naga/back/spv/
helpers.rs

1use alloc::{vec, vec::Vec};
2
3use arrayvec::ArrayVec;
4use spirv::Word;
5
6use crate::{Handle, UniqueArena};
7
8pub(super) fn bytes_to_words(bytes: &[u8]) -> Vec<Word> {
9    bytes
10        .chunks(4)
11        .map(|chars| chars.iter().rev().fold(0u32, |u, c| (u << 8) | *c as u32))
12        .collect()
13}
14
15pub(super) fn string_to_words(input: &str) -> Vec<Word> {
16    let bytes = input.as_bytes();
17
18    str_bytes_to_words(bytes)
19}
20
21pub(super) fn str_bytes_to_words(bytes: &[u8]) -> Vec<Word> {
22    let mut words = bytes_to_words(bytes);
23    if bytes.len() % 4 == 0 {
24        // nul-termination
25        words.push(0x0u32);
26    }
27
28    words
29}
30
31/// split a string into chunks and keep utf8 valid
32#[allow(unstable_name_collisions)]
33pub(super) fn string_to_byte_chunks(input: &str, limit: usize) -> Vec<&[u8]> {
34    let mut offset: usize = 0;
35    let mut start: usize = 0;
36    let mut words = vec![];
37    while offset < input.len() {
38        offset = input.floor_char_boundary_polyfill(offset + limit);
39        // Clippy wants us to call as_bytes() first to avoid the UTF-8 check,
40        // but we want to assert the output is valid UTF-8.
41        #[allow(clippy::sliced_string_as_bytes)]
42        words.push(input[start..offset].as_bytes());
43        start = offset;
44    }
45
46    words
47}
48
49pub(super) const fn map_storage_class(space: crate::AddressSpace) -> spirv::StorageClass {
50    match space {
51        crate::AddressSpace::Handle => spirv::StorageClass::UniformConstant,
52        crate::AddressSpace::Function => spirv::StorageClass::Function,
53        crate::AddressSpace::Private => spirv::StorageClass::Private,
54        crate::AddressSpace::Storage { .. } => spirv::StorageClass::StorageBuffer,
55        crate::AddressSpace::Uniform => spirv::StorageClass::Uniform,
56        crate::AddressSpace::WorkGroup => spirv::StorageClass::Workgroup,
57        crate::AddressSpace::Immediate => spirv::StorageClass::PushConstant,
58        crate::AddressSpace::TaskPayload => spirv::StorageClass::TaskPayloadWorkgroupEXT,
59    }
60}
61
62pub(super) fn contains_builtin(
63    binding: Option<&crate::Binding>,
64    ty: Handle<crate::Type>,
65    arena: &UniqueArena<crate::Type>,
66    built_in: crate::BuiltIn,
67) -> bool {
68    if let Some(&crate::Binding::BuiltIn(bi)) = binding {
69        bi == built_in
70    } else if let crate::TypeInner::Struct { ref members, .. } = arena[ty].inner {
71        members
72            .iter()
73            .any(|member| contains_builtin(member.binding.as_ref(), member.ty, arena, built_in))
74    } else {
75        false // unreachable
76    }
77}
78
79impl crate::AddressSpace {
80    pub(super) const fn to_spirv_semantics_and_scope(
81        self,
82    ) -> (spirv::MemorySemantics, spirv::Scope) {
83        match self {
84            Self::Storage { .. } => (spirv::MemorySemantics::empty(), spirv::Scope::Device),
85            Self::WorkGroup => (spirv::MemorySemantics::empty(), spirv::Scope::Workgroup),
86            Self::Uniform => (spirv::MemorySemantics::empty(), spirv::Scope::Device),
87            Self::Handle => (spirv::MemorySemantics::empty(), spirv::Scope::Device),
88            _ => (spirv::MemorySemantics::empty(), spirv::Scope::Invocation),
89        }
90    }
91}
92
93/// Return true if the global requires a type decorated with `Block`.
94///
95/// See [`back::spv::GlobalVariable`] for details.
