* ARMeilleure: Add AVX512{F,VL,DQ,BW} detection
Add `UseAvx512Ortho` and `UseAvx512OrthoFloat` optimization flags as
short-hands for `F+VL` and `F+VL+DQ`.
* ARMeilleure: Add initial support for EVEX instruction encoding
Does not implement rounding, or exception controls.
* ARMeilleure: Add `X86Vpternlogd`
Accelerates the vector-`Not` instruction.
* ARMeilleure: Add check for `OSXSAVE` for AVX{2,512}
* ARMeilleure: Add check for `XCR0` flags
Add XCR0 register checks for AVX and AVX512F, following the guidelines
from section 14.3 and 15.2 from the Intel Architecture Software
Developer's Manual.
* ARMeilleure: Increment InternalVersion
* ARMeilleure: Remove redundant `ReProtect` and `Dispose`, formatting
* ARMeilleure: Move XCR0 procedure to GetXcr0Eax
* ARMeilleure: Add `XCR0` to `FeatureInfo` structure
* ARMeilleure: Utilize `ReadOnlySpan` for Xcr0 assembly
Avoids an additional allocation
* ARMeilleure: Formatting fixes
* Make all structs readonly when applicable. It should reduce amount of needless defensive copies
* Make structs with trivial boilerplate equality code record structs
* Remove unnecessary readonly modifiers from TextureCreateInfo
* Make BitMap structs readonly too
* ARMeilleure: Add `GFNI` detection
This is intended for utilizing the `gf2p8affineqb` instruction
* ARMeilleure: Add `gf2p8affineqb`
Not using the VEX or EVEX-form of this instruction is intentional. There
are `GFNI`-chips that do not support AVX(so no VEX encoding) such as
Tremont(Lakefield) chips as well as Jasper Lake.
13df339fe7/GenuineIntel/GenuineIntel00806A1_Lakefield_LC_InstLatX64.txt (L1297-L1299)13df339fe7/GenuineIntel/GenuineIntel00906C0_JasperLake_InstLatX64.txt (L1252-L1254)
* ARMeilleure: Add `gfni` acceleration of `Rbit_V`
Passes all `Rbit_V*` unit tests on my `i9-11900k`
* ARMeilleure: Add `gfni` acceleration of `S{l,r}i_V`
Also added a fast-path for when the shift amount is greater than the
size of the element.
* ARMeilleure: Add `gfni` acceleration of `Shl_V` and `Sshr_V`
* ARMeilleure: Increment InternalVersion
* ARMeilleure: Fix Intrinsic and Assembler Table alignment
`gf2p8affineqb` is the longest instruction name I know of. It shouldn't
get any wider than this.
* ARMeilleure: Remove SSE2+SHA requirement for GFNI
* ARMeilleure Add `X86GetGf2p8LogicalShiftLeft`
Used to generate GF(2^8) 8x8 bit-matrices for bit-shifting for the `gf2p8affineqb` instruction.
* ARMeilleure: Append `FeatureInfo7Ecx` to `FeatureInfo`
* Add `Operand.Label` support to `Assembler`
This adds label support to `Assembler` and enables branch tightening
when compiling with relocatables. Jump management and patching has been
moved to the `Assembler`.
* Move instruction table to `Assembler.Table`
* Set PTC internal version
* Rename `Assembler.Table` to `AssemblerTable`
* Store constant `Operand`s in the `LocalInfo`
Since the spill slot and register assigned is fixed, we can just store
the `Operand` reference in the `LocalInfo` struct. This allows skipping
hitting the intern-table for a look up.
* Skip `Uses`/`Assignments` management
Since the `HybridAllocator` is the last pass and we do not care about
uses/assignments we can skip managing that when setting destinations or
sources.
* Make `GetLocalInfo` inlineable
Also fix a possible issue where with numbered locals. See or-assignment
operator in `SetVisited(local)` before patch.
* Do not run `BlockPlacement` in LCQ
With the host mapped memory manager, there is a lot less cold code to
split from hot code. So disabling this in LCQ gives some extra
throughput - where we need it.
