JitArm64: Update registers last used before start of instruction #9472
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leoetlino
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Jan 26, 2021
If the register pressure is high when allocating registers, Arm64FPRCache may spill a guest register which we are going to allocate later during the current instruction, which has the side effect of turning it into double precision. This will have bad consequences if we are assuming that it is single precision, so let's add some asserts to detect if that ever happens.
It obscures more than it helps in my opinion.
Let's reset m_last_used for each register that will be used in an instruction before we start allocating any of them, so that one of the earlier allocations doesn't spill a register that we want in a later allocation. (We must still also increment/reset m_last_used in R and RW, otherwise we end up in trouble when emulating lmw/stmw since those access more guest registers than there are available host registers.) This should ensure that the asserts added earlier in this pull request are never triggered.
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leoetlino
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Jan 26, 2021
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Apparently the asserts I added are getting triggered in certain games (e.g. Wind Waker) :/ Will try to investigate. EDIT: All the instances I've found should be fixed by PR #9478. |
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Let's reset
m_last_usedfor each register that will be used in an instruction before we start allocating any of them, so that one of the earlier allocations doesn't spill a register that we want in a later allocation.See the individual commits for details.