Replace some helper functions with Parse trait instances

compiler/gen_wasm/src/wasm_module/dead_code.rs

@@ -2,7 +2,7 @@ use bumpalo::collections::vec::Vec;
 use bumpalo::Bump;
 
 use super::opcodes::OpCode;
-use super::parse::{parse_u32_or_panic, SkipBytes};
+use super::parse::{Parse, SkipBytes};
 use super::serialize::{SerialBuffer, Serialize};
 use super::CodeBuilder;
 
@@ -92,13 +92,13 @@ pub fn parse_preloads_call_graph<'a>(
         call_graph.code_offsets.push(cursor as u32);
         call_graph.calls_offsets.push(call_graph.calls.len() as u32);
 
-        let func_size = parse_u32_or_panic(code_section_body, &mut cursor);
+        let func_size = u32::parse((), code_section_body, &mut cursor).unwrap();
         let func_end = cursor + func_size as usize;
 
         // Skip over local variable declarations
-        let local_groups_count = parse_u32_or_panic(code_section_body, &mut cursor);
+        let local_groups_count = u32::parse((), code_section_body, &mut cursor).unwrap();
         for _ in 0..local_groups_count {
-            parse_u32_or_panic(code_section_body, &mut cursor);
+            u32::parse((), code_section_body, &mut cursor).unwrap();
             cursor += 1; // ValueType
         }
 
@@ -107,12 +107,12 @@ pub fn parse_preloads_call_graph<'a>(
             let opcode_byte: u8 = code_section_body[cursor];
             if opcode_byte == OpCode::CALL as u8 {
                 cursor += 1;
-                let call_index = parse_u32_or_panic(code_section_body, &mut cursor);
+                let call_index = u32::parse((), code_section_body, &mut cursor).unwrap();
                 call_graph.calls.push(call_index as u32);
             } else if opcode_byte == OpCode::CALLINDIRECT as u8 {
                 cursor += 1;
                 // Insert all indirect callees with a matching type signature
-                let sig = parse_u32_or_panic(code_section_body, &mut cursor);
+                let sig = u32::parse((), code_section_body, &mut cursor).unwrap();
                 call_graph.calls.extend(
                     indirect_callees
                         .iter()

compiler/gen_wasm/src/wasm_module/parse.rs

@@ -1,7 +1,5 @@
 use super::serialize::MAX_SIZE_ENCODED_U32;
-use bumpalo::collections::vec::Vec;
 use bumpalo::Bump;
-use roc_error_macros::internal_error;
 
 /// Parse serialized bytes into a data structure
 /// Specific parsers may need contextual data from other parts of the .wasm file
@@ -41,32 +39,16 @@ impl Parse<()> for u32 {
     }
 }
 
-// Parse a vector of bytes (used for strings, but we don't bother with utf8 validation)
+// Parse string bytes without utf8 validation
-impl<'a> Parse<&'a Bump> for Vec<'a, u8> {
+impl<'a> Parse<&'a Bump> for &'a [u8] {
     fn parse(arena: &'a Bump, bytes: &[u8], cursor: &mut usize) -> Result<Self, String> {
-        let len = parse_u32_or_panic(bytes, cursor);
+        let len = u32::parse((), bytes, cursor)?;
-        let end = *cursor + len as usize;
-        let bytes: &[u8] = &bytes[*cursor..end];
-        let mut copy = Vec::with_capacity_in(bytes.len(), arena);
-        copy.extend_from_slice(bytes);
-        *cursor = end;
-        Ok(copy)
-    }
-}
-
-pub fn parse_u32_or_panic(bytes: &[u8], cursor: &mut usize) -> u32 {
-    let (value, len) = decode_u32(&bytes[*cursor..]).unwrap_or_else(|e| internal_error!("{}", e));
-    *cursor += len;
-    value
-}
-
-pub fn parse_string_bytes<'a>(arena: &'a Bump, bytes: &[u8], cursor: &mut usize) -> &'a [u8] {
-    let len = parse_u32_or_panic(bytes, cursor);
         let end = *cursor + len as usize;
         let bytes: &[u8] = &bytes[*cursor..end];
         let copy = arena.alloc_slice_copy(bytes);
         *cursor = end;
-    copy
+        Ok(copy)
+    }
 }
 
