[clang] b6c4903 - A constexpr virtual function is implicitly inline so should never be a

[Richard Smith via cfe-commits]

Author: Richard Smith
Date: 2020-06-30T16:07:50-07:00
New Revision: b6c490349d1524aefeb1c4a686411f860e6a3555

URL: https://github.com/llvm/llvm-project/commit/b6c490349d1524aefeb1c4a686411f860e6a3555
DIFF: https://github.com/llvm/llvm-project/commit/b6c490349d1524aefeb1c4a686411f860e6a3555.diff

LOG: A constexpr virtual function is implicitly inline so should never be a
key function.

Added: 
    clang/test/CodeGenCXX/vtable-constexpr.cpp

Modified: 
    clang/lib/AST/RecordLayoutBuilder.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/AST/RecordLayoutBuilder.cpp b/clang/lib/AST/RecordLayoutBuilder.cpp
index 028e82a5df4d..3d5f785e943e 100644
--- a/clang/lib/AST/RecordLayoutBuilder.cpp
+++ b/clang/lib/AST/RecordLayoutBuilder.cpp
@@ -2107,7 +2107,7 @@ static const CXXMethodDecl *computeKeyFunction(ASTContext &Context,
     if (MD->isImplicit())
       continue;
 
-    if (MD->isInlineSpecified())
+    if (MD->isInlineSpecified() || MD->isConstexpr())
       continue;
 
     if (MD->hasInlineBody())

diff  --git a/clang/test/CodeGenCXX/vtable-constexpr.cpp b/clang/test/CodeGenCXX/vtable-constexpr.cpp
new file mode 100644
index 000000000000..e398a9e5835d
--- /dev/null
+++ b/clang/test/CodeGenCXX/vtable-constexpr.cpp
@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -std=c++20 %s -emit-llvm -o - -triple %itanium_abi_triple | FileCheck %s --implicit-check-not=DoNotEmit
+
+// constexpr virtual functions can be called at runtime and go in the vtable as
+// normal. But they are implicitly inline so are never the key function.
+
+struct DoNotEmit {
+  virtual constexpr void f();
+};
+constexpr void DoNotEmit::f() {}
+
+// CHECK-DAG: @_ZTV1B = {{.*}} constant { [3 x i8*] } { {{.*}} null, {{.*}} @_ZTI1B {{.*}} @_ZN1B1fEv
+struct B {
+  // CHECK-DAG: define {{.*}} @_ZN1B1fEv
+  virtual constexpr void f() {}
+};
+B b;
+
+struct CBase {
+  virtual constexpr void f(); // not key function
+};
+
+// CHECK-DAG: @_ZTV1C = {{.*}} constant {{.*}} null, {{.*}} @_ZTI1C {{.*}} @_ZN1C1fEv
+struct C : CBase {
+  void f(); // key function
+};
+// CHECK-DAG: define {{.*}} @_ZN1C1fEv
+void C::f() {}