r311857 - Emit static constexpr member as available_externally definition
Mehdi AMINI via cfe-commits
cfe-commits at lists.llvm.org
Mon Sep 4 21:04:36 PDT 2017
Hey Hans,
Just a heads up that I fixed the issue and reapplies the commit in r312512.
Let me know if any new issues occur! (and feel free to revert of course).
Thanks,
--
Mehdi
2017-08-28 14:18 GMT-07:00 Mehdi AMINI <joker.eph at gmail.com>:
> Sorry for the inconvenience!
>
> I will follow-up in the PR.
>
> --
> Mehdi
>
>
> 2017-08-28 12:42 GMT-07:00 Hans Wennborg <hans at chromium.org>:
>
>> I reverted this in r311898 as it caused Chromium builds to fail with
>> an assertion; see PR34348.
>>
>> On Sun, Aug 27, 2017 at 1:24 PM, Mehdi Amini via cfe-commits
>> <cfe-commits at lists.llvm.org> wrote:
>> > Author: mehdi_amini
>> > Date: Sun Aug 27 13:24:09 2017
>> > New Revision: 311857
>> >
>> > URL: http://llvm.org/viewvc/llvm-project?rev=311857&view=rev
>> > Log:
>> > Emit static constexpr member as available_externally definition
>> >
>> > By exposing the constant initializer, the optimizer can fold many
>> > of these constructs.
>> >
>> > Differential Revision: https://reviews.llvm.org/D34992
>> >
>> > Added:
>> > cfe/trunk/test/CodeGenCXX/cxx11-extern-constexpr.cpp
>> > Modified:
>> > cfe/trunk/lib/CodeGen/CodeGenModule.cpp
>> >
>> > Modified: cfe/trunk/lib/CodeGen/CodeGenModule.cpp
>> > URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/Co
>> deGenModule.cpp?rev=311857&r1=311856&r2=311857&view=diff
>> > ============================================================
>> ==================
>> > --- cfe/trunk/lib/CodeGen/CodeGenModule.cpp (original)
>> > +++ cfe/trunk/lib/CodeGen/CodeGenModule.cpp Sun Aug 27 13:24:09 2017
>> > @@ -2437,6 +2437,28 @@ CodeGenModule::GetOrCreateLLVMGlobal(Str
>> > D->getType().isConstant(Context) &&
>> > isExternallyVisible(D->getLinkageAndVisibility().getLinkage(
>> )))
>> > GV->setSection(".cp.rodata");
>> > +
>> > + // Check if we a have a const declaration with an initializer, we
>> may be
>> > + // able to emit it as available_externally to expose it's value to
>> the
>> > + // optimizer.
>> > + if (Context.getLangOpts().CPlusPlus && GV->hasExternalLinkage() &&
>> > + D->getType().isConstQualified() && !GV->hasInitializer() &&
>> > + !D->hasDefinition() && D->hasInit() &&
>> !D->hasAttr<DLLImportAttr>()) {
>> > + const auto *Record =
>> > + Context.getBaseElementType(D->getType())->getAsCXXRecordDecl
>> ();
>> > + bool HasMutableFields = Record && Record->hasMutableFields();
>> > + if (!HasMutableFields) {
>> > + const VarDecl *InitDecl;
>> > + const Expr *InitExpr = D->getAnyInitializer(InitDecl);
>> > + if (InitExpr) {
>> > + GV->setConstant(true);
>> > + GV->setLinkage(llvm::GlobalValue::AvailableExternallyLinkage
>> );
>> > + ConstantEmitter emitter(*this);
>> > + GV->setInitializer(emitter.tryEmitForInitializer(*InitDecl))
>> ;
>> > + emitter.finalize(GV);
>> > + }
>> > + }
>> > + }
>> > }
>> >
>> > auto ExpectedAS =
>> >
>> > Added: cfe/trunk/test/CodeGenCXX/cxx11-extern-constexpr.cpp
>> > URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCX
>> X/cxx11-extern-constexpr.cpp?rev=311857&view=auto
>> > ============================================================
>> ==================
>> > --- cfe/trunk/test/CodeGenCXX/cxx11-extern-constexpr.cpp (added)
>> > +++ cfe/trunk/test/CodeGenCXX/cxx11-extern-constexpr.cpp Sun Aug 27
>> 13:24:09 2017
>> > @@ -0,0 +1,55 @@
>> > +// RUN: %clang_cc1 -std=c++11 %s -emit-llvm -o - -triple
>> x86_64-linux-gnu | FileCheck %s --check-prefix=CHECK --check-prefix=CXX11
>> > +// RUN: %clang_cc1 -std=c++1z %s -emit-llvm -o - -triple
>> x86_64-linux-gnu | FileCheck %s --check-prefix=CHECK --check-prefix=CXX17
>> > +
>> > +struct A {
>> > + static const int Foo = 123;
>> > +};
>> > +// CHECK: @_ZN1A3FooE = constant i32 123, align 4
>> > +const int *p = &A::Foo; // emit available_externally
>> > +const int A::Foo; // convert to full definition
>> > +
>> > +struct Bar {
>> > + int b;
>> > +};
>> > +
>> > +struct MutableBar {
>> > + mutable int b;
>> > +};
>> > +
>> > +struct Foo {
>> > + // CXX11: @_ZN3Foo21ConstexprStaticMemberE = available_externally
>> constant i32 42,
>> > + // CXX17: @_ZN3Foo21ConstexprStaticMemberE = linkonce_odr constant
>> i32 42,
>> > + static constexpr int ConstexprStaticMember = 42;
>> > + // CHECK: @_ZN3Foo17ConstStaticMemberE = available_externally
>> constant i32 43,
>> > + static const int ConstStaticMember = 43;
>> > +
>> > + // CXX11: @_ZN3Foo23ConstStaticStructMemberE = available_externally
>> constant %struct.Bar { i32 44 },
>> > + // CXX17: @_ZN3Foo23ConstStaticStructMemberE = linkonce_odr
>> constant %struct.Bar { i32 44 },
>> > + static constexpr Bar ConstStaticStructMember = {44};
>> > +
>> > + // CXX11: @_ZN3Foo34ConstexprStaticMutableStructMemberE = external
>> global %struct.MutableBar,
>> > + // CXX17: @_ZN3Foo34ConstexprStaticMutableStructMemberE =
>> linkonce_odr global %struct.MutableBar { i32 45 },
>> > + static constexpr MutableBar ConstexprStaticMutableStructMember =
>> {45};
>> > +};
>> > +// CHECK: @_ZL15ConstStaticexpr = internal constant i32 46,
>> > +static constexpr int ConstStaticexpr = 46;
>> > +// CHECK: @_ZL9ConstExpr = internal constant i32 46, align 4
>> > +static const int ConstExpr = 46;
>> > +
>> > +// CHECK: @_ZL21ConstexprStaticStruct = internal constant %struct.Bar
>> { i32 47 },
>> > +static constexpr Bar ConstexprStaticStruct = {47};
>> > +
>> > +// CHECK: @_ZL28ConstexprStaticMutableStruct = internal global
>> %struct.MutableBar { i32 48 },
>> > +static constexpr MutableBar ConstexprStaticMutableStruct = {48};
>> > +
>> > +void use(const int &);
>> > +void foo() {
>> > + use(Foo::ConstexprStaticMember);
>> > + use(Foo::ConstStaticMember);
>> > + use(Foo::ConstStaticStructMember.b);
>> > + use(Foo::ConstexprStaticMutableStructMember.b);
>> > + use(ConstStaticexpr);
>> > + use(ConstExpr);
>> > + use(ConstexprStaticStruct.b);
>> > + use(ConstexprStaticMutableStruct.b);
>> > +}
>> >
>> >
>> > _______________________________________________
>> > cfe-commits mailing list
>> > cfe-commits at lists.llvm.org
>> > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
>>
>
>
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