[RISCV] Remove RISCVFeatures::validate function

[StephenFan]

Summary

Feature validation is done by parseFeature function. This RISCVFeature::validate function is redundant.

[StephenFan]

[RISCV] Generate correct ELF EFlags when .ll file has target-abi attribute

In the past, when construct RISCVAsmBackend, MCTargetOptions.ABIName would be passed and stored in RISCVAsmBackend.
But MCTargetOptions.ABIName can only be specified by -target-abi xxx in command line, if the .ll file has target-abi attribute, the codegen module will ignore it. And the generated object file would have incorrect EFlags value.

https://github.com/llvm/llvm-project/issues/50591 also caused by this problem.

This patch override the AsmPrinter::emitFunctionEntryLabel function and use it to set the target abi value that get from .ll file's target-abi attribute. And storing the target-abi in RISCVTargetStreamer instead of RISCVAsmBackend.

[craig.topper]

In D121073#3366178, @StephenFan wrote:

[RISCV] Generate correct ELF EFlags when .ll file has target-abi attribute

In the past, when construct RISCVAsmBackend, MCTargetOptions.ABIName would be passed and stored in RISCVAsmBackend.
But MCTargetOptions.ABIName can only be specified by -target-abi xxx in command line, if the .ll file has target-abi attribute, the codegen module will ignore it. And the generated object file would have incorrect EFlags value.

https://github.com/llvm/llvm-project/issues/50591 also caused by this problem.

This patch override the AsmPrinter::emitFunctionEntryLabel function and use it to set the target abi value that get from .ll file's target-abi attribute. And storing the target-abi in RISCVTargetStreamer instead of RISCVAsmBackend.

Was this supposed to be a new review?

[StephenFan]

undo

[StephenFan]

ping.

[StephenFan]

Ping. :)

llvm/lib/Target/RISCV/MCTargetDesc/RISCVAsmBackend.h

 
 public:
   RISCVAsmBackend(const MCSubtargetInfo &STI, uint8_t OSABI, bool Is64Bit,
                   const MCTargetOptions &Options)
       : MCAsmBackend(support::little), STI(STI), OSABI(OSABI), Is64Bit(Is64Bit),
         TargetOptions(Options) {
     TargetABI = RISCVABI::computeTargetABI(
         STI.getTargetTriple(), STI.getFeatureBits(), Options.getABIName());
-    RISCVFeatures::validate(STI.getTargetTriple(), STI.getFeatureBits());
   }
   ~RISCVAsmBackend() override = default;
 
   void setForceRelocs() { ForceRelocs = true; }
 
   // Return Size with extra Nop Bytes for alignment directive in code section.
   bool shouldInsertExtraNopBytesForCodeAlign(const MCAlignFragment &AF,
                                              unsigned &Size) override;

llvm/lib/Target/RISCV/MCTargetDesc/RISCVBaseInfo.h

 
 // Returns the register holding shadow call stack pointer.
 MCRegister getSCSPReg();
 
 } // namespace RISCVABI
 
 namespace RISCVFeatures {
 
-// Validates if the given combination of features are valid for the target
-// triple. Exits with report_fatal_error if not.
-void validate(const Triple &TT, const FeatureBitset &FeatureBits);
-
 llvm::Expected<std::unique_ptr<RISCVISAInfo>>
 parseFeatureBits(bool IsRV64, const FeatureBitset &FeatureBits);
 
 } // namespace RISCVFeatures
 
 namespace RISCVVType {
 // Is this a SEW value that can be encoded into the VTYPE format.
 inline static bool isValidSEW(unsigned SEW) {

llvm/lib/Target/RISCV/MCTargetDesc/RISCVBaseInfo.cpp

 
 // Returns the register holding shadow call stack pointer.
 MCRegister getSCSPReg() { return RISCV::X18; }
 
 } // namespace RISCVABI
 
 namespace RISCVFeatures {
 
-void validate(const Triple &TT, const FeatureBitset &FeatureBits) {
-  if (TT.isArch64Bit() && !FeatureBits[RISCV::Feature64Bit])
-    report_fatal_error("RV64 target requires an RV64 CPU");
-  if (!TT.isArch64Bit() && FeatureBits[RISCV::Feature64Bit])
-    report_fatal_error("RV32 target requires an RV32 CPU");
-  if (TT.isArch64Bit() && FeatureBits[RISCV::FeatureRV32E])
-    report_fatal_error("RV32E can't be enabled for an RV64 target");
-}
-
 llvm::Expected<std::unique_ptr<RISCVISAInfo>>
 parseFeatureBits(bool IsRV64, const FeatureBitset &FeatureBits) {
   unsigned XLen = IsRV64 ? 64 : 32;
   std::vector<std::string> FeatureVector;
   // Convert FeatureBitset to FeatureVector.
   for (auto Feature : RISCVFeatureKV) {
     if (FeatureBits[Feature.Value] &&
         llvm::RISCVISAInfo::isSupportedExtensionFeature(Feature.Key))

llvm/lib/Target/RISCV/RISCVSubtarget.cpp

RISCVSubtarget::initializeSubtargetDependencies(const Triple &TT, StringRef CPU,
 
   ParseSubtargetFeatures(CPU, TuneCPU, FS);
   if (Is64Bit) {
     XLenVT = MVT::i64;
     XLen = 64;
   }
 
   TargetABI = RISCVABI::computeTargetABI(TT, getFeatureBits(), ABIName);
-  RISCVFeatures::validate(TT, getFeatureBits());
   return *this;
 }
 
 RISCVSubtarget::RISCVSubtarget(const Triple &TT, StringRef CPU,
                                StringRef TuneCPU, StringRef FS,
                                StringRef ABIName, const TargetMachine &TM)
     : RISCVGenSubtargetInfo(TT, CPU, TuneCPU, FS),
       UserReservedRegister(RISCV::NUM_TARGET_REGS),