Add comments about offset convention

near · Jan 26, 2024 · fe4edfb · fe4edfb
1 parent f5b9c55
commit fe4edfb
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diff --git a/cranelift/codegen/src/isa/zkasm/lower.isle b/cranelift/codegen/src/isa/zkasm/lower.isle
@@ -353,6 +353,7 @@
   (load_ext_name name 0))
 
 ;;;;;  Rules for `symbol_value`;;;;;;;;;
+;; Heap starts at offset 0 in zkAsm machine memory.
 (rule
    (lower (symbol_value (zkasm_base ZkasmBase.Heap)))
    (imm $I32 0))

diff --git a/cranelift/codegen/src/isa/zkasm/lower/isle.rs b/cranelift/codegen/src/isa/zkasm/lower/isle.rs
@@ -375,6 +375,10 @@ impl generated_code::Context for ZkAsmIsleContext<'_, '_, MInst, ZkAsmBackend> {
             match name {
                 ExternalName::User(user_name_ref) => {
                     // All ZKASM "memory"-like accesses use this name, but different offsets.
+                    // This is our convention as is not related to the actual offsets in zkAsm
+                    // machine memory that will be used by each base.
+                    // These offsets need to be aligned with the offsets used in
+                    // `cranelift_wasm::environ::zkasm::ZkasmFuncEnvironment`.
                     if user_name_ref.index() != 0 {
                         return None;
                     }