[Diffusion] rL257984: [Cygwin] Use -femulated-tls by default since r257718 introduced the new pass.

[Hans Wennborg via cfe-commits]

On Tue, Jan 19, 2016 at 3:43 PM, NAKAMURA Takumi <geek4civic at gmail.com> wrote:
> May I push it (llvm and clang) into release_38?
> It depends on r257718.

r257718 was committed after the branch. Are you suggesting we merge that too?

This looks like a pretty significant change. Can't it wait until 3.9?


> 2016-01-16 12:48 GMT+09:00 NAKAMURA Takumi <geek4civic at gmail.com>:
>> chapuni committed rL257984: [Cygwin] Use -femulated-tls by default since r257718 introduced the new pass..
>>
>> [Cygwin] Use -femulated-tls by default since r257718 introduced the new pass.
>>
>> FIXME: Add more targets to use emutls into clang/test/Driver/emulated-tls.cpp.
>> FIXME: Add cygwin tests into llvm/test/CodeGen/X86. Working in progress.
>>
>>
>> Files:
>>   /cfe/trunk/docs/ReleaseNotes.rst
>>   /cfe/trunk/lib/Driver/Tools.cpp
>>   /cfe/trunk/test/Driver/emulated-tls.cpp
>>   /llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
>>
>> PATCH
>>
>> Index: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
>> ===================================================================
>> --- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp       (revision 257983)
>> +++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp       (revision 257984)
>> @@ -12477,17 +12477,13 @@
>>
>>    GlobalAddressSDNode *GA = cast<GlobalAddressSDNode>(Op);
>>
>> -  // Cygwin uses emutls.
>> -  // FIXME: It may be EmulatedTLS-generic also for X86-Android.
>> -  if (Subtarget->isTargetWindowsCygwin())
>> +  if (DAG.getTarget().Options.EmulatedTLS)
>>      return LowerToTLSEmulatedModel(GA, DAG);
>>
>>    const GlobalValue *GV = GA->getGlobal();
>>    auto PtrVT = getPointerTy(DAG.getDataLayout());
>>
>>    if (Subtarget->isTargetELF()) {
>> -    if (DAG.getTarget().Options.EmulatedTLS)
>> -      return LowerToTLSEmulatedModel(GA, DAG);
>>      TLSModel::Model model = DAG.getTarget().getTLSModel(GV);
>>      switch (model) {
>>        case TLSModel::GeneralDynamic:
>> Index: cfe/trunk/test/Driver/emulated-tls.cpp
>> ===================================================================
>> --- cfe/trunk/test/Driver/emulated-tls.cpp      (revision 0)
>> +++ cfe/trunk/test/Driver/emulated-tls.cpp      (revision 257984)
>> @@ -0,0 +1,5 @@
>> +// Cygwin uses emutls. Clang should pass -femulated-tls to cc1 and cc1 should pass EmulatedTLS to LLVM CodeGen.
>> +// FIXME: Add more targets here to use emutls.
>> +// RUN: %clang -### -std=c++11 -target i686-pc-cygwin %s 2>&1 | FileCheck %s
>> +
>> +// CHECK: "-cc1" {{.*}}"-femulated-tls"
>> Index: cfe/trunk/docs/ReleaseNotes.rst
>> ===================================================================
>> --- cfe/trunk/docs/ReleaseNotes.rst     (revision 257983)
>> +++ cfe/trunk/docs/ReleaseNotes.rst     (revision 257984)
>> @@ -74,6 +74,8 @@
>>
>>  Clang's support for building native Windows programs ...
>>
>> +TLS is enabled for Cygwin defaults to -femulated-tls.
>> +
>>
>>  C Language Changes in Clang
>>  ---------------------------
>> Index: cfe/trunk/lib/Driver/Tools.cpp
>> ===================================================================
>> --- cfe/trunk/lib/Driver/Tools.cpp      (revision 257983)
>> +++ cfe/trunk/lib/Driver/Tools.cpp      (revision 257984)
>> @@ -4597,7 +4597,7 @@
>>    Args.AddLastArg(CmdArgs, options::OPT_fno_operator_names);
>>    // Emulated TLS is enabled by default on Android, and can be enabled manually
>>    // with -femulated-tls.
>> -  bool EmulatedTLSDefault = Triple.isAndroid();
>> +  bool EmulatedTLSDefault = Triple.isAndroid() || Triple.isWindowsCygwinEnvironment();
>>    if (Args.hasFlag(options::OPT_femulated_tls, options::OPT_fno_emulated_tls,
>>                     EmulatedTLSDefault))
>>      CmdArgs.push_back("-femulated-tls");
>>
>> Users:
>>   chapuni (Author)
>>
>> http://reviews.llvm.org/rL257984
>>
>>
>>