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From: William Tambe <tambewilliam@gmail.com>
Date: Sat, 12 Sep 2020 15:17:03 -0500
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Subject: Unconditional trap
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I am currently using following for trap instruction:

(define_insn "trap"
  [(trap_if (const_int 1) (const_int 0))]
  ""
  "brk")

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 ?