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

[Hans Wennborg via cfe-commits]

Reverted in r325576 due to PR36453, and merged the revert to 6.0 in r325577.

On Mon, Feb 19, 2018 at 3:09 PM, Hans Wennborg <hans at chromium.org> wrote:
> 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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