 impl SkipBytes for u32 {
@@ -105,7 +87,7 @@ impl SkipBytes for u8 {
 /// Note: This is just for skipping over Wasm bytes. We don't actually care about String vs str!
 impl SkipBytes for String {
     fn skip_bytes(bytes: &[u8], cursor: &mut usize) -> Result<(), String> {
-        let len = parse_u32_or_panic(bytes, cursor);
+        let len = u32::parse((), bytes, cursor)?;
 
         if false {
             let str_bytes = &bytes[*cursor..(*cursor + len as usize)];
@@ -123,7 +105,7 @@ impl SkipBytes for String {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::wasm_module::parse::{decode_u32, parse_u32_or_panic};
+    use crate::wasm_module::parse::decode_u32;
 
     #[test]
     fn test_decode_u32() {
@@ -148,13 +130,13 @@ mod tests {
         let expected = [0, 128, u32::MAX];
         let mut cursor = 0;
 
-        assert_eq!(parse_u32_or_panic(bytes, &mut cursor), expected[0]);
+        assert_eq!(u32::parse((), bytes, &mut cursor).unwrap(), expected[0]);
         assert_eq!(cursor, 1);
 
-        assert_eq!(parse_u32_or_panic(bytes, &mut cursor), expected[1]);
+        assert_eq!(u32::parse((), bytes, &mut cursor).unwrap(), expected[1]);
         assert_eq!(cursor, 3);
 
-        assert_eq!(parse_u32_or_panic(bytes, &mut cursor), expected[2]);
+        assert_eq!(u32::parse((), bytes, &mut cursor).unwrap(), expected[2]);
         assert_eq!(cursor, 8);
     }
 }

compiler/gen_wasm/src/wasm_module/sections.rs

@@ -11,7 +11,7 @@ use super::dead_code::{
 };
 use super::linking::RelocationEntry;
 use super::opcodes::OpCode;
-use super::parse::{parse_string_bytes, parse_u32_or_panic, Parse, SkipBytes};
+use super::parse::{Parse, SkipBytes};
 use super::serialize::{SerialBuffer, Serialize, MAX_SIZE_ENCODED_U32};
 use super::{CodeBuilder, ValueType};
 
@@ -118,9 +118,9 @@ fn parse_section<'a>(id: SectionId, module_bytes: &'a [u8], cursor: &mut usize)
     }
     *cursor += 1;
 
-    let section_size = parse_u32_or_panic(module_bytes, cursor);
+    let section_size = u32::parse((), module_bytes, cursor).unwrap();
     let count_start = *cursor;
-    let count = parse_u32_or_panic(module_bytes, cursor);
+    let count = u32::parse((), module_bytes, cursor).unwrap();
     let body_start = *cursor;
 
     let next_section_start = count_start + section_size as usize;
@@ -237,7 +237,7 @@ impl<'a> TypeSection<'a> {
             debug_assert!(self.bytes[i] == Signature::SEPARATOR);
             i += 1;
 
-            let n_params = parse_u32_or_panic(&self.bytes, &mut i);
+            let n_params = u32::parse((), &self.bytes, &mut i).unwrap();
             i += n_params as usize; // skip over one byte per param type
 
             let n_return_values = self.bytes[i];
@@ -421,7 +421,7 @@ impl<'a> FunctionSection<'a> {
         let mut signatures = Vec::with_capacity_in(count, arena);
         let mut cursor = 0;
         for _ in 0..count {
-            signatures.push(parse_u32_or_panic(&self.bytes, &mut cursor));
+            signatures.push(u32::parse((), &self.bytes, &mut cursor).unwrap());
         }
         signatures
     }
@@ -579,9 +579,9 @@ impl Limits {
         let variant_id = bytes[*cursor];
         *cursor += 1;
 
-        let min = parse_u32_or_panic(bytes, cursor);
+        let min = u32::parse((), bytes, cursor).unwrap();
         if variant_id == LimitsId::MinMax as u8 {
-            let max = parse_u32_or_panic(bytes, cursor);
+            let max = u32::parse((), bytes, cursor).unwrap();
             Limits::MinMax(min, max)
         } else {
             Limits::Min(min)
@@ -663,7 +663,7 @@ impl ConstExpr {
         }
         *cursor += 1;
 
