[MS ABI] Workaround corner-case bug in the ABI for operator delete

MSVC only genreates array cookies if the class has a destructor.  This
is problematic when having to call T::operator delete[](void *, size_t)
because the second argument's argument is impossible to synthesize
correctly if the class has no destructor (because there will be no array
cookie).

Instead, MSVC passes the size of the class.  Do the same, for
compatibility, instead of crashing.

This fixes PR23990.

llvm-svn: 241038

2 files changed, 12 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CGExprCXX.cpp b/clang/lib/CodeGen/CGExprCXX.cpp
index f0f706d7b95..c7adccaeeae 100644
--- a/clang/lib/CodeGen/CGExprCXX.cpp
+++ b/clang/lib/CodeGen/CGExprCXX.cpp
@@ -1548,7 +1548,8 @@ namespace {
         // The size of an element, multiplied by the number of elements.
         llvm::Value *Size
           = llvm::ConstantInt::get(SizeTy, ElementTypeSize.getQuantity());
-        Size = CGF.Builder.CreateMul(Size, NumElements);
+        if (NumElements)
+          Size = CGF.Builder.CreateMul(Size, NumElements);
 
         // Plus the size of the cookie if applicable.
         if (!CookieSize.isZero()) {
diff --git a/clang/test/CodeGenCXX/microsoft-abi-array-cookies.cpp b/clang/test/CodeGenCXX/microsoft-abi-array-cookies.cpp
index 619b1b8a948..62ead4fb69d 100644
--- a/clang/test/CodeGenCXX/microsoft-abi-array-cookies.cpp
+++ b/clang/test/CodeGenCXX/microsoft-abi-array-cookies.cpp
@@ -58,4 +58,14 @@ void check_array_cookies_aligned() {
 // CHECK: getelementptr inbounds i8, i8* [[ARRAY_AS_CHAR]], i64 -8
 }
 
+namespace PR23990 {
+struct S {
+  char x[42];
+  void operator delete[](void *p, __SIZE_TYPE__);
+  // CHECK-LABEL: define void @"\01?delete_s@PR23990@@YAXPAUS@1@@Z"(
+  // CHECK: call void @"\01??_VS@PR23990@@SAXPAXI@Z"(i8* {{.*}}, i32 42)
+};
+void delete_s(S *s) { delete[] s; }
+}
+
 // CHECK: attributes [[NUW]] = { nounwind{{.*}} }