[clang] [clang][CodeGen] Switch declaration of vtable information to be [0 x ptr] (PR #65596)
Nuno Lopes via cfe-commits
cfe-commits at lists.llvm.org
Thu Sep 7 04:07:31 PDT 2023
https://github.com/nunoplopes created https://github.com/llvm/llvm-project/pull/65596:
Continuing the discussion in https://discourse.llvm.org/t/codegen-layout-of-si-class-type-info-doesnt-match-the-actual-size/73274
Before we had this code:
@_ZTVN10__cxxabiv117__class_type_infoE = external global ptr
now we'll produce:
@_ZTVN10__cxxabiv117__class_type_infoE = external global [0 x ptr]
This is because we may not know the exact size of this data, and clang issues gep inbounds with idx=2. Before, that gep would always result in poison.
>From 8585d37c6526d46e08efb2b573ca9ba50dd68a9b Mon Sep 17 00:00:00 2001
From: Nuno Lopes <nuno.lopes at tecnico.ulisboa.pt>
Date: Thu, 7 Sep 2023 11:07:03 +0100
Subject: [PATCH] [clang][CodeGen] Switch declaration of vtable information to
be [0 x ptr]
Before we had this code:
@_ZTVN10__cxxabiv117__class_type_infoE = external global ptr
now we'll produce:
@_ZTVN10__cxxabiv117__class_type_infoE = external global [0 x ptr]
This is because we may not know the exact size of this data, and clang
issues gep inbounds with idx=2. Before, that gep would always result
in poison.
---
clang/lib/CodeGen/ItaniumCXXABI.cpp | 7 ++++---
.../RelativeVTablesABI/child-vtable-in-comdat.cpp | 2 +-
.../RelativeVTablesABI/parent-vtable-in-comdat.cpp | 2 +-
.../RelativeVTablesABI/simple-vtable-definition.cpp | 2 +-
clang/test/CodeGenCXX/RelativeVTablesABI/type-info.cpp | 4 ++--
clang/test/CodeGenCXX/typeinfo-with-address-space.cpp | 4 ++--
6 files changed, 11 insertions(+), 10 deletions(-)
diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index d64287ddf1217cb..58fb3defa830aad 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -3669,9 +3669,10 @@ void ItaniumRTTIBuilder::BuildVTablePointer(const Type *Ty) {
// Check if the alias exists. If it doesn't, then get or create the global.
if (CGM.getItaniumVTableContext().isRelativeLayout())
VTable = CGM.getModule().getNamedAlias(VTableName);
- if (!VTable)
- VTable =
- CGM.getModule().getOrInsertGlobal(VTableName, CGM.GlobalsInt8PtrTy);
+ if (!VTable) {
+ llvm::Type *Ty = llvm::ArrayType::get(CGM.VoidPtrTy, 0);
+ VTable = CGM.getModule().getOrInsertGlobal(VTableName, Ty);
+ }
CGM.setDSOLocal(cast<llvm::GlobalValue>(VTable->stripPointerCasts()));
diff --git a/clang/test/CodeGenCXX/RelativeVTablesABI/child-vtable-in-comdat.cpp b/clang/test/CodeGenCXX/RelativeVTablesABI/child-vtable-in-comdat.cpp
index f7d7bc0e94a08f0..48b1d8ed65d7e55 100644
--- a/clang/test/CodeGenCXX/RelativeVTablesABI/child-vtable-in-comdat.cpp
+++ b/clang/test/CodeGenCXX/RelativeVTablesABI/child-vtable-in-comdat.cpp
@@ -14,7 +14,7 @@
// CHECK-DAG: @_ZTV1B.local = linkonce_odr hidden unnamed_addr constant { [3 x i32] } { [3 x i32] [i32 0, i32 trunc (i64 sub (i64 ptrtoint (ptr @_ZTI1B.rtti_proxy to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [3 x i32] }, ptr @_ZTV1B.local, i32 0, i32 0, i32 2) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr dso_local_equivalent @_ZN1B3fooEv to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [3 x i32] }, ptr @_ZTV1B.local, i32 0, i32 0, i32 2) to i64)) to i32)] }, comdat($_ZTV1B), align 4
// The RTTI objects aren’t that important, but it is good to know that they are emitted here since they are used in the vtable for B, and external references are used for RTTI stuff from A.