-        let value = parse_u32_or_panic(bytes, cursor);
+        let value = u32::parse((), bytes, cursor).unwrap();
 
         if bytes[*cursor] != OpCode::END as u8 {
             return err;
@@ -791,12 +791,12 @@ pub struct Export<'a> {
 
 impl<'a> Export<'a> {
     fn parse(arena: &'a Bump, bytes: &[u8], cursor: &mut usize) -> Self {
-        let name = parse_string_bytes(arena, bytes, cursor);
+        let name = <&'a [u8]>::parse(arena, bytes, cursor).unwrap();
 
         let ty = ExportType::from(bytes[*cursor]);
         *cursor += 1;
 
-        let index = parse_u32_or_panic(bytes, cursor);
+        let index = u32::parse((), bytes, cursor).unwrap();
 
         Export { name, ty, index }
     }
@@ -895,14 +895,14 @@ impl<'a> ElementSegment<'a> {
         let const_expr_opcode = bytes[*cursor];
         debug_assert!(const_expr_opcode == OpCode::I32CONST as u8);
         *cursor += 1;
-        let offset = parse_u32_or_panic(bytes, cursor);
+        let offset = u32::parse((), bytes, cursor).unwrap();
         debug_assert!(bytes[*cursor] == OpCode::END as u8);
         *cursor += 1;
 
-        let num_elems = parse_u32_or_panic(bytes, cursor);
+        let num_elems = u32::parse((), bytes, cursor).unwrap();
         let mut fn_indices = Vec::with_capacity_in(num_elems as usize, arena);
         for _ in 0..num_elems {
-            let fn_idx = parse_u32_or_panic(bytes, cursor);
+            let fn_idx = u32::parse((), bytes, cursor).unwrap();
 
             fn_indices.push(fn_idx);
         }
@@ -1219,7 +1219,7 @@ impl<'a> OpaqueSection<'a> {
         } else {
             let section_start = *cursor;
             *cursor += 1;
-            let section_size = parse_u32_or_panic(module_bytes, cursor);
+            let section_size = u32::parse((), module_bytes, cursor).unwrap();
             let next_section_start = *cursor + section_size as usize;
             bytes = &module_bytes[section_start..next_section_start];
             *cursor = next_section_start;
@@ -1293,7 +1293,7 @@ impl<'a> NameSection<'a> {
         *cursor += 1;
 
         // Section size
-        let section_size = parse_u32_or_panic(module_bytes, cursor) as usize;
+        let section_size = u32::parse((), module_bytes, cursor).unwrap() as usize;
         let section_end = *cursor + section_size;
 
         let mut section = NameSection {
@@ -1312,7 +1312,7 @@ impl<'a> NameSection<'a> {
         cursor: &mut usize,
         section_end: usize,
     ) {
-        let section_name = parse_string_bytes(arena, module_bytes, cursor);
+        let section_name = <&'a [u8]>::parse(arena, module_bytes, cursor).unwrap();
         if section_name != Self::NAME.as_bytes() {
             internal_error!(
                 "Expected Custom section {:?}, found {:?}",
@@ -1326,7 +1326,7 @@ impl<'a> NameSection<'a> {
         for _possible_subsection_id in 0..2 {
             let subsection_id = module_bytes[*cursor];
             *cursor += 1;
-            let subsection_size = parse_u32_or_panic(module_bytes, cursor);
+            let subsection_size = u32::parse((), module_bytes, cursor).unwrap();
             if subsection_id == NameSubSections::FunctionNames as u8 {
                 found_function_names = true;
                 break;
@@ -1341,12 +1341,11 @@ impl<'a> NameSection<'a> {
         }
 
         // Function names
-        let num_entries = parse_u32_or_panic(module_bytes, cursor) as usize;
+        let num_entries = u32::parse((), module_bytes, cursor).unwrap() as usize;
         let fn_names_start = *cursor;
         for _ in 0..num_entries {
-            let fn_index = parse_u32_or_panic(module_bytes, cursor);
+            let fn_index = u32::parse((), module_bytes, cursor).unwrap();
-            let name_bytes = parse_string_bytes(arena, module_bytes, cursor);
+            let name_bytes = <&'a [u8]>::parse(arena, module_bytes, cursor).unwrap();
-
             self.functions
                 .insert(arena.alloc_slice_copy(name_bytes), fn_index);
         }