Allow reading (g)megabuf

captbaritone · captbaritone · commit a2a5bc6e215a · 2021-04-05T21:25:43.000-07:00
diff --git a/compiler-rs/src/builtin_functions.rs b/compiler-rs/src/builtin_functions.rs
@@ -1,16 +1,24 @@
-use parity_wasm::elements::{BlockType, FuncBody, Instruction, Instructions, Local, ValueType};
+use parity_wasm::elements::{
+    BlockType, FuncBody, FunctionType, Instruction, Instructions, Local, ValueType,
+};
 
+use crate::constants::{BUFFER_SIZE, EPSILON};
+use crate::utils::f64_const;
 use crate::EelFunctionType;
 
 #[derive(PartialEq, Eq, Hash)]
 pub enum BuiltinFunction {
     Div,
+    GetBufferIndex,
 }
 
 impl BuiltinFunction {
     pub fn get_type(&self) -> EelFunctionType {
         match self {
-            Self::Div => (2, 1),
+            Self::Div => {
+                FunctionType::new(vec![ValueType::F64, ValueType::F64], vec![ValueType::F64])
+            }
+            Self::GetBufferIndex => FunctionType::new(vec![ValueType::F64], vec![ValueType::I32]),
         }
     }
 
@@ -32,6 +40,50 @@ impl BuiltinFunction {
                     Instruction::End,
                 ]),
             ),
+            // Takes a float buffer index and converts it to an int. Values out of range
+            // are returned as `-1`.
+            //
+            // NOTE: There's actually a subtle bug that exists in Milkdrop's Eel
+            // implementation, which we reproduce here.
+            //
+            // Wasm's `trunc()` rounds towards zero. This means that for index `-1` we
+            // will return zero, since: `roundTowardZero(-1 + EPSILON) == 0`
+            //
+            // A subsequent check handles negative indexes, so negative indexes > than
+            // `-1` are not affected.
+            Self::GetBufferIndex => FuncBody::new(
+                vec![Local::new(1, ValueType::F64), Local::new(1, ValueType::I32)],
+                Instructions::new(vec![
+                    Instruction::F64Const(f64_const(EPSILON)),
+                    Instruction::GetLocal(0),
+                    Instruction::F64Add,
+                    // STACK: [$i + EPSILON]
+                    Instruction::TeeLocal(1), // $with_near
+                    Instruction::I32TruncSF64,
+                    // TODO We could probably make this a tee and get rid of the next get if we swap the final condition
+                    Instruction::SetLocal(2),
+                    // STACK: []
+                    Instruction::I32Const(-1),
+                    Instruction::GetLocal(2),
+                    // STACK: [-1, $truncated]
+                    Instruction::I32Const(8),
+                    Instruction::I32Mul,
+                    // STACK: [-1, $truncated * 8]
+                    Instruction::GetLocal(2), // $truncated
+                    Instruction::I32Const(0),
+                    // STACK: [-1, $truncated * 8, $truncated, 0]
+                    Instruction::I32LtS,
+                    // STACK: [-1, $truncated * 8, <is index less than 0>]
+                    Instruction::GetLocal(2), // $truncated
+                    Instruction::I32Const(BUFFER_SIZE as i32 - 1),
+                    Instruction::I32GtS,
+                    // STACK: [-1, $truncated * 8, <is index less than 0>, <is index more than MAX>]
+                    Instruction::I32Or,
+                    // STACK: [-1, $truncated * 8, <is index out of range>]
+                    Instruction::Select,
+                    Instruction::End,
+                ]),
+            ),
         }
     }
 }
diff --git a/compiler-rs/src/constants.rs b/compiler-rs/src/constants.rs
@@ -0,0 +1,12 @@
+pub static EPSILON: f64 = 0.00001;
+
+pub static WASM_PAGE_SIZE: u32 = 65536;
+
+static BYTES_PER_F64: u32 = 8;
+static BUFFER_COUNT: u32 = 2;
+
+// The number of items allowed in each buffer (megabuf/gmegabuf).
+// https://github.com/WACUP/vis_milk2/blob/de9625a89e724afe23ed273b96b8e48496095b6c/ns-eel2/ns-eel.h#L145
+pub static BUFFER_SIZE: u32 = 65536 * 128;
+
+pub static WASM_MEMORY_SIZE: u32 = (BUFFER_SIZE * BYTES_PER_F64 * BUFFER_COUNT) / WASM_PAGE_SIZE;
diff --git a/compiler-rs/src/emitter.rs b/compiler-rs/src/emitter.rs
@@ -1,27 +1,31 @@
-use std::collections::{HashMap, HashSet};
+use std::{
+    collections::{HashMap, HashSet},
+    mem,
+};
 
