[clang] Add a "don't override" mapping for -fvisibility-from-dllstorageclass (PR #74629)
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Wed Dec 6 09:20:02 PST 2023
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang-driver
@llvm/pr-subscribers-clang-codegen
Author: bd1976bris (bd1976bris)
<details>
<summary>Changes</summary>
`-fvisibility-from-dllstorageclass` allows for overriding the visibility of globals from their DLL storage class. The visibility to apply can be customised for the different classes of globals via a set of dependent options that specify the mapping values:
- `-fvisibility-dllexport=<value>`
- `-fvisibility-nodllstorageclass=<value>`
- `-fvisibility-externs-dllimport=<value>`
- `-fvisibility-externs-nodllstorageclass=<value>`
Currently, one of the existing LLVM visibilities, `hidden`, `protected`, `default`, can be used as a mapping value. This change adds a new mapping value: `keep`, which specifies that the visibility should not be overridden for that class of globals. The behaviour of `-fvisibility-from-dllstorageclass` is otherwise unchanged and existing uses of this set of options will be unaffected.
The background to this change is that currently the PS4 and PS5 compilers effectively ignore visibility - dllimport/export is the supported method for export control in C/C++ source code. Now, we would like to support visibility attributes and options in our frontend, in addition to dllimport/export. To support this, we will override the visibility of globals with explicit dllimport/export annotations but use the `keep` setting for globals which do not have an explicit dllimport/export.
There are also some minor improvements to the existing options:
- Make the `LANGOPS` `BENIGN` as they don't involve the AST.
- Correct/clarify the help text for the options.
---
Full diff: https://github.com/llvm/llvm-project/pull/74629.diff
6 Files Affected:
- (modified) clang/include/clang/Basic/LangOptions.def (+10-10)
- (modified) clang/include/clang/Basic/LangOptions.h (+11)
- (modified) clang/include/clang/Driver/Options.td (+14-9)
- (modified) clang/lib/CodeGen/CodeGenModule.cpp (+54-27)
- (modified) clang/test/CodeGenCXX/visibility-dllstorageclass.cpp (+26-2)
- (modified) clang/test/Driver/visibility-dllstorageclass.c (+33-1)
``````````diff
diff --git a/clang/include/clang/Basic/LangOptions.def b/clang/include/clang/Basic/LangOptions.def
index c3d5399905a3f..1ebe33f7151e8 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -357,16 +357,16 @@ BENIGN_ENUM_LANGOPT(TypeVisibilityMode, Visibility, 3, DefaultVisibility,
"default visibility for types [-ftype-visibility]")
LANGOPT(SetVisibilityForExternDecls, 1, 0,
"apply global symbol visibility to external declarations without an explicit visibility")
-LANGOPT(VisibilityFromDLLStorageClass, 1, 0,
- "set the visiblity of globals from their DLL storage class [-fvisibility-from-dllstorageclass]")
-ENUM_LANGOPT(DLLExportVisibility, Visibility, 3, DefaultVisibility,
- "visibility for functions and variables with dllexport annotations [-fvisibility-from-dllstorageclass]")
-ENUM_LANGOPT(NoDLLStorageClassVisibility, Visibility, 3, HiddenVisibility,
- "visibility for functions and variables without an explicit DLL storage class [-fvisibility-from-dllstorageclass]")
-ENUM_LANGOPT(ExternDeclDLLImportVisibility, Visibility, 3, DefaultVisibility,
- "visibility for external declarations with dllimport annotations [-fvisibility-from-dllstorageclass]")
-ENUM_LANGOPT(ExternDeclNoDLLStorageClassVisibility, Visibility, 3, HiddenVisibility,
