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add support for leading_zeros, trailing_zeros and fix count_ones #213

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merged 15 commits into from
Mar 21, 2025
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Merged

add support for leading_zeros, trailing_zeros and fix count_ones #213

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15f5a5b
leading_zeros: add support for leading_zeros and trailing_zeros, limi…
Firestar99 Jan 29, 2025
ce566fa
leading_zeros: add tests for non 32bit integers, failing
Firestar99 Feb 10, 2025
70507e9
leading_zeros: support 8bit, 16bit and emulate 64bit
Firestar99 Feb 10, 2025
31ce03f
leading_zeros: fix unused warning for `enabled_extensions`
Firestar99 Feb 10, 2025
7d3452c
count_ones: add failing tests for count_ones and bit_reverse
Firestar99 Feb 10, 2025
5083b9e
count_ones: fix pointer cast errors
Firestar99 Feb 10, 2025
4c046f7
count_ones: fix count_ones, must be u32-only in vulkan
Firestar99 Feb 10, 2025
6733b1a
count_ones: fix bit_reverse, must be u32-only in vulkan
Firestar99 Feb 10, 2025
ef1d3ff
count_ones: fix u64 bitshifts in all new functions
Firestar99 Mar 13, 2025
ac49f2f
count_ones: fix mismatched error messages to methods containing them
Firestar99 Mar 13, 2025
1449527
count_ones: cargo fmt
Firestar99 Mar 13, 2025
57c7d9d
leading_zeros: fix leading zeros for u32
Firestar99 Mar 21, 2025
ee1904b
leading_zeros: remove sign conversions, always unsigned, except for l…
Firestar99 Mar 21, 2025
ad3ace9
leading_zeros: make all conversions unsigned
Firestar99 Mar 21, 2025
00f41df
leading_zeros: code cleanup
Firestar99 Mar 21, 2025
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33 changes: 3 additions & 30 deletions crates/rustc_codegen_spirv/src/builder/ext_inst.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,8 +1,8 @@
use super::Builder;
use crate::builder_spirv::{SpirvValue, SpirvValueExt};
use crate::custom_insts;
use rspirv::dr::Operand;
use rspirv::spirv::{GLOp, Word};
use rspirv::{dr::Operand, spirv::Capability};

const GLSL_STD_450: &str = "GLSL.std.450";

Expand All @@ -13,7 +13,6 @@ pub struct ExtInst {
custom: Option<Word>,

glsl: Option<Word>,
integer_functions_2_intel: bool,
}

impl ExtInst {
Expand All @@ -38,32 +37,11 @@ impl ExtInst {
id
}
}

pub fn require_integer_functions_2_intel(&mut self, bx: &Builder<'_, '_>, to_zombie: Word) {
if !self.integer_functions_2_intel {
self.integer_functions_2_intel = true;
if !bx
.builder
.has_capability(Capability::IntegerFunctions2INTEL)
{
bx.zombie(to_zombie, "capability IntegerFunctions2INTEL is required");
}
if !bx
.builder
.has_extension(bx.sym.spv_intel_shader_integer_functions2)
{
bx.zombie(
to_zombie,
"extension SPV_INTEL_shader_integer_functions2 is required",
);
}
}
}
}

impl<'a, 'tcx> Builder<'a, 'tcx> {
pub fn custom_inst(
&mut self,
&self,
result_type: Word,
inst: custom_insts::CustomInst<Operand>,
) -> SpirvValue {
Expand All @@ -80,12 +58,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
.with_type(result_type)
}

pub fn gl_op(
&mut self,
op: GLOp,
result_type: Word,
args: impl AsRef<[SpirvValue]>,
) -> SpirvValue {
pub fn gl_op(&self, op: GLOp, result_type: Word, args: impl AsRef<[SpirvValue]>) -> SpirvValue {
let args = args.as_ref();
let glsl = self.ext_inst.borrow_mut().import_glsl(self);
self.emit()
Expand Down
283 changes: 245 additions & 38 deletions crates/rustc_codegen_spirv/src/builder/intrinsics.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -211,46 +211,15 @@ impl<'a, 'tcx> IntrinsicCallBuilderMethods<'tcx> for Builder<'a, 'tcx> {
self.rotate(val, shift, is_left)
}

