, Tmp2, LD->getOffset());
- Tmp1 = Result.getValue(0);
- Tmp2 = Result.getValue(1);
-
- if (isCustom) {
- Tmp3 = TLI.LowerOperation(Result, DAG);
- if (Tmp3.Val) {
- Tmp1 = LegalizeOp(Tmp3);
- Tmp2 = LegalizeOp(Tmp3.getValue(1));
- }
+ unsigned SrcWidth = MVT::getSizeInBits(SrcVT);
+ int SVOffset = LD->getSrcValueOffset();
+ unsigned Alignment = LD->getAlignment();
+ bool isVolatile = LD->isVolatile();
+
+ if (SrcWidth != MVT::getStoreSizeInBits(SrcVT) &&
+ // Some targets pretend to have an i1 loading operation, and actually
+ // load an i8. This trick is correct for ZEXTLOAD because the top 7
+ // bits are guaranteed to be zero; it helps the optimizers understand
+ // that these bits are zero. It is also useful for EXTLOAD, since it
+ // tells the optimizers that those bits are undefined. It would be
+ // nice to have an effective generic way of getting these benefits...
+ // Until such a way is found, don't insist on promoting i1 here.
+ (SrcVT != MVT::i1 ||
+ TLI.getLoadXAction(ExtType, MVT::i1) == TargetLowering::Promote)) {
+ // Promote to a byte-sized load if not loading an integral number of
+ // bytes. For example, promote EXTLOAD:i20 -> EXTLOAD:i24.
+ unsigned NewWidth = MVT::getStoreSizeInBits(SrcVT);
+ MVT::ValueType NVT = MVT::getIntegerType(NewWidth);
+ SDOperand Ch;
+
+ // The extra bits are guaranteed to be zero, since we stored them that
+ // way. A zext load from NVT thus automatically gives zext from SrcVT.
+
+ ISD::LoadExtType NewExtType =
+ ExtType == ISD::ZEXTLOAD ? ISD::ZEXTLOAD : ISD::EXTLOAD;
+
+ Result = DAG.getExtLoad(NewExtType, Node->getValueType(0),
+ Tmp1, Tmp2, LD->getSrcValue(), SVOffset,
+ NVT, isVolatile, Alignment);
+
+ Ch = Result.getValue(1); // The chain.
+
+ if (ExtType == ISD::SEXTLOAD)
+ // Having the top bits zero doesn't help when sign extending.
+ Result = DAG.getNode(ISD::SIGN_EXTEND_INREG, Result.getValueType(),
+ Result, DAG.getValueType(SrcVT));
+ else if (ExtType == ISD::ZEXTLOAD || NVT == Result.getValueType())
+ // All the top bits are guaranteed to be zero - inform the optimizers.
+ Result = DAG.getNode(ISD::AssertZext, Result.getValueType(), Result,
+ DAG.getValueType(SrcVT));
+
+ Tmp1 = LegalizeOp(Result);
+ Tmp2 = LegalizeOp(Ch);
+ } else if (SrcWidth & (SrcWidth - 1)) {
+ // If not loading a power-of-2 number of bits, expand as two loads.
+ assert(MVT::isExtendedVT(SrcVT) && !MVT::isVector(SrcVT) &&
+ "Unsupported extload!");
+ unsigned RoundWidth = 1 << Log2_32(SrcWidth);
+ assert(RoundWidth < SrcWidth);
+ unsigned ExtraWidth = SrcWidth - RoundWidth;
+ assert(ExtraWidth < RoundWidth);
+ assert(!(RoundWidth % 8) && !(ExtraWidth % 8) &&
+ "Load size not an integral number of bytes!");
+ MVT::ValueType RoundVT = MVT::getIntegerType(RoundWidth);
+ MVT::ValueType ExtraVT = MVT::getIntegerType(ExtraWidth);
+ SDOperand Lo, Hi, Ch;
+ unsigned IncrementSize;
+
+ if (TLI.isLittleEndian()) {
+ // EXTLOAD:i24 -> ZEXTLOAD:i16 | (shl EXTLOAD@+2:i8, 16)
+ // Load the bottom RoundWidth bits.
+ Lo = DAG.getExtLoad(ISD::ZEXTLOAD, Node->getValueType(0), Tmp1, Tmp2,
+ LD->getSrcValue(), SVOffset, RoundVT, isVolatile,
+ Alignment);
+
+ // Load the remaining ExtraWidth bits.
