Fix duplicate annotation issue

Summary: Our outer annotations can sometimes end up colliding with things that we emit in a LIR instruction. For example "Boxed return wrapper" does a kPrologue instruction. This lets the outer annotation which is more interesting override the inner annotation.

Reviewed By: yoney

Differential Revision: D103307683

fbshipit-source-id: a832a87338f3038cca7799b51fdf81955e49f555

Author: DinoV

cinderx/Jit/codegen/annotations.cpp

@@ -37,7 +37,11 @@ std::string Annotations::disassembleSection(
     }
     auto inserted =
         annot_bounds.emplace(begin, std::make_pair(&annot, end)).second;
-    JIT_DCHECK(inserted, "Duplicate start address for annotation");
+    JIT_DCHECK(
+        inserted,
+        "Duplicate start address for annotation {} {}",
+        annot.str,
+        annot_bounds[begin].first->str);
   }
 
   Annotation* prev_annot = nullptr;

cinderx/Jit/codegen/environ.h

@@ -101,9 +101,18 @@ struct Environ {
 
   template <typename T>
   void addAnnotation(T&& item, asmjit::BaseNode* start_cursor) {
+    if (suppress_annotations) {
+      return;
+    }
     annotations.add(std::forward<T>(item), as, start_cursor);
   }
 
+  // When true, addAnnotation() calls are suppressed. Set by
+  // generateAssemblyBody() while a text annotation is active so that
+  // translator-internal annotations (e.g. "Set up frame pointer") don't
+  // conflict with the higher-level text annotation.
+  bool suppress_annotations{false};
+
   // Map of GenYieldPoints which need their resume_target_ setting after code-
   // gen is complete.
   UnorderedMap<GenYieldPoint*, asmjit::Label> unresolved_gen_entry_labels;

cinderx/Jit/codegen/gen_asm.cpp

@@ -453,7 +453,9 @@ void emitLIRBlocks(
         annotation_cursor = cursor;
       }
 
+      env->suppress_annotations = !pending_annotation.empty();
       autogen::AutoTranslator::getInstance().translateInstr(env, instr.get());
+      env->suppress_annotations = false;
 
       if (!pending_annotation.empty()) {
         // Under an active annotation — don't emit per-instruction annotations.