Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

EE Cache: Shrink tag size by 4 bytes #12154

Merged
merged 1 commit into from
Jan 8, 2025
+25 −10
Merged

EE Cache: Shrink tag size by 4 bytes #12154

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
35 changes: 25 additions & 10 deletions pcsx2/Cache.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -23,10 +23,11 @@ namespace
// When this happens, the cache still fills with the data and when it gets evicted the data is lost.
// We don't emulate memory access on a logic level, so we need to ensure that we don't try to load/store to a non-existant physical address.
// This fixes the Find My Own Way demo.
bool validPFN = true;

// The lower parts of a cache tags structure is as follows:
// 31 - 12: The physical address cache tag.
// 11 - 7: Unused.
// 11: Used by PCSX2 to indicate if the physical address is valid.
// 10 - 7: Unused.
// 6: Dirty flag.
// 5: Valid flag.
// 4: LRF flag - least recently filled flag.
Expand All @@ -39,7 +40,8 @@ namespace
VALID_FLAG = 0x20,
LRF_FLAG = 0x10,
LOCK_FLAG = 0x8,
ALL_FLAGS = 0xFFF
ALL_FLAGS = 0x7FF,
ALL_BITS = 0xFFF
};

int flags() const
Expand All @@ -65,23 +67,36 @@ namespace
void clearLocked() { rawValue &= ~LOCK_FLAG; }
void toggleLRF() { rawValue ^= LRF_FLAG; }

uptr addr() const { return rawValue & ~ALL_FLAGS; }
uptr addr() const { return rawValue & ~ALL_BITS; }

void setAddr(uptr addr)
{
rawValue &= ALL_FLAGS;
rawValue |= (addr & ~ALL_FLAGS);
rawValue &= ALL_BITS;
rawValue |= (addr & ~ALL_BITS);
}

bool matches(uptr other) const
{
return isValid() && addr() == (other & ~ALL_FLAGS);
return isValid() && addr() == (other & ~ALL_BITS);
}

void clear()
{
rawValue &= LRF_FLAG;
}

constexpr bool isValidPFN() const
{
return rawValue & 0x800;
}

constexpr void setValidPFN(bool valid)
{
if (valid)
rawValue |= 0x800;
else
rawValue &= ~0x800;
}
};

struct CacheLine
Expand All @@ -103,7 +118,7 @@ namespace
uptr target = addr();

CACHE_LOG("Write back at %zx", target);
if (tag.validPFN)
if (tag.isValidPFN())
*reinterpret_cast<CacheData*>(target) = data;
tag.clearDirty();
}
Expand All @@ -113,7 +128,7 @@ namespace
pxAssertMsg(!tag.isDirtyAndValid(), "Loaded a value into cache without writing back the old one!");

tag.setAddr(ppf);
if (!tag.validPFN)
if (!tag.isValidPFN())
{
// Reading from invalid physical addresses seems to return 0 on hardware
std::memset(&data, 0, sizeof(data));
Expand Down Expand Up @@ -238,7 +253,7 @@ static int getFreeCache(u32 mem, int* way, bool validPFN)

CacheLine line = cache.lineAt(setIdx, newWay);
line.writeBackIfNeeded();
line.tag.validPFN = validPFN;
line.tag.setValidPFN(validPFN);
line.load(ppf);
line.tag.toggleLRF();
}
Expand Down
Loading