+ IncrementSize = RoundWidth / 8;
+ Tmp2 = DAG.getNode(ISD::ADD, Tmp2.getValueType(), Tmp2,
+ DAG.getIntPtrConstant(IncrementSize));
+ Hi = DAG.getExtLoad(ExtType, Node->getValueType(0), Tmp1, Tmp2,
+ LD->getSrcValue(), SVOffset + IncrementSize,
+ ExtraVT, isVolatile,
+ MinAlign(Alignment, IncrementSize));
+
+ // Build a factor node to remember that this load is independent of the
+ // other one.
+ Ch = DAG.getNode(ISD::TokenFactor, MVT::Other, Lo.getValue(1),
+ Hi.getValue(1));
+
+ // Move the top bits to the right place.
+ Hi = DAG.getNode(ISD::SHL, Hi.getValueType(), Hi,
+ DAG.getConstant(RoundWidth, TLI.getShiftAmountTy()));
+
+ // Join the hi and lo parts.
+ Result = DAG.getNode(ISD::OR, Node->getValueType(0), Lo, Hi);
} else {
- // If this is an unaligned load and the target doesn't support it,
- // expand it.
- if (!TLI.allowsUnalignedMemoryAccesses()) {
- unsigned ABIAlignment = TLI.getTargetData()->
- getABITypeAlignment(MVT::getTypeForValueType(LD->getLoadedVT()));
- if (LD->getAlignment() < ABIAlignment){
- Result = ExpandUnalignedLoad(cast<LoadSDNode>(Result.Val), DAG,
- TLI);
- Tmp1 = Result.getOperand(0);
- Tmp2 = Result.getOperand(1);
- Tmp1 = LegalizeOp(Tmp1);
- Tmp2 = LegalizeOp(Tmp2);
+ // Big endian - avoid unaligned loads.
+ // EXTLOAD:i24 -> (shl EXTLOAD:i16, 8) | ZEXTLOAD@+2:i8
+ // Load the top RoundWidth bits.
+ Hi = DAG.getExtLoad(ExtType, Node->getValueType(0), Tmp1, Tmp2,
+ LD->getSrcValue(), SVOffset, RoundVT, isVolatile,
+ Alignment);
+
+ // Load the remaining ExtraWidth bits.
+ IncrementSize = RoundWidth / 8;
+ Tmp2 = DAG.getNode(ISD::ADD, Tmp2.getValueType(), Tmp2,
+ DAG.getIntPtrConstant(IncrementSize));
+ Lo = DAG.getExtLoad(ISD::ZEXTLOAD, Node->getValueType(0), Tmp1, Tmp2,
+ LD->getSrcValue(), SVOffset + IncrementSize,
+ ExtraVT, isVolatile,
+ MinAlign(Alignment, IncrementSize));
+
+ // Build a factor node to remember that this load is independent of the
+ // other one.
+ Ch = DAG.getNode(ISD::TokenFactor, MVT::Other, Lo.getValue(1),
+ Hi.getValue(1));
+
+ // Move the top bits to the right place.
+ Hi = DAG.getNode(ISD::SHL, Hi.getValueType(), Hi,
+ DAG.getConstant(ExtraWidth, TLI.getShiftAmountTy()));
+
+ // Join the hi and lo parts.
+ Result = DAG.getNode(ISD::OR, Node->getValueType(0), Lo, Hi);
+ }
+
+ Tmp1 = LegalizeOp(Result);
+ Tmp2 = LegalizeOp(Ch);
+ } else {
+ switch (TLI.getLoadXAction(ExtType, SrcVT)) {
+ default: assert(0 && "This action is not supported yet!");
+ case TargetLowering::Custom:
+ isCustom = true;
+ // FALLTHROUGH
+ case TargetLowering::Legal:
+ Result = DAG.UpdateNodeOperands(Result, Tmp1, Tmp2, LD->getOffset());
+ Tmp1 = Result.getValue(0);
+ Tmp2 = Result.getValue(1);
+
+ if (isCustom) {
+ Tmp3 = TLI.LowerOperation(Result, DAG);
+ if (Tmp3.Val) {
+ Tmp1 = LegalizeOp(Tmp3);
+ Tmp2 = LegalizeOp(Tmp3.getValue(1));
+ }
+ } else {
+ // If this is an unaligned load and the target doesn't support it,
+ // expand it.