* Address Mou-Ikkai's feedback
* Apply suggestions from code review
Co-authored-by: VocalFan <45863583+Mou-Ikkai@users.noreply.github.com>
* Move check to an assert
Co-authored-by: VocalFan <45863583+Mou-Ikkai@users.noreply.github.com>
* Refactor `PtcInfo`
This change reduces the coupling of `PtcInfo` by moving relocation
tracking to the backend. `RelocEntry`s remains as `RelocEntry`s through
out the pipeline until it actually needs to be written to the PTC
streams. Keeping this representation makes inspecting and manipulating
relocations after compilations less painful. This is something I needed
to do to patch relocations to 0 to diff dumps.
Contributes to #1125.
* Turn `Symbol` & `RelocInfo` into readonly structs
* Add documentation to `CompiledFunction`
* Remove `Compiler.Compile<T>`
Remove `Compiler.Compile<T>` and replace it by `Map<T>` of the
`CompiledFunction` returned.
* Turn `MemoryOperand` into a struct
* Remove `IntrinsicOperation`
* Remove `PhiNode`
* Remove `Node`
* Turn `Operand` into a struct
* Turn `Operation` into a struct
* Clean up pool management methods
* Add `Arena` allocator
* Move `OperationHelper` to `Operation.Factory`
* Move `OperandHelper` to `Operand.Factory`
* Optimize `Operation` a bit
* Fix `Arena` initialization
* Rename `NativeList<T>` to `ArenaList<T>`
* Reduce `Operand` size from 88 to 56 bytes
* Reduce `Operation` size from 56 to 40 bytes
* Add optimistic interning of Register & Constant operands
* Optimize `RegisterUsage` pass a bit
* Optimize `RemoveUnusedNodes` pass a bit
Iterating in reverse-order allows killing dependency chains in a single
pass.
* Fix PPTC symbols
* Optimize `BasicBlock` a bit
Reduce allocations from `_successor` & `DominanceFrontiers`
* Fix `Operation` resize
* Make `Arena` expandable
Change the arena allocator to be expandable by allocating in pages, with
some of them being pooled. Currently 32 pages are pooled. An LRU removal
mechanism should probably be added to it.
Apparently MHR can allocate bitmaps large enough to exceed the 16MB
limit for the type.
* Move `Arena` & `ArenaList` to `Common`
* Remove `ThreadStaticPool` & co
* Add `PhiOperation`
* Reduce `Operand` size from 56 from 48 bytes
* Add linear-probing to `Operand` intern table
* Optimize `HybridAllocator` a bit
* Add `Allocators` class
* Tune `ArenaAllocator` sizes
* Add page removal mechanism to `ArenaAllocator`
Remove pages which have not been used for more than 5s after each reset.
I am on fence if this would be better using a Gen2 callback object like
the one in System.Buffers.ArrayPool<T>, to trim the pool. Because right
now if a large translation happens, the pages will be freed only after a
reset. This reset may not happen for a while because no new translation
is hit, but the arena base sizes are rather small.
* Fix `OOM` when allocating larger than page size in `ArenaAllocator`
Tweak resizing mechanism for Operand.Uses and Assignemnts.
* Optimize `Optimizer` a bit
* Optimize `Operand.Add<T>/Remove<T>` a bit
* Clean up `PreAllocator`
* Fix phi insertion order
Reduce codegen diffs.
* Fix code alignment
* Use new heuristics for degree of parallelism
* Suppress warnings
* Address gdkchan's feedback
Renamed `GetValue()` to `GetValueUnsafe()` to make it more clear that
`Operand.Value` should usually not be modified directly.
* Add fast path to `ArenaAllocator`
* Assembly for `ArenaAllocator.Allocate(ulong)`:
.L0:
mov rax, [rcx+0x18]
lea r8, [rax+rdx]
cmp r8, [rcx+0x10]
ja short .L2
.L1:
mov rdx, [rcx+8]
add rax, [rdx+8]
mov [rcx+0x18], r8
ret
.L2:
jmp ArenaAllocator.AllocateSlow(UInt64)
A few variable/field had to be changed to ulong so that RyuJIT avoids
emitting zero-extends.
* Implement a new heuristic to free pooled pages.
If an arena is used often, it is more likely that its pages will be
needed, so the pages are kept for longer (e.g: during PPTC rebuild or
burst sof compilations). If is not used often, then it is more likely
that its pages will not be needed (e.g: after PPTC rebuild or bursts
of compilations).
* Address riperiperi's feedback
* Use `EqualityComparer<T>` in `IntrusiveList<T>`
Avoids a potential GC hole in `Equals(T, T)`.
