eandrews updated this revision to Diff 116581.
eandrews added a comment.
I've modified the patch to emit a warning for re-declarations only. I also
removed the isUsed check.
https://reviews.llvm.org/D36487
Files:
include/clang/Basic/DiagnosticSemaKinds.td
lib/CodeGen/CodeGenModule.cpp
lib/Sema/SemaDecl.cpp
test/CodeGenCXX/extern-section-attribute.cpp
test/Sema/attr-section.c
Index: test/Sema/attr-section.c
===================================================================
--- test/Sema/attr-section.c
+++ test/Sema/attr-section.c
@@ -19,3 +19,7 @@
void __attribute__((section("bar,zed"))) test2(void) {} // expected-warning
{{section does not match previous declaration}}
enum __attribute__((section("NEAR,x"))) e { one }; // expected-error
{{'section' attribute only applies to functions, methods, properties, and
global variables}}
+
+extern int a; // expected-note {{previous declaration is here}}
+int *b = &a;
+extern int a __attribute__((section("foo,zed"))); // expected-warning
{{section attribute is specified on redeclared variable}}
Index: test/CodeGenCXX/extern-section-attribute.cpp
===================================================================
--- /dev/null
+++ test/CodeGenCXX/extern-section-attribute.cpp
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -emit-llvm %s -o - -triple=x86_64-pc-linux-gnu | FileCheck
%s
+
+extern int aa __attribute__((section(".sdata")));
+// CHECK-DAG: @aa = external global i32, section ".sdata", align 4
+
+extern int bb __attribute__((section(".sdata"))) = 1;
+// CHECK-DAG: @bb = global i32 1, section ".sdata", align 4
+
+int foo() {
+ return aa + bb;
+}
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -2607,6 +2607,16 @@
}
}
+ // This redeclaration adds a section attribute.
+ if (New->hasAttr<SectionAttr>() && !Old->hasAttr<SectionAttr>()) {
+ if (auto *VD = dyn_cast<VarDecl>(New)) {
+ if (VD->isThisDeclarationADefinition() != VarDecl::Definition) {
+ Diag(New->getLocation(),
diag::warn_attribute_section_on_redeclaration);
+ Diag(Old->getLocation(), diag::note_previous_declaration);
+ }
+ }
+ }
+
if (!Old->hasAttrs())
return;
Index: lib/CodeGen/CodeGenModule.cpp
===================================================================
--- lib/CodeGen/CodeGenModule.cpp
+++ lib/CodeGen/CodeGenModule.cpp
@@ -2436,6 +2436,12 @@
EmitGlobalVarDefinition(D);
}
+ // Emit section information for extern variables.
+ if (D->hasExternalStorage()) {
+ if (const SectionAttr *SA = D->getAttr<SectionAttr>())
+ GV->setSection(SA->getName());
+ }
+
// Handle XCore specific ABI requirements.
if (getTriple().getArch() == llvm::Triple::xcore &&
D->getLanguageLinkage() == CLanguageLinkage &&
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -2620,6 +2620,8 @@
"argument to 'section' attribute is not valid for this target: %0">;
def warn_mismatched_section : Warning<
"section does not match previous declaration">, InGroup<Section>;
+def warn_attribute_section_on_redeclaration : Warning<
+ "section attribute is specified on redeclared variable">, InGroup<Section>;
def err_anonymous_property: Error<
"anonymous property is not supported">;
Index: test/Sema/attr-section.c
===================================================================
--- test/Sema/attr-section.c
+++ test/Sema/attr-section.c
@@ -19,3 +19,7 @@
void __attribute__((section("bar,zed"))) test2(void) {} // expected-warning {{section does not match previous declaration}}
enum __attribute__((section("NEAR,x"))) e { one }; // expected-error {{'section' attribute only applies to functions, methods, properties, and global variables}}
+
+extern int a; // expected-note {{previous declaration is here}}
+int *b = &a;
+extern int a __attribute__((section("foo,zed"))); // expected-warning {{section attribute is specified on redeclared variable}}
Index: test/CodeGenCXX/extern-section-attribute.cpp
===================================================================
--- /dev/null
+++ test/CodeGenCXX/extern-section-attribute.cpp
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -emit-llvm %s -o - -triple=x86_64-pc-linux-gnu | FileCheck %s
+
+extern int aa __attribute__((section(".sdata")));
+// CHECK-DAG: @aa = external global i32, section ".sdata", align 4
+
+extern int bb __attribute__((section(".sdata"))) = 1;
+// CHECK-DAG: @bb = global i32 1, section ".sdata", align 4
+
+int foo() {
+ return aa + bb;
+}
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -2607,6 +2607,16 @@
}
}
+ // This redeclaration adds a section attribute.
+ if (New->hasAttr<SectionAttr>() && !Old->hasAttr<SectionAttr>()) {
+ if (auto *VD = dyn_cast<VarDecl>(New)) {
+ if (VD->isThisDeclarationADefinition() != VarDecl::Definition) {
+ Diag(New->getLocation(), diag::warn_attribute_section_on_redeclaration);
+ Diag(Old->getLocation(), diag::note_previous_declaration);
+ }
+ }
+ }
+
if (!Old->hasAttrs())
return;
Index: lib/CodeGen/CodeGenModule.cpp
===================================================================
--- lib/CodeGen/CodeGenModule.cpp
+++ lib/CodeGen/CodeGenModule.cpp
@@ -2436,6 +2436,12 @@
EmitGlobalVarDefinition(D);
}
+ // Emit section information for extern variables.
+ if (D->hasExternalStorage()) {
+ if (const SectionAttr *SA = D->getAttr<SectionAttr>())
+ GV->setSection(SA->getName());
+ }
+
// Handle XCore specific ABI requirements.
if (getTriple().getArch() == llvm::Triple::xcore &&
D->getLanguageLinkage() == CLanguageLinkage &&
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -2620,6 +2620,8 @@
"argument to 'section' attribute is not valid for this target: %0">;
def warn_mismatched_section : Warning<
"section does not match previous declaration">, InGroup<Section>;
+def warn_attribute_section_on_redeclaration : Warning<
+ "section attribute is specified on redeclared variable">, InGroup<Section>;
def err_anonymous_property: Error<
"anonymous property is not supported">;
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