On 6/7/21 2:22 AM, LIU Zhiwei wrote:
I am implementing RVP to get rid of TARGET_RISCV64. After we have recognized an
instruction only used by a 32-bit CPU,
1) Should we only use the lowest 32bits of the 64bits register in RV64?
TCGv s;
TCGv_i32 s32;
s = tcg_new_temp();
s32 = tcg_new_temp_i32();
gen_get_gpr(src1, a->rs1);
tcg_gen_trunc_tl_i32(s32, s);
Then we can use TCGv_i32 s32 to stand for rs1 register.
Changing from _tl to _i32 is wrong for most things, because you'll just have to
convert back in order to store the result.
Most often you'll get the correct results by just using _tl as is. One
operation I can think of right away which probably requires extra attention is
right-shift. In which case just sign- or zero-extend the input first.
r~
