JitArm64: Skip redundant imm to register writes #11094
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When a guest register is an immediate, it may be necessary to move this value into a register. This is handled by gpr.R(), which lacks context on how the register will be used. This leads to cases where the immediate is written to a register, only for it to be overwritten. Take for example this code generated by srwx: 0x5280031b mov w27, #0x18 0x53187edb lsr w27, w22, dolphin-emu#24 gpr.BindToRegister() does have this context through the do_load parameter, but didn't handle immediates. By adding this logic, we can intelligently skip the write when do_load is false.
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F-Zero broken after this PR and Rogue Squadron won’t start. All I get is a black screen. M1 Arm MacBook.
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FYI, I can reproduce the F-Zero issue on x86, so it's unlikely that this PR caused it. |
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I checked out the commit before this and it was fixed. Not sure what’s going on here. |
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This PR seems to be causing the issue in F-Zero GX for me. Android, AArch64, OpenGL. |
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I don't have access to this game myself, but perhaps unconditionally setting the dirty flag can fix this. |
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Unconditionally setting the dirty flag can mess things up in MMU games when do_load is false. I'll try to debug this. |
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Perhaps changing the condition to |
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This PR uncovered an underlying bug in JitArm64 that I've now fixed in PR #11114. Can't reproduce the problem on x86-64. |
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That's on x86. |
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I would advise bisecting. |
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My issue seems to be related to the x86 JIT. It's fixed with the cached interpreter and if I disable "JIT Floating Point". |
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Runs fine here:
You seem to be running a custom build, with that |
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After some back and forth on IRC it turned out that my build was simply missing the game ini workaround for F-Zero. |
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The Rogue Squadron II issue was indeed related to the dirty flag. Fixed in PR #11117. |
When a guest register is an immediate, it may be necessary to move this value into a register. This is handled by
gpr.R(), which lacks context on how the register will be used. This leads to cases where the immediate is written to a register, only for it to be overwritten. Take for example this code generated bysrwx:gpr.BindToRegister()does have this context through thedo_loadparameter, but didn't handle immediates. By adding this logic, we can intelligently skip the write whendo_loadis false.