 use crate::{
     ast::{
         Assignment, BinaryExpression, BinaryOperator, EelFunction, Expression, ExpressionBlock,
         FunctionCall, UnaryExpression, UnaryOperator,
     },
     builtin_functions::BuiltinFunction,
+    constants::{BUFFER_SIZE, EPSILON, WASM_MEMORY_SIZE},
     error::CompilerError,
     index_store::IndexStore,
     shim::Shim,
     span::Span,
+    utils::f64_const,
     EelFunctionType,
 };
 use parity_wasm::elements::{
     BlockType, CodeSection, ExportEntry, ExportSection, External, Func, FuncBody, FunctionSection,
     FunctionType, GlobalEntry, GlobalSection, GlobalType, ImportEntry, ImportSection, InitExpr,
-    Instruction, Instructions, Internal, Module, Section, Serialize, Type, TypeSection, ValueType,
+    Instruction, Instructions, Internal, Local, MemorySection, MemoryType, Module, Section,
+    Serialize, Type, TypeSection, ValueType,
 };
 
 type EmitterResult<T> = Result<T, CompilerError>;
 
-static EPSILON: f64 = 0.00001;
-
 pub fn emit(
     eel_functions: Vec<(String, EelFunction, String)>,
     globals_map: HashMap<String, HashSet<String>>,
@@ -37,6 +41,7 @@ struct Emitter {
     builtin_functions: IndexStore<BuiltinFunction>,
     function_types: IndexStore<EelFunctionType>,
     builtin_offset: Option<u32>,
+    locals: Vec<ValueType>,
 }
 
 impl Emitter {
@@ -48,6 +53,7 @@ impl Emitter {
             function_types: Default::default(),
             builtin_functions: IndexStore::new(),
             builtin_offset: None,
+            locals: Default::default(),
         }
     }
     fn emit(
@@ -90,6 +96,11 @@ impl Emitter {
             sections.push(Section::Import(import_section));
         }
         sections.push(Section::Function(self.emit_function_section(funcs)));
+
+        sections.push(Section::Memory(MemorySection::with_entries(vec![
+            MemoryType::new(WASM_MEMORY_SIZE, Some(WASM_MEMORY_SIZE)),
+        ])));
+
         if let Some(global_section) = self.emit_global_section() {
             sections.push(Section::Global(global_section));
         }
@@ -113,11 +124,12 @@ impl Emitter {
         let function_types = self
             .function_types
             .keys()
-            .iter()
-            .map(|(args, returns)| {
+            .into_iter()
+            .map(|function_type| {
                 Type::Function(FunctionType::new(
-                    vec![ValueType::F64; *args],
-                    vec![ValueType::F64; *returns],
+                    // TODO: This is clone with more steps. What's going on
+                    function_type.params().to_vec(),
+                    function_type.results().to_vec(),
                 ))
             })
             .collect();
@@ -178,15 +190,25 @@ impl Emitter {
         let mut function_bodies = Vec::new();
         let mut function_definitions = Vec::new();
         for (i, (name, program, pool_name)) in eel_functions.into_iter().enumerate() {
+            // Note: We assume self.locals has been rest during the previous run.
             self.current_pool = pool_name;
             exports.push(ExportEntry::new(
                 name,
                 Internal::Function(i as u32 + offset),
             ));
-            let locals = Vec::new();
-            function_bodies.push(FuncBody::new(locals, self.emit_program(program)?));
 
