#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/SelectionDAGISel.h"
+#include "llvm/IR/Constants.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Support/Endian.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
+
using namespace llvm;
#define DEBUG_TYPE "bpf-isel"
return "BPF DAG->DAG Pattern Instruction Selection";
}
+ void PreprocessISelDAG() override;
+
private:
// Include the pieces autogenerated from the target description.
#include "BPFGenDAGISel.inc"
// Complex Pattern for address selection.
bool SelectAddr(SDValue Addr, SDValue &Base, SDValue &Offset);
bool SelectFIAddr(SDValue Addr, SDValue &Base, SDValue &Offset);
+
+ // Find constants from a constant structure
+ typedef std::vector<unsigned char> val_vec_type;
+ bool fillGenericConstant(const DataLayout &DL, const Constant *CV,
+ val_vec_type &Vals, uint64_t Offset);
+ bool fillConstantDataArray(const DataLayout &DL, const ConstantDataArray *CDA,
+ val_vec_type &Vals, int Offset);
+ bool fillConstantArray(const DataLayout &DL, const ConstantArray *CA,
+ val_vec_type &Vals, int Offset);
+ bool fillConstantStruct(const DataLayout &DL, const ConstantStruct *CS,
+ val_vec_type &Vals, int Offset);
+ bool getConstantFieldValue(const GlobalAddressSDNode *Node, uint64_t Offset,
+ uint64_t Size, unsigned char *ByteSeq);
+
+ // Mapping from ConstantStruct global value to corresponding byte-list values
+ std::map<const void *, val_vec_type> cs_vals_;
};
-}
+} // namespace
// ComplexPattern used on BPF Load/Store instructions
bool BPFDAGToDAGISel::SelectAddr(SDValue Addr, SDValue &Base, SDValue &Offset) {
// if Address is FI, get the TargetFrameIndex.
SDLoc DL(Addr);
if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>(Addr)) {
- Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), MVT::i64);
+ Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), MVT::i64);
Offset = CurDAG->getTargetConstant(0, DL, MVT::i64);
return true;
}
}
}
- Base = Addr;
+ Base = Addr;
Offset = CurDAG->getTargetConstant(0, DL, MVT::i64);
return true;
}
// ComplexPattern used on BPF FI instruction
-bool BPFDAGToDAGISel::SelectFIAddr(SDValue Addr, SDValue &Base, SDValue &Offset) {
+bool BPFDAGToDAGISel::SelectFIAddr(SDValue Addr, SDValue &Base,
+ SDValue &Offset) {
SDLoc DL(Addr);
if (!CurDAG->isBaseWithConstantOffset(Addr))
if (isInt<16>(CN->getSExtValue())) {
// If the first operand is a FI, get the TargetFI Node
- if (FrameIndexSDNode *FIN =
- dyn_cast<FrameIndexSDNode>(Addr.getOperand(0)))
+ if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>(Addr.getOperand(0)))
Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), MVT::i64);
else
return false;
// tablegen selection should be handled here.
switch (Opcode) {
- default: break;
+ default:
+ break;
case ISD::SDIV: {
DebugLoc Empty;
const DebugLoc &DL = Node->getDebugLoc();
SelectCode(Node);
}
+void BPFDAGToDAGISel::PreprocessISelDAG() {
+ // Iterate through all nodes, only interested in loads from ConstantStruct
+ // ConstantArray should have converted by IR->DAG processing
+ for (SelectionDAG::allnodes_iterator I = CurDAG->allnodes_begin(),
+ E = CurDAG->allnodes_end();
+ I != E;) {
+ SDNode *Node = &*I++;
+ unsigned Opcode = Node->getOpcode();
+ if (Opcode != ISD::LOAD)
+ continue;
+
+ unsigned char new_val[8]; // hold up the constant values replacing loads.