96///
97/// [`back::spv::GlobalVariable`]: super::GlobalVariable
98pub fn global_needs_wrapper(ir_module: &crate::Module, var: &crate::GlobalVariable) -> bool {
99    match var.space {
100        crate::AddressSpace::Uniform
101        | crate::AddressSpace::Storage { .. }
102        | crate::AddressSpace::Immediate => {}
103        _ => return false,
104    };
105    match ir_module.types[var.ty].inner {
106        crate::TypeInner::Struct {
107            ref members,
108            span: _,
109        } => match members.last() {
110            Some(member) => match ir_module.types[member.ty].inner {
111                // Structs with dynamically sized arrays can't be copied and can't be wrapped.
112                crate::TypeInner::Array {
113                    size: crate::ArraySize::Dynamic,
114                    ..
115                } => false,
116                _ => true,
117            },
118            None => false,
119        },
120        crate::TypeInner::BindingArray { .. } => false,
121        // if it's not a structure or a binding array, let's wrap it to be able to put "Block"
122        _ => true,
123    }
124}
125
126/// Returns true if `pointer` refers to two-row matrix which is a member of a
127/// struct in the [`crate::AddressSpace::Uniform`] address space.
128pub fn is_uniform_matcx2_struct_member_access(
129    ir_function: &crate::Function,
130    fun_info: &crate::valid::FunctionInfo,
131    ir_module: &crate::Module,
132    pointer: Handle<crate::Expression>,
133) -> bool {
134    if let crate::TypeInner::Pointer {
135        base: pointer_base_type,
136        space: crate::AddressSpace::Uniform,
137    } = *fun_info[pointer].ty.inner_with(&ir_module.types)
138    {
139        if let crate::TypeInner::Matrix {
140            rows: crate::VectorSize::Bi,
141            ..
142        } = ir_module.types[pointer_base_type].inner
143        {
144            if let crate::Expression::AccessIndex {
145                base: parent_pointer,
146                ..
147            } = ir_function.expressions[pointer]
148            {
149                if let crate::TypeInner::Pointer {
150                    base: parent_type, ..
151                } = *fun_info[parent_pointer].ty.inner_with(&ir_module.types)
152                {
153                    if let crate::TypeInner::Struct { .. } = ir_module.types[parent_type].inner {
154                        return true;
155                    }
156                }
157            }
158        }
159    }
160
161    false
162}
163
164///HACK: this is taken from std unstable, remove it when std's floor_char_boundary is stable
165/// and available in our msrv.
166trait U8Internal {
167    fn is_utf8_char_boundary_polyfill(&self) -> bool;
168}
169
170impl U8Internal for u8 {
171    fn is_utf8_char_boundary_polyfill(&self) -> bool {
172        // This is bit magic equivalent to: b < 128 || b >= 192
173        (*self as i8) >= -0x40
174    }
175}
176
177trait StrUnstable {
178    fn floor_char_boundary_polyfill(&self, index: usize) -> usize;
179}
180
181impl StrUnstable for str {
182    fn floor_char_boundary_polyfill(&self, index: usize) -> usize {
183        if index >= self.len() {
184            self.len()
185        } else {
186            let lower_bound = index.saturating_sub(3);
187            let new_index = self.as_bytes()[lower_bound..=index]
188                .iter()
189                .rposition(|b| b.is_utf8_char_boundary_polyfill());
190
191            // SAFETY: we know that the character boundary will be within four bytes
192            unsafe { lower_bound + new_index.unwrap_unchecked() }
193        }
194    }
195}
196
197pub enum BindingDecorations {
198    BuiltIn(spirv::BuiltIn, ArrayVec<spirv::Decoration, 2>),
199    Location {
200        location: u32,
201        others: ArrayVec<spirv::Decoration, 5>,
202        /// If this is `Some`, use Decoration::Index with blend_src as an operand
203        blend_src: Option<Word>,
204    },
205    None,
206}
naga/back/spv/helpers.rs

naga/back/spv/
helpers.rs
