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Lor takes advantave of STUFF_OK_47 

It is ot uncommon for the arguments to logical or to leave stuff
in bit registers 4-7. Allow the lor itself to take advantage of
that to save some %mov instructions.
This commit is contained in:
Stephen Williams 2008-11-22 10:45:15 -08:00
parent bc8b97dbcd
commit 83a7497912
1 changed files with 31 additions and 8 deletions
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39
tgt-vvp/eval_expr.c
View File

@ -475,7 +475,7 @@ static struct vector_info draw_binary_expr_eq(ivl_expr_t exp,
assert(0);
}
if ((stuff_ok_flag&STUFF_OK_47) && (wid == 1)) {
if ((stuff_ok_flag&STUFF_OK_47) && (ewid == 1)) {
return lv;
}
@ -584,7 +584,8 @@ static struct vector_info draw_binary_expr_land(ivl_expr_t exp, unsigned wid)
return lv;
}
static struct vector_info draw_binary_expr_lor(ivl_expr_t exp, unsigned wid)
static struct vector_info draw_binary_expr_lor(ivl_expr_t exp, unsigned wid,
int stuff_ok_flag)
{
ivl_expr_t le = ivl_expr_oper1(exp);
ivl_expr_t re = ivl_expr_oper2(exp);
@ -607,7 +608,9 @@ static struct vector_info draw_binary_expr_lor(ivl_expr_t exp, unsigned wid)
lv = tmp;
}
rv = draw_eval_expr(re, STUFF_OK_XZ);
/* The right expression may be left in registers 4-7 because
I'll be using it immediately. */
rv = draw_eval_expr(re, STUFF_OK_XZ|STUFF_OK_47);
/* if the right operand has width, then evaluate the single-bit
logical equivalent. */
@ -637,20 +640,40 @@ static struct vector_info draw_binary_expr_lor(ivl_expr_t exp, unsigned wid)
lv.base = 2;
}
} else if (lv.base==0) {
lv = rv;
} else {
fprintf(vvp_out, " %%or %u, %u, 1;\n", rv.base, lv.base);
lv = rv;
}
} else if (rv.base == 0) {
; /* Just return lv. */
} else {
if (rv.base >= 8 && lv.base < 8 && !(stuff_ok_flag&STUFF_OK_47)) {
/* If STUFF_OK_47 is false, and rv is not in the
47 area (and lv is) then plan to or the result
into the rv instead. This can case a %mov later. */
struct vector_info tmp = lv;
lv = rv;
rv = tmp;
}
fprintf(vvp_out, " %%or %u, %u, 1;\n", lv.base, rv.base);
clr_vector(rv);
if (rv.base >= 8) clr_vector(rv);
}
if (wid==1 && (lv.base<4 || lv.base>=8 || (stuff_ok_flag&STUFF_OK_47)))
return lv;
/* If we only want the single bit result, then we are done. */
if (wid == 1)
if (wid == 1) {
if (lv.base >= 4 && lv.base < 8) {
unsigned tmp = allocate_vector(1);
fprintf(vvp_out, " %%mov %u, %u, 1;\n", tmp, lv.base);
lv.base = tmp;
}
return lv;
}
/* Write the result into a zero-padded result. */
{ unsigned base = allocate_vector(wid);
@ -663,7 +686,7 @@ static struct vector_info draw_binary_expr_lor(ivl_expr_t exp, unsigned wid)
}
fprintf(vvp_out, " %%mov %u, %u, 1;\n", base, lv.base);
clr_vector(lv);
if (lv.base >= 8) clr_vector(lv);
lv.base = base;
lv.wid = wid;
fprintf(vvp_out, " %%mov %u, 0, %u;\n", base+1, wid-1);
@ -1503,7 +1526,8 @@ static struct vector_info draw_binary_expr(ivl_expr_t exp,
break;
case 'o': /* || (logical or) */
rv = draw_binary_expr_lor(exp, wid);
rv = draw_binary_expr_lor(exp, wid, stuff_ok_flag);
stuff_ok_used_flag = 1;
break;
case '&':
@ -1563,7 +1587,6 @@ static struct vector_info draw_concat_expr(ivl_expr_t exp, unsigned wid,
vvp_errors += 1;
}
/* Get the repeat count. This must be a constant that has been
evaluated at compile time. The operands will be repeated to
form the result. */