The efficient function (that is nearly the same as
https://graphics.stanford.edu/~seander/bithacks.html#DetermineIfPowerOf2)
replaces one loop based instance (which also reused the xx variable
afterwards, whereas it should have used htabmask instead) and one
instance using the population count a.k.a. Hamming weigth.
If the delimiters of a memory aren't exactly the same as an address, but their size includes the memory breakpoint delimiter, the break will not go through. This makes it so that you can specify a search for a memory breakpoint with a data size and will check if the data fits with that size on all memory breakpoints so the breaks go through.
Currently, slowmem is used at any time that memory breakpoints are in use. This commit makes it so that whenever the DBAT gets updated, if the address is overllaping any memchecks, it forces the use of slowmem. This allows to keep fastmem for any other cases and noticably increases performance when using memory breakpoints.
Currently, slowmem is used at any time that memory breakpoints are in use. This commit makes it so that whenever the DBAT gets updated, if the address is overllaping any memchecks, it forces the use of slowmem. This allows to keep fastmem for any other cases and noticably increases performance when using memory breakpoints.
TryReadInstruction doesn't validate the address it resolves, that
can result in Memory::GetPointer failing and returning nullptr
which then leads to a nullptr dereference and a crash.
Created PowerPC::HostIsInstructionRAMAddress which works the same
way as PowerPC::HostIsRAMAddress for the IBAT.
Dolphin emulates GeckoCodes by fiddling with the CPU state when a
VI Interrupt occurs. The problem with this is that we don't know
where the PC is so it's non-deterministic and not necessarily
suitable for use with the codehandler.
There are two options: Patch the game like Gecko OS either directly
or using HLE::Patch, or use a trampoline so we can branch from any
PC even if it would otherwise not be valid. The problem with Gecko OS
patches is there are 10 of them and they have to be configured
manually (i.e. Game INIs to would need to have a [Core]GeckoHookType
property).
HLE_Misc::GeckoReturnTrampoline enables the Code Handler to be
entered from anywhere, the trampoline restores all the registers that
had to be secretly saved to the stack.
It wouldn't impact performance until at least one memcheck is enabled. Because of this, it can be used in release builds without much impact, the only thing that woudl change is the use of HasAny method instead of preprocessor conditionals. Since the perforamnce decrease comes right when the first memcheck is added and restored when the last is removed, it basically is all beneficial and works the same way.
Fundamentally, all this does is enforce the invariant that we always
translate effective addresses based on the current BAT registers and
page table before we do anything else with them.
This change can be logically divided into three parts. The first part is
creating a table to represent the current BAT state, and keeping it up to
date (PowerPC::IBATUpdated, PowerPC::DBATUpdated, etc.). This does
nothing by itself, but it's necessary for the other parts.
The second part (mostly in MMU.cpp) is simply removing all the hardcoded
checks for specific untranslated addresses, and consistently translating
addresses using the current BAT configuration. Very straightforward, but a
lot of code changes because we hardcoded assumptions all over the place.
The third part (mostly in Memmap.cpp) is making the fastmem arena reflect
the current BAT configuration. We do this by redoing the mapping (calling
memmap()) based on the BAT table whenever it changes.
One additional minor change is that translation can fail in two ways:
either the segment is a direct store segment, or page table lookup failed.
The difference doesn't usually matter, but the difference affects cache
instructions, like dcbz.
Specifically, don't make any assumptions about what effective addresses
are used for code, and correctly handle changes to MSR.DR/MSR.IR.
(Split off from dynamic-bat.)
Specifically, don't make any assumptions about what effective addresses
are used for code, and correctly handle changes to MSR.DR/MSR.IR.
(Split off from dynamic-bat.)
Change TMemCheck::Action to return whether to break rather than calling
PPCDebugInterface::BreakNow, as this simplified the implementation; then
remove said method, as that was its only caller. One "interface" method
down, many to go...
Without fastmem, the JIT code still does an inline check for RAM
addresses. With watchpoints we have to disable that too. (Hardware
watchpoints would avoid all the slow, but be complicated to implement
and limited in number - I doubt most people debugging games care much if
they run slower.)
With this change and watchpoints enabled, Melee runs at no more than 40%
speed, despite running at full speed without them. Oh well. Better
works slowly than doesn't bloody work.
Incidentally, I'm getting an unrelated crash in
PowerPC::HostIsRAMAddress when shutting down a game. This code sucks.
Niels Boehm
Lioncash
Michael Maltese
aldelaro5
degasus
EmptyChaos
BhaaL
aldelaro5
magumagu
Scott Mansell
Pierre Bourdon
shuffle2
comex
JosJuice
Tillmann Karras