Author: Richard Smith
Date: 2020-07-30T14:50:01-07:00
New Revision: 1e7f026c3b59bea22491819f86d8388d0c3e0c07

URL: 
https://github.com/llvm/llvm-project/commit/1e7f026c3b59bea22491819f86d8388d0c3e0c07
DIFF: 
https://github.com/llvm/llvm-project/commit/1e7f026c3b59bea22491819f86d8388d0c3e0c07.diff

LOG: PR46908: Emit undef destroying_delete_t as an aggregate RValue.

We previously used a non-aggregate RValue to represent the passed value,
which violated the assumptions of call arg lowering in some cases, in
particular on 32-bit Windows, where we'd end up producing an FCA store
with TBAA metadata, that the IR verifier would reject.

Added: 
    

Modified: 
    clang/lib/CodeGen/CGExprCXX.cpp
    clang/test/CodeGenCXX/cxx2a-destroying-delete.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/CodeGen/CGExprCXX.cpp b/clang/lib/CodeGen/CGExprCXX.cpp
index d59aa6ce0fb9..d0e0c7d6c060 100644
--- a/clang/lib/CodeGen/CGExprCXX.cpp
+++ b/clang/lib/CodeGen/CGExprCXX.cpp
@@ -1788,11 +1788,14 @@ void CodeGenFunction::EmitDeleteCall(const FunctionDecl 
*DeleteFD,
   DeleteArgs.add(RValue::get(DeletePtr), ArgTy);
 
   // Pass the std::destroying_delete tag if present.
+  llvm::AllocaInst *DestroyingDeleteTag = nullptr;
   if (Params.DestroyingDelete) {
     QualType DDTag = *ParamTypeIt++;
-    // Just pass an 'undef'. We expect the tag type to be an empty struct.
-    auto *V = llvm::UndefValue::get(getTypes().ConvertType(DDTag));
-    DeleteArgs.add(RValue::get(V), DDTag);
+    llvm::Type *Ty = getTypes().ConvertType(DDTag);
+    CharUnits Align = CGM.getNaturalTypeAlignment(DDTag);
+    DestroyingDeleteTag = CreateTempAlloca(Ty, "destroying.delete.tag");
+    DestroyingDeleteTag->setAlignment(Align.getAsAlign());
+    DeleteArgs.add(RValue::getAggregate(Address(DestroyingDeleteTag, Align)), 
DDTag);
   }
 
   // Pass the size if the delete function has a size_t parameter.
@@ -1829,6 +1832,11 @@ void CodeGenFunction::EmitDeleteCall(const FunctionDecl 
*DeleteFD,
 
   // Emit the call to delete.
   EmitNewDeleteCall(*this, DeleteFD, DeleteFTy, DeleteArgs);
+
+  // If call argument lowering didn't use the destroying_delete_t alloca,
+  // remove it again.
+  if (DestroyingDeleteTag && DestroyingDeleteTag->use_empty())
+    DestroyingDeleteTag->eraseFromParent();
 }
 
 namespace {

diff  --git a/clang/test/CodeGenCXX/cxx2a-destroying-delete.cpp 
b/clang/test/CodeGenCXX/cxx2a-destroying-delete.cpp
index 60c5970cb94f..e689afa62092 100644
--- a/clang/test/CodeGenCXX/cxx2a-destroying-delete.cpp
+++ b/clang/test/CodeGenCXX/cxx2a-destroying-delete.cpp
@@ -1,5 +1,11 @@
-// RUN: %clang_cc1 -std=c++2a -emit-llvm %s -triple x86_64-linux-gnu -o - | 
FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-ITANIUM
-// RUN: %clang_cc1 -std=c++2a -emit-llvm %s -triple x86_64-windows -o - | 
FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-MSABI
+// RUN: %clang_cc1 -std=c++2a -emit-llvm %s -triple x86_64-linux-gnu -o - | 
FileCheck %s --check-prefixes=CHECK,CHECK-ITANIUM,CHECK-64BIT
+// RUN: %clang_cc1 -std=c++2a -emit-llvm %s -triple x86_64-windows -o - | 
FileCheck %s --check-prefixes=CHECK,CHECK-MSABI,CHECK-MSABI64,CHECK-64BIT
+// RUN: %clang_cc1 -std=c++2a -emit-llvm %s -triple i386-windows -o - | 
FileCheck %s --check-prefixes=CHECK,CHECK-MSABI,CHECK-MSABI32,CHECK-32BIT
+
+// PR46908: ensure the IR passes the verifier with optimizations enabled.
+// RUN: %clang_cc1 -std=c++2a -emit-llvm-only %s -triple x86_64-linux-gnu -O2
+// RUN: %clang_cc1 -std=c++2a -emit-llvm-only %s -triple x86_64-windows -O2
+// RUN: %clang_cc1 -std=c++2a -emit-llvm-only %s -triple i386-windows -O2
 
