On 10/19/21 2:48 AM, Frédéric Pétrot wrote:
+static bool gen_setcond_i128(TCGv rl, TCGv rh,
+ TCGv al, TCGv ah,
+ TCGv bl, TCGv bh,
+ TCGCond cond)
+{
+ switch (cond) {
+ case TCG_COND_EQ:
+ tcg_gen_setcond_tl(TCG_COND_EQ, rl, al, bl);
+ tcg_gen_setcond_tl(TCG_COND_EQ, rh, ah, bh);
+ tcg_gen_and_tl(rl, rl, rh);
+ break;
+
+ case TCG_COND_NE:
+ tcg_gen_setcond_tl(TCG_COND_NE, rl, al, bl);
+ tcg_gen_setcond_tl(TCG_COND_NE, rh, ah, bh);
+ tcg_gen_or_tl(rl, rl, rh);
+ break;
But of course setcond is more expensive than logic
Better as xor + xor + or + setcond.
+ case TCG_COND_LTU:
+ {
+ TCGv tmp1 = tcg_temp_new(),
+ tmp2 = tcg_temp_new();
+
+ tcg_gen_sub2_tl(rl, rh, al, ah, bl, bh);
+ tcg_gen_eqv_tl(tmp1, ah, bh);
+ tcg_gen_and_tl(tmp1, tmp1, rh);
+ tcg_gen_andc_tl(tmp2, bh, ah);
+ tcg_gen_or_tl(tmp1, tmp1, tmp2);
+ tcg_gen_shri_tl(rl, tmp1, 63);
Hmm. Seems like it would work.
I make that 7 operations.
Or GEU in 6 operations:
/* borrow in to second word */
setcond_tl(TCG_COND_LTU, t1, al, bl);
/* seed third word with 1, which will be result */
sub2_tl(t1, t2, ah, one, t1, zero);
sub2_tl(t1, rl, t1, t2, bh, zero);
+ } else {
+ gen_setcond_i128(tmpl, tmph, src1, src1h, src2, src2h, cond);
+ tcg_gen_brcondi_tl(TCG_COND_NE, tmpl, 0, l);
+ }
There are two setcond cases that invert their result; you should fold that in here and
invert the branch condition. As long as you're special casing 0, you might as well
special case TCG_COND_LT/GE and test the sign of the high word.
r~