- "visibility for external declarations without an explicit DLL storage class [-fvisibility-from-dllstorageclass]")
+BENIGN_LANGOPT(VisibilityFromDLLStorageClass, 1, 0,
+ "override the visibility of globals based on their final DLL storage class [-fvisibility-from-dllstorageclass]")
+BENIGN_ENUM_LANGOPT(DLLExportVisibility, VisibilityFromDLLStorageClassKinds, 3, VisibilityFromDLLStorageClassKinds::Default,
+ "how to adjust the visibility for functions and variables with dllexport annotations [-fvisibility-dllexport]")
+BENIGN_ENUM_LANGOPT(NoDLLStorageClassVisibility, VisibilityFromDLLStorageClassKinds, 3, VisibilityFromDLLStorageClassKinds::Hidden,
+ "how to adjust the visibility for functions and variables without an explicit DLL storage class [-fvisibility-nodllstorageclass]")
+BENIGN_ENUM_LANGOPT(ExternDeclDLLImportVisibility, VisibilityFromDLLStorageClassKinds, 3, VisibilityFromDLLStorageClassKinds::Default,
+ "how to adjust the visibility for external declarations with dllimport annotations [-fvisibility-externs-dllimport]")
+BENIGN_ENUM_LANGOPT(ExternDeclNoDLLStorageClassVisibility, VisibilityFromDLLStorageClassKinds, 3, VisibilityFromDLLStorageClassKinds::Hidden,
+ "how to adjust the visibility for external declarations without an explicit DLL storage class [-fvisibility-externs-nodllstorageclass]")
BENIGN_LANGOPT(SemanticInterposition , 1, 0, "semantic interposition")
BENIGN_LANGOPT(HalfNoSemanticInterposition, 1, 0,
"Like -fno-semantic-interposition but don't use local aliases")
diff --git a/clang/include/clang/Basic/LangOptions.h b/clang/include/clang/Basic/LangOptions.h
index 2d167dd2bdf12..5688aae0fd23c 100644
--- a/clang/include/clang/Basic/LangOptions.h
+++ b/clang/include/clang/Basic/LangOptions.h
@@ -380,6 +380,17 @@ class LangOptions : public LangOptionsBase {
All,
};
+ enum class VisibilityFromDLLStorageClassKinds {
+ /// Keep the IR-gen assigned visibility.
+ Keep,
+ /// Override the IR-gen assigned visibility with default visibility.
+ Default,
+ /// Override the IR-gen assigned visibility with hidden visibility.
+ Hidden,
+ /// Override the IR-gen assigned visibility with protected visibility.
+ Protected,
+ };
+
enum class StrictFlexArraysLevelKind {
/// Any trailing array member is a FAM.
Default = 0,
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index db2190318c931..0400e93528564 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -3821,27 +3821,32 @@ def dA : Flag<["-"], "dA">, Alias<fverbose_asm>;
defm visibility_from_dllstorageclass : BoolFOption<"visibility-from-dllstorageclass",
LangOpts<"VisibilityFromDLLStorageClass">, DefaultFalse,
PosFlag<SetTrue, [], [ClangOption, CC1Option],
- "Set the visibility of symbols in the generated code from their DLL storage class">,
+ "Override the visibility of globals based on their final DLL storage class.s">,
NegFlag<SetFalse>>;
+class MarshallingInfoVisibilityFromDLLStorage<KeyPathAndMacro kpm, code default>
+ : MarshallingInfoEnum<kpm, default>,
+ Values<"keep,hidden,protected,default">,
+ NormalizedValuesScope<"LangOptions::VisibilityFromDLLStorageClassKinds">,
+ NormalizedValues<["Keep", "Hidden", "Protected", "Default"]> {}
def fvisibility_dllexport_EQ : Joined<["-"], "fvisibility-dllexport=">, Group<f_Group>,
Visibility<[ClangOption, CC1Option]>,
- HelpText<"The visibility for dllexport definitions [-fvisibility-from-dllstorageclass]">,
- MarshallingInfoVisibility<LangOpts<"DLLExportVisibility">, "DefaultVisibility">,
+ HelpText<"The visibility for dllexport definitions. If Keep is specified the visibility is not adjusted [-fvisibility-from-dllstorageclass]">,
+ MarshallingInfoVisibilityFromDLLStorage<LangOpts<"DLLExportVisibility">, "Default">,
