On 3/3/22 05:04, Peter Maydell wrote:
if (USE_GUEST_BASE) {
tcg_out_qemu_ld_direct(s, memop, ext, data_reg,
- TCG_REG_GUEST_BASE, otype, addr_reg);
+ TCG_REG_GUEST_BASE, option, addr_reg);
} else {
tcg_out_qemu_ld_direct(s, memop, ext, data_reg,
- addr_reg, TCG_TYPE_I64, TCG_REG_XZR);
+ addr_reg, option, TCG_REG_XZR);
This doesn't look right. 'option' specifies how we extend the offset
register, but here that is XZR, which is 0 no matter how we choose
to extend it, whereas we aren't going to be extending the base
register 'addr_reg' which is what we do need to either zero or
sign extend. Unfortunately we can't just flip addr_reg and XZR
around, because XZR isn't valid as the base reg.
Is this a pre-existing bug? If addr_reg needs zero extending
we won't be doing that.
It's just confusing, because stuff is hidden in macros:
#define USE_GUEST_BASE (guest_base != 0 || TARGET_LONG_BITS == 32)
We *always* use TCG_REG_GUEST_BASE when we require an extension, so the else case you
point out will always have option == 3 /* LSL #0 */.
Previously I had a named constant I could use here, but I didn't create names for the full
'option' field being filled, so I thought it clearer to just pass along the variable.
Would it be clearer as
3 /* LSL #0 */
or with some LDST_OPTION_LSL0?
r~
