Hi!
On Sat, Sep 12, 2020 at 03:17:03PM -0500, William Tambe via Gcc-help wrote:
> I am currently using following for trap instruction:
>
> (define_insn "trap"
> [(trap_if (const_int 1) (const_int 0))]
> ""
> "brk")
This looks fine.
> However it causes the compiler to generate a trap when address 0 is
> used; in the example below, I have a function that prints characters
> through the UART using address 0; but the resulting assembly generates
> a function that traps instead.
>
> #define UART_ADDR 0
> void uart_print (char *s) {
> while (*s) {
> *(volatile char *)UART_ADDR = *s;
> ++s;
> }
> }
>
> How can one implement unconditional trap ?
You should implement TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID to make 0 a
valid address.
Segher
