* [SpirvTranslator] Load dword-aligned 32-bit formatted buffer components as words
A formatted untyped buffer load decodes the descriptor format at run time,
reading every component byte by byte through the generic layout select
chain. For dword-aligned 32-bit data formats (32, 32_32, 32_32_32,
32_32_32_32) with a raw-bit number format (UINT, SINT, FLOAT) a component is
one buffer word; that branch loads it directly and applies the same swizzle
and bounds rules. The descriptor is uniform, so the branch does not diverge.
UE GPU-skinning vertex shaders fetch bone data this way; Silent Hill: The
Short Message's menu goes from 1.3 to 2.0 FPS.
(cherry picked from commit 20540cd153855964d817daf065de3e243fd547bd)
* [SpirvTranslator] Convert f16 with the native pack/unpack when the host measured it exact
Every packed-f16 (VOP3P) lane widens its operands to f32 and rounds the
result back, and both conversions were the branchless integer sequences in
EmitHalfToFloat / EmitFloatToHalf: about twenty scalar ops each, because
GLSL UnpackHalf2x16 / PackHalf2x16 have no guaranteed rounding or subnormal
behaviour without float-controls execution modes. A device capability bit
does not settle it either - MoltenVK on Apple silicon reports
shaderRoundingModeRTEFloat16 and shaderSignedZeroInfNanPreserveFloat16 yet
not shaderDenormPreserveFloat16 - so only a measurement can.
ShaderCompileRequest.NativeHalfConversionExact, which the host sets only
after measuring the two ext instructions against these sequences on the
running device, swaps both helpers for the single ext instruction the
driver lowers to one hardware convert. It defaults to false, so an
unmeasured device keeps the exact emulation.
Silent Hill f2 volumetric fog dispatch: 30.7 -> 21.9 ms per dispatch in
replay, output unchanged.
(cherry picked from commit 10f76eeac0d4306172e41ecff86b737f6a3c9634)
(cherry picked from commit 7f18cc96ae58ac5fd47da6562c4ba3abe22ccb4a)
(cherry picked from commit 972f658033f8339effe42c5d305af87bcbab93f0)
* [Vk] Probe f16 conversion at device setup and report the verdict
A one-time compute pass at device setup measures the device's GLSL
UnpackHalf2x16 / PackHalf2x16 against the translator's own f16 conversion
before any guest shader is compiled, and only a clean measurement lets the
translator use them (ShaderCompileRequest.NativeHalfConversionExact). The
vectors cover all 65536 f16 bit patterns, every f16 value widened to f32,
the midpoint between adjacent f16 values and that midpoint one f32 ulp
either way, the overflow edge, signed zeroes, infinities, NaNs and f32
subnormals, and each is measured in both directions: 643200 comparisons.
Every finite value, zero and infinity must be bit-exact, sign included. A
NaN only has to stay a NaN, because neither side defines its payload: the
emulation picks sign | 0x7C00 | 0x200 narrowing and carries the f16 payload
widening, while the measured hardware convert canonicalizes to a positive
quiet NaN. On an Apple M4 that is the only disagreement - 2314 of 643200,
every one a negative NaN whose sign the hardware cleared - and f16
subnormals convert exactly despite shaderDenormPreserveFloat16 being false.
The probe never fails device setup: any error leaves the exact emulation in
place and says so on the reported line. SHARPEMU_NATIVE_HALF=0 forces the
emulation, =1 takes native without measuring. The result is one line:
[VK][F16] native half conversion exact=True mismatches=0 tested=643200
The flag reaches the translator through IShaderPipelineHost, so it is
process-constant and cannot mix two translations of one program; the saved
driver pipeline cache keys its entries by the module it was given, and the
Metal host does not probe and keeps the emulation. Offline replays run the
same probe, so a case translates the way the game would.
(cherry picked from commit 6a343683d890b4c6d123c84fdacb41e718ec4c19)
(cherry picked from commit 65ca663aa2bfb1fcc69709c73ab6189b07ead3c1)
(cherry picked from commit 003b1216bd311e5c5fb1d48ca01a66efa3fc51de)
* [SpirvTranslator] Read an unaligned buffer word as a funnel shift of two words
The byte-wise decode of a formatted buffer load read each byte of a component
from its own bounds-checked word load: four loads, four range tests and a byte
assembly for a value that spans at most two words. One funnel shift of those
two words is the same value, including out of range, where a word reads zero on
both paths and so contributes zero bytes. Every sub-dword buffer load goes
through the same helper.
The decode is the branch a formatted load takes when its address is not dword
aligned, so its size also sets the register pressure of the aligned branch next
to it. Silent Hill: The Short Message's volumetric fog dispatch
(0xD5DF9DC46C4E35EA, 8 formatted loads in its light loop) goes from 8.68 to
7.28 ms in offline replay, and the module from 394 to 360 KiB. An experiment
that dropped the byte-wise branch entirely measured 7.35 ms, so the funnel
shift is worth all of what the branch cost.
(cherry picked from commit 0c996ffab38144d795517e68cb2ca9d8d48e8988)
* [SpirvTranslator] Load a guest buffer word unchecked where the device zeroes out-of-range reads
Every guest buffer word is read through a range test, an address clamp and a
zero select: three operations whose only purpose is to produce the zero the
hardware returns past the end of a V#. A device with robustBufferAccess2 that
honours it returns that zero itself, so the three are pure overhead there -
dropping them measured about 12% of Silent Hill's volumetric fog dispatch, 482
checked words in one program.
ShaderCompileRequest.ZeroOutOfBoundsBufferReads turns them off and defaults to
false: an out-of-range read is undefined without the promise, so only a host
that measured the device may set it. It is set from a device probe, never from
a capability bit, because MoltenVK runs on Metal, which has no hardware bounds
checking.
(cherry picked from commit 2ba626a0ac7157f93f348cfe7573ff1092762d8c)
* [Vk] Probe out-of-range buffer reads at device setup and report the verdict
A one-time compute pass binds 1 KiB of a 4 KiB allocation that carries a
sentinel everywhere and reads all 4 KiB back through the descriptor: the words
inside the range must still read their sentinel and the words past it must read
zero. Only a clean measurement lets the translator drop the range test, address
clamp and zero select it puts around every guest buffer word
(ShaderCompileRequest.ZeroOutOfBoundsBufferReads).
The probe only runs where the device enabled robustBufferAccess2, because an
out-of-range read is undefined without it and can fault the device; everywhere
else it reports the reason and the checks stay. On this Apple M4 through
MoltenVK the feature is not supported at all, so nothing changes:
[VK][OOB] out-of-range buffer reads zero=False mismatches=unprobed tested=0
note=robustBufferAccess2 is not enabled on this device
SHARPEMU_ZERO_OOB_READS=0 keeps the checks, =1 drops them without measuring.
The flag reaches the translator through IShaderPipelineHost, so it is
process-constant and cannot mix two translations of one program.
(cherry picked from commit e81d924349042acc1122a66d4c767268bd6ef2a4)
da0953845b