mehdi_amini updated this revision to Diff 109694.
mehdi_amini marked 12 inline comments as done.
mehdi_amini added a comment.
Address Richard's comment
https://reviews.llvm.org/D34992
Files:
clang/lib/CodeGen/CodeGenModule.cpp
clang/test/CodeGenCXX/cxx11-extern-constexpr.cpp
Index: clang/test/CodeGenCXX/cxx11-extern-constexpr.cpp
===================================================================
--- /dev/null
+++ clang/test/CodeGenCXX/cxx11-extern-constexpr.cpp
@@ -0,0 +1,48 @@
+// 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 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);
+}
Index: clang/lib/CodeGen/CodeGenModule.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenModule.cpp
+++ clang/lib/CodeGen/CodeGenModule.cpp
@@ -2436,6 +2436,22 @@
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 its value to the
+ // optimizer.
+ if (GV->hasExternalLinkage() && isTypeConstant(D->getType(), true) &&
+ !D->hasDefinition() && D->hasInit() &&
+ /* C++17 static constexpr are inlined */ !D->isInline() &&
+ !D->hasAttr<DLLImportAttr>() && D->isInitKnownICE()) {
+ const VarDecl *InitDecl;
+ const Expr *InitExpr = D->getAnyInitializer(InitDecl);
+ if (InitExpr) {
+ GV->setConstant(true);
+ GV->setLinkage(llvm::GlobalValue::AvailableExternallyLinkage);
+ GV->setInitializer(EmitConstantInit(*InitDecl));
+ }
+ }
}
auto ExpectedAS =
Index: clang/test/CodeGenCXX/cxx11-extern-constexpr.cpp
===================================================================
--- /dev/null
+++ clang/test/CodeGenCXX/cxx11-extern-constexpr.cpp
@@ -0,0 +1,48 @@
+// 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 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);
+}
Index: clang/lib/CodeGen/CodeGenModule.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenModule.cpp
+++ clang/lib/CodeGen/CodeGenModule.cpp
@@ -2436,6 +2436,22 @@
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 its value to the
+ // optimizer.
+ if (GV->hasExternalLinkage() && isTypeConstant(D->getType(), true) &&
+ !D->hasDefinition() && D->hasInit() &&
+ /* C++17 static constexpr are inlined */ !D->isInline() &&
+ !D->hasAttr<DLLImportAttr>() && D->isInitKnownICE()) {
+ const VarDecl *InitDecl;
+ const Expr *InitExpr = D->getAnyInitializer(InitDecl);
+ if (InitExpr) {
+ GV->setConstant(true);
+ GV->setLinkage(llvm::GlobalValue::AvailableExternallyLinkage);
+ GV->setInitializer(EmitConstantInit(*InitDecl));
+ }
+ }
}
auto ExpectedAS =
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