//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "systemz-selectiondag-info"
#include "SystemZTargetMachine.h"
+#include "llvm/CodeGen/SelectionDAG.h"
+
using namespace llvm;
-SystemZSelectionDAGInfo::SystemZSelectionDAGInfo(const SystemZTargetMachine &TM)
- : TargetSelectionDAGInfo(TM) {
+#define DEBUG_TYPE "systemz-selectiondag-info"
+
+// Decide whether it is best to use a loop or straight-line code for
+// a block operation of Size bytes with source address Src and destination
+// address Dest. Sequence is the opcode to use for straight-line code
+// (such as MVC) and Loop is the opcode to use for loops (such as MVC_LOOP).
+// Return the chain for the completed operation.
+static SDValue emitMemMem(SelectionDAG &DAG, SDLoc DL, unsigned Sequence,
+ unsigned Loop, SDValue Chain, SDValue Dst,
+ SDValue Src, uint64_t Size) {
+ EVT PtrVT = Src.getValueType();
+ // The heuristic we use is to prefer loops for anything that would
+ // require 7 or more MVCs. With these kinds of sizes there isn't
+ // much to choose between straight-line code and looping code,
+ // since the time will be dominated by the MVCs themselves.
+ // However, the loop has 4 or 5 instructions (depending on whether
+ // the base addresses can be proved equal), so there doesn't seem
+ // much point using a loop for 5 * 256 bytes or fewer. Anything in
+ // the range (5 * 256, 6 * 256) will need another instruction after
+ // the loop, so it doesn't seem worth using a loop then either.
+ // The next value up, 6 * 256, can be implemented in the same
+ // number of straight-line MVCs as 6 * 256 - 1.
+ if (Size > 6 * 256)
+ return DAG.getNode(Loop, DL, MVT::Other, Chain, Dst, Src,
+ DAG.getConstant(Size, DL, PtrVT),
+ DAG.getConstant(Size / 256, DL, PtrVT));
+ return DAG.getNode(Sequence, DL, MVT::Other, Chain, Dst, Src,
+ DAG.getConstant(Size, DL, PtrVT));
+}
+
+SDValue SystemZSelectionDAGInfo::
+EmitTargetCodeForMemcpy(SelectionDAG &DAG, SDLoc DL, SDValue Chain,
+ SDValue Dst, SDValue Src, SDValue Size, unsigned Align,
+ bool IsVolatile, bool AlwaysInline,
+ MachinePointerInfo DstPtrInfo,
+ MachinePointerInfo SrcPtrInfo) const {
+ if (IsVolatile)
+ return SDValue();
+
+ if (auto *CSize = dyn_cast<ConstantSDNode>(Size))
+ return emitMemMem(DAG, DL, SystemZISD::MVC, SystemZISD::MVC_LOOP,
+ Chain, Dst, Src, CSize->getZExtValue());
+ return SDValue();
+}
+
+// Handle a memset of 1, 2, 4 or 8 bytes with the operands given by
+// Chain, Dst, ByteVal and Size. These cases are expected to use
+// MVI, MVHHI, MVHI and MVGHI respectively.
+static SDValue memsetStore(SelectionDAG &DAG, SDLoc DL, SDValue Chain,
+ SDValue Dst, uint64_t ByteVal, uint64_t Size,
+ unsigned Align,
+ MachinePointerInfo DstPtrInfo) {
+ uint64_t StoreVal = ByteVal;
+ for (unsigned I = 1; I < Size; ++I)
+ StoreVal |= ByteVal << (I * 8);
+ return DAG.getStore(Chain, DL,
+ DAG.getConstant(StoreVal, DL,
+ MVT::getIntegerVT(Size * 8)),
+ Dst, DstPtrInfo, false, false, Align);
+}
+
+SDValue SystemZSelectionDAGInfo::
+EmitTargetCodeForMemset(SelectionDAG &DAG, SDLoc DL, SDValue Chain,
+ SDValue Dst, SDValue Byte, SDValue Size,
+ unsigned Align, bool IsVolatile,
+ MachinePointerInfo DstPtrInfo) const {
+ EVT PtrVT = Dst.getValueType();
+
+ if (IsVolatile)
+ return SDValue();
+
+ if (auto *CSize = dyn_cast<ConstantSDNode>(Size)) {
+ uint64_t Bytes = CSize->getZExtValue();
+ if (Bytes == 0)
+ return SDValue();
+ if (auto *CByte = dyn_cast<ConstantSDNode>(Byte)) {
+ // Handle cases that can be done using at most two of
+ // MVI, MVHI, MVHHI and MVGHI. The latter two can only be
+ // used if ByteVal is all zeros or all ones; in other casees,
+ // we can move at most 2 halfwords.