+ bool to_replace = false;
+ SDLoc DL(Node);
+ const LoadSDNode *LD = cast<LoadSDNode>(Node);
+ uint64_t size = LD->getMemOperand()->getSize();
+ if (!size || size > 8 || (size & (size - 1)))
+ continue;
+
+ SDNode *LDAddrNode = LD->getOperand(1).getNode();
+ // Match LDAddr against either global_addr or (global_addr + offset)
+ unsigned opcode = LDAddrNode->getOpcode();
+ if (opcode == ISD::ADD) {
+ SDValue OP1 = LDAddrNode->getOperand(0);
+ SDValue OP2 = LDAddrNode->getOperand(1);
+
+ // We want to find the pattern global_addr + offset
+ SDNode *OP1N = OP1.getNode();
+ if (OP1N->getOpcode() <= ISD::BUILTIN_OP_END ||
+ OP1N->getNumOperands() == 0)
+ continue;
+
+ DEBUG(dbgs() << "Check candidate load: "; LD->dump(); dbgs() << '\n');
+
+ const GlobalAddressSDNode *GADN =
+ dyn_cast<GlobalAddressSDNode>(OP1N->getOperand(0).getNode());
+ const ConstantSDNode *CDN = dyn_cast<ConstantSDNode>(OP2.getNode());
+ if (GADN && CDN)
+ to_replace =
+ getConstantFieldValue(GADN, CDN->getZExtValue(), size, new_val);
+ } else if (LDAddrNode->getOpcode() > ISD::BUILTIN_OP_END &&
+ LDAddrNode->getNumOperands() > 0) {
+ DEBUG(dbgs() << "Check candidate load: "; LD->dump(); dbgs() << '\n');
+
+ SDValue OP1 = LDAddrNode->getOperand(0);
+ if (const GlobalAddressSDNode *GADN =
+ dyn_cast<GlobalAddressSDNode>(OP1.getNode()))
+ to_replace = getConstantFieldValue(GADN, 0, size, new_val);
+ }
+
+ if (!to_replace)
+ continue;
+
+ // replacing the old with a new value
+ uint64_t val;
+ if (size == 1)
+ val = *(uint8_t *)new_val;
+ else if (size == 2)
+ val = *(uint16_t *)new_val;
+ else if (size == 4)
+ val = *(uint32_t *)new_val;
+ else {
+ val = *(uint64_t *)new_val;
+ }
+
+ DEBUG(dbgs() << "Replacing load of size " << size << " with constant "
+ << val << '\n');
+ SDValue NVal = CurDAG->getConstant(val, DL, MVT::i64);
+
+ // After replacement, the current node is dead, we need to
+ // go backward one step to make iterator still work
+ I--;
+ SDValue From[] = {SDValue(Node, 0), SDValue(Node, 1)};
+ SDValue To[] = {NVal, NVal};
+ CurDAG->ReplaceAllUsesOfValuesWith(From, To, 2);
+ I++;
+ // It is safe to delete node now
+ CurDAG->DeleteNode(Node);
+ }
+}
+
+bool BPFDAGToDAGISel::getConstantFieldValue(const GlobalAddressSDNode *Node,
+ uint64_t Offset, uint64_t Size,
+ unsigned char *ByteSeq) {
+ const GlobalVariable *V = dyn_cast<GlobalVariable>(Node->getGlobal());
+
+ if (!V || !V->hasInitializer())
+ return false;
+
+ const Constant *Init = V->getInitializer();
+ const DataLayout &DL = CurDAG->getDataLayout();
+ val_vec_type TmpVal;
+
+ auto it = cs_vals_.find(static_cast<const void *>(Init));
+ if (it != cs_vals_.end()) {
+ TmpVal = it->second;
+ } else {
+ uint64_t total_size = 0;
+ if (const ConstantStruct *CS = dyn_cast<ConstantStruct>(Init))
+ total_size =
+ DL.getStructLayout(cast<StructType>(CS->getType()))->getSizeInBytes();
+ else if (const ConstantArray *CA = dyn_cast<ConstantArray>(Init))
+ total_size = DL.getTypeAllocSize(CA->getType()->getElementType()) *
+ CA->getNumOperands();
+ else
+ return false;
+
+ val_vec_type Vals(total_size, 0);
