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In IBM compiler Xlclang , there is option -fnovisibiilty. The option is
description as
https://www.ibm.com/support/knowledgecenter/SSGH3R_16.1.0/com.ibm.xlcpp161.aix.doc/compiler_ref/opt_visibility.html
we need to add the option -fnovisibiilty for clang in the IBM AIX OS(and the
option is enabled by default in AIX OS).
I will implement the option in the other OS platform.(but the option is
disabled by default in other OS).
For example, the file test.c
bash-4.2$ test.c
__attribute__((visibility ("protected"))) int b;
1 In AIX OS:
1.1 Compiled with
clang -fnovisibility -target powerpc-unknown-aix -emit-llvm -S test.c
or
clang -target powerpc-unknown-aix -emit-llvm -S test.c ( the
-fnovisibility is enabled by default in AIX OS)
Generate IR as :
@b = global i32 0, align 4
1.2 Compiled with
(If have "-fnovisibility -fvisibility=*" at the same time. the compile will
ignore the -fnovisibility).
clang -fnovisibility -fvisibility=default -target powerpc-unknown-aix
-emit-llvm -S test.c
Or
clang -fvisibility=default -target powerpc-unknown-aix -emit-llvm -S
test.c
Generate IR as :
@b = protected global i32 0, align 4
2. In Other OS(not AIX) 2.1 clang -fnovisibility -target
powerpc-unknown-linux -emit-llvm -S test.c
Generate IR as : @b = global i32 0, align 4
2.2 clang -target powerpc-unknown-linux -emit-llvm -S test.c ( the
-fnovisibility is disabled by default in not AIX OS) Or (if have
"-fnovisibility -fvisibility=*" at the same time. the compile will ignore the
-fnovisibility). clang -fnovisibility -fvisibility=default -target
powerpc-unknown-linux -emit-llvm -S test.c Or clang -fvisibility=default
-target powerpc-unknown-linux -emit-llvm -S test.c
Generate IR as : @b = protected global i32 0, align 4
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D87451
Files:
clang/docs/ClangCommandLineReference.rst
clang/include/clang/Basic/LangOptions.def
clang/include/clang/Driver/Options.td
clang/lib/AST/Decl.cpp
clang/lib/Driver/ToolChains/Clang.cpp
clang/lib/Frontend/CompilerInvocation.cpp
clang/test/Driver/fnovisibility.cpp
Index: clang/test/Driver/fnovisibility.cpp
===================================================================
--- /dev/null
+++ clang/test/Driver/fnovisibility.cpp
@@ -0,0 +1,69 @@
+// RUN: %clang -target powerpc-unknown-aix -emit-llvm -o - -S %s |\
+// RUN: FileCheck --check-prefixes=NOVISIBILITY,AIX-NOVISIBILITY %s
+
+// RUN: %clang -fnovisibility -target powerpc-unknown-aix -emit-llvm -o - -S %s | \
+// RUN: FileCheck -check-prefixes=NOVISIBILITY,AIX-NOVISIBILITY %s
+
+// RUN: %clang -fnovisibility -target powerpc-unknown-linux -emit-llvm -o - -S %s | \
+// RUN: FileCheck -check-prefixes=NOVISIBILITY,LINUX-NOVISIBILITY %s
+
+// RUN: %clang -fnovisibility -fvisibility=default -target powerpc-unknown-aix -emit-llvm -o - -S %s | \
+// RUN: FileCheck -check-prefix=VISIBILITY %s
+
+// RUN: %clang -target powerpc-unknown-linux -emit-llvm -o - -S %s | \
+// RUN: FileCheck -check-prefix=VISIBILITY %s
+
+// RUN: %clang -fnovisibility -fvisibility=default -target powerpc-unknown-linux -emit-llvm -o - -S %s | \
+// RUN: FileCheck -check-prefix=VISIBILITY %s
+
+__attribute__((visibility("hidden"))) void foo_h(int *p) {
+ (*p)++;
+}
+
+__attribute__((visibility("protected"))) int b;
+
+extern __attribute__((visibility("hidden"))) void zoo_extern_h(void);
+
+void (*foo_p)(void) = zoo_extern_h;
+
+__attribute__((visibility("protected"))) void bar() {
+ foo_h(&b);
+ foo_p();
+}
+
+class TestClass {
+public:
+ __attribute__((__visibility__("hidden"))) int value() const noexcept { return 0; }
+};
+
+int main() {
+ TestClass TC;
+ return TC.value();
+}
+
+template <class T>
+class basic {
+public:
+ __attribute__((__visibility__("protected"))) int getdata() { return 1; }
+};
+
+template class basic<int>;
+
+// AIX-NOVISIBILITY: @b = global i32 0
+// LINUX-NOVISIBILITY: @b = dso_local global i32 0
+// AIX-NOVISIBILITY: define void @_Z5foo_hPi(i32* %p)
+// LINUX-NOVISIBILITY: define dso_local void @_Z5foo_hPi(i32* %p)
+// NOVISIBILITY: declare void @_Z12zoo_extern_hv()
+// AIX-NOVISIBILITY: define void @_Z3barv()
+// LINUX-NOVISIBILITY: define dso_local void @_Z3barv()
+// AIX-NOVISIBILITY: define linkonce_odr i32 @_ZNK9TestClass5valueEv(%class.TestClass* %this)
+// LINUX-NOVISIBILITY: define linkonce_odr dso_local i32 @_ZNK9TestClass5valueEv(%class.TestClass* %this)
+// AIX-NOVISIBILITY: define weak_odr i32 @_ZN5basicIiE7getdataEv(%class.basic* %this)
+// LINUX-NOVISIBILITY: define weak_odr dso_local i32 @_ZN5basicIiE7getdataEv(%class.basic* %this)
+
+// VISIBILITY: @b = protected global i32 0
+// VISIBILITY: define hidden void @_Z5foo_hPi(i32* %p)
+// VISIBILITY: declare hidden void @_Z12zoo_extern_hv()
+// VISIBILITY: define protected void @_Z3barv()
+// VISIBILITY: define linkonce_odr hidden i32 @_ZNK9TestClass5valueEv(%class.TestClass* %this)
+// VISIBILITY: define weak_odr protected i32 @_ZN5basicIiE7getdataEv(%class.basic* %this)
Index: clang/lib/Frontend/CompilerInvocation.cpp
===================================================================
--- clang/lib/Frontend/CompilerInvocation.cpp
+++ clang/lib/Frontend/CompilerInvocation.cpp
@@ -2752,6 +2752,9 @@
Opts.setValueVisibilityMode(parseVisibility(visOpt, Args, Diags));
} else {
Opts.setValueVisibilityMode(DefaultVisibility);
+ // In AIX oS, the -fnovisibility is enable by default.
