[MS] Make constexpr static data members implicitly inline

This handles them exactly the same way that we handle const integral
static data members with inline definitions, which is what MSVC does.

As a follow-up, now that we have a way to mark variables inline in the
AST, we should consider marking them implicitly inline there instead of
only treating them as inline in CodeGen. Unfortunately, this breaks a
lot of dllimport test cases, so that is future work for now.

Fixes PR36125.

llvm-svn: 325375

1 files changed, 36 insertions, 4 deletions

diff --git a/clang/test/CodeGenCXX/static-data-member.cpp b/clang/test/CodeGenCXX/static-data-member.cpp
index 5ffd83ff023..5f4d9b6599b 100644
--- a/clang/test/CodeGenCXX/static-data-member.cpp
+++ b/clang/test/CodeGenCXX/static-data-member.cpp
@@ -1,6 +1,10 @@
-// RUN: %clang_cc1 -triple x86_64-pc-linux -emit-llvm -o - %s | FileCheck %s
-// RUN: %clang_cc1 -triple x86_64-apple-darwin -emit-llvm -o - %s | \
-// RUN: FileCheck --check-prefix=MACHO %s
+// RUN: %clang_cc1 -triple x86_64-pc-linux -std=c++14 -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin -std=c++14 -emit-llvm -o - %s \
+// RUN:     | FileCheck %s --check-prefix=MACHO
+// RUN: %clang_cc1 -triple x86_64-pc-windows-msvc -std=c++14 -emit-llvm -o - %s \
+// RUN:     | FileCheck %s --check-prefix=MSVC
+// RUN: %clang_cc1 -triple x86_64-pc-windows-msvc -std=c++17 -emit-llvm -o - %s \
+// RUN:     | FileCheck %s --check-prefix=MSVC
 
 // CHECK: @_ZN5test11A1aE = constant i32 10, align 4
 // CHECK: @_ZN5test212_GLOBAL__N_11AIiE1xE = internal global i32 0, align 4
@@ -9,12 +13,25 @@
 // MACHO: @_ZGVN5test31AIiE1xE = weak_odr global i64 0
 // MACHO-NOT: comdat
 
+// MSVC: @"\01?a@A@test1@@2HB" = linkonce_odr constant i32 10, comdat, align 4
+// MSVC: @"\01?i@S@test1@@2HA" = external global i32
+// MSVC: @"\01?x@?$A@H@?A@test2@@2HA" = internal global i32 0, align 4
+
 // CHECK: _ZN5test51U2k0E = global i32 0
 // CHECK: _ZN5test51U2k1E = global i32 0
 // CHECK: _ZN5test51U2k2E = constant i32 76
 // CHECK-NOT: test51U2k3E
 // CHECK-NOT: test51U2k4E
 
+// On Linux in C++14, neither of these are inline.
+// CHECK: @_ZN16inline_constexpr1A10just_constE = available_externally constant i32 42
+// CHECK: @_ZN16inline_constexpr1A10const_exprE = available_externally constant i32 43
+//
+// In MSVC, these are both implicitly inline regardless of the C++ standard
+// version.
+// MSVC: @"\01?just_const@A@inline_constexpr@@2HB" = linkonce_odr constant i32 42, comdat, align 4
+// MSVC: @"\01?const_expr@A@inline_constexpr@@2HB" = linkonce_odr constant i32 43, comdat, align 4
+
 // PR5564.
 namespace test1 {
   struct A {
@@ -28,7 +45,7 @@ namespace test1 {
   };
 
   void f() { 
-    int a = S::i;
+    int a = *&A::a + S::i;
   }
 }
 
@@ -50,6 +67,11 @@ namespace test2 {
   // CHECK:      [[TMP:%.*]] = call i32 @_ZN5test23fooEv()
   // CHECK-NEXT: store i32 [[TMP]], i32* @_ZN5test212_GLOBAL__N_11AIiE1xE, align 4
   // CHECK-NEXT: ret void
+
+  // MSVC-LABEL: define internal void @"\01??__Ex@?$A@H@?A@test2@@2HA@YAXXZ"()
+  // MSVC:      [[TMP:%.*]] = call i32 @"\01?foo@test2@@YAHXZ"()
+  // MSVC-NEXT: store i32 [[TMP]], i32* @"\01?x@?$A@H@?A@test2@@2HA", align 4
+  // MSVC-NEXT: ret void
 }
 
 // Test that we don't use threadsafe statics when initializing
@@ -108,3 +130,13 @@ namespace test5 {
   // CHECK: store i32 {{.*}}, i32* @_ZN5test51U2k1E
   // CHECK-NOT: store {{.*}} i32* @_ZN5test51U2k2E
 }
+
+// Test that MSVC mode static constexpr data members are always inline, even pre
+// C++17.
+namespace inline_constexpr {
+struct A {
+  static const int just_const = 42;
+  static constexpr int const_expr = 43;
+};
+int useit() { return *&A::just_const + *&A::const_expr; }
+}