commit 185f18ae490552cb8e16e23c6c9f145b55d2f101 parent da6f12fa617d04c526120ae4f53b873ac17519c1 Author: Nihal Jere <nihal@nihaljere.xyz> Date: Mon, 10 Jan 2022 14:39:01 -0600 ir: replace regalloc loop with ffs Diffstat:
| M | ir.c | | | 17 | ++++++++--------- |
1 file changed, 8 insertions(+), 9 deletions(-)
diff --git a/ir.c b/ir.c @@ -3,6 +3,7 @@ #include <stddef.h> #include <stdint.h> #include <stdio.h> +#include <strings.h> #include "array.h" #include "nooc.h" @@ -33,17 +34,15 @@ uint64_t out_index; static uint8_t regalloc() { - // FIXME: can probably use ffs or something - for (uint8_t i = 0; i < 16; i++) { - if (regs & (1 << i)) - continue; + int free = ffs(~regs); + if (!free) + die("out of registers!"); - regs |= (1 << i); - return i; - } + // the nth register being free corresponds to shifting by n-1 + free--; + regs |= (1 << free); - die("out of registers!"); - return 0; + return free; } static void