+ uint64_t ByteVal = CByte->getZExtValue();
+ if (ByteVal == 0 || ByteVal == 255 ?
+ Bytes <= 16 && countPopulation(Bytes) <= 2 :
+ Bytes <= 4) {
+ unsigned Size1 = Bytes == 16 ? 8 : 1 << findLastSet(Bytes);
+ unsigned Size2 = Bytes - Size1;
+ SDValue Chain1 = memsetStore(DAG, DL, Chain, Dst, ByteVal, Size1,
+ Align, DstPtrInfo);
+ if (Size2 == 0)
+ return Chain1;
+ Dst = DAG.getNode(ISD::ADD, DL, PtrVT, Dst,
+ DAG.getConstant(Size1, DL, PtrVT));
+ DstPtrInfo = DstPtrInfo.getWithOffset(Size1);
+ SDValue Chain2 = memsetStore(DAG, DL, Chain, Dst, ByteVal, Size2,
+ std::min(Align, Size1), DstPtrInfo);
+ return DAG.getNode(ISD::TokenFactor, DL, MVT::Other, Chain1, Chain2);
+ }
+ } else {
+ // Handle one and two bytes using STC.
+ if (Bytes <= 2) {
+ SDValue Chain1 = DAG.getStore(Chain, DL, Byte, Dst, DstPtrInfo,
+ false, false, Align);
+ if (Bytes == 1)
+ return Chain1;
+ SDValue Dst2 = DAG.getNode(ISD::ADD, DL, PtrVT, Dst,
+ DAG.getConstant(1, DL, PtrVT));
+ SDValue Chain2 = DAG.getStore(Chain, DL, Byte, Dst2,
+ DstPtrInfo.getWithOffset(1),
+ false, false, 1);
+ return DAG.getNode(ISD::TokenFactor, DL, MVT::Other, Chain1, Chain2);
+ }
+ }
+ assert(Bytes >= 2 && "Should have dealt with 0- and 1-byte cases already");
+
+ // Handle the special case of a memset of 0, which can use XC.
+ auto *CByte = dyn_cast<ConstantSDNode>(Byte);
+ if (CByte && CByte->getZExtValue() == 0)
+ return emitMemMem(DAG, DL, SystemZISD::XC, SystemZISD::XC_LOOP,
+ Chain, Dst, Dst, Bytes);
+
+ // Copy the byte to the first location and then use MVC to copy
+ // it to the rest.
+ Chain = DAG.getStore(Chain, DL, Byte, Dst, DstPtrInfo,
+ false, false, Align);
+ SDValue DstPlus1 = DAG.getNode(ISD::ADD, DL, PtrVT, Dst,
+ DAG.getConstant(1, DL, PtrVT));
+ return emitMemMem(DAG, DL, SystemZISD::MVC, SystemZISD::MVC_LOOP,
+ Chain, DstPlus1, Dst, Bytes - 1);
+ }
+ return SDValue();
+}
+
+// Use CLC to compare [Src1, Src1 + Size) with [Src2, Src2 + Size),
+// deciding whether to use a loop or straight-line code.
+static SDValue emitCLC(SelectionDAG &DAG, SDLoc DL, SDValue Chain,
+ SDValue Src1, SDValue Src2, uint64_t Size) {
+ SDVTList VTs = DAG.getVTList(MVT::Other, MVT::Glue);
+ EVT PtrVT = Src1.getValueType();
+ // A two-CLC sequence is a clear win over a loop, not least because it
+ // needs only one branch. A three-CLC sequence needs the same number
+ // of branches as a loop (i.e. 2), but is shorter. That brings us to
+ // lengths greater than 768 bytes. It seems relatively likely that
+ // a difference will be found within the first 768 bytes, so we just
+ // optimize for the smallest number of branch instructions, in order
+ // to avoid polluting the prediction buffer too much. A loop only ever
+ // needs 2 branches, whereas a straight-line sequence would need 3 or more.
