feat: candid subtype check

nix/sources.json

@@ -1,15 +1,15 @@
 {
     "candid": {
-        "branch": "master",
+        "branch": "claudio/candid-subtype-check",
         "builtin": false,
         "description": "Candid Library for the Internet Computer",
         "homepage": "",
         "owner": "dfinity",
         "repo": "candid",
-        "rev": "a555d77704d691bb8f34e21a049d44ba0acee3f8",
-        "sha256": "0vn171lcadpznrl5nq2mws2zjjqj9jxyvndb2is3dixbjqyvjssx",
+        "rev": "0889e288c8c44ce36682ffa67df010c83e912a33",
+        "sha256": "122v440prlcr0z6zj1a7j0rjpk1a2xwpvj8vxrdbldl6ss1krbff",
         "type": "tarball",
-        "url": "https://github.com/dfinity/candid/archive/a555d77704d691bb8f34e21a049d44ba0acee3f8.tar.gz",
+        "url": "https://github.com/dfinity/candid/archive/0889e288c8c44ce36682ffa67df010c83e912a33.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
     "esm": {

rts/motoko-rts/src/bitrel.rs

@@ -0,0 +1,107 @@
+//! This module implements a simple subtype cache used by the compiler (in generated code)
+
+use crate::constants::WORD_SIZE;
+use crate::idl_trap_with;
+use crate::mem_utils::memzero;
+use crate::types::Words;
+
+const BITS: u32 = 2;
+
+#[repr(packed)]
+pub struct BitRel {
+    /// Pointer into the bit set
+    pub ptr: *mut u32,
+    /// Pointer to the end of the bit set
+    /// must allow at least 2 * size1 * size2 bits
+    pub end: *mut u32,
+    pub size1: u32,
+    pub size2: u32,
+}
+
+impl BitRel {
+    pub(crate) fn words(size1: u32, size2: u32) -> u32 {
+        return ((2 * size1 * size2 * BITS) + (usize::BITS - 1)) / usize::BITS;
+    }
+
+    pub(crate) unsafe fn init(&self) {
+        if (self.end as usize) < (self.ptr as usize) {
+            idl_trap_with("BitRel invalid fields");
+        };
+
+        let bytes = ((self.end as usize) - (self.ptr as usize)) as u32;
+        if (2 * self.size1 * self.size2 * BITS) > bytes * 8 {
+            idl_trap_with("BitRel not enough bytes");
+        };
+        memzero(self.ptr as usize, Words(bytes / WORD_SIZE));
+    }
+
+    unsafe fn locate_ptr_bit(
+        self: &Self,
+        p: bool,
+        i_j: u32,
+        j_i: u32,
+        bit: u32,
+    ) -> (*mut u32, u32) {
+        let size1 = self.size1;
+        let size2 = self.size2;
+        let (base, i, j) = if p {
+            (0, i_j, j_i)
+        } else {
+            (size1 * size2 * BITS, j_i, i_j)
+        };
+        if i >= size1 {
+            idl_trap_with("BitRel i out of bounds");
+        };
+        if j >= size2 {
+            idl_trap_with("BitRel j out of bounds");
+        };
+        if bit >= BITS {
+            idl_trap_with("BitRel bit out of bounds");
+        };
+        let k = base + i * size2 * BITS + j + bit;
+        let word = (k / usize::BITS) as usize;
+        let bit = (k % usize::BITS) as u32;
+        let ptr = self.ptr.add(word);
+        if ptr > self.end {
+            idl_trap_with("BitRel ptr out of bounds");
+        };
+        return (ptr, bit);
+    }
+
+    unsafe fn set(&self, p: bool, i_j: u32, j_i: u32, bit: u32, v: bool) {
+        let (ptr, bit) = self.locate_ptr_bit(p, i_j, j_i, bit);
+        if v {
+            *ptr = *ptr | (1 << bit);
+        } else {
+            *ptr = *ptr & !(1 << bit);
+        }
+    }
+
+    unsafe fn get(&self, p: bool, i_j: u32, j_i: u32, bit: u32) -> bool {
+        let (ptr, bit) = self.locate_ptr_bit(p, i_j, j_i, bit);
+        let mask = 1 << bit;
+        return *ptr & mask == mask;
+    }
+
+    pub(crate) unsafe fn visited(&self, p: bool, i_j: u32, j_i: u32) -> bool {
+        self.get(p, i_j, j_i, 0)
+    }
+
+    pub(crate) unsafe fn visit(&self, p: bool, i_j: u32, j_i: u32) -> () {
+        self.set(p, i_j, j_i, 0, true)
+    }
+
+    // NB: we store related bits in negated form to avoid setting on assumption
+    // This code is a nop in production code.
+    pub(crate) unsafe fn assume(&self, p: bool, i_j: u32, j_i: u32) -> () {
+        debug_assert!(!self.get(p, i_j, j_i, 1));
+    }
+
+    pub(crate) unsafe fn related(&self, p: bool, i_j: u32, j_i: u32) -> bool {
+        !self.get(p, i_j, j_i, 1)
+    }
+
+    pub(crate) unsafe fn disprove(&self, p: bool, i_j: u32, j_i: u32) -> () {
+        self.set(p, i_j, j_i, 1, true)
+    }
+}