Jit64: Treat branch-to-self instruction as an idle loop #4452
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The normal block exit is redundant as the exception exit will jump out of the block first, meaning this code is never executed.
stenzek
commented
Nov 14, 2016
| ABI_PushRegistersAndAdjustStack({}, 0); | ||
| ABI_CallFunction(CoreTiming::Idle); | ||
| ABI_PopRegistersAndAdjustStack({}, 0); | ||
| MOV(32, PPCSTATE(pc), Imm32(destination)); |
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LGTM |
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I need to test this actually; there are potentially games that only work on JIT that could run into this and cause a problem. |
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checked the CPU backend games and they're unaffected. LGTM |
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I'm guessing this is the result of calling VIDEO_WaitVSync in libogc (perhaps indirectly, I haven't looked closely at the code for this function).
Both Interpreter and JitIL interpret this as an idle loop, Jit64 looked like it did at some point, but it has been commented out for a long time. Was there a reason for this?
JitArm64 has a similar optimization, except it was emitting redundant code as the exception exit would jump out of the block before the normal exit was executed.
This change is