ShouldParseIf<fvisibility_from_dllstorageclass.KeyPath>;
def fvisibility_nodllstorageclass_EQ : Joined<["-"], "fvisibility-nodllstorageclass=">, Group<f_Group>,
Visibility<[ClangOption, CC1Option]>,
- HelpText<"The visibility for definitions without an explicit DLL export class [-fvisibility-from-dllstorageclass]">,
- MarshallingInfoVisibility<LangOpts<"NoDLLStorageClassVisibility">, "HiddenVisibility">,
+ HelpText<"The visibility for definitions without an explicit DLL storage class. If Keep is specified the visibility is not adjusted [-fvisibility-from-dllstorageclass]">,
+ MarshallingInfoVisibilityFromDLLStorage<LangOpts<"NoDLLStorageClassVisibility">, "Hidden">,
ShouldParseIf<fvisibility_from_dllstorageclass.KeyPath>;
def fvisibility_externs_dllimport_EQ : Joined<["-"], "fvisibility-externs-dllimport=">, Group<f_Group>,
Visibility<[ClangOption, CC1Option]>,
- HelpText<"The visibility for dllimport external declarations [-fvisibility-from-dllstorageclass]">,
- MarshallingInfoVisibility<LangOpts<"ExternDeclDLLImportVisibility">, "DefaultVisibility">,
+ HelpText<"The visibility for dllimport external declarations. If Keep is specified the visibility is not adjusted [-fvisibility-from-dllstorageclass]">,
+ MarshallingInfoVisibilityFromDLLStorage<LangOpts<"ExternDeclDLLImportVisibility">, "Default">,
ShouldParseIf<fvisibility_from_dllstorageclass.KeyPath>;
def fvisibility_externs_nodllstorageclass_EQ : Joined<["-"], "fvisibility-externs-nodllstorageclass=">, Group<f_Group>,
Visibility<[ClangOption, CC1Option]>,
- HelpText<"The visibility for external declarations without an explicit DLL dllstorageclass [-fvisibility-from-dllstorageclass]">,
- MarshallingInfoVisibility<LangOpts<"ExternDeclNoDLLStorageClassVisibility">, "HiddenVisibility">,
+ HelpText<"The visibility for external declarations without an explicit DLL storage class. If Keep is specified the visibility is not adjusted [-fvisibility-from-dllstorageclass]">,
+ MarshallingInfoVisibilityFromDLLStorage<LangOpts<"ExternDeclNoDLLStorageClassVisibility">, "Hidden">,
ShouldParseIf<fvisibility_from_dllstorageclass.KeyPath>;
def fvisibility_EQ : Joined<["-"], "fvisibility=">, Group<f_Group>,
Visibility<[ClangOption, CC1Option]>,
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index dea58a7ff4146..6c573853bc9a3 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -721,43 +721,70 @@ void InstrProfStats::reportDiagnostics(DiagnosticsEngine &Diags,
}
}
+static std::optional<llvm::GlobalValue::VisibilityTypes>
+getLLVMVisibility(clang::LangOptions::VisibilityFromDLLStorageClassKinds K) {
+ // Map to LLVM visibility.
+ switch (K) {
+ case clang::LangOptions::VisibilityFromDLLStorageClassKinds::Keep:
+ return std::nullopt;
+ case clang::LangOptions::VisibilityFromDLLStorageClassKinds::Default:
+ return llvm::GlobalValue::DefaultVisibility;
+ case clang::LangOptions::VisibilityFromDLLStorageClassKinds::Hidden:
+ return llvm::GlobalValue::HiddenVisibility;
+ case clang::LangOptions::VisibilityFromDLLStorageClassKinds::Protected:
+ return llvm::GlobalValue::ProtectedVisibility;
+ }
+ llvm_unreachable("unknown option value!");
+}
+
+void setLLVMVisibility(llvm::GlobalValue &GV,
+ std::optional<llvm::GlobalValue::VisibilityTypes> V) {
+ if (!V)
+ return;
+
+ // Reset DSO locality before setting the visibility. This removes
+ // any effects that visibility options and annotations may have
+ // had on the DSO locality. Setting the visibility will implicitly set
+ // appropriate globals to DSO Local; however, this will be pessimistic
+ // w.r.t. to the normal compiler IRGen.
