+
+// Mechanism to get the descriptor for a CALL MachineInstr.
+// We get the LLVM CallInstr from the ret. addr. register argument
+// of the CALL MachineInstr (which is explicit operand #3 for indirect
+// calls or the last implicit operand for direct calls). We then get
+// the CallArgsDescriptor from the MachineCodeForInstruction object for
+// the CallInstr.
+// This is roundabout but avoids adding a new map or annotation just
+// to keep track of CallArgsDescriptors.
+//
+CallArgsDescriptor *CallArgsDescriptor::get(const MachineInstr* MI) {
+ const TmpInstruction* retAddrReg =
+ cast<TmpInstruction>(isa<Function>(MI->getOperand(0).getVRegValue())
+ ? MI->getImplicitRef(MI->getNumImplicitRefs()-1)
+ : MI->getOperand(2).getVRegValue());
+
+ assert(retAddrReg->getNumOperands() == 1 &&
+ isa<CallInst>(retAddrReg->getOperand(0)) &&
+ "Location of callInstr arg for CALL instr. changed? FIX THIS CODE!");
+
+ const CallInst* callInstr = cast<CallInst>(retAddrReg->getOperand(0));
+
+ CallArgsDescriptor* desc =
+ MachineCodeForInstruction::get(callInstr).getCallArgsDescriptor();
+ assert(desc->getCallInst()==callInstr && "Incorrect call args descriptor?");
+ return desc;
+}