-            let function_type = self.function_types.get((0, 0));
+            let instructions = self.emit_program(program)?;
+
+            let local_types = mem::replace(&mut self.locals, Vec::new());
+
+            let locals = local_types
+                .into_iter()
+                .map(|type_| Local::new(1, type_))
+                .collect();
+
+            function_bodies.push(FuncBody::new(locals, instructions));
+
+            let function_type = self.function_types.get(FunctionType::new(vec![], vec![]));
 
             function_definitions.push(Func::new(function_type))
         }
@@ -334,6 +356,10 @@ impl Emitter {
                 self.emit_expression(alternate, instructions)?;
                 instructions.push(Instruction::End);
             }
+            "megabuf" => self.emit_memory_access(&mut function_call, 0, instructions)?,
+            "gmegabuf" => {
+                self.emit_memory_access(&mut function_call, BUFFER_SIZE * 8, instructions)?
+            }
             shim_name if Shim::from_str(shim_name).is_some() => {
                 let shim = Shim::from_str(shim_name).unwrap();
                 assert_arity(&function_call, shim.arity())?;
@@ -353,6 +379,33 @@ impl Emitter {
         Ok(())
     }
 
+    fn emit_memory_access(
+        &mut self,
+        function_call: &mut FunctionCall,
+        memory_offset: u32,
+        instructions: &mut Vec<Instruction>,
+    ) -> EmitterResult<()> {
+        assert_arity(&function_call, 1)?;
+        let index = self.resolve_local(ValueType::I32);
+        self.emit_expression(function_call.arguments.pop().unwrap(), instructions)?;
+        instructions.push(Instruction::Call(
+            self.resolve_builtin_function(BuiltinFunction::GetBufferIndex),
+        ));
+        //
+        instructions.push(Instruction::TeeLocal(index));
+        instructions.push(Instruction::I32Const(-1));
+        instructions.push(Instruction::I32Ne);
+        // STACK: [in range]
+        instructions.push(Instruction::If(BlockType::Value(ValueType::F64)));
+        instructions.push(Instruction::GetLocal(index));
+        instructions.push(Instruction::F64Load(3, memory_offset));
+        instructions.push(Instruction::Else);
+        instructions.push(Instruction::F64Const(f64_const(0.0)));
+        instructions.push(Instruction::End);
+
+        Ok(())
+    }
+
     fn resolve_variable(&mut self, name: String) -> u32 {
         let pool = if variable_is_register(&name) {
             None
@@ -363,6 +416,11 @@ impl Emitter {
         self.globals.get((pool, name))
     }
 
+    fn resolve_local(&mut self, type_: ValueType) -> u32 {
+        self.locals.push(type_);
+        return self.locals.len() as u32 - 1;
+    }
+
     fn resolve_builtin_function(&mut self, builtin: BuiltinFunction) -> u32 {
         self.function_types.ensure(builtin.get_type());
         let offset = self
@@ -378,11 +436,6 @@ fn emit_is_not_zeroish(instructions: &mut Vec<Instruction>) {
     instructions.push(Instruction::F64Gt);
 }
 
-// TODO: There's got to be a better way.
-fn f64_const(value: f64) -> u64 {
-    u64::from_le_bytes(value.to_le_bytes())
-}
-
 fn variable_is_register(name: &str) -> bool {
     let chars: Vec<_> = name.chars().collect();
     // We avoided pulling in the regex crate! (But at what cost?)
diff --git a/compiler-rs/src/index_store.rs b/compiler-rs/src/index_store.rs
@@ -36,18 +36,3 @@ impl<T: Eq + Hash> IndexStore<T> {
         self.map.keys().collect()
     }
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use crate::EelFunctionType;
-    #[test]
-    fn tuple() {
-        let mut function_types: IndexStore<EelFunctionType> = IndexStore::new();
-        let one_arg_one_return = function_types.get((1, 1));
-        let no_arg_one_return = function_types.get((0, 1));
-
-        assert_eq!(one_arg_one_return, 0);
-        assert_eq!(no_arg_one_return, 1);
-    }
-}
diff --git a/compiler-rs/src/lib.rs b/compiler-rs/src/lib.rs
@@ -1,5 +1,6 @@
 mod ast;
 mod builtin_functions;
+mod constants;
 mod emitter;
 mod error;
 mod file_chars;
@@ -9,6 +10,7 @@ mod parser;
 mod shim;
 mod span;
 mod tokens;
+mod utils;
 
 use std::collections::{HashMap, HashSet};
 