 namespace std {
   using size_t = decltype(sizeof(0));
@@ -21,7 +27,8 @@ void delete_A(A *a) { delete a; }
 // Ensure that we call the destroying delete and not the destructor.
 // CHECK-NOT: call
 // CHECK-ITANIUM: call void @_ZN1AdlEPS_St19destroying_delete_t(%{{.*}}* 
%[[a]])
-// CHECK-MSABI: call void 
@"??3A@@SAXPEAU0@Udestroying_delete_t@std@@@Z"(%{{.*}}* %[[a]], i8
+// CHECK-MSABI64: call void 
@"??3A@@SAXPEAU0@Udestroying_delete_t@std@@@Z"(%{{.*}}* %[[a]], i8
+// CHECK-MSABI32: call void 
@"??3A@@SAXPAU0@Udestroying_delete_t@std@@@Z"(%{{.*}}* %[[a]], %{{.*}}* 
byval(%{{.*}}) align 4 %{{.*}})
 // CHECK-NOT: call
 // CHECK: }
 
@@ -39,7 +46,7 @@ void delete_B(B *b) { delete b; }
 // CHECK-NOT: call
 // CHECK: %[[VTABLE:.*]] = load
 // CHECK: %[[DTOR:.*]] = load
-// CHECK: call {{void|i8\*}} %[[DTOR]](%{{.*}}* %[[b]]
+// CHECK: call {{void|i8\*|x86_thiscallcc i8\*}} %[[DTOR]](%{{.*}}* %[[b]]
 // CHECK-MSABI-SAME: , i32 1)
 // CHECK-NOT: call
 // CHECK: }
@@ -56,7 +63,8 @@ void delete_C(C *c) { delete c; }
 // CHECK: icmp eq %{{.*}} %[[c]], null
 // CHECK: br i1
 //
-// CHECK: %[[base:.*]] = getelementptr {{.*}}, i64 8
+// CHECK-64BIT: %[[base:.*]] = getelementptr {{.*}}, i64 8
+// CHECK-32BIT: %[[base:.*]] = getelementptr {{.*}}, i32 4
 // CHECK: %[[castbase:.*]] = bitcast {{.*}} %[[base]]
 //
 // CHECK: %[[a:.*]] = phi {{.*}} %[[castbase]]
@@ -65,7 +73,8 @@ void delete_C(C *c) { delete c; }
 //
 // CHECK-NOT: call
 // CHECK-ITANIUM: call void @_ZN1AdlEPS_St19destroying_delete_t(%{{.*}}* 
%[[a]])
-// CHECK-MSABI: call void 
@"??3A@@SAXPEAU0@Udestroying_delete_t@std@@@Z"(%{{.*}}* %[[a]], i8
+// CHECK-MSABI64: call void 
@"??3A@@SAXPEAU0@Udestroying_delete_t@std@@@Z"(%{{.*}}* %[[a]], i8
+// CHECK-MSABI32: call void 
@"??3A@@SAXPAU0@Udestroying_delete_t@std@@@Z"(%{{.*}}* %[[a]], %{{.*}}* 
byval(%{{.*}}) align 4 %{{.*}})
 // CHECK-NOT: call
 // CHECK: }
 
@@ -81,13 +90,14 @@ void delete_D(D *d) { delete d; }
 // For MS, we don't add a new vtable slot to the primary vtable for the virtual
 // destructor. Instead we cast to the VDel base class.
 // CHECK-MSABI: bitcast {{.*}} %[[d]]
-// CHECK-MSABI-NEXT: getelementptr {{.*}}, i64 8
+// CHECK-MSABI64-NEXT: getelementptr {{.*}}, i64 8
+// CHECK-MSABI32-NEXT: getelementptr {{.*}}, i32 4
 // CHECK-MSABI-NEXT: %[[d:.*]] = bitcast i8*
 //
 // CHECK: %[[VTABLE:.*]] = load
 // CHECK: %[[DTOR:.*]] = load
 //
-// CHECK: call {{void|i8\*}} %[[DTOR]](%{{.*}}* %[[d]]
+// CHECK: call {{void|i8\*|x86_thiscallcc i8\*}} %[[DTOR]](%{{.*}}* %[[d]]
 // CHECK-MSABI-SAME: , i32 1)
 // CHECK-NOT: call
 // CHECK: }
@@ -100,7 +110,8 @@ void delete_G(G *g) { delete g; }
 // CHECK-LABEL: define {{.*}}delete_G
 // CHECK-NOT: call
 // CHECK-ITANIUM: call void 
@_ZN1FdlEPS_St19destroying_delete_tmSt11align_val_t(%{{.*}}* %[[a]], i64 32, 
i64 16)
-// CHECK-MSABI: call void 
@"??3F@@SAXPEAU0@Udestroying_delete_t@std@@_KW4align_val_t@2@@Z"(%{{.*}}* 
%[[a]], i8 {{[^,]*}}, i64 32, i64 16)
+// CHECK-MSABI64: call void 
@"??3F@@SAXPEAU0@Udestroying_delete_t@std@@_KW4align_val_t@2@@Z"(%{{.*}}* 
%[[a]], i8 {{[^,]*}}, i64 32, i64 16)
+// CHECK-MSABI32: call void 
@"??3F@@SAXPAU0@Udestroying_delete_t@std@@IW4align_val_t@2@@Z"(%{{.*}}* %[[a]], 
%{{.*}}* byval(%{{.*}}) align 4 %{{.*}}, i32 16, i32 16)
 // CHECK-NOT: call
 // CHECK: }
 
