Hi Richard,
On 9/23/21 02:51, Richard Henderson wrote:
On 9/22/21 11:09 AM, WANG Xuerui wrote:
+ if (sextreg(val, 0, 52) == val) {
+ /*
+ * Fits in 52-bits, upper bits are already properly
sign-extended by
+ * cu32i.d.
+ */
+ return;
+ }
+ tcg_out_opc_cu52i_d(s, rd, rd, top);
+}
Oh, future improvement: constants with 52 low zero bits can be loaded
with cu52i(rd, zero, val >> 52).
Which means there's a set of interesting constants:
abc0_0000_0000_0def
ori rd, zero, 0xdef
cu52i rd, rd, 0xabc
abcf_ffff_ffff_fdef
cu52i rd, zero, 0xabc - 1
addi.d rd, rd, 0xdef
I think I'll try to implement this in some kind of follow-up patch, yeah.
Also,
+ tcg_out_opc_lu12i_w(s, rd, upper);
+ if (low != 0) {
+ tcg_out_opc_ori(s, rd, rd, low & 0xfff);
+ }
when upper == 0 and low != 0, we can omit the lu12i.
This optimization can't be blindly implemented though; because cu32i.d
only takes one input register, in case upper == low == 0 but higher !=
0, we would have no proper input. So in that case something like "move
rd, zero" is necessary, and logic is a little bit complicated. I'll
include this in v4 though.
r~