+ GV.setDSOLocal(false);
+ GV.setVisibility(*V);
+}
+
static void setVisibilityFromDLLStorageClass(const clang::LangOptions &LO,
llvm::Module &M) {
if (!LO.VisibilityFromDLLStorageClass)
return;
- llvm::GlobalValue::VisibilityTypes DLLExportVisibility =
- CodeGenModule::GetLLVMVisibility(LO.getDLLExportVisibility());
- llvm::GlobalValue::VisibilityTypes NoDLLStorageClassVisibility =
- CodeGenModule::GetLLVMVisibility(LO.getNoDLLStorageClassVisibility());
- llvm::GlobalValue::VisibilityTypes ExternDeclDLLImportVisibility =
- CodeGenModule::GetLLVMVisibility(LO.getExternDeclDLLImportVisibility());
- llvm::GlobalValue::VisibilityTypes ExternDeclNoDLLStorageClassVisibility =
- CodeGenModule::GetLLVMVisibility(
- LO.getExternDeclNoDLLStorageClassVisibility());
+ std::optional<llvm::GlobalValue::VisibilityTypes> DLLExportVisibility =
+ getLLVMVisibility(LO.getDLLExportVisibility());
+
+ std::optional<llvm::GlobalValue::VisibilityTypes>
+ NoDLLStorageClassVisibility =
+ getLLVMVisibility(LO.getNoDLLStorageClassVisibility());
+
+ std::optional<llvm::GlobalValue::VisibilityTypes>
+ ExternDeclDLLImportVisibility =
+ getLLVMVisibility(LO.getExternDeclDLLImportVisibility());
+
+ std::optional<llvm::GlobalValue::VisibilityTypes>
+ ExternDeclNoDLLStorageClassVisibility =
+ getLLVMVisibility(LO.getExternDeclNoDLLStorageClassVisibility());
for (llvm::GlobalValue &GV : M.global_values()) {
if (GV.hasAppendingLinkage() || GV.hasLocalLinkage())
continue;
- // Reset DSO locality before setting the visibility. This removes
- // any effects that visibility options and annotations may have
- // had on the DSO locality. Setting the visibility will implicitly set
- // appropriate globals to DSO Local; however, this will be pessimistic
- // w.r.t. to the normal compiler IRGen.
- GV.setDSOLocal(false);
-
- if (GV.isDeclarationForLinker()) {
- GV.setVisibility(GV.getDLLStorageClass() ==
- llvm::GlobalValue::DLLImportStorageClass
- ? ExternDeclDLLImportVisibility
- : ExternDeclNoDLLStorageClassVisibility);
- } else {
- GV.setVisibility(GV.getDLLStorageClass() ==
- llvm::GlobalValue::DLLExportStorageClass
- ? DLLExportVisibility
- : NoDLLStorageClassVisibility);
- }
+ if (GV.isDeclarationForLinker())
+ setLLVMVisibility(GV, GV.getDLLStorageClass() ==
+ llvm::GlobalValue::DLLImportStorageClass
+ ? ExternDeclDLLImportVisibility
+ : ExternDeclNoDLLStorageClassVisibility);
+ else
+ setLLVMVisibility(GV, GV.getDLLStorageClass() ==
+ llvm::GlobalValue::DLLExportStorageClass
+ ? DLLExportVisibility
+ : NoDLLStorageClassVisibility);
GV.setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass);
}
diff --git a/clang/test/CodeGenCXX/visibility-dllstorageclass.cpp b/clang/test/CodeGenCXX/visibility-dllstorageclass.cpp
index 6520e7039728e..9f10a016ed90d 100644
--- a/clang/test/CodeGenCXX/visibility-dllstorageclass.cpp
+++ b/clang/test/CodeGenCXX/visibility-dllstorageclass.cpp
@@ -1,7 +1,7 @@
// REQUIRES: x86-registered-target
-// Test that -fvisibility-from-dllstorageclass maps DLL storage class to visibility
-// and that it overrides the effect of visibility options and annotations.