// TODO: Do we want to manually implement these instead of using intel instructions?
sym::ctlz | sym::ctlz_nonzero => {
let result = self
.emit()
.u_count_leading_zeros_intel(
args[0].immediate().ty,
None,
args[0].immediate().def(self),
)
.unwrap();
self.ext_inst
.borrow_mut()
.require_integer_functions_2_intel(self, result);
result.with_type(args[0].immediate().ty)
}
sym::cttz | sym::cttz_nonzero => {
let result = self
.emit()
.u_count_trailing_zeros_intel(
args[0].immediate().ty,
None,
args[0].immediate().def(self),
)
.unwrap();
self.ext_inst
.borrow_mut()
.require_integer_functions_2_intel(self, result);
result.with_type(args[0].immediate().ty)
sym::ctlz => self.count_leading_trailing_zeros(args[0].immediate(), false, false),
sym::ctlz_nonzero => {
self.count_leading_trailing_zeros(args[0].immediate(), false, true)
}
sym::cttz => self.count_leading_trailing_zeros(args[0].immediate(), true, false),
sym::cttz_nonzero => self.count_leading_trailing_zeros(args[0].immediate(), true, true),

sym::ctpop => self
.emit()
.bit_count(args[0].immediate().ty, None, args[0].immediate().def(self))
.unwrap()
.with_type(args[0].immediate().ty),
sym::bitreverse => self
.emit()
.bit_reverse(args[0].immediate().ty, None, args[0].immediate().def(self))
.unwrap()
.with_type(args[0].immediate().ty),
sym::ctpop => self.count_ones(args[0].immediate()),
sym::bitreverse => self.bit_reverse(args[0].immediate()),
sym::bswap => {
// https://github.com/KhronosGroup/SPIRV-LLVM/pull/221/files
// TODO: Definitely add tests to make sure this impl is right.
Expand Down Expand Up @@ -398,6 +367,244 @@ impl<'a, 'tcx> IntrinsicCallBuilderMethods<'tcx> for Builder<'a, 'tcx> {
}

impl Builder<'_, '_> {
pub fn count_ones(&self, arg: SpirvValue) -> SpirvValue {
let ty = arg.ty;
match self.cx.lookup_type(ty) {
SpirvType::Integer(bits, false) => {
let u32 = SpirvType::Integer(32, false).def(self.span(), self);

match bits {
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Just a style thing, but I generally feel it is clearer to matched on signed as well, it makes all the cases clearer, similar to what you did in bitcast.

8 | 16 => {
let arg = arg.def(self);
let arg = self.emit().u_convert(u32, None, arg).unwrap();
self.emit().bit_count(u32, None, arg).unwrap()
}
32 => self.emit().bit_count(u32, None, arg.def(self)).unwrap(),
64 => {
let u32_32 = self.constant_u32(self.span(), 32).def(self);
let arg = arg.def(self);
let lower = self.emit().u_convert(u32, None, arg).unwrap();
let higher = self
.emit()
.shift_right_logical(ty, None, arg, u32_32)
.unwrap();
let higher = self.emit().u_convert(u32, None, higher).unwrap();

let lower_bits = self.emit().bit_count(u32, None, lower).unwrap();
let higher_bits = self.emit().bit_count(u32, None, higher).unwrap();
self.emit()
.i_add(u32, None, lower_bits, higher_bits)
.unwrap()
}
_ => {
let undef = self.undef(ty).def(self);
self.zombie(
undef,
&format!("count_ones() on unsupported {ty:?} bit integer type"),
);
undef
}
}
.with_type(u32)
}
_ => self.fatal(format!(
"count_ones() expected an unsigned integer type, got {:?}",
self.cx.lookup_type(ty)
)),
}
}

pub fn bit_reverse(&self, arg: SpirvValue) -> SpirvValue {
let ty = arg.ty;
match self.cx.lookup_type(ty) {
SpirvType::Integer(bits, false) => {
let u32 = SpirvType::Integer(32, false).def(self.span(), self);
let uint = SpirvType::Integer(bits, false).def(self.span(), self);

match bits {
8 | 16 => {
let arg = arg.def(self);
let arg = self.emit().u_convert(u32, None, arg).unwrap();

let reverse = self.emit().bit_reverse(u32, None, arg).unwrap();
let shift = self.constant_u32(self.span(), 32 - bits).def(self);
let reverse = self
.emit()
.shift_right_logical(u32, None, reverse, shift)
.unwrap();
self.emit().u_convert(uint, None, reverse).unwrap()
}
32 => self.emit().bit_reverse(u32, None, arg.def(self)).unwrap(),
64 => {
let u32_32 = self.constant_u32(self.span(), 32).def(self);
let arg = arg.def(self);
let lower = self.emit().u_convert(u32, None, arg).unwrap();
let higher = self
.emit()
.shift_right_logical(ty, None, arg, u32_32)
.unwrap();
let higher = self.emit().u_convert(u32, None, higher).unwrap();

