From f5af7d2d987b0b16d7a641b7aa9086a75d533944 Mon Sep 17 00:00:00 2001
From: Krasimir Georgiev <krasimir@google.com>
Date: Tue, 23 May 2023 07:59:38 +0000
Subject: [PATCH] Revert "[clang][ExprConstant] fix __builtin_object_size for
 flexible array members"

This reverts commit 57c5c1ab2a188b7962c9de5ac0f95e3c7441940a.

Causes an assertion failure: https://reviews.llvm.org/D150892#4363080
---
 clang/docs/ReleaseNotes.rst      |  9 ---------
 clang/lib/AST/ExprConstant.cpp   |  9 +--------
 clang/test/CodeGen/object-size.c | 27 ---------------------------
 3 files changed, 1 insertion(+), 44 deletions(-)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index a124617..915c9b0 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -51,11 +51,6 @@ C/C++ Language Potentially Breaking Changes
 
     foo: asm goto ("# %0 %1"::"i"(&&foo)::foo);
 
-- ``__builtin_object_size`` and ``__builtin_dynamic_object_size`` now add the
-  ``sizeof`` the elements specified in designated initializers of flexible
-  array members for structs that contain them. This change is more consistent
-  with the behavior of GCC.
-
 C++ Specific Potentially Breaking Changes
 -----------------------------------------
 - Clang won't search for coroutine_traits in std::experimental namespace any more.
@@ -429,10 +424,6 @@ Bug Fixes in This Version
   (`#61746 <https://github.com/llvm/llvm-project/issues/61746>`_).
 - Clang `TextNodeDumper` enabled through `-ast-dump` flag no longer evaluates the
   initializer of constexpr `VarDecl` if the declaration has a dependent type.
-- Match GCC's behavior for ``__builtin_object_size`` and
-  ``__builtin_dynamic_object_size`` on structs containing flexible array
-  members.
-  (`#62789 <https://github.com/llvm/llvm-project/issues/62789>`_).
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index f1a30da..ce3c525 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -11733,14 +11733,7 @@ static bool determineEndOffset(EvalInfo &Info, SourceLocation ExprLoc,
   auto CheckedHandleSizeof = [&](QualType Ty, CharUnits &Result) {
     if (Ty.isNull() || Ty->isIncompleteType() || Ty->isFunctionType())
       return false;
-    bool Ret = HandleSizeof(Info, ExprLoc, Ty, Result);
-    if (Ty->isStructureType() &&
-        Ty->getAsStructureType()->getDecl()->hasFlexibleArrayMember()) {
-      const auto *VD =
-          cast<VarDecl>(LVal.getLValueBase().get<const ValueDecl *>());
-      Result += VD->getFlexibleArrayInitChars(Info.Ctx);
-    }
-    return Ret;
+    return HandleSizeof(Info, ExprLoc, Ty, Result);
   };
 
   // We want to evaluate the size of the entire object. This is a valid fallback
diff --git a/clang/test/CodeGen/object-size.c b/clang/test/CodeGen/object-size.c
index ac15513..157926d 100644
--- a/clang/test/CodeGen/object-size.c
+++ b/clang/test/CodeGen/object-size.c
@@ -525,33 +525,6 @@ void test31(void) {
   gi = OBJECT_SIZE_BUILTIN(&dsv[9].snd[0], 1);
 }
 
-// CHECK-LABEL: @test32
-static struct DynStructVar D32 = {
-  .fst = {},
-  .snd = { 0, 1, 2, },
-};
-unsigned long test32(void) {
-  // CHECK: ret i64 19
-  return OBJECT_SIZE_BUILTIN(&D32, 1);
-}
-// CHECK-LABEL: @test33
-static struct DynStructVar D33 = {
-  .fst = {},
-  .snd = {},
-};
-unsigned long test33(void) {
-  // CHECK: ret i64 16
-  return OBJECT_SIZE_BUILTIN(&D33, 1);
-}
-// CHECK-LABEL: @test34
-static struct DynStructVar D34 = {
-  .fst = {},
-};
-unsigned long test34(void) {
-  // CHECK: ret i64 16
-  return OBJECT_SIZE_BUILTIN(&D34, 1);
-}
-
 // CHECK-LABEL: @PR30346
 void PR30346(void) {
   struct sa_family_t {};
-- 
2.7.4