+ if (Size > 3 * 256)
+ return DAG.getNode(SystemZISD::CLC_LOOP, DL, VTs, Chain, Src1, Src2,
+ DAG.getConstant(Size, DL, PtrVT),
+ DAG.getConstant(Size / 256, DL, PtrVT));
+ return DAG.getNode(SystemZISD::CLC, DL, VTs, Chain, Src1, Src2,
+ DAG.getConstant(Size, DL, PtrVT));
+}
+
+// Convert the current CC value into an integer that is 0 if CC == 0,
+// less than zero if CC == 1 and greater than zero if CC >= 2.
+// The sequence starts with IPM, which puts CC into bits 29 and 28
+// of an integer and clears bits 30 and 31.
+static SDValue addIPMSequence(SDLoc DL, SDValue Glue, SelectionDAG &DAG) {
+ SDValue IPM = DAG.getNode(SystemZISD::IPM, DL, MVT::i32, Glue);
+ SDValue SRL = DAG.getNode(ISD::SRL, DL, MVT::i32, IPM,
+ DAG.getConstant(SystemZ::IPM_CC, DL, MVT::i32));
+ SDValue ROTL = DAG.getNode(ISD::ROTL, DL, MVT::i32, SRL,
+ DAG.getConstant(31, DL, MVT::i32));
+ return ROTL;
+}
+
+std::pair<SDValue, SDValue> SystemZSelectionDAGInfo::
+EmitTargetCodeForMemcmp(SelectionDAG &DAG, SDLoc DL, SDValue Chain,
+ SDValue Src1, SDValue Src2, SDValue Size,
+ MachinePointerInfo Op1PtrInfo,
+ MachinePointerInfo Op2PtrInfo) const {
+ if (auto *CSize = dyn_cast<ConstantSDNode>(Size)) {
+ uint64_t Bytes = CSize->getZExtValue();
+ assert(Bytes > 0 && "Caller should have handled 0-size case");
+ Chain = emitCLC(DAG, DL, Chain, Src1, Src2, Bytes);
+ SDValue Glue = Chain.getValue(1);
+ return std::make_pair(addIPMSequence(DL, Glue, DAG), Chain);
+ }
+ return std::make_pair(SDValue(), SDValue());
+}
+
+std::pair<SDValue, SDValue> SystemZSelectionDAGInfo::
+EmitTargetCodeForMemchr(SelectionDAG &DAG, SDLoc DL, SDValue Chain,
+ SDValue Src, SDValue Char, SDValue Length,
+ MachinePointerInfo SrcPtrInfo) const {
+ // Use SRST to find the character. End is its address on success.
+ EVT PtrVT = Src.getValueType();
+ SDVTList VTs = DAG.getVTList(PtrVT, MVT::Other, MVT::Glue);
+ Length = DAG.getZExtOrTrunc(Length, DL, PtrVT);
+ Char = DAG.getZExtOrTrunc(Char, DL, MVT::i32);
+ Char = DAG.getNode(ISD::AND, DL, MVT::i32, Char,
+ DAG.getConstant(255, DL, MVT::i32));
+ SDValue Limit = DAG.getNode(ISD::ADD, DL, PtrVT, Src, Length);
+ SDValue End = DAG.getNode(SystemZISD::SEARCH_STRING, DL, VTs, Chain,
+ Limit, Src, Char);
+ Chain = End.getValue(1);
+ SDValue Glue = End.getValue(2);
+
+ // Now select between End and null, depending on whether the character
+ // was found.