@@ -17,11 +19,12 @@ use emitter::emit;
 use error::CompilerError;
 // Only exported for tests
 pub use lexer::Lexer;
+use parity_wasm::elements::FunctionType;
 pub use parser::parse;
 pub use tokens::Token;
 pub use tokens::TokenKind;
 
-pub type EelFunctionType = (usize, usize);
+pub type EelFunctionType = FunctionType;
 
 use wasm_bindgen::prelude::*;
 
diff --git a/compiler-rs/src/shim.rs b/compiler-rs/src/shim.rs
@@ -1,4 +1,5 @@
 use crate::EelFunctionType;
+use parity_wasm::elements::{FunctionType, ValueType};
 
 // TODO: We could use https://docs.rs/strum_macros/0.20.1/strum_macros/index.html
 #[derive(PartialEq, Eq, Hash)]
@@ -8,7 +9,9 @@ pub enum Shim {
 
 impl Shim {
     pub fn get_type(&self) -> EelFunctionType {
-        (self.arity(), 1)
+        match self {
+            Shim::Sin => FunctionType::new(vec![ValueType::F64], vec![ValueType::F64]),
+        }
     }
     pub fn arity(&self) -> usize {
         match self {
diff --git a/compiler-rs/src/utils.rs b/compiler-rs/src/utils.rs
@@ -0,0 +1,4 @@
+// TODO: There's got to be a better way.
+pub fn f64_const(value: f64) -> u64 {
+    u64::from_le_bytes(value.to_le_bytes())
+}
diff --git a/compiler-rs/tests/compatibility_test.rs b/compiler-rs/tests/compatibility_test.rs
@@ -430,7 +430,6 @@ fn compatibility_tests() {
         "Less than or equal (false)",
         "Greater than or equal (true)",
         "Greater than or equal (false)",
-        "Megabuf access",
         "Max index megabuf",
         "Max index + 1 megabuf",
         "Max index gmegabuf",
@@ -456,7 +455,6 @@ fn compatibility_tests() {
         "Assign return value",
         "EPSILON buffer indexes",
         "+EPSILON & rounding -#s toward 0",
-        "Negative buffer index read as 0",
         "Negative buffer index",
         "Negative buffer index gmegabuf",
         "Negative buf index execs right hand side",
diff --git a/compiler-rs/tests/fixtures/wat/div.snapshot b/compiler-rs/tests/fixtures/wat/div.snapshot
@@ -24,5 +24,6 @@ g = 100 / 0
     else
       f64.const 0x0p+0 (;=0;)
     end)
+  (memory (;0;) 2048 2048)
   (global (;0;) (mut f64) (f64.const 0x0p+0 (;=0;)))
   (export "test" (func 1)))
diff --git a/compiler-rs/tests/fixtures/wat/one_plus_one.snapshot b/compiler-rs/tests/fixtures/wat/one_plus_one.snapshot
@@ -9,4 +9,5 @@
     f64.const 0x1p+0 (;=1;)
     f64.add
     drop)
+  (memory (;0;) 2048 2048)
   (export "test" (func 1)))
diff --git a/compiler-rs/tests/fixtures/wat/reg.snapshot b/compiler-rs/tests/fixtures/wat/reg.snapshot
@@ -9,5 +9,6 @@ reg00=10
     global.set 0
     global.get 0
     drop)
+  (memory (;0;) 2048 2048)
   (global (;0;) (mut f64) (f64.const 0x0p+0 (;=0;)))
   (export "test" (func 1)))
diff --git a/compiler-rs/tests/fixtures/wat/sin.snapshot b/compiler-rs/tests/fixtures/wat/sin.snapshot
@@ -8,4 +8,5 @@ sin(100)
     f64.const 0x1.9p+6 (;=100;)
     call 0
     drop)
+  (memory (;0;) 2048 2048)
   (export "test" (func 1)))