+ if (!TLI.allowsUnalignedMemoryAccesses()) {
+ unsigned ABIAlignment = TLI.getTargetData()->
+ getABITypeAlignment(MVT::getTypeForValueType(LD->getLoadedVT()));
+ if (LD->getAlignment() < ABIAlignment){
+ Result = ExpandUnalignedLoad(cast<LoadSDNode>(Result.Val), DAG,
+ TLI);
+ Tmp1 = Result.getOperand(0);
+ Tmp2 = Result.getOperand(1);
+ Tmp1 = LegalizeOp(Tmp1);
+ Tmp2 = LegalizeOp(Tmp2);
+ }
}
}
- }
- break;
- case TargetLowering::Expand:
- // f64 = EXTLOAD f32 should expand to LOAD, FP_EXTEND
- if (SrcVT == MVT::f32 && Node->getValueType(0) == MVT::f64) {
- SDOperand Load = DAG.getLoad(SrcVT, Tmp1, Tmp2, LD->getSrcValue(),
- LD->getSrcValueOffset(),
- LD->isVolatile(), LD->getAlignment());
- Result = DAG.getNode(ISD::FP_EXTEND, Node->getValueType(0), Load);
- Tmp1 = LegalizeOp(Result); // Relegalize new nodes.
- Tmp2 = LegalizeOp(Load.getValue(1));
+ break;
+ case TargetLowering::Expand:
+ // f64 = EXTLOAD f32 should expand to LOAD, FP_EXTEND
+ if (SrcVT == MVT::f32 && Node->getValueType(0) == MVT::f64) {
+ SDOperand Load = DAG.getLoad(SrcVT, Tmp1, Tmp2, LD->getSrcValue(),
+ LD->getSrcValueOffset(),
+ LD->isVolatile(), LD->getAlignment());
+ Result = DAG.getNode(ISD::FP_EXTEND, Node->getValueType(0), Load);
+ Tmp1 = LegalizeOp(Result); // Relegalize new nodes.
+ Tmp2 = LegalizeOp(Load.getValue(1));
+ break;
+ }
+ assert(ExtType != ISD::EXTLOAD &&"EXTLOAD should always be supported!");
+ // Turn the unsupported load into an EXTLOAD followed by an explicit
+ // zero/sign extend inreg.
+ Result = DAG.getExtLoad(ISD::EXTLOAD, Node->getValueType(0),
+ Tmp1, Tmp2, LD->getSrcValue(),
+ LD->getSrcValueOffset(), SrcVT,
+ LD->isVolatile(), LD->getAlignment());
+ SDOperand ValRes;
+ if (ExtType == ISD::SEXTLOAD)
+ ValRes = DAG.getNode(ISD::SIGN_EXTEND_INREG, Result.getValueType(),
+ Result, DAG.getValueType(SrcVT));
+ else
+ ValRes = DAG.getZeroExtendInReg(Result, SrcVT);
+ Tmp1 = LegalizeOp(ValRes); // Relegalize new nodes.
+ Tmp2 = LegalizeOp(Result.getValue(1)); // Relegalize new nodes.
break;
}
- assert(ExtType != ISD::EXTLOAD &&"EXTLOAD should always be supported!");
- // Turn the unsupported load into an EXTLOAD followed by an explicit
- // zero/sign extend inreg.
- Result = DAG.getExtLoad(ISD::EXTLOAD, Node->getValueType(0),
- Tmp1, Tmp2, LD->getSrcValue(),
- LD->getSrcValueOffset(), SrcVT,
- LD->isVolatile(), LD->getAlignment());
- SDOperand ValRes;
- if (ExtType == ISD::SEXTLOAD)
- ValRes = DAG.getNode(ISD::SIGN_EXTEND_INREG, Result.getValueType(),
- Result, DAG.getValueType(SrcVT));
- else
- ValRes = DAG.getZeroExtendInReg(Result, SrcVT);
- Tmp1 = LegalizeOp(ValRes); // Relegalize new nodes.
- Tmp2 = LegalizeOp(Result.getValue(1)); // Relegalize new nodes.
- break;
}
+
// Since loads produce two values, make sure to remember that we legalized
// both of them.
AddLegalizedOperand(SDOperand(Node, 0), Tmp1);