C++ MCSubtargetInfo::hasFeature方法代码示例

static bool isV8M(const MCSubtargetInfo &STI) {
  // Note that v8M Baseline is a subset of v6T2!
  return (STI.hasFeature(ARM::HasV8MBaselineOps) &&
          !STI.hasFeature(ARM::HasV6T2Ops)) ||
         STI.hasFeature(ARM::HasV8MMainlineOps);
}

/// Emit the build attributes that only depend on the hardware that we expect
// /to be available, and not on the ABI, or any source-language choices.
void ARMTargetStreamer::emitTargetAttributes(const MCSubtargetInfo &STI) {
  switchVendor("aeabi");

  const StringRef CPUString = STI.getCPU();
  if (!CPUString.empty() && !CPUString.startswith("generic")) {
    // FIXME: remove krait check when GNU tools support krait cpu
    if (STI.hasFeature(ARM::ProcKrait)) {
      emitTextAttribute(ARMBuildAttrs::CPU_name, "cortex-a9");
      // We consider krait as a "cortex-a9" + hwdiv CPU
      // Enable hwdiv through ".arch_extension idiv"
      if (STI.hasFeature(ARM::FeatureHWDivThumb) ||
          STI.hasFeature(ARM::FeatureHWDivARM))
        emitArchExtension(ARM::AEK_HWDIVTHUMB | ARM::AEK_HWDIVARM);
    } else {
      emitTextAttribute(ARMBuildAttrs::CPU_name, CPUString);
    }
  }

  emitAttribute(ARMBuildAttrs::CPU_arch, getArchForCPU(STI));

  if (STI.hasFeature(ARM::FeatureAClass)) {
    emitAttribute(ARMBuildAttrs::CPU_arch_profile,
                      ARMBuildAttrs::ApplicationProfile);
  } else if (STI.hasFeature(ARM::FeatureRClass)) {
    emitAttribute(ARMBuildAttrs::CPU_arch_profile,
                      ARMBuildAttrs::RealTimeProfile);
  } else if (STI.hasFeature(ARM::FeatureMClass)) {
    emitAttribute(ARMBuildAttrs::CPU_arch_profile,
                      ARMBuildAttrs::MicroControllerProfile);
  }

  emitAttribute(ARMBuildAttrs::ARM_ISA_use, STI.hasFeature(ARM::FeatureNoARM)
                                                ? ARMBuildAttrs::Not_Allowed
                                                : ARMBuildAttrs::Allowed);

  if (isV8M(STI)) {
    emitAttribute(ARMBuildAttrs::THUMB_ISA_use,
                      ARMBuildAttrs::AllowThumbDerived);
  } else if (STI.hasFeature(ARM::FeatureThumb2)) {
    emitAttribute(ARMBuildAttrs::THUMB_ISA_use,
                      ARMBuildAttrs::AllowThumb32);
  } else if (STI.hasFeature(ARM::HasV4TOps)) {
    emitAttribute(ARMBuildAttrs::THUMB_ISA_use, ARMBuildAttrs::Allowed);
  }

