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improvement in registerization 

R=r
OCL=29317
CL=29317
This commit is contained in:
Ken Thompson 2009-05-23 16:36:43 -07:00
parent 4238b18344
commit 798b19bf77
1 changed files with 56 additions and 14 deletions
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70
src/cmd/6g/reg.c
View File

@ -748,11 +748,40 @@ doregbits(int r)
return b;
}
static int
overlap(Var *v, int o2, int w2)
{
int o1, w1, t1, t2, z;
Bits bit;
o1 = v->offset;
w1 = v->width;
t1 = o1+w1;
t2 = o2+w2;
if(!(t1 > o2 && t2 > o1))
return 0;
// set to max extent
if(o2 < o1)
v->offset = o2;
if(t1 > t2)
v->width = t1-v->offset;
else
v->width = t2-v->offset;
// and dont registerize
bit = blsh(v-var);
for(z=0; z<BITS; z++)
addrs.b[z] |= bit.b[z];
return 1;
}
Bits
mkvar(Reg *r, Adr *a)
{
Var *v;
int i, t, n, et, z, w;
int i, t, n, et, z, w, flag;
int32 o;
Bits bit;
Sym *s;
@ -793,12 +822,26 @@ mkvar(Reg *r, Adr *a)
o = a->offset;
w = a->width;
v = var;
flag = 0;
for(i=0; i<nvar; i++) {
if(s == v->sym)
if(n == v->name)
goto out;
if(n == v->name) {
// if it is the same, use it
if(v->etype == et)
if(v->width == w)
if(v->offset == o)
goto out;
// if it overlaps, set max
// width and dont registerize
if(overlap(v, o, w))
flag = 1;
}
v++;
}
if(flag)
goto none;
switch(et) {
case 0:
@ -826,18 +869,9 @@ mkvar(Reg *r, Adr *a)
out:
bit = blsh(i);
if(n == D_EXTERN || n == D_STATIC)
for(z=0; z<BITS; z++)
externs.b[z] |= bit.b[z];
if(n == D_PARAM)
for(z=0; z<BITS; z++)
params.b[z] |= bit.b[z];
// this has horrible consequences -
// no structure elements are registerized,
// but i dont know how to be more specific
if(v->etype != et || v->width != w || v->offset != o) {
/* funny punning */
// funny punning
if(v->etype != et) {
if(debug['R'])
print("pun et=%d/%d w=%d/%d o=%d/%d %D\n",
v->etype, et,
@ -845,8 +879,16 @@ out:
v->offset, o, a);
for(z=0; z<BITS; z++)
addrs.b[z] |= bit.b[z];
goto none;
}
if(n == D_EXTERN || n == D_STATIC)
for(z=0; z<BITS; z++)
externs.b[z] |= bit.b[z];
if(n == D_PARAM)
for(z=0; z<BITS; z++)
params.b[z] |= bit.b[z];
return bit;
none: