Revert "Improve performance of toplevel code (#47578)"

This reverts commit 526cbf7.

src/codegen.cpp

@@ -7786,6 +7786,13 @@ static jl_llvm_functions_t
             ctx.builder.SetInsertPoint(tryblk);
         }
         else {
+            if (!jl_is_method(ctx.linfo->def.method) && !ctx.is_opaque_closure) {
+                // TODO: inference is invalid if this has any effect (which it often does)
+                LoadInst *world = ctx.builder.CreateAlignedLoad(getSizeTy(ctx.builder.getContext()),
+                    prepare_global_in(jl_Module, jlgetworld_global), Align(sizeof(size_t)));
+                world->setOrdering(AtomicOrdering::Acquire);
+                ctx.builder.CreateAlignedStore(world, world_age_field, Align(sizeof(size_t)));
+            }
             emit_stmtpos(ctx, stmt, cursor);
             mallocVisitStmt(debuginfoloc, nullptr);
         }
@@ -8011,12 +8018,12 @@ static jl_llvm_functions_t
     }
 
     // step 12. Perform any delayed instantiations
-    bool in_prologue = true;
-    for (auto &BB : *ctx.f) {
-        for (auto &I : BB) {
-            CallBase *call = dyn_cast<CallBase>(&I);
-            if (call) {
-                if (ctx.debug_enabled && !I.getDebugLoc()) {
+    if (ctx.debug_enabled) {
+        bool in_prologue = true;
+        for (auto &BB : *ctx.f) {
+            for (auto &I : BB) {
+                CallBase *call = dyn_cast<CallBase>(&I);
+                if (call && !I.getDebugLoc()) {
                     // LLVM Verifier: inlinable function call in a function with debug info must have a !dbg location
                     // make sure that anything we attempt to call has some inlining info, just in case optimization messed up
                     // (except if we know that it is an intrinsic used in our prologue, which should never have its own debug subprogram)
@@ -8025,24 +8032,12 @@ static jl_llvm_functions_t
                         I.setDebugLoc(topdebugloc);
                     }
                 }
-                if (toplevel && !ctx.is_opaque_closure && !in_prologue) {
-                    // we're at toplevel; insert an atomic barrier between every instruction
-                    // TODO: inference is invalid if this has any effect (which it often does)
-                    LoadInst *load_world = new LoadInst(getSizeTy(ctx.builder.getContext()),
-                        prepare_global_in(jl_Module, jlgetworld_global), Twine(),
-                        /*isVolatile*/false, Align(sizeof(size_t)), /*insertBefore*/&I);
-                    load_world->setOrdering(AtomicOrdering::Monotonic);
-                    StoreInst *store_world = new StoreInst(load_world, world_age_field,
-                        /*isVolatile*/false, Align(sizeof(size_t)), /*insertBefore*/&I);
-                    (void)store_world;
-                }
+                if (&I == &prologue_end)
+                    in_prologue = false;
             }
-            if (&I == &prologue_end)
-                in_prologue = false;
         }
-    }
-    if (ctx.debug_enabled)
         dbuilder.finalize();
+    }
 
     if (ctx.vaSlot > 0) {
         // remove VA allocation if we never referenced it