  if (STI.hasFeature(ARM::FeatureNEON)) {
    /* NEON is not exactly a VFP architecture, but GAS emit one of
     * neon/neon-fp-armv8/neon-vfpv4/vfpv3/vfpv2 for .fpu parameters */
    if (STI.hasFeature(ARM::FeatureFPARMv8)) {
      if (STI.hasFeature(ARM::FeatureCrypto))
        emitFPU(ARM::FK_CRYPTO_NEON_FP_ARMV8);
      else
        emitFPU(ARM::FK_NEON_FP_ARMV8);
    } else if (STI.hasFeature(ARM::FeatureVFP4))
      emitFPU(ARM::FK_NEON_VFPV4);
    else
      emitFPU(STI.hasFeature(ARM::FeatureFP16) ? ARM::FK_NEON_FP16
                                               : ARM::FK_NEON);
    // Emit Tag_Advanced_SIMD_arch for ARMv8 architecture
    if (STI.hasFeature(ARM::HasV8Ops))
      emitAttribute(ARMBuildAttrs::Advanced_SIMD_arch,
                    STI.hasFeature(ARM::HasV8_1aOps)
                        ? ARMBuildAttrs::AllowNeonARMv8_1a
                        : ARMBuildAttrs::AllowNeonARMv8);
  } else {
    if (STI.hasFeature(ARM::FeatureFPARMv8))
      // FPv5 and FP-ARMv8 have the same instructions, so are modeled as one
      // FPU, but there are two different names for it depending on the CPU.
      emitFPU(STI.hasFeature(ARM::FeatureD16)
                  ? (STI.hasFeature(ARM::FeatureVFPOnlySP) ? ARM::FK_FPV5_SP_D16
                                                           : ARM::FK_FPV5_D16)
                  : ARM::FK_FP_ARMV8);
    else if (STI.hasFeature(ARM::FeatureVFP4))
      emitFPU(STI.hasFeature(ARM::FeatureD16)
                  ? (STI.hasFeature(ARM::FeatureVFPOnlySP) ? ARM::FK_FPV4_SP_D16
                                                           : ARM::FK_VFPV4_D16)
                  : ARM::FK_VFPV4);
    else if (STI.hasFeature(ARM::FeatureVFP3))
      emitFPU(
          STI.hasFeature(ARM::FeatureD16)
              // +d16
              ? (STI.hasFeature(ARM::FeatureVFPOnlySP)
                     ? (STI.hasFeature(ARM::FeatureFP16) ? ARM::FK_VFPV3XD_FP16
                                                         : ARM::FK_VFPV3XD)
                     : (STI.hasFeature(ARM::FeatureFP16)
                            ? ARM::FK_VFPV3_D16_FP16
                            : ARM::FK_VFPV3_D16))
              // -d16
              : (STI.hasFeature(ARM::FeatureFP16) ? ARM::FK_VFPV3_FP16
                                                  : ARM::FK_VFPV3));
    else if (STI.hasFeature(ARM::FeatureVFP2))
      emitFPU(ARM::FK_VFPV2);
  }

  // ABI_HardFP_use attribute to indicate single precision FP.
  if (STI.hasFeature(ARM::FeatureVFPOnlySP))
    emitAttribute(ARMBuildAttrs::ABI_HardFP_use,
                  ARMBuildAttrs::HardFPSinglePrecision);
//.........这里部分代码省略.........

static ARMBuildAttrs::CPUArch getArchForCPU(const MCSubtargetInfo &STI) {
  if (STI.getCPU() == "xscale")
    return ARMBuildAttrs::v5TEJ;

  if (STI.hasFeature(ARM::HasV8Ops)) {
    if (STI.hasFeature(ARM::FeatureRClass))
      return ARMBuildAttrs::v8_R;
    return ARMBuildAttrs::v8_A;
  } else if (STI.hasFeature(ARM::HasV8MMainlineOps))
    return ARMBuildAttrs::v8_M_Main;
  else if (STI.hasFeature(ARM::HasV7Ops)) {
    if (STI.hasFeature(ARM::FeatureMClass) && STI.hasFeature(ARM::FeatureDSP))
      return ARMBuildAttrs::v7E_M;
    return ARMBuildAttrs::v7;
  } else if (STI.hasFeature(ARM::HasV6T2Ops))
    return ARMBuildAttrs::v6T2;
  else if (STI.hasFeature(ARM::HasV8MBaselineOps))
    return ARMBuildAttrs::v8_M_Base;
  else if (STI.hasFeature(ARM::HasV6MOps))
    return ARMBuildAttrs::v6S_M;
  else if (STI.hasFeature(ARM::HasV6Ops))
    return ARMBuildAttrs::v6;
  else if (STI.hasFeature(ARM::HasV5TEOps))
    return ARMBuildAttrs::v5TE;
  else if (STI.hasFeature(ARM::HasV5TOps))
    return ARMBuildAttrs::v5T;
  else if (STI.hasFeature(ARM::HasV4TOps))
    return ARMBuildAttrs::v4T;
  else
    return ARMBuildAttrs::v4;
}