Merge pull request #48 from NilFoundation/zkllvm-outdated-info

Zkllvm outdated info

Author: khannanov-nil

sidebar-zkllvm.js

@@ -33,7 +33,7 @@ export default {
             type: 'category',
             label: 'Getting started',
             collapsible: true,
-            collapsed: false,
+            collapsed: true,
             items: [
                 {
                     type: 'doc',
@@ -121,20 +121,12 @@ export default {
                     label: 'Unrolling loops',
                     id: 'best-practices-limitations/unrolling-loops'
                 },
-            ]
-        },
-        {
-            type: 'category',
-            label: 'Circuit development',
-            collapsible: true,
-            collapsed: true,
-            items: [
                 {
                     type: 'doc',
-                    label: 'Standard library',
-                    id: 'circuit-development/standalone-clang',
-                },
-            ],
+                    label: 'Structs and enums in Rust',
+                    id: 'best-practices-limitations/rust-derive'
+                }
+            ]
         },
         {
             type: 'category',
@@ -144,24 +136,38 @@ export default {
             items: [
                 {
                     type: 'doc',
-                    label: 'First circuit with hashes',
-                    id: 'tutorials/hashes'
-                },
-                {
-                    type: 'doc',
-                    label: 'EsDSA signature verifications',
-                    id: 'tutorials/eddsa'
-                },
-                {
-                    type: 'doc',
-                    label: 'Merkle tree commitment schemes',
-                    id: 'tutorials/merkle-tree'
+                    label: 'Primer',
+                    id: 'use-cases/primer'
                 },
                 {
-                    type: 'doc',
-                    label: 'Constructing a zkBridge',
-                    id: 'tutorials/zkbridge'
+                    type: 'category',
+                    label: 'Construct a zkBridge',
+                    collapsible: true,
+                    collapsed: true,
+                    items: [
+                        {
+                            type: 'doc',
+                            label: 'Write a circuit with hashes',
+                            id: 'use-cases/zk-bridge/hashes'
+                        },
+                        {
+                            type: 'doc',
+                            label: 'Verify EdDSA signatures',
+                            id: 'use-cases/zk-bridge/eddsa'
+                        },
+                        {
+                            type: 'doc',
+                            label: 'Create a Merkle tree commitment scheme',
+                            id: 'use-cases/zk-bridge/merkle-tree'
+                        },
+                        {
+                            type: 'doc',
+                            label: 'Write an algorithm for state-proof verification',
+                            id: 'use-cases/zk-bridge/zkbridge'
+                        },
+                    ]
                 },
+
             ]
         },
         {
@@ -170,21 +176,11 @@ export default {
             collapsible: true,
             collapsed: true,
             items: [
-                {
-                    type: 'doc',
-                    label: 'Contributing',
-                    id: 'misc/contributing'
-                },
                 {
                     type: 'doc',
                     label: 'Code of conduct',
                     id: 'misc/code-of-conduct'
                 },
-                {
-                    type: 'doc',
-                    label: 'Contact',
-                    id: 'misc/contact'
-                },
             ]
         },
     ],

zkllvm/best-practices-limitations/rust-derive.mdx

@@ -0,0 +1,60 @@
+# Structs and enums in Rust
+
+Whenever a Rust circuit is compiled, `rustc` applies various optimizations to reduce its memory usage.
+
+Among these memory optimizations is [**reordering fields in structs and enums to avoid unnecessary 'paddings' in circuit IRs**](https://doc.rust-lang.org/nomicon/repr-rust.html). Consider the following example:
+
+```rust
+use ark_pallas::Fq;
+
+type BlockType = [Fq; 2];
+
+pub struct BlockDataType {
+    prev_block_hash: BlockType,
+    data: BlockType,
+    validators_signature: i32,
+    validators_key: u64,
+}
+```
+
+The public input representation of the `BlockDataType` struct would look as follows:
+
+```json
+"struct": [
+    {
+        "array": [{"field": 1}, {"field": 1}]
+    },
+    {
+        "array": [{"field": 3}, {"field": 1}]
+    },
+    {
+        "int": 1
+    },
+    {
+        "int": 1
+    }
+]
+```
+
+When compiling the `BlockDataType` struct, `rustc` may reorder its fields.
+
+When `assigner` is called on a circuit with this struct, the circuit IR would conflict with the public input as the field order in the IR and the public input file would no longer match.
+
+To avoid this problem, use the `#[repr(C)]` directive:
+
+```rust
+
+use ark_pallas::Fq;
+
+type BlockType = [Fq; 2];
+
+#[repr(C)]
+pub struct BlockDataType {
+    prev_block_hash: BlockType,
+    data: BlockType,
+    validators_signature: i32,
+    validators_key: u64,
+}
+```
+
+If this directive is included, Rust will treat structs and enums as C-like types, meaning that `rustc` will never reorder fields in them.