+ if (T.isOSAIX() || Args.hasArg(OPT_fnovisibility))
+ Opts.NoVisibility = 1;
}
// The type-visibility mode defaults to the value-visibility mode.
Index: clang/lib/Driver/ToolChains/Clang.cpp
===================================================================
--- clang/lib/Driver/ToolChains/Clang.cpp
+++ clang/lib/Driver/ToolChains/Clang.cpp
@@ -5198,6 +5198,9 @@
}
}
+ if (Args.getLastArg(options::OPT_fnovisibility))
+ CmdArgs.push_back("-fnovisibility");
+
Args.AddLastArg(CmdArgs, options::OPT_fvisibility_inlines_hidden);
Args.AddLastArg(CmdArgs, options::OPT_fvisibility_global_new_delete_hidden);
Index: clang/lib/AST/Decl.cpp
===================================================================
--- clang/lib/AST/Decl.cpp
+++ clang/lib/AST/Decl.cpp
@@ -1477,10 +1477,16 @@
}
LinkageInfo LinkageComputer::getDeclLinkageAndVisibility(const NamedDecl *D) {
- return getLVForDecl(D,
- LVComputationKind(usesTypeVisibility(D)
- ? NamedDecl::VisibilityForType
- : NamedDecl::VisibilityForValue));
+ NamedDecl::ExplicitVisibilityKind EK = usesTypeVisibility(D)
+ ? NamedDecl::VisibilityForType
+ : NamedDecl::VisibilityForValue;
+ LVComputationKind CK(EK);
+
+ // In AIX OS, if there is -fnovisibility and -fvisibility is default
+ // visibility, the clang will ignore all visibility.
+ return getLVForDecl(D, D->getASTContext().getLangOpts().NoVisibility
+ ? CK.forLinkageOnly()
+ : CK);
}
Module *Decl::getOwningModuleForLinkage(bool IgnoreLinkage) const {
Index: clang/include/clang/Driver/Options.td
===================================================================
--- clang/include/clang/Driver/Options.td
+++ clang/include/clang/Driver/Options.td
@@ -1936,6 +1936,9 @@
def fverbose_asm : Flag<["-"], "fverbose-asm">, Group<f_Group>,
HelpText<"Generate verbose assembly output">;
def dA : Flag<["-"], "dA">, Alias<fverbose_asm>;
+def fnovisibility : Flag<["-"], "fnovisibility">, Group<f_Group>,
+ HelpText<"Ignore all the visibility attributes in source code">,
+ Flags<[CC1Option]>;
def fvisibility_EQ : Joined<["-"], "fvisibility=">, Group<f_Group>,
HelpText<"Set the default symbol visibility for all global declarations">, Values<"hidden,default">;
def fvisibility_inlines_hidden : Flag<["-"], "fvisibility-inlines-hidden">, Group<f_Group>,
Index: clang/include/clang/Basic/LangOptions.def
===================================================================
--- clang/include/clang/Basic/LangOptions.def
+++ clang/include/clang/Basic/LangOptions.def
@@ -297,6 +297,7 @@
"type's inheritance model would be determined under the Microsoft ABI")
ENUM_LANGOPT(GC, GCMode, 2, NonGC, "Objective-C Garbage Collection mode")
+BENIGN_LANGOPT(NoVisibility, 1, 0, "All the visibility attributes that are specified in the source are ignored.")
ENUM_LANGOPT(ValueVisibilityMode, Visibility, 3, DefaultVisibility,
"default visibility for functions and variables [-fvisibility]")
ENUM_LANGOPT(TypeVisibilityMode, Visibility, 3, DefaultVisibility,
Index: clang/docs/ClangCommandLineReference.rst
===================================================================
--- clang/docs/ClangCommandLineReference.rst
+++ clang/docs/ClangCommandLineReference.rst
@@ -2309,6 +2309,10 @@
.. option:: -fvisibility-ms-compat
+Ignore all the visibility attributes in source code
+
+.. option:: -fnovisibility
+
Give global types 'default' visibility and global functions and variables 'hidden' visibility by default
.. option:: -fvisibility=<arg>
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