+//// Test that -fvisibility-from-dllstorageclass maps DLL storage class to visibility
+//// and that it overrides the effect of visibility options and annotations.
// RUN: %clang_cc1 -triple x86_64-unknown-windows-itanium -fdeclspec \
// RUN: -fvisibility=hidden \
@@ -32,12 +32,23 @@
// RUN: -x c++ %s -S -emit-llvm -o - | \
// RUN: FileCheck %s --check-prefixes=ALL_DEFAULT
+// RUN: %clang_cc1 -triple x86_64-unknown-windows-itanium -fdeclspec \
+// RUN: -fvisibility=hidden \
+// RUN: -fapply-global-visibility-to-externs \
+// RUN: -fvisibility-from-dllstorageclass \
+// RUN: -fvisibility-dllexport=protected \
+// RUN: -fvisibility-nodllstorageclass=keep \
+// RUN: -fvisibility-externs-dllimport=default \
+// RUN: -fvisibility-externs-nodllstorageclass=keep \
+// RUN: -x c++ %s -S -emit-llvm -o - | tee %t.log | \
+// RUN: FileCheck %s --check-prefixes=ALL_KEEP
// Local
static void l() {}
void use_locals(){l();}
// DEFAULTS-DAG: define internal void @_ZL1lv()
// EXPLICIT-DAG: define internal void @_ZL1lv()
// ALL_DEFAULT-DAG: define internal void @_ZL1lv()
+// ALL_KEEP-DAG: define internal void @_ZL1lv()
// Function
void f() {}
@@ -48,6 +59,8 @@ void __declspec(dllexport) exported_f() {}
// EXPLICIT-DAG: define hidden void @_Z10exported_fv()
// ALL_DEFAULT-DAG: define void @_Z1fv()
// ALL_DEFAULT-DAG: define void @_Z10exported_fv()
+// ALL_KEEP-DAG: define hidden void @_Z1fv()
+// ALL_KEEP-DAG: define protected void @_Z10exported_fv()
// Variable
int d = 123;
@@ -58,6 +71,8 @@ __declspec(dllexport) int exported_d = 123;
// EXPLICIT-DAG: @exported_d = hidden global
// ALL_DEFAULT-DAG: @d = global
// ALL_DEFAULT-DAG: @exported_d = global
+// ALL_KEEP-DAG: @d = hidden global
+// ALL_KEEP-DAG: @exported_d = protected global
// Alias
extern "C" void aliased() {}
@@ -69,6 +84,8 @@ void __declspec(dllexport) a_exported() __attribute__((alias("aliased")));
// EXPLICIT-DAG: @_Z10a_exportedv = hidden alias
// ALL_DEFAULT-DAG: @_Z1av = alias
// ALL_DEFAULT-DAG: @_Z10a_exportedv = alias
+// ALL_KEEP-DAG: @_Z1av = hidden alias
+// ALL_KEEP-DAG: @_Z10a_exportedv = protected alias
// Declaration
extern void e();
@@ -79,6 +96,8 @@ extern void __declspec(dllimport) imported_e();
// EXPLICIT-DAG: declare hidden void @_Z10imported_ev()
// ALL_DEFAULT-DAG: declare void @_Z1ev()
// ALL_DEFAULT-DAG: declare void @_Z10imported_ev()
+// ALL_KEEP-DAG: declare hidden void @_Z1ev()
+// ALL_KEEP-DAG: void @_Z10imported_ev()
// Weak Declaration
__attribute__((weak))
@@ -91,6 +110,8 @@ extern void __declspec(dllimport) imported_w();
// EXPLICIT-DAG: declare extern_weak hidden void @_Z10imported_wv()
// ALL_DEFAULT-DAG: declare extern_weak void @_Z1wv()
// ALL_DEFAULT-DAG: declare extern_weak void @_Z10imported_wv()
+// ALL_KEEP-DAG: declare extern_weak hidden void @_Z1wv()
