ZJIT: Write DEBUG_INFO before CODE_LOAD in jitdump

samply expects JIT_CODE_DEBUG_INFO to precede JIT_CODE_LOAD so it
can associate source line info with the code. Swap the record order.

This makes HIR instructions appear as source lines in the Firefox
Profiler when profiling with samply.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: tekknolagi

zjit/src/codegen.rs

@@ -204,11 +204,6 @@ fn emit_jitdump_for_function(
     // Read the generated code bytes for the CODE_LOAD record
     let code_bytes = unsafe { std::slice::from_raw_parts(start_ptr.raw_ptr(cb), code_size) };
     let func_name = format!("zjit::{iseq_name}");
-    if let Err(e) = jitdump.write_code_load(&func_name, start_addr, &code_bytes) {
-        debug!("Failed to write jitdump code load: {e}");
-        return;
-    }
-
     // Build HIR text and line mapping for this function.
     // We write HIR as text to a single shared file, appending each method.
     // The line numbers in the debug entries reference lines in this file.
@@ -230,9 +225,14 @@ fn emit_jitdump_for_function(
         }
     }
 
+    // Write DEBUG_INFO before CODE_LOAD — samply expects this ordering
     if let Err(e) = jitdump.write_debug_info(start_addr, &debug_entries) {
         debug!("Failed to write jitdump debug info: {e}");
     }
+
+    if let Err(e) = jitdump.write_code_load(&func_name, start_addr, &code_bytes) {
+        debug!("Failed to write jitdump code load: {e}");
+    }
 }
 
 /// Format a function's HIR as text for the jitdump source file.