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Define weak and __weak to mean ARC-style weak references, even in MRC.

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Previously, __weak was silently accepted and ignored in MRC mode.
That makes this a potentially source-breaking change that we have to
roll out cautiously.  Accordingly, for the time being, actual support
for __weak references in MRC is experimental, and the compiler will
reject attempts to actually form such references.  The intent is to
eventually enable the feature by default in all non-GC modes.
(It is, of course, incompatible with ObjC GC's interpretation of
__weak.)

If you like, you can enable this feature with
  -Xclang -fobjc-weak
but like any -Xclang option, this option may be removed at any point,
e.g. if/when it is eventually enabled by default.

This patch also enables the use of the ARC __unsafe_unretained qualifier
in MRC.  Unlike __weak, this is being enabled immediately.  Since
variables are essentially __unsafe_unretained by default in MRC,
the only practical uses are (1) communication and (2) changing the
default behavior of by-value block capture.

As an implementation matter, this means that the ObjC ownership
qualifiers may appear in any ObjC language mode, and so this patch
removes a number of checks for getLangOpts().ObjCAutoRefCount
that were guarding the processing of these qualifiers.  I don't
expect this to be a significant drain on performance; it may even
be faster to just check for these qualifiers directly on a type
(since it's probably in a register anyway) than to do N dependent
loads to grab the LangOptions.

rdar://9674298

llvm-svn: 251041
This commit is contained in:
John McCall
2015-10-22 18:38:17 +00:00
parent 63d23d1b12
commit 460ce58fa6
35 changed files with 570 additions and 212 deletions
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48
clang/lib/Frontend/InitPreprocessor.cpp
View File

@@ -323,15 +323,17 @@ static void AddObjCXXARCLibstdcxxDefines(const LangOptions &LangOpts,
Out << "template<typename _Tp> struct __is_scalar;\n"
<< "\n";
if (LangOpts.ObjCAutoRefCount) {
Out << "template<typename _Tp>\n"
<< "struct __is_scalar<__attribute__((objc_ownership(strong))) _Tp> {\n"
<< " enum { __value = 0 };\n"
<< " typedef __false_type __type;\n"
<< "};\n"
<< "\n";
}
Out << "template<typename _Tp>\n"
<< "struct __is_scalar<__attribute__((objc_ownership(strong))) _Tp> {\n"
<< " enum { __value = 0 };\n"
<< " typedef __false_type __type;\n"
<< "};\n"
<< "\n";
if (LangOpts.ObjCARCWeak) {
if (LangOpts.ObjCWeak) {
Out << "template<typename _Tp>\n"
<< "struct __is_scalar<__attribute__((objc_ownership(weak))) _Tp> {\n"
<< " enum { __value = 0 };\n"
@@ -340,13 +342,15 @@ static void AddObjCXXARCLibstdcxxDefines(const LangOptions &LangOpts,
<< "\n";
}
Out << "template<typename _Tp>\n"
<< "struct __is_scalar<__attribute__((objc_ownership(autoreleasing)))"
<< " _Tp> {\n"
<< " enum { __value = 0 };\n"
<< " typedef __false_type __type;\n"
<< "};\n"
<< "\n";
if (LangOpts.ObjCAutoRefCount) {
Out << "template<typename _Tp>\n"
<< "struct __is_scalar<__attribute__((objc_ownership(autoreleasing)))"
<< " _Tp> {\n"
<< " enum { __value = 0 };\n"
<< " typedef __false_type __type;\n"
<< "};\n"
<< "\n";
}
Out << "}\n";
}
@@ -851,9 +855,6 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
else if (LangOpts.getStackProtector() == LangOptions::SSPReq)
Builder.defineMacro("__SSP_ALL__", "3");
if (FEOpts.ProgramAction == frontend::RewriteObjC)
Builder.defineMacro("__weak", "__attribute__((objc_gc(weak)))");
// Define a macro that exists only when using the static analyzer.
if (FEOpts.ProgramAction == frontend::RunAnalysis)
Builder.defineMacro("__clang_analyzer__");
@@ -861,7 +862,11 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
if (LangOpts.FastRelaxedMath)
Builder.defineMacro("__FAST_RELAXED_MATH__");
if (LangOpts.ObjCAutoRefCount) {
if (FEOpts.ProgramAction == frontend::RewriteObjC ||
LangOpts.getGC() != LangOptions::NonGC) {
Builder.defineMacro("__weak", "__attribute__((objc_gc(weak)))");
Builder.defineMacro("__strong", "__attribute__((objc_gc(strong)))");
} else if (LangOpts.ObjC1) {
Builder.defineMacro("__weak", "__attribute__((objc_ownership(weak)))");
Builder.defineMacro("__strong", "__attribute__((objc_ownership(strong)))");
Builder.defineMacro("__autoreleasing",
@@ -928,10 +933,11 @@ void clang::InitializePreprocessor(
// Install definitions to make Objective-C++ ARC work well with various
// C++ Standard Library implementations.
if (LangOpts.ObjC1 && LangOpts.CPlusPlus && LangOpts.ObjCAutoRefCount) {
if (LangOpts.ObjC1 && LangOpts.CPlusPlus &&
(LangOpts.ObjCAutoRefCount || LangOpts.ObjCWeak)) {
switch (InitOpts.ObjCXXARCStandardLibrary) {
case ARCXX_nolib:
case ARCXX_libcxx:
case ARCXX_libcxx:
break;
case ARCXX_libstdcxx: