Use "main" instead of start function

This allows us to avoid abusing "start" section which has a special
meaning in WASM and also makes it easier to generate the correct WASM
module for Rust programs where adding "start" section in not trivial.

cranelift/filetests/src/test_zkasm.rs

@@ -28,7 +28,9 @@ mod tests {
         linker.func_wrap("env", "assert_eq_i64", |a: i64, b: i64| {
             assert_eq!(a, b);
         })?;
-        linker.instantiate(&mut store, &module)?;
+        let instance = linker.instantiate(&mut store, &module)?;
+        let main = instance.get_typed_func::<(), ()>(&mut store, "main")?;
+        main.call(&mut store, ())?;
         Ok(())
     }
 
@@ -118,7 +120,7 @@ mod tests {
                 testcase.push_str(&format!("\t{function_type}.{}\n", function_name));
             }
             testcase.push_str(&format!(
-                "\t{}\n\tcall $assert_eq_{})\n (start $main))\n",
+                "\t{}\n\tcall $assert_eq_{})\n (export \"main\" (func $main)))\n",
                 expected_result.trim(),
                 assert_type
             ));

cranelift/filetests/src/zkasm_codegen.rs

@@ -35,13 +35,16 @@ pub fn generate_zkasm(settings: &ZkasmSettings, wasm_module: &[u8]) -> String {
 
     let mut program: Vec<String> = Vec::new();
 
-    let start_func = zkasm_environ
+    let main_func = zkasm_environ
         .info
-        .start_func
-        .expect("Must have a start function");
+        .functions
+        .iter()
+        .find(|&(_, exportable_func)| exportable_func.export_names.contains(&"main".to_string()))
+        .expect("Must have a `main` function");
+
     // TODO: Preamble should be generated by a linker and/or clift itself.
     program.append(&mut generate_preamble(
-        start_func.index(),
+        main_func.0.index(),
         &zkasm_environ.info.global_inits,
         &zkasm_environ.info.data_inits,
     ));
@@ -87,7 +90,7 @@ fn handle_zkasm_settings(
 
 /// Generates a preamble.
 pub fn generate_preamble(
-    start_func_index: usize,
+    main_func_index: usize,
     globals: &[(cranelift_wasm::GlobalIndex, cranelift_wasm::GlobalInit)],
     data_segments: &[(u64, Vec<u8>)],
 ) -> Vec<String> {
@@ -142,7 +145,7 @@ pub fn generate_preamble(
     // Stack memory is a separate region that is independent from the heap.
     program.push("  0xffff => SP".to_string());
     program.push("  zkPC + 2 => RR".to_string());
-    program.push(format!("  :JMP(function_{})", start_func_index));
+    program.push(format!("  :JMP(function_{})", main_func_index));
     program.push("  :JMP(finalizeExecution)".to_string());
     program
 }

cranelift/zkasm_data/_should_fail_unreachable.wat

@@ -3,4 +3,4 @@
  (func $main
 	unreachable
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/add.wat

@@ -6,4 +6,4 @@
 	i32.add
 	i32.const 1999999999
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/add_func.wat

@@ -12,4 +12,4 @@
 		(local.get $rhs)
 	)
  )
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/analyze-zkasm/testfiles/simple.wat

@@ -1,4 +1,4 @@
 (module
     (func $main 
         nop)
-    (start $main))
+    (export "main" (func $main)))

cranelift/zkasm_data/and.wat

@@ -6,4 +6,4 @@
 	i32.and
 	i32.const 0
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/benchmarks/fibonacci/handwritten_wat.wat

@@ -29,4 +29,4 @@
 	(local.get $fp)
 	(i64.const -2872092127636481573)
 	call $assert_eq_i64)
-(start $main))
+	(export "main" (func $main)))

cranelift/zkasm_data/counter.wat

@@ -21,4 +21,4 @@
 	(local.get $counter)
 	(i32.const 10)
 	call $assert_eq_i32)
-(start $main))
+(export "main" (func $main)))

cranelift/zkasm_data/div.wat

@@ -6,4 +6,4 @@
 	i32.div_s
 	i32.const 2
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/eqz.wat

@@ -9,4 +9,4 @@
     i32.eqz
     i32.const 1
     call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/global.wat

@@ -9,4 +9,4 @@
 	i32.add
 	i32.const 1
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/i32_add_overflows.wat

@@ -6,4 +6,4 @@
 	i32.add
 	i32.const 0
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/i32_const.wat

@@ -4,4 +4,4 @@
 	i32.const 4
 	i32.const 4
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/i32_mul_overflows.wat

@@ -6,4 +6,4 @@
 	i32.mul
 	i32.const 0
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/i64_const.wat

@@ -4,4 +4,4 @@
 	i64.const 9223372036854775807
 	i64.const 9223372036854775807
 	call $assert_eq_i64)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/i64_div.wat

@@ -10,4 +10,4 @@
     i64.div_s
     i64.const 214748366
 	call $assert_eq_i64)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/i64_mul.wat

@@ -12,4 +12,4 @@
 	i64.mul
     i64.mul
 	call $assert_eq_i64)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/i64_mul_overflows.wat

@@ -6,4 +6,4 @@
     i64.mul
     i64.const 0
 	call $assert_eq_i64)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/i64_rem.wat

@@ -11,4 +11,4 @@
     i64.rem_s
     i64.const 2
     call $assert_eq_i64)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/locals.wat