* Add AddressTable<T>
* Use AddressTable<T> for dispatch
* Remove JumpTable & co.
* Add fallback for out of range addresses
* Add PPTC support
* Add documentation to `AddressTable<T>`
* Make AddressTable<T> configurable
* Fix table walk
* Fix IsMapped check
* Remove CountTableCapacity
* Add PPTC support for fast path
* Rename IsMapped to IsValid
* Remove stale comment
* Change format of address in exception message
* Add TranslatorStubs
* Split DispatchStub
Avoids recompilation of stubs during tests.
* Add hint for 64bit or 32bit
* Add documentation to `Symbol`
* Add documentation to `TranslatorStubs`
Make `TranslatorStubs` disposable as well.
* Add documentation to `SymbolType`
* Add `AddressTableEventSource` to monitor function table size
Add an EventSource which measures the amount of unmanaged bytes
allocated by AddressTable<T> instances.
dotnet-counters monitor -n Ryujinx --counters ARMeilleure
* Add `AllowLcqInFunctionTable` optimization toggle
This is to reduce the impact this change has on the test duration.
Before everytime a test was ran, the FunctionTable would be initialized
and populated so that the newly compiled test would get registered to
it.
* Implement unmanaged dispatcher
Uses the DispatchStub to dispatch into the next translation, which
allows execution to stay in unmanaged for longer and skips a
ConcurrentDictionary look up when the target translation has been
registered to the FunctionTable.
* Remove redundant null check
* Tune levels of FunctionTable
Uses 5 levels instead of 4 and change unit of AddressTableEventSource
from KB to MB.
* Use 64-bit function table
Improves codegen for direct branches:
mov qword [rax+0x408],0x10603560
- mov rcx,sub_10603560_OFFSET
- mov ecx,[rcx]
- mov ecx,ecx
- mov rdx,JIT_CACHE_BASE
- add rdx,rcx
+ mov rcx,sub_10603560
+ mov rdx,[rcx]
mov rcx,rax
Improves codegen for dispatch stub:
and rax,byte +0x1f
- mov eax,[rcx+rax*4]
- mov eax,eax
- mov rcx,JIT_CACHE_BASE
- lea rax,[rcx+rax]
+ mov rax,[rcx+rax*8]
mov rcx,rbx
* Remove `JitCacheSymbol` & `JitCache.Offset`
* Turn `Translator.Translate` into an instance method
We do not have to add more parameter to this method and related ones as
new structures are added & needed for translation.
* Add symbol only when PTC is enabled
Address LDj3SNuD's feedback
* Change `NativeContext.Running` to a 32-bit integer
* Fix PageTable symbol for host mapped
* PPTC & Pool Enhancements.
* Avoid buffer allocations in CodeGenContext.GetCode(). Avoid stream allocations in PTC.PtcInfo.
Refactoring/nits.
* Use XXHash128, for Ptc.Load & Ptc.Save, x10 faster than Md5.
* Why not a nice Span.
* Added a simple PtcFormatter library for deserialization/serialization, which does not require reflection, in use at PtcJumpTable and PtcProfiler; improves maintainability and simplicity/readability of affected code.
* Nits.
* Revert #1987.
* Revert "Revert #1987."
This reverts commit 998be765cf.
* Optimization | Modify Add Instruction to use LEA instead.
Currently, the add instruction requires 4 registers to take place. By using LEA, we can effectively perform the same working using 3 registers, reducing memory spills and improving translation efficiency.
* Fix IsSameOperandDestSrc1 Check for Add
* Use LEA if Dest != SRC1
* Update IsSameOperandDestSrc1 to account for Cases where Dest and Src1 can be same for add
* Fix error in logic
* Typo
* Add paranthesis for clarity
* Compare registers as requested.
* Cleanup if statement, use same comparison method as generateCopy
* Make change as recommended by gdk
* Perform check only when Add calls are made
* use ensure sametype for lea, fix else
* Update comment
* Update version #
* Implement VFNMA.F<32/64>
* Update PTC Version
* Update Implementation & Renames & Correct Order
* Fix alignment
* Update implementation to not trigger assert
* Actually use the intrinsic that makes sense :)
* Implement block placement
Implement a simple pass which re-orders cold blocks at the end of the
list of blocks in the CFG.
* Set PPTC version
* Use Array.Resize
Address gdkchan's feedback
* Relax block ordering constraints
Before `block.Next` had to follow `block.ListNext`, now it does not.
Instead `CodeGenerator` will now emit the necessary jump instructions
to ensure control flow.
This makes control flow and block order modifications easier. It also
eliminates some simple cases of redundant branches.
* Set PPTC version
* Add Compare instruction
* Add BranchIf instruction
* Use test when BranchIf & Compare against 0
* Propagate Compare into BranchIfTrue/False use
- Propagate Compare operations into their BranchIfTrue/False use and
turn these into a BranchIf.
- Clean up Comparison enum.
* Replace BranchIfTrue/False with BranchIf
* Use BranchIf in EmitPtPointerLoad
- Using BranchIf early instead of BranchIfTrue/False improves LCQ and
reduces the amount of work needed by the Optimizer.
EmitPtPointerLoader was a/the big producer of BranchIfTrue/False.
- Fix asserts firing when assembling BitwiseAnd because of type
mismatch in EmitStoreExclusive. This is harmless and should not
cause any diffs.
* Increment PPTC interval version
* Improve IRDumper for BranchIf & Compare
* Use BranchIf in EmitNativeCall
* Clean up
* Do not emit test when immediately preceded by and
* Use movd,movq for i32/64 VectorExtract %x, 0x0
* Increment PPTC interval version
* Use else-if instead
- Address gdkchan's feedback.
- Clean up Debug.Assert calls
* Inline `count` expression into Debug.Assert
Apparently the CoreCLR JIT will not eliminate this. :(
* Add CRC32 A32 instructions.
* Fix CRC32 instructions.
* Add CRC intrinsic and fast path.
Loop is currently unrolled, will look into adding temp vars after tests are added.
* Begin work on Crc tests
* Fix SSE4.2 path for CRC32C, finialize tests.
* Remove unused IR path.
* Fix spacing between prefix checks.
* This should be Src.
* PTC Version
* OpCodeTable Order
* Integer check improvement. Value and Crc can be either 32 or 64 size.
* This wasn't necessary...
* If size is 3, value type must be I64.
* Fix same src+dest handling for non crc intrinsics.
* Pre-fix (ha) issue with vex encodings
* Delete DelegateTypes.cs
* Delete DelegateCache.cs
* Add files via upload
* Update Horizon.cs
* Update Program.cs
* Update MainWindow.cs
* Update Aot.cs
* Update RelocEntry.cs
* Update Translator.cs
* Update MemoryManager.cs
* Update InstEmitMemoryHelper.cs
* Update Delegates.cs
* Nit.
* Nit.
* Nit.
* 10 fewer MSIL bytes for us
* Add comment. Nits.
* Update Translator.cs
* Update Aot.cs
* Nits.
* Opt..
* Opt..
* Opt..
* Opt..
* Allow to change compression level.
* Update MemoryManager.cs
* Update Translator.cs
* Manage corner cases during the save phase. Nits.
* Update Aot.cs
* Translator response tweak for Aot disabled. Nit.
* Nit.
* Nits.
* Create DelegateHelpers.cs
* Update Delegates.cs
* Nit.
* Nit.
* Nits.
* Fix due to #784.
* Fixes due to #757 & #841.
* Fix due to #846.
* Fix due to #847.
* Use MethodInfo for managed method calls.
Use IR methods instead of managed methods about Max/Min (S/U).
Follow-ups & Nits.
* Add missing exception messages.
Reintroduce slow path for Fmov_Vi.
Implement slow path for Fmov_Si.
* Switch to the new folder structure.
Nits.
* Impl. index-based relocation information. Impl. cache file version field.
* Nit.
* Address gdkchan comments.
Mainly:
- fixed cache file corruption issue on exit; - exposed a way to disable AOT on the GUI.
* Address AcK77 comment.
* Address Thealexbarney, jduncanator & emmauss comments.
Header magic, CpuId (FI) & Aot -> Ptc.
* Adaptation to the new application reloading system.
Improvements to the call system of managed methods.
Follow-ups.
Nits.
* Get the same boot times as on master when PTC is disabled.
* Profiled Aot.
* A32 support (#897).
* #975 support (1 of 2).
* #975 support (2 of 2).
* Rebase fix & nits.
