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Optimize the %load/vp0 to use subarrays. 

This instruction adds an integer value to the value being loaded. This
optimization uses subarrays instead of the += operator. This is faster
because the value is best loaded into the vector as a subarray anyhow.
This commit is contained in:
Stephen Williams 2008-05-26 16:44:58 -07:00
parent 5cc376ebd4
commit 6987d16bd3
1 changed files with 26 additions and 7 deletions
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33
vvp/vthread.cc
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@ -2476,7 +2476,7 @@ bool of_LOAD_NX(vthread_t thr, vvp_code_t cp)
* The functor to read from is the vvp_net_t object pointed to by the
* cp->net pointer.
*/
vvp_vector4_t load_base(vthread_t thr, vvp_code_t cp)
static vvp_vector4_t load_base(vthread_t thr, vvp_code_t cp)
{
assert(cp->bit_idx[0] >= 4);
assert(cp->bit_idx[1] > 0);
@ -2490,9 +2490,8 @@ vvp_vector4_t load_base(vthread_t thr, vvp_code_t cp)
if (sig == 0) {
cerr << "%%load/v error: Net arg not a vector signal? "
<< typeid(*net->fun).name() << endl;
assert(sig);
}
assert(sig);
vvp_vector4_t sig_value = sig->vec4_value();
sig_value.resize(wid);
@ -2532,15 +2531,35 @@ bool of_LOAD_VP0(vthread_t thr, vvp_code_t cp)
vvp_vector4_t sig_value(wid, BIT4_0);
sig_value.copy_bits(load_base(thr, cp));
/* Add the addend value */
sig_value += addend;
/* Check the address once, before we scan the vector. */
thr_check_addr(thr, bit+wid-1);
unsigned long*val = sig_value.subarray(0, wid);
if (val == 0) {
vvp_vector4_t tmp(wid, BIT4_X);
thr->bits4.set_vec(bit, tmp);
return true;
}
unsigned words = (wid + CPU_WORD_BITS - 1) / CPU_WORD_BITS;
unsigned long carry = 0;
unsigned long imm = addend;
if (addend >= 0) {
for (unsigned idx = 0 ; idx < words ; idx += 1) {
val[idx] = add_with_carry(val[idx], imm, carry);
imm = 0UL;
}
} else {
for (unsigned idx = 0 ; idx < words ; idx += 1) {
val[idx] = add_with_carry(val[idx], imm, carry);
imm = -1UL;
}
}
/* Copy the vector bits into the bits4 vector. Do the copy
directly to skip the excess calls to thr_check_addr. */
thr->bits4.set_vec(bit, sig_value);
thr->bits4.setarray(bit, wid, val);
delete[]val;
return true;
}