cyclone/asm-test.c
2019-12-04 09:32:32 -05:00

33 lines
1.7 KiB
C

// Example from: https://stackoverflow.com/q/37502841/101258
int main()
{
const char* test = "test\n";
long dummyreg; /* dummyreg used to allow GCC to pick available register */
__asm__ __volatile__ (
"add $-128, %%rsp\n\t" /* Skip the current redzone */
"mov %%rsp, %[temp]\n\t" /* Copy RSP to available register */
"and $-16, %%rsp\n\t" /* Align stack to 16-byte boundary */
"mov %[test], %%rdi\n\t" /* RDI is address of string */
"xor %%eax, %%eax\n\t" /* Variadic function set AL. This case 0 */
"call printf\n\t"
"mov %[test], %%rdi\n\t" /* RDI is address of string again */
"xor %%eax, %%eax\n\t" /* Variadic function set AL. This case 0 */
"call printf\n\t"
"mov %[temp], %%rsp\n\t" /* Restore RSP */
"sub $-128, %%rsp\n\t" /* Add 128 to RSP to restore to orig */
: [temp]"=&r"(dummyreg) /* Allow GCC to pick available output register. Modified
before all inputs consumed so use & for early clobber*/
: [test]"r"(test), /* Choose available register as input operand */
"m"(test) /* Dummy constraint to make sure test array
is fully realized in memory before inline
assembly is executed */
: "rax", "rcx", "rdx", "rsi", "rdi", "r8", "r9", "r10", "r11",
"xmm0","xmm1", "xmm2", "xmm3", "xmm4", "xmm5", "xmm6", "xmm7",
"xmm8","xmm9", "xmm10", "xmm11", "xmm12", "xmm13", "xmm14", "xmm15",
"mm0","mm1", "mm2", "mm3", "mm4", "mm5", "mm6", "mm6",
"st", "st(1)", "st(2)", "st(3)", "st(4)", "st(5)", "st(6)", "st(7)"
);
return 0;
}