// note that higher and lower have swapped
let higher_bits = self.emit().bit_reverse(u32, None, lower).unwrap();
let lower_bits = self.emit().bit_reverse(u32, None, higher).unwrap();

let higher_bits = self.emit().u_convert(uint, None, higher_bits).unwrap();
let higher_bits = self
.emit()
.shift_left_logical(uint, None, higher_bits, u32_32)
.unwrap();
let lower_bits = self.emit().u_convert(uint, None, lower_bits).unwrap();

self.emit()
.bitwise_or(ty, None, lower_bits, higher_bits)
.unwrap()
}
_ => {
let undef = self.undef(ty).def(self);
self.zombie(
undef,
&format!("bit_reverse() on unsupported {ty:?} bit integer type"),
);
undef
}
}
.with_type(ty)
}
_ => self.fatal(format!(
"bit_reverse() expected an unsigned integer type, got {:?}",
self.cx.lookup_type(ty)
)),
}
}

pub fn count_leading_trailing_zeros(
&self,
arg: SpirvValue,
trailing: bool,
non_zero: bool,
) -> SpirvValue {
let ty = arg.ty;
match self.cx.lookup_type(ty) {
SpirvType::Integer(bits, false) => {
let bool = SpirvType::Bool.def(self.span(), self);
let u32 = SpirvType::Integer(32, false).def(self.span(), self);

let glsl = self.ext_inst.borrow_mut().import_glsl(self);
let find_xsb = |arg| {
if trailing {
self.emit()
.ext_inst(u32, None, glsl, GLOp::FindILsb as u32, [Operand::IdRef(
arg,
)])
.unwrap()
} else {
// rust is always unsigned, so FindUMsb
let msb_bit = self
.emit()
.ext_inst(u32, None, glsl, GLOp::FindUMsb as u32, [Operand::IdRef(
arg,
)])
.unwrap();
// the glsl op returns the Msb bit, not the amount of leading zeros of this u32
// leading zeros = 31 - Msb bit
let u32_31 = self.constant_u32(self.span(), 31).def(self);
self.emit().i_sub(u32, None, u32_31, msb_bit).unwrap()
}
};

let converted = match bits {
8 | 16 => {
if trailing {
let arg = self.emit().u_convert(u32, None, arg.def(self)).unwrap();
find_xsb(arg)
} else {
let arg = arg.def(self);
let arg = self.emit().u_convert(u32, None, arg).unwrap();
let xsb = find_xsb(arg);
let subtrahend = self.constant_u32(self.span(), 32 - bits).def(self);
self.emit().i_sub(u32, None, xsb, subtrahend).unwrap()
}
}
32 => find_xsb(arg.def(self)),
64 => {
let u32_0 = self.constant_int(u32, 0).def(self);
let u32_32 = self.constant_u32(self.span(), 32).def(self);

let arg = arg.def(self);
let lower = self.emit().u_convert(u32, None, arg).unwrap();
let higher = self
.emit()
.shift_right_logical(ty, None, arg, u32_32)
.unwrap();
let higher = self.emit().u_convert(u32, None, higher).unwrap();

let lower_bits = find_xsb(lower);
let higher_bits = find_xsb(higher);

if trailing {
let use_lower = self.emit().i_equal(bool, None, higher, u32_0).unwrap();
let lower_bits =
self.emit().i_add(u32, None, lower_bits, u32_32).unwrap();
self.emit()
.select(u32, None, use_lower, lower_bits, higher_bits)
.unwrap()
} else {
let use_higher = self.emit().i_equal(bool, None, lower, u32_0).unwrap();
let higher_bits =
self.emit().i_add(u32, None, higher_bits, u32_32).unwrap();
self.emit()
.select(u32, None, use_higher, higher_bits, lower_bits)
.unwrap()
}
}
_ => {
let undef = self.undef(ty).def(self);
self.zombie(undef, &format!(
"count_leading_trailing_zeros() on unsupported {ty:?} bit integer type"
));
undef
}
};

if non_zero {
converted
} else {
let int_0 = self.constant_int(ty, 0).def(self);
let int_bits = self.constant_int(u32, bits as u128).def(self);
let is_0 = self
.emit()
.i_equal(bool, None, arg.def(self), int_0)
.unwrap();
self.emit()
.select(u32, None, is_0, int_bits, converted)
.unwrap()
}
.with_type(u32)
}
SpirvType::Integer(bits, true) => {
// rustc wants `[i8,i16,i32,i64]::leading_zeros()` with `non_zero: true` for some reason. I do not know
// how these are reachable, marking them as zombies makes none of our compiletests fail.
let unsigned = SpirvType::Integer(bits, false).def(self.span(), self);
let arg = self
.emit()
.bitcast(unsigned, None, arg.def(self))
.unwrap()
.with_type(unsigned);
let result = self.count_leading_trailing_zeros(arg, trailing, non_zero);
self.emit()
.bitcast(ty, None, result.def(self))
.unwrap()
.with_type(ty)
}
e => {
self.fatal(format!(
"count_leading_trailing_zeros(trailing: {trailing}, non_zero: {non_zero}) expected an integer type, got {e:?}",
));
}
}
}

pub fn abort_with_kind_and_message_debug_printf(
&mut self,
kind: &str,
Expand Down
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