Skip to content

Vectorize [un]pack4x{I, U}8[Clamp] on spv and msl #7664

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

Merged
merged 5 commits into from
May 23, 2025
Merged

Vectorize [un]pack4x{I, U}8[Clamp] on spv and msl #7664

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
cba9b21
[naga] Vectorize `[un]pack4x{I, U}8[Clamp]` on spv
robamler May 3, 2025
8f7f940
[naga] Vectorize `[un]pack4x{I, U}8[Clamp]` on msl
robamler May 3, 2025
9569fa0
Add changelog entry for #7664
robamler May 3, 2025
19bdf88
[wgpu-hal] separate 2 float16-related vk features
robamler May 4, 2025
871d295
[wgpu-hal] Add `PrivateCapabilities::shader_int8` on Vulkan
robamler May 4, 2025
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
1 change: 1 addition & 0 deletions CHANGELOG.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -64,6 +64,7 @@ Naga now infers the correct binding layout when a resource appears only in an as
- Apply necessary automatic conversions to the `value` argument of `textureStore`. By @jimblandy in [#7567](https://github.com/gfx-rs/wgpu/pull/7567).
- Properly apply WGSL's automatic conversions to the arguments to texture sampling functions. By @jimblandy in [#7548](https://github.com/gfx-rs/wgpu/pull/7548).
- Properly evaluate `abs(most negative abstract int)`. By @jimblandy in [#7507](https://github.com/gfx-rs/wgpu/pull/7507).
- Generate vectorized code for `[un]pack4x{I,U}8[Clamp]` on SPIR-V and MSL 2.1+. By @robamler in [#7664](https://github.com/gfx-rs/wgpu/pull/7664).

#### DX12

Expand Down
140 changes: 93 additions & 47 deletions naga/src/back/msl/writer.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1497,6 +1497,58 @@ impl<W: Write> Writer<W> {
Ok(())
}

/// Emit code for the WGSL functions `pack4x{I, U}8[Clamp]`.
fn put_pack4x8(
&mut self,
arg: Handle<crate::Expression>,
context: &ExpressionContext<'_>,
was_signed: bool,
clamp_bounds: Option<(&str, &str)>,
) -> Result<(), Error> {
let write_arg = |this: &mut Self| -> BackendResult {
if let Some((min, max)) = clamp_bounds {
// Clamping with scalar bounds works (component-wise) even for packed_[u]char4.
write!(this.out, "{NAMESPACE}::clamp(")?;
this.put_expression(arg, context, true)?;
write!(this.out, ", {min}, {max})")?;
} else {
this.put_expression(arg, context, true)?;
}
Ok(())
};

if context.lang_version >= (2, 1) {
let packed_type = if was_signed {
"packed_char4"
} else {
"packed_uchar4"
};
// Metal uses little endian byte order, which matches what WGSL expects here.
write!(self.out, "as_type<uint>({packed_type}(")?;
write_arg(self)?;
write!(self.out, "))")?;
} else {
// MSL < 2.1 doesn't support `as_type` casting between packed chars and scalars.
if was_signed {
write!(self.out, "uint(")?;
}
write!(self.out, "(")?;
write_arg(self)?;
write!(self.out, "[0] & 0xFF) | ((")?;
write_arg(self)?;
write!(self.out, "[1] & 0xFF) << 8) | ((")?;
write_arg(self)?;
write!(self.out, "[2] & 0xFF) << 16) | ((")?;
write_arg(self)?;
write!(self.out, "[3] & 0xFF) << 24)")?;
if was_signed {
write!(self.out, ")")?;
}
}

