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//===-------------- BPFMIChecking.cpp - MI Checking Legality -------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass performs checking to signal errors for certain illegal usages at
// MachineInstruction layer. Specially, the result of XADD{32,64} insn should
// not be used. The pass is done at the PreEmit pass right before the
// machine code is emitted at which point the register liveness information
// is still available.
//
//===----------------------------------------------------------------------===//
#include "BPF.h"
#include "BPFInstrInfo.h"
#include "BPFTargetMachine.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
using namespace llvm;
#define DEBUG_TYPE "bpf-mi-checking"
namespace {
struct BPFMIPreEmitChecking : public MachineFunctionPass {
static char ID;
MachineFunction *MF;
const TargetRegisterInfo *TRI;
BPFMIPreEmitChecking() : MachineFunctionPass(ID) {
initializeBPFMIPreEmitCheckingPass(*PassRegistry::getPassRegistry());
}
private:
// Initialize class variables.
void initialize(MachineFunction &MFParm);
void checkingIllegalXADD(void);
public:
// Main entry point for this pass.
bool runOnMachineFunction(MachineFunction &MF) override {
if (!skipFunction(MF.getFunction())) {
initialize(MF);
checkingIllegalXADD();
}
return false;
}
};
// Initialize class variables.
void BPFMIPreEmitChecking::initialize(MachineFunction &MFParm) {
MF = &MFParm;
TRI = MF->getSubtarget<BPFSubtarget>().getRegisterInfo();
LLVM_DEBUG(dbgs() << "*** BPF PreEmit checking pass ***\n\n");
}
void BPFMIPreEmitChecking::checkingIllegalXADD(void) {
for (MachineBasicBlock &MBB : *MF) {
for (MachineInstr &MI : MBB) {
if (MI.getOpcode() != BPF::XADD32 && MI.getOpcode() != BPF::XADD64)
continue;
LLVM_DEBUG(MI.dump());
if (!MI.allDefsAreDead()) {
DebugLoc Empty;
const DebugLoc &DL = MI.getDebugLoc();
if (DL != Empty)
report_fatal_error("line " + std::to_string(DL.getLine()) +
": Invalid usage of the XADD return value", false);
else
report_fatal_error("Invalid usage of the XADD return value", false);
}
}
}
return;
}
} // end default namespace
INITIALIZE_PASS(BPFMIPreEmitChecking, "bpf-mi-pemit-checking",
"BPF PreEmit Checking", false, false)
char BPFMIPreEmitChecking::ID = 0;
FunctionPass* llvm::createBPFMIPreEmitCheckingPass()
{
return new BPFMIPreEmitChecking();
}
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