+// ALL_KEEP-DAG: declare extern_weak void @_Z10imported_wv()
void use_declarations(){e(); imported_e(); w(); imported_w();}
@@ -101,11 +122,14 @@ struct __attribute__((type_visibility("protected"))) t {
};
void t::foo() {}
// DEFAULTS-DAG: @_ZTV1t = hidden unnamed_addr constant
+// ALL_KEEP-DAG: @_ZTV1t = protected unnamed_addr constant
int v __attribute__ ((__visibility__ ("protected"))) = 123;
// DEFAULTS-DAG: @v = hidden global
+// ALL_KEEP-DAG: @v = protected global
#pragma GCC visibility push(protected)
int p = 345;
#pragma GCC visibility pop
// DEFAULTS-DAG: @p = hidden global
+// ALL_KEEP-DAG: @p = protected global
diff --git a/clang/test/Driver/visibility-dllstorageclass.c b/clang/test/Driver/visibility-dllstorageclass.c
index 1e495f694a5a5..65d13d348cc97 100644
--- a/clang/test/Driver/visibility-dllstorageclass.c
+++ b/clang/test/Driver/visibility-dllstorageclass.c
@@ -1,4 +1,4 @@
-// Check behaviour of -fvisibility-from-dllstorageclass options
+//// Check behaviour of -fvisibility-from-dllstorageclass options
// RUN: %clang -target x86_64-unknown-windows-itanium -fdeclspec \
// RUN: -Werror -S -### %s 2>&1 | \
@@ -85,3 +85,35 @@
// ALL-SAME: "-fvisibility-nodllstorageclass=protected"
// ALL-SAME: "-fvisibility-externs-dllimport=hidden"
// ALL-SAME: "-fvisibility-externs-nodllstorageclass=protected"
+
+//// Test that "keep" can be specified, which means that the visibility of
+//// the matching globals will not be adjusted.
+
+// RUN: %clang -target x86_64-unknown-windows-itanium -fdeclspec \
+// RUN: -fvisibility-from-dllstorageclass \
+// RUN: -fvisibility-dllexport=keep \
+// RUN: -fvisibility-nodllstorageclass=keep \
+// RUN: -fvisibility-externs-dllimport=keep \
+// RUN: -fvisibility-externs-nodllstorageclass=keep \
+// RUN: -Werror -S -### %s 2>&1 | \
+// RUN: FileCheck %s --check-prefixes=KEEP
+
+// KEEP: "-fvisibility-from-dllstorageclass"
+// KEEP-SAME: "-fvisibility-dllexport=keep"
+// KEEP-SAME: "-fvisibility-nodllstorageclass=keep"
+// KEEP-SAME: "-fvisibility-externs-dllimport=keep"
+// KEEP-SAME: "-fvisibility-externs-nodllstorageclass=keep"
+
+// RUN: %clang -target x86_64-unknown-windows-itanium -fdeclspec \
+// RUN: -fvisibility-from-dllstorageclass \
+// RUN: -fvisibility-dllexport=default \
+// RUN: -fvisibility-dllexport=keep \
+// RUN: -fvisibility-nodllstorageclass=default \
+// RUN: -fvisibility-nodllstorageclass=keep \
+// RUN: -fvisibility-externs-dllimport=default \
+// RUN: -fvisibility-externs-dllimport=keep \
+// RUN: -fvisibility-externs-nodllstorageclass=default \
+// RUN: -fvisibility-externs-nodllstorageclass=keep \
+// RUN: -Werror -S -### %s 2>&1 | \
+// RUN: FileCheck %s --check-prefixes=KEEP
+
``````````
</details>
https://github.com/llvm/llvm-project/pull/74629
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