@@ -116,19 +127,23 @@ H::~H() { call_in_dtor(); }
 // CHECK-ITANIUM-NOT: call
 // CHECK-ITANIUM: }
 
-// CHECK-MSABI: define {{.*}} @"??_GH@@UEAAPEAXI@Z"(
+// CHECK-MSABI64: define {{.*}} @"??_GH@@UEAAPEAXI@Z"(
+// CHECK-MSABI32: define {{.*}} @"??_GH@@UAEPAXI@Z"(
 // CHECK-MSABI-NOT: call{{ }}
 // CHECK-MSABI: load i32
 // CHECK-MSABI: icmp eq i32 {{.*}}, 0
 // CHECK-MSABI: br i1
 //
 // CHECK-MSABI-NOT: call{{ }}
-// CHECK-MSABI: getelementptr {{.*}}, i64 24
+// CHECK-MSABI64: getelementptr {{.*}}, i64 24
+// CHECK-MSABI32: getelementptr {{.*}}, i32 20
 // CHECK-MSABI-NOT: call{{ }}
-// CHECK-MSABI: call void 
@"??3F@@SAXPEAU0@Udestroying_delete_t@std@@_KW4align_val_t@2@@Z"({{.*}}, i64 
48, i64 16)
+// CHECK-MSABI64: call void 
@"??3F@@SAXPEAU0@Udestroying_delete_t@std@@_KW4align_val_t@2@@Z"({{.*}}, i64 
48, i64 16)
+// CHECK-MSABI32: call void 
@"??3F@@SAXPAU0@Udestroying_delete_t@std@@IW4align_val_t@2@@Z"({{.*}}, i32 32, 
i32 16)
 // CHECK-MSABI: br label %[[RETURN:.*]]
 //
-// CHECK-MSABI: call void @"??1H@@UEAA@XZ"(
+// CHECK-MSABI64: call void @"??1H@@UEAA@XZ"(
+// CHECK-MSABI32: call x86_thiscallcc void @"??1H@@UAE@XZ"(
 // CHECK-MSABI: br label %[[RETURN]]
 //
 // CHECK-MSABI: }
@@ -143,19 +158,23 @@ I::~I() { call_in_dtor(); }
 // CHECK-ITANIUM-NOT: call
 // CHECK-ITANIUM: }
 
-// CHECK-MSABI: define {{.*}} @"??_GI@@UEAAPEAXI@Z"(
+// CHECK-MSABI64: define {{.*}} @"??_GI@@UEAAPEAXI@Z"(
+// CHECK-MSABI32: define {{.*}} @"??_GI@@UAEPAXI@Z"(
 // CHECK-MSABI-NOT: call{{ }}
 // CHECK-MSABI: load i32
 // CHECK-MSABI: icmp eq i32 {{.*}}, 0
 // CHECK-MSABI: br i1
 //
 // CHECK-MSABI-NOT: call{{ }}
-// CHECK-MSABI: getelementptr {{.*}}, i64 24
+// CHECK-MSABI64: getelementptr {{.*}}, i64 24
+// CHECK-MSABI32: getelementptr {{.*}}, i32 20
 // CHECK-MSABI-NOT: call{{ }}
-// CHECK-MSABI: call void 
@"??3F@@SAXPEAU0@Udestroying_delete_t@std@@_KW4align_val_t@2@@Z"({{.*}}, i64 
96, i64 32)
+// CHECK-MSABI64: call void 
@"??3F@@SAXPEAU0@Udestroying_delete_t@std@@_KW4align_val_t@2@@Z"({{.*}}, i64 
96, i64 32)
+// CHECK-MSABI32: call void 
@"??3F@@SAXPAU0@Udestroying_delete_t@std@@IW4align_val_t@2@@Z"({{.*}}, i32 64, 
i32 32)
 // CHECK-MSABI: br label %[[RETURN:.*]]
 //
-// CHECK-MSABI: call void @"??1I@@UEAA@XZ"(
+// CHECK-MSABI64: call void @"??1I@@UEAA@XZ"(
+// CHECK-MSABI32: call x86_thiscallcc void @"??1I@@UAE@XZ"(
 // CHECK-MSABI: br label %[[RETURN]]
 //
 // CHECK-MSABI: }


        
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