* Some fixes and nits (still one bug left).
* One fix & nits.
* Tests fix (by gdk) & nits.
* Support translations not only in high quality and rejit.
Nits.
* Added possibility to skip translations and continue execution, using `ESC` key.
* Update SettingsWindow.cs
* Update GLRenderer.cs
* Update Ptc.cs
* Disabled Profiled PTC by default as requested in the past by gdk.
* Fix rejit bug. Increased number of parallel translations. Add stack unwinding stuffs support (1 of 2).
Nits.
* Add stack unwinding stuffs support (2 of 2). Tuned number of parallel translations.
* Restored the ability to assemble jumps with 8-bit offset when Profiled PTC is disabled or during profiling.
Modifications due to rebase.
Nits.
* Limited profiling of the functions to be translated to the addresses belonging to the range of static objects only.
* Nits.
* Nits.
* Update Delegates.cs
* Nit.
* Update InstEmitSimdArithmetic.cs
* Address riperiperi comments.
* Fixed the issue of unjustifiably longer boot times at the second boot than at the first boot, measured at the same time or reference point and with the same number of translated functions.
* Implemented a simple redundant load/save mechanism.
Halved the value of Decoder.MaxInstsPerFunction more appropriate for the current performance of the Translator.
Replaced by Logger.PrintError to Logger.PrintDebug in TexturePool.cs about the supposed invalid texture format to avoid the spawn of the log.
Nits.
* Nit.
Improved Logger.PrintError in TexturePool.cs to avoid log spawn.
Added missing code for FZ handling (in output) for fp max/min instructions (slow paths).
* Add configuration migration for PTC
Co-authored-by: Thog <me@thog.eu>
* Implement a new physical memory manager and replace DeviceMemory
* Proper generic constraints
* Fix debug build
* Add memory tests
* New CPU memory manager and general code cleanup
* Remove host memory management from CPU project, use Ryujinx.Memory instead
* Fix tests
* Document exceptions on MemoryBlock
* Fix leak on unix memory allocation
* Proper disposal of some objects on tests
* Fix JitCache not being set as initialized
* GetRef without checks for 8-bits and 16-bits CAS
* Add MemoryBlock destructor
* Throw in separate method to improve codegen
* Address PR feedback
* QueryModified improvements
* Fix memory write tracking not marking all pages as modified in some cases
* Simplify MarkRegionAsModified
* Remove XML doc for ghost param
* Add back optimization to avoid useless buffer updates
* Add Ryujinx.Cpu project, move MemoryManager there and remove MemoryBlockWrapper
* Some nits
* Do not perform address translation when size is 0
* Address PR feedback and format NativeInterface class
* Remove ghost parameter description
* Update Ryujinx.Cpu to .NET Core 3.1
* Address PR feedback
* Fix build
* Return a well defined value for GetPhysicalAddress with invalid VA, and do not return unmapped ranges as modified
* Typo
* Start of JIT garbage collection improvements
- thread static pool for Operand, MemoryOperand, Operation
- Operands and Operations are always to be constructed via their static
helper classes, so they can be pooled.
- removing LinkedList from Node for sources/destinations (replaced with
List<>s for now, but probably could do arrays since size is bounded)
- removing params constructors from Node
- LinkedList<> to List<> with Clear() for Operand assignments/uses
- ThreadStaticPool is very simple and basically just exists for the
purpose of our specific translation allocation problem. Right now it
will stay at the worst case allocation count for that thread (so far) -
the pool can never shrink.
- Still some cases of Operand[] that haven't been removed yet. Will need
to evaluate them (eg. is there a reasonable max number of params for
Calls?)
* ConcurrentStack instead of ConcurrentQueue for Rejit
* Optimize some parts of LSRA
- BitMap now operates on 64-bit int rather than 32-bit
- BitMap is now pooled in a ThreadStatic pool (within lrsa)
- BitMap now is now its own iterator. Marginally speeds up iterating
through the bits.
- A few cases where enumerators were generated have been converted to
forms that generate less garbage.
- New data structure for sorting _usePositions in LiveIntervals. Much
faster split, NextUseAfter, initial insertion. Random insertion is
slightly slower.
- That last one is WIP since you need to insert the values backwards. It
would be ideal if it just flipped it for you, uncomplicating things on
the caller side.
* Use a static pool of thread static pools. (yes.)
