[llvm] r206211 - [ARM64][MC] Set the default CPU to cyclone when initilizating the MC layer.

[Quentin Colombet]

Well, in fact, I am not sure what is the best approach here.

ARM and X86 already seem to duplicate this logic somehow, see below.

So if we are about to duplicate something I’d prefer to keep it minimal like in the current patch.

What do you think?

** X86 **

— X86Subtarget.cpp:
void X86Subtarget::resetSubtargetFeatures(StringRef CPU, StringRef FS) {
  std::string CPUName = CPU;
  if (CPUName.empty())
    CPUName = "generic";

— X86MCTargetDesc.cpp:
MCSubtargetInfo *X86_MC::createX86MCSubtargetInfo(StringRef TT, StringRef CPU,
                                                  StringRef FS) {
[…]
  std::string CPUName = CPU;
  if (CPUName.empty()) {
#if defined(i386) || defined(__i386__) || defined(__x86__) || defined(_M_IX86)\
    || defined(__x86_64__) || defined(_M_AMD64) || defined (_M_X64)
    CPUName = sys::getHostCPUName();
#else
    CPUName = "generic";
#endif
  }


** ARM **

— ARMSubtarget.cpp:
void ARMSubtarget::resetSubtargetFeatures(StringRef CPU, StringRef FS) {
  if (CPUString.empty()) {
    if (isTargetIOS() && TargetTriple.getArchName().endswith("v7s"))
      // Default to the Swift CPU when targeting armv7s/thumbv7s.
      CPUString = "swift";
    else
      CPUString = "generic";
  }

— ARMMCTargetDesc.cpp:
std::string ARM_MC::ParseARMTriple(StringRef TT, StringRef CPU) {
[...]
  bool NoCPU = CPU == "generic" || CPU.empty();
  std::string ARMArchFeature;
  if (Idx) {
    unsigned SubVer = TT[Idx];
    if (SubVer == '8') {
      if (NoCPU)
        // v8a: FeatureDB, FeatureFPARMv8, FeatureNEON, FeatureDSPThumb2,
        //      FeatureMP, FeatureHWDiv, FeatureHWDivARM, FeatureTrustZone,
        //      FeatureT2XtPk, FeatureCrypto, FeatureCRC
        ARMArchFeature = "+v8,+db,+fp-armv8,+neon,+t2dsp,+mp,+hwdiv,+hwdiv-arm,"
                         "+trustzone,+t2xtpk,+crypto,+crc";
      else
        // Use CPU to figure out the exact features
        ARMArchFeature = "+v8”;
[…]

-Quentin

On Apr 14, 2014, at 3:02 PM, Eric Christopher <echristo at gmail.com> wrote:

> Thanks!
> 
> I'd probably see the ARM one as closer... it doesn't cope well if
> there's no cpu given it doesn't look like :)
> 
> -eric
> 
> On Mon, Apr 14, 2014 at 3:00 PM, Quentin Colombet <qcolombet at apple.com> wrote:
>> Sorry, I thought I was doing the same thing as X86 here.
>> I’ve been misled by this sequence:
>> MCSubtargetInfo *X86_MC::createX86MCSubtargetInfo(StringRef TT, StringRef
>> CPU,
>>                                                  StringRef FS) {
>> [...]
>>  std::string CPUName = CPU;
>>  if (CPUName.empty()) {
>> #if defined(i386) || defined(__i386__) || defined(__x86__) ||
>> defined(_M_IX86)\
>>    || defined(__x86_64__) || defined(_M_AMD64) || defined (_M_X64)
>>    CPUName = sys::getHostCPUName();
>> #else
>>    CPUName = "generic";
>> #endif
>>  }
>> 
>> Let me rework my copy then!
>> 
>> -Quentin
>> 
>> On Apr 14, 2014, at 2:42 PM, Eric Christopher <echristo at gmail.com> wrote:
>> 
>> Uh, what?
>> 
>> How about taking the same code from the ARM or X86 backends? Or something
>> else?
>> 
>> -eric
>> 
>> On Mon, Apr 14, 2014 at 2:25 PM, Quentin Colombet <qcolombet at apple.com>
>> wrote:
>> 
>> Author: qcolombet
>> Date: Mon Apr 14 16:25:53 2014
>> New Revision: 206211
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=206211&view=rev
>> Log:
>> [ARM64][MC] Set the default CPU to cyclone when initilizating the MC layer.
>> This matches that ARM64Subtarget does for now.
>> 
>> This is related to <rdar://problem/16573920>
>> 
>> Modified:
>>   llvm/trunk/lib/Target/ARM64/MCTargetDesc/ARM64MCTargetDesc.cpp
>> 
>> Modified: llvm/trunk/lib/Target/ARM64/MCTargetDesc/ARM64MCTargetDesc.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM64/MCTargetDesc/ARM64MCTargetDesc.cpp?rev=206211&r1=206210&r2=206211&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Target/ARM64/MCTargetDesc/ARM64MCTargetDesc.cpp
>> (original)
>> +++ llvm/trunk/lib/Target/ARM64/MCTargetDesc/ARM64MCTargetDesc.cpp Mon Apr
>> 14 16:25:53 2014
>> @@ -43,6 +43,12 @@ static MCInstrInfo *createARM64MCInstrIn
>> static MCSubtargetInfo *createARM64MCSubtargetInfo(StringRef TT, StringRef
>> CPU,
>>                                                   StringRef FS) {
>>  MCSubtargetInfo *X = new MCSubtargetInfo();
>> +
>> +  // FIXME: Make this darwin-only.
>> +  if (CPU.empty())
>> +    // We default to Cyclone for now, on Darwin.
>> +    CPU = "cyclone";
>> +
>>  InitARM64MCSubtargetInfo(X, TT, CPU, FS);
>>  return X;
>> }
>> 
>> 
>> _______________________________________________
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>> llvm-commits at cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>> 
>> 

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