From c26597c528a156117a79605375aae32d7fcaf7be Mon Sep 17 00:00:00 2001
From: Jonas Hahnfeld <jonas.hahnfeld@cern.ch>
Date: Tue, 3 Oct 2023 17:03:11 +0200
Subject: [PATCH] [cling] Emit const variables only once

Otherwise they are emitted as internal and we get double-construction
and -destruction on the same memory address due to the way we promote
internal declarations in KeepLocalGVPass.

According to upstream tests, the de-duplication doesn't work on Windows
(yet), but I think this problem is severe enough to fix it on the other
platforms sooner rather than later.

Fixes #13429

(cherry picked from commit 2dc57866c1d18010d3ebee681cc5e7777cd4d017)
---
 interpreter/cling/test/CodeGeneration/const.C | 37 +++++++++++++++++++
 .../src/lib/ExecutionEngine/Orc/LLJIT.cpp     |  2 +-
 .../src/tools/clang/lib/AST/ASTContext.cpp    |  9 +++++
 3 files changed, 47 insertions(+), 1 deletion(-)
 create mode 100644 interpreter/cling/test/CodeGeneration/const.C

diff --git a/interpreter/cling/test/CodeGeneration/const.C b/interpreter/cling/test/CodeGeneration/const.C
new file mode 100644
index 0000000000000..8fe1397be30d8
--- /dev/null
+++ b/interpreter/cling/test/CodeGeneration/const.C
@@ -0,0 +1,37 @@
+//------------------------------------------------------------------------------
+// CLING - the C++ LLVM-based InterpreterG :)
+//
+// This file is dual-licensed: you can choose to license it under the University
+// of Illinois Open Source License or the GNU Lesser General Public License. See
+// LICENSE.TXT for details.
+//------------------------------------------------------------------------------
+
+// RUN: cat %s |  %cling 2>&1 | FileCheck %s
+
+extern "C" int printf(const char*, ...);
+
+struct A {
+  int val;
+  A(int v) : val(v) {
+    printf("A(%d), this = %p\n", val, this);
+  }
+  ~A() {
+    printf("~A(%d), this = %p\n", val, this);
+  }
+  int getVal() const { return val; }
+};
+
+const A a(1);
+// CHECK: A(1), this = [[PTR:.+]]
+
+a.val
+// CHECK-NEXT: (const int) 1
+a.getVal()
+// CHECK-NEXT: (int) 1
+a.val
+// CHECK-NEXT: (const int) 1
+a.getVal()
+// CHECK-NEXT: (int) 1
+
+// CHECK-NEXT: ~A(1), this = [[PTR]]
+// CHECK-NOT: ~A
diff --git a/interpreter/llvm/src/lib/ExecutionEngine/Orc/LLJIT.cpp b/interpreter/llvm/src/lib/ExecutionEngine/Orc/LLJIT.cpp
index 6c52998dc633b..4d304f7bca7b8 100644
--- a/interpreter/llvm/src/lib/ExecutionEngine/Orc/LLJIT.cpp
+++ b/interpreter/llvm/src/lib/ExecutionEngine/Orc/LLJIT.cpp
@@ -483,7 +483,7 @@ GlobalCtorDtorScraper::operator()(ThreadSafeModule TSM,
       Inits.push_back(std::make_pair(E.Func, E.Priority));
     llvm::sort(Inits, [](const std::pair<Function *, unsigned> &LHS,
                          const std::pair<Function *, unsigned> &RHS) {
-      return LHS.first < RHS.first;
+      return LHS.second < RHS.second;
     });
     auto *EntryBlock = BasicBlock::Create(Ctx, "entry", InitFunc);
     IRBuilder<> IB(EntryBlock);
diff --git a/interpreter/llvm/src/tools/clang/lib/AST/ASTContext.cpp b/interpreter/llvm/src/tools/clang/lib/AST/ASTContext.cpp
index 00ec96abae66d..4e80e859443fc 100644
--- a/interpreter/llvm/src/tools/clang/lib/AST/ASTContext.cpp
+++ b/interpreter/llvm/src/tools/clang/lib/AST/ASTContext.cpp
@@ -10833,6 +10833,15 @@ GVALinkage ASTContext::GetGVALinkageForFunction(const FunctionDecl *FD) const {
 
 static GVALinkage basicGVALinkageForVariable(const ASTContext &Context,
                                              const VarDecl *VD) {
+  // As an extension for interactive REPLs, make sure constant variables are
+  // only emitted once instead of LinkageComputer::getLVForNamespaceScopeDecl
+  // marking them as internal.
+  if (Context.getLangOpts().CPlusPlus &&
+      VD->getType().isConstQualified() &&
+      !VD->getType().isVolatileQualified() && !VD->isInline() &&
+      !isa<VarTemplateSpecializationDecl>(VD) && !VD->getDescribedVarTemplate())
+    return GVA_DiscardableODR;
+
   if (!VD->isExternallyVisible())
     return GVA_Internal;