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Disabled GIFtag optimization added in r3305. Added detailed comments explaining why its not safe. Not totally ruling out the potential to fix and restore it to working order, but am fairly skeptical that it will provide any worthwhile speed gain once its been safe-guarded. 

git-svn-id: http://pcsx2.googlecode.com/svn/trunk@3353 96395faa-99c1-11dd-bbfe-3dabce05a288
This commit is contained in:
Jake.Stine 2010-06-30 12:16:26 +00:00
parent 1cde49455a
commit 709fa71a92
1 changed files with 27 additions and 2 deletions
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29
pcsx2/ps2/GIFpath.cpp
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@ -511,7 +511,9 @@ __forceinline int GIFPath::ParseTag(GIF_PATH pathidx, const u8* pMem, u32 size)
case GIF_FLG_PACKED:
GIF_LOG("Packed Mode EOP %x", tag.EOP);
PrepPackedRegs();
if(DetectE > 0)
//if(DetectE > 0)
if(true) // Optimization Disabled! (see below)
{
do {
if (GetReg() == 0xe) {
@ -520,8 +522,31 @@ __forceinline int GIFPath::ParseTag(GIF_PATH pathidx, const u8* pMem, u32 size)
incTag(16, 1);
} while(StepReg() && size > 0);
}
else //Save doing the while loop and repeat conditionals for nothing :P
else
{
// Purpose: To save doing the while loop and repeat conditionals for nothing :P (and whales)
// Problem(s):
// * Doesn't wrap around VU1 memory properly. It needs to have additional checks
// against VU1 wrap-around and either split the copy into two parts, or just use
// the above "Brute force" approach. (via added top-level path1 checks)
//
// * Cannot assume curreg is 1 on partial transfers. Games can transfer *anything*
// -- and I mean *anything* -- right down to individual QWCs. So this code must
// also use some clever math to calculate the actual register the partial transfer
// ends at. Math that will almost certainly involve a modulus -- which is still the
// slowest instruction known to computer-kind.
// By the time we're done handling both of those, I seriously doubt there will be much
// speedup left, and the code here would be a nightmare to comprehend or debug. So this
// should probably be slated for removal, and we'll just need to resolve ourselves to finding
// other ways to reduce GIF/GS overhead. --air
// (history: this optimization existed in early 0.9.5 and earlier PCSX2's and was always
// buggy for the same reasons. cottonvibes later tried to implement the same optimization
// into the new cleaned-up GIFtag parser here, but ran into the same problems noted above
// and after he and I worked on it for a few hours we mutually decided it's just not
// worth the effort. --air)
//DevCon.Warning("No E detected Path%d nloop %x", pathidx + 1, nloop);
u32 len = aMin(size, nloop * numregs);
if(len < (nloop * numregs)) nloop -= len / numregs;