// put rt_val into rt, potentially making use of rs with value rs_val
static void emit_movimm_from(u_int rs_val,int rs,u_int rt_val,int rt)
{
- u_int xor=rs_val^rt_val;
+ u_int armval;
+ int diff;
+ if(genimm(rt_val,&armval)) {
+ assem_debug("mov %s,#%d\n",regname[rt],rt_val);
+ output_w32(0xe3a00000|rd_rn_rm(rt,0,0)|armval);
+ return;
+ }
+ if(genimm(~rt_val,&armval)) {
+ assem_debug("mvn %s,#%d\n",regname[rt],rt_val);
+ output_w32(0xe3e00000|rd_rn_rm(rt,0,0)|armval);
+ return;
+ }
+ diff=rt_val-rs_val;
+ if(genimm(diff,&armval)) {
+ assem_debug("add %s,%s,#%d\n",regname[rt],regname[rs],diff);
+ output_w32(0xe2800000|rd_rn_rm(rt,rs,0)|armval);
+ return;
+ }else if(genimm(-diff,&armval)) {
+ assem_debug("sub %s,%s,#%d\n",regname[rt],regname[rs],-diff);
+ output_w32(0xe2400000|rd_rn_rm(rt,rs,0)|armval);
+ return;
+ }
+ emit_movimm(rt_val,rt);
+}
+
+// return 1 if above function can do it's job cheaply
+static int is_similar_value(u_int v1,u_int v2)
+{
u_int xs;
- for(xs=xor;xs!=0&&(xs&3)==0;xs>>=2)
+ int diff;
+ if(v1==v2) return 1;
+ diff=v2-v1;
+ for(xs=diff;xs!=0&&(xs&3)==0;xs>>=2)
;
- if(xs<0x100)
- emit_xorimm(rs,xor,rt);
- else
- emit_movimm(rt_val,rt);
+ if(xs<0x100) return 1;
+ for(xs=-diff;xs!=0&&(xs&3)==0;xs>>=2)
+ ;
+ if(xs<0x100) return 1;
+ return 0;
}
// trashes r2