-// CHECK-DAG: @_ZTVN10__cxxabiv120__si_class_type_infoE = external global ptr
+// CHECK-DAG: @_ZTVN10__cxxabiv120__si_class_type_infoE = external global [0 x ptr]
// CHECK-DAG: @_ZTS1B =
// CHECK-DAG: @_ZTI1A =
// CHECK-DAG: @_ZTI1B =
diff --git a/clang/test/CodeGenCXX/RelativeVTablesABI/parent-vtable-in-comdat.cpp b/clang/test/CodeGenCXX/RelativeVTablesABI/parent-vtable-in-comdat.cpp
index f9e3382c489b4e1..5f5f9edf411a809 100644
--- a/clang/test/CodeGenCXX/RelativeVTablesABI/parent-vtable-in-comdat.cpp
+++ b/clang/test/CodeGenCXX/RelativeVTablesABI/parent-vtable-in-comdat.cpp
@@ -15,7 +15,7 @@
// The VTable for A is emitted here and in a comdat section since it has no key function, and is used in this module when creating an instance of A.
// CHECK: @_ZTV1A.local = linkonce_odr hidden unnamed_addr constant { [3 x i32] } { [3 x i32] [i32 0, i32 trunc (i64 sub (i64 ptrtoint (ptr @_ZTI1A.rtti_proxy to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [3 x i32] }, ptr @_ZTV1A.local, i32 0, i32 0, i32 2) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr dso_local_equivalent @_ZN1A3fooEv to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [3 x i32] }, ptr @_ZTV1A.local, i32 0, i32 0, i32 2) to i64)) to i32)] }, comdat($_ZTV1A), align 4
-// CHECK: @_ZTVN10__cxxabiv117__class_type_infoE = external global ptr
+// CHECK: @_ZTVN10__cxxabiv117__class_type_infoE = external global [0 x ptr]
// CHECK: @_ZTS1A = linkonce_odr constant [3 x i8] c"1A\00", comdat, align 1
// CHECK: @_ZTI1A = linkonce_odr constant { ptr, ptr } { ptr getelementptr inbounds (i8, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i32 8), ptr @_ZTS1A }, comdat, align 8
// CHECK: @_ZTI1A.rtti_proxy = hidden unnamed_addr constant ptr @_ZTI1A, comdat
diff --git a/clang/test/CodeGenCXX/RelativeVTablesABI/simple-vtable-definition.cpp b/clang/test/CodeGenCXX/RelativeVTablesABI/simple-vtable-definition.cpp
index a59d47dc816c03f..76de83d9d2cd466 100644
--- a/clang/test/CodeGenCXX/RelativeVTablesABI/simple-vtable-definition.cpp
+++ b/clang/test/CodeGenCXX/RelativeVTablesABI/simple-vtable-definition.cpp
@@ -9,7 +9,7 @@
// The vtable definition itself is private so we can take relative references to
// it. The vtable symbol will be exposed through a public alias.