Prevents each execution thread creating its own lowCq pool and making me cry.
* Move constant value to top, change naming convention.
* Fix iteration of memory operands.
* Increase max thread count.
* Address Feedback
* Implement Jump Table for Native Calls
NOTE: this slows down rejit considerably! Not recommended to be used
without codegen optimisation or AOT.
- Does not work on Linux
- A32 needs an additional commit.
* A32 Support
(WIP)
* Actually write Direct Call pointers to the table
That would help.
* Direct Calls: Rather than returning to the translator, attempt to keep within the native stack frame.
A return to the translator can still happen, but only by exceptionally
bubbling up to it.
Also:
- Always translate lowCq as a function. Faster interop with the direct
jumps, and this will be useful in future if we want to do speculative
translation.
- Tail Call Detection: after the decoding stage, detect if we do a tail
call, and avoid translating into it. Detected if a jump is made to an
address outwith the contiguous sequence of blocks surrounding the entry
point. The goal is to reduce code touched by jit and rejit.
* A32 Support
* Use smaller max function size for lowCq, fix exceptional returns
When a return has an unexpected value and there is no code block
following this one, we now return the value rather than continuing.
* CompareAndSwap (buggy)
* Ensure CompareAndSwap does not get optimized away.
* Use CompareAndSwap to make the dynamic table thread safe.
* Tail call for linux, throw on too many arguments.
* Combine CompareAndSwap 128 and 32/64.
They emit different IR instructions since their PreAllocator behaviour
is different, but now they just have one function on EmitterContext.
* Fix issues separating from optimisations.
* Use a stub to find and execute missing functions.
This allows us to skip doing many runtime comparisons and branches, and reduces the amount of code we need to emit significantly.
For the indirect call table, this stub also does the work of moving in the highCq address to the table when one is found.
* Make Jump Tables and Jit Cache dynmically resize
Reserve virtual memory, commit as needed.
* Move TailCallRemover to its own class.
* Multithreaded Translation (based on heuristic)
A poor one, at that. Need to get core count for a better one, which
means a lot of OS specific garbage.
* Better priority management for background threads.
* Bound core limit a bit more
Past a certain point the load is not paralellizable and starts stealing from the main thread. Likely due to GC, memory, heap allocation thread contention. Reduce by one core til optimisations come to improve the situation.
* Fix memory management on linux.
* Temporary solution to some sync problems.
This will make sure threads exit correctly, most of the time. There is a potential race where setting the sync counter to 0 does nothing (counter stays at what it was before, thread could take too long to exit), but we need to find a better way to do this anyways. Synchronization frequency has been tightened as we never enter blockwise segments of code. Essentially this means, check every x functions or loop iterations, before lowcq blocks existed and were worth just as much. Ideally it should be done in a better way, since functions can be anywhere from 1 to 5000 instructions. (maybe based on host timer, or an interrupt flag from a scheduler thread)
* Address feedback minus CompareAndSwap change.
* Use default ReservedRegion granularity.
* Merge CompareAndSwap with its V128 variant.
* We already got the source, no need to do it again.
* Make sure all background translation threads exit.
* Fix CompareAndSwap128
Detection criteria was a bit scuffed.
* Address Comments.
* Begin work on A32 SIMD Intrinsics
* More instructions, some cleanup.
* Intrinsics for Move instructions (zip etc)
These pass the existing tests.
* Intrinsics for some of Cvt
While doing this I noticed that the conversion for int/fp was incorrect
in the slow path. I'll fix this in the original repo.
* Intrinsics for more Arithmetic instructions.
* Intrinsics for Vext
* Fix VEXT Intrinsic for double words.
* Use InsertPs to move scalar values.
* Cleanup, fix VPADD.f32 and VMIN signed integer.
* Cleanup, add SSE2 support for scalar insert.
Works similarly to the IR scalar insert, but obviously this one works
directly on V128.
* Minor cleanup.
* Enable intrinsic for FP64 to integer conversion.
* Address feedback apart from splitting out intrinsic float abs
Also: bad VREV encodings as undefined rather than throwing in translation.
* Move float abs to helper, fix bug with cvt
* Rename opc2 & 3 to match A32 docs, use ArgumentOutOfRangeException appropriately.
* Get name of variable at compilation rather than string literal.
* Use correct double sign mask.