+ SDValue Ops[] = {End, DAG.getConstant(0, DL, PtrVT),
+ DAG.getConstant(SystemZ::CCMASK_SRST, DL, MVT::i32),
+ DAG.getConstant(SystemZ::CCMASK_SRST_FOUND, DL, MVT::i32),
+ Glue};
+ VTs = DAG.getVTList(PtrVT, MVT::Glue);
+ End = DAG.getNode(SystemZISD::SELECT_CCMASK, DL, VTs, Ops);
+ return std::make_pair(End, Chain);
+}
+
+std::pair<SDValue, SDValue> SystemZSelectionDAGInfo::
+EmitTargetCodeForStrcpy(SelectionDAG &DAG, SDLoc DL, SDValue Chain,
+ SDValue Dest, SDValue Src,
+ MachinePointerInfo DestPtrInfo,
+ MachinePointerInfo SrcPtrInfo, bool isStpcpy) const {
+ SDVTList VTs = DAG.getVTList(Dest.getValueType(), MVT::Other);
+ SDValue EndDest = DAG.getNode(SystemZISD::STPCPY, DL, VTs, Chain, Dest, Src,
+ DAG.getConstant(0, DL, MVT::i32));
+ return std::make_pair(isStpcpy ? EndDest : Dest, EndDest.getValue(1));
+}
+
+std::pair<SDValue, SDValue> SystemZSelectionDAGInfo::
+EmitTargetCodeForStrcmp(SelectionDAG &DAG, SDLoc DL, SDValue Chain,
+ SDValue Src1, SDValue Src2,
+ MachinePointerInfo Op1PtrInfo,
+ MachinePointerInfo Op2PtrInfo) const {
+ SDVTList VTs = DAG.getVTList(Src1.getValueType(), MVT::Other, MVT::Glue);
+ SDValue Unused = DAG.getNode(SystemZISD::STRCMP, DL, VTs, Chain, Src1, Src2,
+ DAG.getConstant(0, DL, MVT::i32));
+ Chain = Unused.getValue(1);
+ SDValue Glue = Chain.getValue(2);
+ return std::make_pair(addIPMSequence(DL, Glue, DAG), Chain);
+}
+
+// Search from Src for a null character, stopping once Src reaches Limit.
+// Return a pair of values, the first being the number of nonnull characters
+// and the second being the out chain.
+//
+// This can be used for strlen by setting Limit to 0.
+static std::pair<SDValue, SDValue> getBoundedStrlen(SelectionDAG &DAG, SDLoc DL,
+ SDValue Chain, SDValue Src,
+ SDValue Limit) {
+ EVT PtrVT = Src.getValueType();
+ SDVTList VTs = DAG.getVTList(PtrVT, MVT::Other, MVT::Glue);
+ SDValue End = DAG.getNode(SystemZISD::SEARCH_STRING, DL, VTs, Chain,
+ Limit, Src, DAG.getConstant(0, DL, MVT::i32));
+ Chain = End.getValue(1);
+ SDValue Len = DAG.getNode(ISD::SUB, DL, PtrVT, End, Src);
+ return std::make_pair(Len, Chain);
+}
+
+std::pair<SDValue, SDValue> SystemZSelectionDAGInfo::
+EmitTargetCodeForStrlen(SelectionDAG &DAG, SDLoc DL, SDValue Chain,
+ SDValue Src, MachinePointerInfo SrcPtrInfo) const {
+ EVT PtrVT = Src.getValueType();
+ return getBoundedStrlen(DAG, DL, Chain, Src, DAG.getConstant(0, DL, PtrVT));
}
-SystemZSelectionDAGInfo::~SystemZSelectionDAGInfo() {
+std::pair<SDValue, SDValue> SystemZSelectionDAGInfo::
+EmitTargetCodeForStrnlen(SelectionDAG &DAG, SDLoc DL, SDValue Chain,
+ SDValue Src, SDValue MaxLength,
+ MachinePointerInfo SrcPtrInfo) const {
+ EVT PtrVT = Src.getValueType();
+ MaxLength = DAG.getZExtOrTrunc(MaxLength, DL, PtrVT);
+ SDValue Limit = DAG.getNode(ISD::ADD, DL, PtrVT, Src, MaxLength);
+ return getBoundedStrlen(DAG, DL, Chain, Src, Limit);
}
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