int DwarfInstructions<A, R>::stepWithDwarf(A &addressSpace, pint_t pc,
pint_t fdeStart, R ®isters) {
FDE_Info fdeInfo;
CIE_Info cieInfo;
if (CFI_Parser<A>::decodeFDE(addressSpace, fdeStart,
&fdeInfo, &cieInfo) == NULL) {
PrologInfo prolog;
if (CFI_Parser<A>::parseFDEInstructions(addressSpace, fdeInfo, cieInfo, pc,
&prolog)) {
// get pointer to cfa (architecture specific)
pint_t cfa = getCFA(addressSpace, prolog, registers);
// restore registers that dwarf says were saved
R newRegisters = registers;
pint_t returnAddress = 0;
const int lastReg = R::lastDwarfRegNum();
assert((int)CFI_Parser<A>::kMaxRegisterNumber > lastReg
&& "register range too large");
assert(lastReg <= (int)cieInfo.returnAddressRegister
&& "register range does not contain return address register");
for (int i = 0; i <= lastReg; ++i) {
if (prolog.savedRegisters[i].location !=
CFI_Parser<A>::kRegisterUnused) {
if (registers.validFloatRegister(i))
newRegisters.setFloatRegister(
i, getSavedFloatRegister(addressSpace, registers, cfa,
prolog.savedRegisters[i]));
else if (registers.validVectorRegister(i))
newRegisters.setVectorRegister(
i, getSavedVectorRegister(addressSpace, registers, cfa,
prolog.savedRegisters[i]));
else if (i == (int)cieInfo.returnAddressRegister)
returnAddress = getSavedRegister(addressSpace, registers, cfa,
prolog.savedRegisters[i]);
else if (registers.validRegister(i))
newRegisters.setRegister(
i, getSavedRegister(addressSpace, registers, cfa,
prolog.savedRegisters[i]));
else
return UNW_EBADREG;
}
}
// By definition, the CFA is the stack pointer at the call site, so
// restoring SP means setting it to CFA.
newRegisters.setSP(cfa);
// Return address is address after call site instruction, so setting IP to
// that does simualates a return.
newRegisters.setIP(returnAddress);
// Simulate the step by replacing the register set with the new ones.
registers = newRegisters;
return UNW_STEP_SUCCESS;
}
}
return UNW_EBADFRAME;
}
step_result DwarfInstructions<A, R>::stepWithDwarf(A &addressSpace, pint_t pc,
pint_t fdeStart,
R ®isters,
unw_proc_info_t *ctx) {
typename CFI_Parser<A, R>::FDE_Info fdeInfo;
typename CFI_Parser<A, R>::CIE_Info cieInfo;
if (!CFI_Parser<A, R>::decodeFDE(addressSpace, fdeStart, &fdeInfo, &cieInfo,
ctx))
return UNW_STEP_FAILED;
typename CFI_Parser<A, R>::PrologInfo prolog;
if (!CFI_Parser<A, R>::parseFDEInstructions(addressSpace, fdeInfo, cieInfo,
pc, &prolog, ctx))
return UNW_STEP_FAILED;
// Create working copy of the register set.
R newRegisters = registers;
// Get pointer to CFA by the architecture-specific code.
pint_t cfa = getCFA(addressSpace, prolog, registers);
// Restore registers according to DWARF instructions
pint_t returnAddress = 0;
for (int i = 0; i <= lastRestoreReg(newRegisters); ++i) {
if (prolog.savedRegisters[i].location == CFI_Parser<A, R>::kRegisterUnused)
continue;
if (i == (int)cieInfo.returnAddressRegister)
returnAddress = getSavedRegister(addressSpace, registers, cfa,
prolog.savedRegisters[i]);
else if (registers.validRegister(i))
newRegisters.setRegister(i, getSavedRegister(addressSpace, registers, cfa,
prolog.savedRegisters[i]));
else if (registers.validFloatVectorRegister(i))
newRegisters.copyFloatVectorRegister(
i, computeRegisterLocation(addressSpace, registers, cfa,
prolog.savedRegisters[i]));
else
return UNW_STEP_FAILED;
}
// The CFA is defined as the stack pointer at the call site.
// Therefore the SP is restored by setting it to the CFA.
newRegisters.setSP(cfa);
newRegisters.setIP(returnAddress + R::RETURN_OFFSET);
returnAddress += R::RETURN_OFFSET;
returnAddress &= ~R::RETURN_MASK;
newRegisters.setIP(returnAddress);
// Now replace register set with the working copy.
registers = newRegisters;
return UNW_STEP_SUCCESS;
}