Ok(())
}

/// Emit code for the isign expression.
///
fn put_isign(
Expand Down Expand Up @@ -2437,53 +2489,41 @@ impl<W: Write> Writer<W> {
write!(self.out, "{fun_name}")?;
self.put_call_parameters(iter::once(arg), context)?;
}
fun @ (Mf::Pack4xI8 | Mf::Pack4xU8 | Mf::Pack4xI8Clamp | Mf::Pack4xU8Clamp) => {
let was_signed = matches!(fun, Mf::Pack4xI8 | Mf::Pack4xI8Clamp);
let clamp_bounds = match fun {
Mf::Pack4xI8Clamp => Some(("-128", "127")),
Mf::Pack4xU8Clamp => Some(("0", "255")),
_ => None,
};
if was_signed {
write!(self.out, "uint(")?;
}
let write_arg = |this: &mut Self| -> BackendResult {
if let Some((min, max)) = clamp_bounds {
write!(this.out, "{NAMESPACE}::clamp(")?;
this.put_expression(arg, context, true)?;
write!(this.out, ", {min}, {max})")?;
} else {
this.put_expression(arg, context, true)?;
}
Ok(())
};
write!(self.out, "(")?;
write_arg(self)?;
write!(self.out, "[0] & 0xFF) | ((")?;
write_arg(self)?;
write!(self.out, "[1] & 0xFF) << 8) | ((")?;
write_arg(self)?;
write!(self.out, "[2] & 0xFF) << 16) | ((")?;
write_arg(self)?;
write!(self.out, "[3] & 0xFF) << 24)")?;
if was_signed {
write!(self.out, ")")?;
}
Mf::Pack4xI8 => self.put_pack4x8(arg, context, true, None)?,
Mf::Pack4xU8 => self.put_pack4x8(arg, context, false, None)?,
Mf::Pack4xI8Clamp => {
self.put_pack4x8(arg, context, true, Some(("-128", "127")))?
}
Mf::Pack4xU8Clamp => {
self.put_pack4x8(arg, context, false, Some(("0", "255")))?
}
fun @ (Mf::Unpack4xI8 | Mf::Unpack4xU8) => {
write!(self.out, "(")?;
if matches!(fun, Mf::Unpack4xU8) {
write!(self.out, "u")?;
let sign_prefix = if matches!(fun, Mf::Unpack4xU8) {
"u"
} else {
""
};

if context.lang_version >= (2, 1) {
// Metal uses little endian byte order, which matches what WGSL expects here.
write!(
self.out,
"{sign_prefix}int4(as_type<packed_{sign_prefix}char4>("
)?;
self.put_expression(arg, context, true)?;
write!(self.out, "))")?;
} else {
// MSL < 2.1 doesn't support `as_type` casting between packed chars and scalars.
write!(self.out, "({sign_prefix}int4(")?;
self.put_expression(arg, context, true)?;
write!(self.out, ", ")?;
self.put_expression(arg, context, true)?;
write!(self.out, " >> 8, ")?;
self.put_expression(arg, context, true)?;
write!(self.out, " >> 16, ")?;
self.put_expression(arg, context, true)?;
write!(self.out, " >> 24) << 24 >> 24)")?;
}
write!(self.out, "int4(")?;
self.put_expression(arg, context, true)?;
write!(self.out, ", ")?;
self.put_expression(arg, context, true)?;
write!(self.out, " >> 8, ")?;
self.put_expression(arg, context, true)?;
write!(self.out, " >> 16, ")?;
self.put_expression(arg, context, true)?;
write!(self.out, " >> 24) << 24 >> 24)")?;
}
Mf::QuantizeToF16 => {
match *context.resolve_type(arg) {
Expand Down Expand Up @@ -3226,14 +3266,20 @@ impl<W: Write> Writer<W> {
self.need_bake_expressions.insert(arg);
self.need_bake_expressions.insert(arg1.unwrap());
}
crate::MathFunction::FirstLeadingBit
| crate::MathFunction::Pack4xI8
crate::MathFunction::FirstLeadingBit => {
self.need_bake_expressions.insert(arg);
}
crate::MathFunction::Pack4xI8
| crate::MathFunction::Pack4xU8
| crate::MathFunction::Pack4xI8Clamp
| crate::MathFunction::Pack4xU8Clamp
| crate::MathFunction::Unpack4xI8
| crate::MathFunction::Unpack4xU8 => {
self.need_bake_expressions.insert(arg);
// On MSL < 2.1, we emit a polyfill for these functions that uses the
// argument multiple times. This is no longer necessary on MSL >= 2.1.
if context.lang_version < (2, 1) {
self.need_bake_expressions.insert(arg);
}
}
crate::MathFunction::ExtractBits => {
// Only argument 1 is re-used.
Expand Down
Loading
Loading