r325375 - [MS] Make constexpr static data members implicitly inline

[Hans Wennborg via cfe-commits]

Merged to 6.0 in r325500.

On Fri, Feb 16, 2018 at 8:44 PM, Reid Kleckner via cfe-commits
<cfe-commits at lists.llvm.org> wrote:
> Author: rnk
> Date: Fri Feb 16 11:44:47 2018
> New Revision: 325375
>
> URL: http://llvm.org/viewvc/llvm-project?rev=325375&view=rev
> Log:
> [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.
>
> Modified:
>     cfe/trunk/lib/AST/ASTContext.cpp
>     cfe/trunk/test/CodeGenCXX/static-data-member.cpp
>
> Modified: cfe/trunk/lib/AST/ASTContext.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ASTContext.cpp?rev=325375&r1=325374&r2=325375&view=diff
> ==============================================================================
> --- cfe/trunk/lib/AST/ASTContext.cpp (original)
> +++ cfe/trunk/lib/AST/ASTContext.cpp Fri Feb 16 11:44:47 2018
> @@ -5857,7 +5857,7 @@ CharUnits ASTContext::getObjCEncodingTyp
>  bool ASTContext::isMSStaticDataMemberInlineDefinition(const VarDecl *VD) const {
>    return getTargetInfo().getCXXABI().isMicrosoft() &&
>           VD->isStaticDataMember() &&
> -         VD->getType()->isIntegralOrEnumerationType() &&
> +         (VD->getType()->isIntegralOrEnumerationType() || VD->isConstexpr()) &&
>           !VD->getFirstDecl()->isOutOfLine() && VD->getFirstDecl()->hasInit();
>  }
>
>
> Modified: cfe/trunk/test/CodeGenCXX/static-data-member.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/static-data-member.cpp?rev=325375&r1=325374&r2=325375&view=diff
> ==============================================================================
> --- cfe/trunk/test/CodeGenCXX/static-data-member.cpp (original)
> +++ cfe/trunk/test/CodeGenCXX/static-data-member.cpp Fri Feb 16 11:44:47 2018
> @@ -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 at A@test1@@2HB" = linkonce_odr constant i32 10, comdat, align 4
> +// MSVC: @"\01?i at S@test1@@2HA" = external global i32
> +// MSVC: @"\01?x@?$A at H@?A at test2@@2HA" = internal global i32 0, align 4
> +
>  // CHECK: _ZN5test51U2k0E = global i32 0
>  // CHECK: _ZN5test51U2k1E = global i32 0
>  // CHECK: _ZN5test51U2k2E = constant i32 76
>  // CHECK-NOT: test51U2k3E
>  // CHECK-NOT: test51U2k4E
>
> +// On Linux in C++14, neither of these are inline.
> +// CHECK: @_ZN16inline_constexpr1A10just_constE = available_externally constant i32 42
> +// CHECK: @_ZN16inline_constexpr1A10const_exprE = available_externally constant i32 43
> +//
> +// In MSVC, these are both implicitly inline regardless of the C++ standard
> +// version.
> +// MSVC: @"\01?just_const at A@inline_constexpr@@2HB" = linkonce_odr constant i32 42, comdat, align 4
> +// MSVC: @"\01?const_expr at A@inline_constexpr@@2HB" = linkonce_odr constant i32 43, comdat, align 4
> +
>  // PR5564.
>  namespace test1 {
>    struct A {
> @@ -28,7 +45,7 @@ namespace test1 {
>    };
>
>    void f() {
> -    int a = S::i;
> +    int a = *&A::a + S::i;
>    }
>  }
>
> @@ -50,6 +67,11 @@ namespace test2 {
>    // CHECK:      [[TMP:%.*]] = call i32 @_ZN5test23fooEv()
>    // CHECK-NEXT: store i32 [[TMP]], i32* @_ZN5test212_GLOBAL__N_11AIiE1xE, align 4
>    // CHECK-NEXT: ret void
> +
> +  // MSVC-LABEL: define internal void @"\01??__Ex@?$A at H@?A at test2@@2HA at YAXXZ"()
> +  // MSVC:      [[TMP:%.*]] = call i32 @"\01?foo at test2@@YAHXZ"()
> +  // MSVC-NEXT: store i32 [[TMP]], i32* @"\01?x@?$A at H@?A at 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; }
> +}
>
>
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