Ian I have one query. I can use a hard register for this task. But will it allow me to modify the memory location, between original return address and saved frame pointer, stored in it? I think it will be just saved in the "saved registers" area of stack. The assembly conversion of the prologue I need is: POP EAX ; new prologue start PUSH EAX ; unencrypted return address PUSH EAX ; duplicate return address PUSH EBP ; standard prologue MOVE EBP, ESP XOR [EBP+4], EBP ; [EBP+4] has EIP and XOR encryptes ret addr(EIP) I want to know the function which allows me to write a value at a memory address specified by a variable (generated by gen_rtx_MEM). I thought force_reg is the one. Now, can I use ebx/ecx/...etc register for the purpose. OR will copy_to_mode_reg() function do the job? OR is there any other function to do the job? On Wed, Apr 14, 2010 at 10:40 AM, Ian Lance Taylor <iant@xxxxxxxxxx> wrote: > Vaibhav Shrimali <vaibhav.shrimali@xxxxxxxxx> writes: > >> I am performing this task in the prologue in the section where the >> hard frame pointer is pushed on the stack. > > This is after register allocation, so you can not use force_reg. > >> If not, please tell me how and where can I allocate the register and >> then use my code accordingly. > > You have to figure out a hard register to use. It should be safe to > use any call used register in the prologue, as long as it is not being > used for anything else in the prologue. If you want this to be > generally useful, watch out for the regparm attribute. The prologue > code is full of examples of using registers; read it and understand > what it is doing. > > Ian > -- Vaibhav Shrimali BTech(ICT), DA-IICT Gandhinagar