@@ -12,4 +12,4 @@
 	(local.get $z)
 	(i32.const 5)
 	call $assert_eq_i32)
-(start $main))
+(export "main" (func $main)))

cranelift/zkasm_data/locals_simple.wat

@@ -6,4 +6,4 @@
 	(local.get $x)
 	(i32.const 2)
 	call $assert_eq_i32)
-(start $main))
+(export "main" (func $main)))

cranelift/zkasm_data/lt_s.wat

@@ -13,4 +13,4 @@
 	i32.lt_s
 	i32.const 0
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/lt_u.wat

@@ -13,4 +13,4 @@
 	i32.lt_u
 	i32.const 0
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/memory.wat

@@ -9,4 +9,4 @@
 	i32.add
 	i32.const 5
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/memory_i32.wat

@@ -103,5 +103,5 @@
         i32.load offset=25 align=4       
         i32.const 122
         call $assert_eq_i32)
-    (start $main)
+    (export "main" (func $main))
 )

cranelift/zkasm_data/mul.wat

@@ -6,4 +6,4 @@
 	i32.mul
 	i32.const 1999999999
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/ne.wat

@@ -11,4 +11,4 @@
     i32.ne
     i32.const 1
     call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/nop.wat

@@ -7,4 +7,4 @@
     nop
 	i32.const 0
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/or.wat

@@ -6,4 +6,4 @@
 	i32.or
 	i32.const 0
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/rem.wat

@@ -11,4 +11,4 @@
     i32.rem_s
     i32.const 2
     call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i32.wrap_i64_1.wat

@@ -5,4 +5,4 @@
 	i32.wrap_i64
 	i32.const -1
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i32.wrap_i64_10.wat

@@ -5,4 +5,4 @@
 	i32.wrap_i64
 	i32.const 0xffffffff
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i32.wrap_i64_11.wat

@@ -5,4 +5,4 @@
 	i32.wrap_i64
 	i32.const 0x00000000
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i32.wrap_i64_12.wat

@@ -5,4 +5,4 @@
 	i32.wrap_i64
 	i32.const 0x00000001
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i32.wrap_i64_2.wat

@@ -5,4 +5,4 @@
 	i32.wrap_i64
 	i32.const -100000
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i32.wrap_i64_3.wat

@@ -5,4 +5,4 @@
 	i32.wrap_i64
 	i32.const 0x80000000
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i32.wrap_i64_4.wat

@@ -5,4 +5,4 @@
 	i32.wrap_i64
 	i32.const 0x7fffffff
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i32.wrap_i64_5.wat

@@ -5,4 +5,4 @@
 	i32.wrap_i64
 	i32.const 0x00000000
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i32.wrap_i64_6.wat

@@ -5,4 +5,4 @@
 	i32.wrap_i64
 	i32.const 0xffffffff
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i32.wrap_i64_7.wat

@@ -5,4 +5,4 @@
 	i32.wrap_i64
 	i32.const 0x00000001
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i32.wrap_i64_8.wat

@@ -5,4 +5,4 @@
 	i32.wrap_i64
 	i32.const 0
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i32.wrap_i64_9.wat

@@ -5,4 +5,4 @@
 	i32.wrap_i64
 	i32.const 0x9abcdef0
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i64.extend_i32_s_1.wat

@@ -5,4 +5,4 @@
 	i64.extend_i32_s
 	i64.const 0
 	call $assert_eq_i64)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i64.extend_i32_s_2.wat

@@ -5,4 +5,4 @@
 	i64.extend_i32_s
 	i64.const 10000
 	call $assert_eq_i64)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i64.extend_i32_s_3.wat

@@ -5,4 +5,4 @@
 	i64.extend_i32_s
 	i64.const -10000
 	call $assert_eq_i64)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i64.extend_i32_s_4.wat

@@ -5,4 +5,4 @@
 	i64.extend_i32_s
 	i64.const -1
 	call $assert_eq_i64)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i64.extend_i32_s_5.wat

@@ -5,4 +5,4 @@
 	i64.extend_i32_s
 	i64.const 0x000000007fffffff
 	call $assert_eq_i64)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i64.extend_i32_s_6.wat

@@ -5,4 +5,4 @@
 	i64.extend_i32_s
 	i64.const 0xffffffff80000000
 	call $assert_eq_i64)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i64.extend_i32_u_1.wat

@@ -5,4 +5,4 @@
 	i64.extend_i32_u
 	i64.const 0
 	call $assert_eq_i64)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i64.extend_i32_u_2.wat

@@ -5,4 +5,4 @@
 	i64.extend_i32_u
 	i64.const 10000
 	call $assert_eq_i64)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i64.extend_i32_u_3.wat

@@ -5,4 +5,4 @@
 	i64.extend_i32_u
 	i64.const 0x00000000ffffd8f0
 	call $assert_eq_i64)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i64.extend_i32_u_4.wat

@@ -5,4 +5,4 @@
 	i64.extend_i32_u
 	i64.const 0xffffffff
 	call $assert_eq_i64)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i64.extend_i32_u_5.wat

@@ -5,4 +5,4 @@
 	i64.extend_i32_u
 	i64.const 0x000000007fffffff
 	call $assert_eq_i64)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/conversions/i64.extend_i32_u_6.wat

@@ -5,4 +5,4 @@
 	i64.extend_i32_u
 	i64.const 0x0000000080000000
 	call $assert_eq_i64)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/i32/add_1.wat

@@ -6,4 +6,4 @@
 	i32.add
 	i32.const 2
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/i32/add_2.wat

@@ -6,4 +6,4 @@
 	i32.add
 	i32.const 1
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))

cranelift/zkasm_data/spectest/i32/add_3.wat

@@ -6,4 +6,4 @@
 	i32.add
 	i32.const -2
 	call $assert_eq_i32)
- (start $main))
+ (export "main" (func $main)))