On 07/23/2016 12:58 AM, Nikunj A Dadhania wrote:
Richard Henderson <r...@twiddle.net> writes:
On 07/18/2016 10:35 PM, Nikunj A Dadhania wrote:
+ tcg_gen_andi_tl(src1, cpu_gpr[rA(ctx->opcode)], 0xFF);
+ for (i = 0; i < 64; i += 8) {
+ tcg_gen_shri_tl(t0, arg1, i);
+ tcg_gen_andi_tl(t0, t0, 0xFF);
+ tcg_gen_brcond_tl(TCG_COND_EQ, src1, t0, l1);
+ }
+ tcg_gen_movi_i32(cpu_crf[crfD(ctx->opcode)], 0);
+ tcg_gen_br(l2);
+ gen_set_label(l1);
+ /* Set match bit, i.e. CRF_GT */
+ tcg_gen_movi_i32(cpu_crf[crfD(ctx->opcode)], 1 << CRF_GT);
Ew. This can be done much better as
http://graphics.stanford.edu/~seander/bithacks.html#ZeroInWord
Which still might be best done in a helper, because of the constants involved
(tcg is not nearly so good as gcc in building full 64-bit constants).
C.f. target-alpha/int_helper.c, helper_cmpbe0 (which computes different
information than cmpeqb, but is still helpful as an example).
Thanks for the hints, that got reduce to following:
#define haszero(v) (((v) - 0x0101010101010101UL) & ~(v) & 0x8080808080808080UL)
#define hasvalue(x,n) (haszero((x) ^ (~0UL/255 * (n))))
uint32_t helper_cmpeqb(target_ulong ra, target_ulong rb)
{
return !!hasvalue(rb, ra);
}
A couple of things:
(1) I don't see N being masked to 0xff before replicating.
(2) You need to use ULL for 32-bit hosts, or casts, e.g.
#define dup(x) (((x) & 0xff) * (~(target_ulong)0 / 0xff))
#define haszero(v) (((v) - dup(0x01)) & ~(v) & dup(0x80))
#define hasvalue(x, n) haszero((x) ^ dup(n))
(3) You probably ought to go ahead and add compute the proper crf value here:
return hasvalue(rb, ra) ? 1 << CRF_GT : 0;
so that within the translator you just have
gen_helper_cmpeqb(cpu_crf[...], cpu_gpr[...], cpu_gpr[...])
r~
