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Move CoreTiming::downcount to PowerPC::ppcState. #503

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merged 1 commit into from Jun 26, 2014

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Sonicadvance1
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This isn't technically the correct place to have the downcount variable, but it is similar to what PPSSPP does to gain a bit of extra speed on ARM.
We access this variable quite a bit, with each exit in a block it is subtracted from.
On ARM this required four instructions to load and store the value, while now it only requires two.

This gives an average of 1FPS gain to most games.
Examples:
Crazy Taxi: 54FPS -> 55FPS
Luigi's Mansion: 20FPS -> 21FPS
Wind Waker(Save Screen): 27FPS -> 28FPS

This seems to average a 6mhz to 16mhz CPU core emulation improvement in the few games I've tested.

@Parlane
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Parlane commented Jun 25, 2014

LGTM

@lioncash
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Looks gr8 m8

This isn't technically the correct place to have the downcount variable, but it is similar to what PPSSPP does to gain a bit of extra speed on ARM.
We access this variable quite a bit, with each exit in a block it is subtracted from.
On ARM this required four instructions to load and store the value, while now it only requires two.

This gives an average of 1FPS gain to most games.
Examples:
Crazy Taxi: 54FPS -> 55FPS
Luigi's Mansion: 20FPS -> 21FPS
Wind Waker(Save Screen): 27FPS -> 28FPS

This seems to average a 6mhz to 16mhz CPU core emulation improvement in the few games I've tested.
@phire
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phire commented Jun 26, 2014

Looks fine to me.

Sonicadvance1 added a commit that referenced this pull request Jun 26, 2014
Move CoreTiming::downcount to PowerPC::ppcState.
@Sonicadvance1 Sonicadvance1 merged commit d0ad84f into dolphin-emu:master Jun 26, 2014
@Sonicadvance1 Sonicadvance1 deleted the PowerPC-downcount branch June 26, 2014 02:20
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