Add zisk cycle scope tracker (#287)

Signed-off-by: jsign <jsign.uy@gmail.com>

Cargo.lock

@@ -4094,6 +4094,7 @@ name = "ere-platform-zisk"
 version = "0.2.0"
 dependencies = [
  "ere-platform-trait",
+ "fnv",
  "ziskos",
 ]
 

Cargo.toml

@@ -57,6 +57,7 @@ clap = "4.5.42"
 dashmap = "6.1.0"
 digest = { version = "0.10.7", default-features = false }
 eyre = "0.6.12"
+fnv = { version = "1.0.7", default-features = false }
 indexmap = "2.10.0"
 paste = "1.0.15"
 postcard = { version = "1.0.8", default-features = false }

crates/zkvm/zisk/platform/Cargo.toml

@@ -9,6 +9,9 @@ license.workspace = true
 # ZisK dependencies
 ziskos.workspace = true
 
+# Hashing
+fnv.workspace = true
+
 # Local dependencies
 ere-platform-trait.workspace = true
 

crates/zkvm/zisk/platform/src/lib.rs

@@ -2,13 +2,123 @@
 
 extern crate alloc;
 
-use core::{array::from_fn, ops::Deref};
+use core::{array::from_fn, cell::UnsafeCell, hash::Hasher, ops::Deref};
 use ere_platform_trait::LengthPrefixedStdin;
+use fnv::FnvHasher;
 use ziskos::ziskos_definitions::ziskos_config::UART_ADDR;
 
 pub use ere_platform_trait::{Digest, OutputHashedPlatform, Platform};
 pub use ziskos;
 
+/// Hashes a scope name to a `u64` for use as a lookup key in the scope registry.
+#[inline]
+fn hash_name(name: &str) -> u64 {
+    let mut hasher = FnvHasher::default();
+    hasher.write(name.as_bytes());
+    hasher.finish()
+}
+
+/// Global registry mapping scope name hashes to sequential tag IDs.
+///
+/// Each unique scope name gets a unique tag ID (0, 1, 2, ...) on first use.
+/// Panics if more than 256 distinct scope names are registered.
+struct ScopeRegistry {
+    entries: UnsafeCell<[u64; 256]>, // name hashes; tag = index
+    count: UnsafeCell<u8>,
+}
+
+// SAFETY: ZiskPlatform runs in a single-threaded zkVM environment.
+unsafe impl Sync for ScopeRegistry {}
+
+impl ScopeRegistry {
+    const fn new() -> Self {
+        Self {
+            entries: UnsafeCell::new([0; 256]),
+            count: UnsafeCell::new(0),
+        }
+    }
+
+    /// Looks up or assigns a tag ID for the given scope name.
+    fn get_or_assign_tag(&self, name: &str) -> u8 {
+        let name_hash = hash_name(name);
+        // SAFETY: Single-threaded zkVM — no concurrent access.
+        unsafe {
+            let entries = &mut *self.entries.get();
+            let count = &mut *self.count.get();
+
+            for i in 0..*count as usize {
+                if entries[i] == name_hash {
+                    return i as u8;
+                }
+            }
+
+            assert!(
+                (*count as u16) < 256,
+                "Too many profiling scopes (max 256), cannot assign tag for scope"
+            );
+            entries[*count as usize] = name_hash;
+            let tag = *count;
+            *count += 1;
+            tag
+        }
+    }
+}
+
+static SCOPE_REGISTRY: ScopeRegistry = ScopeRegistry::new();
+
+/// Dispatches a runtime `u8` tag to a const-generic ziskos profiling function.
+/// Generates a 256-arm match to bridge the runtime value to compile-time const generics.
+macro_rules! dispatch_profile {
+    (start, $tag:expr) => {
+        dispatch_profile!(@start $tag,
+            0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
+            16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
+            32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
+            48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63,
+            64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79,
+            80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95,
+            96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111,
+            112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127,
+            128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143,
+            144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159,
+            160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175,
+            176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191,
+            192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207,
+            208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223,
+            224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239,
+            240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255)
+    };
+    (end, $tag:expr) => {
+        dispatch_profile!(@end $tag,
+            0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
+            16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
+            32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
+            48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63,
+            64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79,
+            80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95,
+            96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111,
+            112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127,
+            128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143,
+            144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159,
+            160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175,
+            176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191,
+            192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207,
+            208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223,
+            224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239,
+            240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255)
+    };
+    (@start $tag:expr, $($n:literal),+) => {
+        match $tag {
+            $($n => ziskos::ziskos_profile_start::<$n>(),)+
+        }
+    };
+    (@end $tag:expr, $($n:literal),+) => {
+        match $tag {
+            $($n => ziskos::ziskos_profile_end::<$n>(),)+
+        }
+    };
+}
+
 /// ZisK [`Platform`] implementation.
 ///
 /// Note that the maximum output size is 256 bytes, and output size will be
@@ -40,4 +150,14 @@ impl Platform for ZiskPlatform {
             }
         }
     }
+
+    fn cycle_scope_start(name: &str) {
+        let tag = SCOPE_REGISTRY.get_or_assign_tag(name);
+        dispatch_profile!(start, tag);
+    }
+
+    fn cycle_scope_end(name: &str) {
+        let tag = SCOPE_REGISTRY.get_or_assign_tag(name);
+        dispatch_profile!(end, tag);
+    }
 }