// CHECK: @_ZTV1A.local = private unnamed_addr constant { [3 x i32] } { [3 x i32] [i32 0, i32 trunc (i64 sub (i64 ptrtoint (ptr @_ZTI1A.rtti_proxy to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [3 x i32] }, ptr @_ZTV1A.local, i32 0, i32 0, i32 2) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr dso_local_equivalent @_ZN1A3fooEv to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [3 x i32] }, ptr @_ZTV1A.local, i32 0, i32 0, i32 2) to i64)) to i32)] }, align 4
-// CHECK: @_ZTVN10__cxxabiv117__class_type_infoE = external global ptr
+// CHECK: @_ZTVN10__cxxabiv117__class_type_infoE = external global [0 x ptr]
// CHECK: @_ZTS1A ={{.*}} constant [3 x i8] c"1A\00", align 1
// CHECK: @_ZTI1A ={{.*}} constant { ptr, ptr } { ptr getelementptr inbounds (i8, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i32 8), ptr @_ZTS1A }, align 8
diff --git a/clang/test/CodeGenCXX/RelativeVTablesABI/type-info.cpp b/clang/test/CodeGenCXX/RelativeVTablesABI/type-info.cpp
index 78db99957dba8cf..42f28a770e72770 100644
--- a/clang/test/CodeGenCXX/RelativeVTablesABI/type-info.cpp
+++ b/clang/test/CodeGenCXX/RelativeVTablesABI/type-info.cpp
@@ -7,10 +7,10 @@
// CHECK: $_ZTI1A.rtti_proxy = comdat any
// CHECK: $_ZTI1B.rtti_proxy = comdat any
-// CHECK: @_ZTVN10__cxxabiv117__class_type_infoE = external global ptr
+// CHECK: @_ZTVN10__cxxabiv117__class_type_infoE = external global [0 x ptr]
// CHECK: @_ZTS1A ={{.*}} constant [3 x i8] c"1A\00", align 1
// CHECK: @_ZTI1A ={{.*}} constant { ptr, ptr } { ptr getelementptr inbounds (i8, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i32 8), ptr @_ZTS1A }, align 8
-// CHECK: @_ZTVN10__cxxabiv120__si_class_type_infoE = external global ptr
+// CHECK: @_ZTVN10__cxxabiv120__si_class_type_infoE = external global [0 x ptr]
// CHECK: @_ZTS1B ={{.*}} constant [3 x i8] c"1B\00", align 1
// CHECK: @_ZTI1B ={{.*}} constant { ptr, ptr, ptr } { ptr getelementptr inbounds (i8, ptr @_ZTVN10__cxxabiv120__si_class_type_infoE, i32 8), ptr @_ZTS1B, ptr @_ZTI1A }, align 8
// CHECK: @_ZTI1A.rtti_proxy = hidden unnamed_addr constant ptr @_ZTI1A, comdat
diff --git a/clang/test/CodeGenCXX/typeinfo-with-address-space.cpp b/clang/test/CodeGenCXX/typeinfo-with-address-space.cpp
index 9f79e3bf05d7e10..dccbc1600135f8a 100644
--- a/clang/test/CodeGenCXX/typeinfo-with-address-space.cpp
+++ b/clang/test/CodeGenCXX/typeinfo-with-address-space.cpp
@@ -14,8 +14,8 @@ class B : A {
// NO-AS: @_ZTISt9type_info = external constant ptr
// AS: @_ZTIi = external addrspace(1) constant ptr addrspace(1)
// NO-AS: @_ZTIi = external constant ptr
-// AS: @_ZTVN10__cxxabiv117__class_type_infoE = external addrspace(1) global ptr addrspace(1)
-// NO-AS: @_ZTVN10__cxxabiv117__class_type_infoE = external global ptr
+// AS: @_ZTVN10__cxxabiv117__class_type_infoE = external addrspace(1) global [0 x ptr]
+// NO-AS: @_ZTVN10__cxxabiv117__class_type_infoE = external global [0 x ptr]
// AS: @_ZTS1A = linkonce_odr addrspace(1) constant [3 x i8] c"1A\00", comdat, align 1
// NO-AS: @_ZTS1A = linkonce_odr constant [3 x i8] c"1A\00", comdat, align 1
// AS: @_ZTI1A = linkonce_odr addrspace(1) constant { ptr addrspace(1), ptr addrspace(1) } { ptr addrspace(1) getelementptr inbounds (ptr addrspace(1), ptr addrspace(1) @_ZTVN10__cxxabiv117__class_type_infoE, i64 2), ptr addrspace(1) @_ZTS1A }, comdat, align 8
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