OpcodeDispatcher: Fixes 32-bit mode LOOP RCX register usage #3504
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In 64-bit mode, the LOOP instruction's RCX register usage is 64-bit or 32-bit. In 32-bit mode, the LOOP instruction's RCX register usage is 32-bit or 16-bit. FEX wasn't handling the 16-bit case at all which was causing the LOOP instruction to effectively always operate at 32-bit size. Now this is correctly supported, and it also stops treating the operation as 64-bit.
32-bit test would fail if the 16-bit address size override wasn't respected.
lioncash
approved these changes
Mar 22, 2024
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In 64-bit mode, the LOOP instruction's RCX register usage is 64-bit or
32-bit.
In 32-bit mode, the LOOP instruction's RCX register usage is 32-bit or
16-bit.
FEX wasn't handling the 16-bit case at all which was causing the LOOP
instruction to effectively always operate at 32-bit size. Now this is
correctly supported, and it also stops treating the operation as 64-bit.