+ if (fillGenericConstant(DL, Init, Vals, 0) == false)
+ return false;
+ cs_vals_[static_cast<const void *>(Init)] = Vals;
+ TmpVal = std::move(Vals);
+ }
+
+ // test whether host endianness matches target
+ uint8_t test_buf[2];
+ uint16_t test_val = 0x2345;
+ if (DL.isLittleEndian())
+ support::endian::write16le(test_buf, test_val);
+ else
+ support::endian::write16be(test_buf, test_val);
+
+ bool endian_match = *(uint16_t *)test_buf == test_val;
+ for (uint64_t i = Offset, j = 0; i < Offset + Size; i++, j++)
+ ByteSeq[j] = endian_match ? TmpVal[i] : TmpVal[Offset + Size - 1 - j];
+
+ return true;
+}
+
+bool BPFDAGToDAGISel::fillGenericConstant(const DataLayout &DL,
+ const Constant *CV,
+ val_vec_type &Vals, uint64_t Offset) {
+ uint64_t Size = DL.getTypeAllocSize(CV->getType());
+
+ if (isa<ConstantAggregateZero>(CV) || isa<UndefValue>(CV))
+ return true; // already done
+
+ if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV)) {
+ uint64_t val = CI->getZExtValue();
+ DEBUG(dbgs() << "Byte array at offset " << Offset << " with value " << val
+ << '\n');
+
+ if (Size > 8 || (Size & (Size - 1)))
+ return false;
+
+ // Store based on target endian
+ for (uint64_t i = 0; i < Size; ++i) {
+ Vals[Offset + i] = DL.isLittleEndian()
+ ? ((val >> (i * 8)) & 0xFF)
+ : ((val >> ((Size - i - 1) * 8)) & 0xFF);
+ }
+ return true;
+ }
+
+ if (const ConstantDataArray *CDA = dyn_cast<ConstantDataArray>(CV))
+ return fillConstantDataArray(DL, CDA, Vals, Offset);
+
+ if (const ConstantArray *CA = dyn_cast<ConstantArray>(CV))
+ return fillConstantArray(DL, CA, Vals, Offset);
+
+ if (const ConstantStruct *CVS = dyn_cast<ConstantStruct>(CV))
+ return fillConstantStruct(DL, CVS, Vals, Offset);
+
+ return false;
+}
+
+bool BPFDAGToDAGISel::fillConstantDataArray(const DataLayout &DL,
+ const ConstantDataArray *CDA,
+ val_vec_type &Vals, int Offset) {
+ for (unsigned i = 0, e = CDA->getNumElements(); i != e; ++i) {
+ if (fillGenericConstant(DL, CDA->getElementAsConstant(i), Vals, Offset) ==
+ false)
+ return false;
+ Offset += DL.getTypeAllocSize(CDA->getElementAsConstant(i)->getType());
+ }
+
+ return true;
+}
+
+bool BPFDAGToDAGISel::fillConstantArray(const DataLayout &DL,
+ const ConstantArray *CA,
+ val_vec_type &Vals, int Offset) {
+ for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i) {
+ if (fillGenericConstant(DL, CA->getOperand(i), Vals, Offset) == false)
+ return false;
+ Offset += DL.getTypeAllocSize(CA->getOperand(i)->getType());
+ }
+
+ return true;
+}
+
+bool BPFDAGToDAGISel::fillConstantStruct(const DataLayout &DL,
+ const ConstantStruct *CS,
+ val_vec_type &Vals, int Offset) {
+ const StructLayout *Layout = DL.getStructLayout(CS->getType());
+ for (unsigned i = 0, e = CS->getNumOperands(); i != e; ++i) {
+ const Constant *Field = CS->getOperand(i);
+ uint64_t SizeSoFar = Layout->getElementOffset(i);
+ if (fillGenericConstant(DL, Field, Vals, Offset + SizeSoFar) == false)
+ return false;
+ }
+ return true;
+}
+
FunctionPass *llvm::createBPFISelDag(BPFTargetMachine &TM) {
return new BPFDAGToDAGISel(TM);
}
projects / llvm / commitdiff