void arm::getARMTargetFeatures(const ToolChain &TC,
const llvm::Triple &Triple,
const ArgList &Args,
ArgStringList &CmdArgs,
std::vector<StringRef> &Features,
bool ForAS) {
const Driver &D = TC.getDriver();
bool KernelOrKext =
Args.hasArg(options::OPT_mkernel, options::OPT_fapple_kext);
arm::FloatABI ABI = arm::getARMFloatABI(TC, Args);
const Arg *WaCPU = nullptr, *WaFPU = nullptr;
const Arg *WaHDiv = nullptr, *WaArch = nullptr;
if (!ForAS) {
// FIXME: Note, this is a hack, the LLVM backend doesn't actually use these
// yet (it uses the -mfloat-abi and -msoft-float options), and it is
// stripped out by the ARM target. We should probably pass this a new
// -target-option, which is handled by the -cc1/-cc1as invocation.
//
// FIXME2: For consistency, it would be ideal if we set up the target
// machine state the same when using the frontend or the assembler. We don't
// currently do that for the assembler, we pass the options directly to the
// backend and never even instantiate the frontend TargetInfo. If we did,
// and used its handleTargetFeatures hook, then we could ensure the
// assembler and the frontend behave the same.
// Use software floating point operations?
if (ABI == arm::FloatABI::Soft)
Features.push_back("+soft-float");
// Use software floating point argument passing?
if (ABI != arm::FloatABI::Hard)
Features.push_back("+soft-float-abi");
} else {
// Here, we make sure that -Wa,-mfpu/cpu/arch/hwdiv will be passed down
// to the assembler correctly.
for (const Arg *A :
Args.filtered(options::OPT_Wa_COMMA, options::OPT_Xassembler)) {
StringRef Value = A->getValue();
if (Value.startswith("-mfpu=")) {
WaFPU = A;
} else if (Value.startswith("-mcpu=")) {
WaCPU = A;
} else if (Value.startswith("-mhwdiv=")) {
WaHDiv = A;
} else if (Value.startswith("-march=")) {
WaArch = A;
}
}
}
// Check -march. ClangAs gives preference to -Wa,-march=.
const Arg *ArchArg = Args.getLastArg(options::OPT_march_EQ);
StringRef ArchName;
if (WaArch) {
if (ArchArg)
D.Diag(clang::diag::warn_drv_unused_argument)
<< ArchArg->getAsString(Args);
ArchName = StringRef(WaArch->getValue()).substr(7);
checkARMArchName(D, WaArch, Args, ArchName, Features, Triple);
// FIXME: Set Arch.
D.Diag(clang::diag::warn_drv_unused_argument) << WaArch->getAsString(Args);
} else if (ArchArg) {
ArchName = ArchArg->getValue();
checkARMArchName(D, ArchArg, Args, ArchName, Features, Triple);
}
// Check -mcpu. ClangAs gives preference to -Wa,-mcpu=.
const Arg *CPUArg = Args.getLastArg(options::OPT_mcpu_EQ);
StringRef CPUName;
if (WaCPU) {
if (CPUArg)
D.Diag(clang::diag::warn_drv_unused_argument)
<< CPUArg->getAsString(Args);
CPUName = StringRef(WaCPU->getValue()).substr(6);
checkARMCPUName(D, WaCPU, Args, CPUName, ArchName, Features, Triple);
} else if (CPUArg) {
CPUName = CPUArg->getValue();
checkARMCPUName(D, CPUArg, Args, CPUName, ArchName, Features, Triple);
}
// Add CPU features for generic CPUs
if (CPUName == "native") {
llvm::StringMap<bool> HostFeatures;
if (llvm::sys::getHostCPUFeatures(HostFeatures))
for (auto &F : HostFeatures)
Features.push_back(
Args.MakeArgString((F.second ? "+" : "-") + F.first()));
} else if (!CPUName.empty()) {
DecodeARMFeaturesFromCPU(D, CPUName, Features);
}
// Honor -mfpu=. ClangAs gives preference to -Wa,-mfpu=.
const Arg *FPUArg = Args.getLastArg(options::OPT_mfpu_EQ);
if (WaFPU) {
if (FPUArg)
D.Diag(clang::diag::warn_drv_unused_argument)
<< FPUArg->getAsString(Args);
getARMFPUFeatures(D, WaFPU, Args, StringRef(WaFPU->getValue()).substr(6),
Features);
} else if (FPUArg) {
getARMFPUFeatures(D, FPUArg, Args, FPUArg->getValue(), Features);
}
// Honor -mhwdiv=. ClangAs gives preference to -Wa,-mhwdiv=.
const Arg *HDivArg = Args.getLastArg(options::OPT_mhwdiv_EQ);
if (WaHDiv) {
if (HDivArg)
D.Diag(clang::diag::warn_drv_unused_argument)
<< HDivArg->getAsString(Args);
getARMHWDivFeatures(D, WaHDiv, Args,
StringRef(WaHDiv->getValue()).substr(8), Features);
} else if (HDivArg)
getARMHWDivFeatures(D, HDivArg, Args, HDivArg->getValue(), Features);
// Setting -msoft-float effectively disables NEON because of the GCC
// implementation, although the same isn't true of VFP or VFP3.
if (ABI == arm::FloatABI::Soft) {
Features.push_back("-neon");
// Also need to explicitly disable features which imply NEON.
Features.push_back("-crypto");
}
// En/disable crc code generation.
if (Arg *A = Args.getLastArg(options::OPT_mcrc, options::OPT_mnocrc)) {
if (A->getOption().matches(options::OPT_mcrc))
Features.push_back("+crc");
else
Features.push_back("-crc");
}
// Look for the last occurrence of -mlong-calls or -mno-long-calls. If
// neither options are specified, see if we are compiling for kernel/kext and
// decide whether to pass "+long-calls" based on the OS and its version.
if (Arg *A = Args.getLastArg(options::OPT_mlong_calls,
options::OPT_mno_long_calls)) {
if (A->getOption().matches(options::OPT_mlong_calls))
Features.push_back("+long-calls");
} else if (KernelOrKext && (!Triple.isiOS() || Triple.isOSVersionLT(6)) &&
!Triple.isWatchOS()) {
Features.push_back("+long-calls");
}
// Generate execute-only output (no data access to code sections).
// This only makes sense for the compiler, not for the assembler.
if (!ForAS) {
// Supported only on ARMv6T2 and ARMv7 and above.
// Cannot be combined with -mno-movt or -mlong-calls
if (Arg *A = Args.getLastArg(options::OPT_mexecute_only, options::OPT_mno_execute_only)) {
if (A->getOption().matches(options::OPT_mexecute_only)) {
if (getARMSubArchVersionNumber(Triple) < 7 &&
llvm::ARM::parseArch(Triple.getArchName()) != llvm::ARM::ArchKind::ARMV6T2)
D.Diag(diag::err_target_unsupported_execute_only) << Triple.getArchName();
else if (Arg *B = Args.getLastArg(options::OPT_mno_movt))
D.Diag(diag::err_opt_not_valid_with_opt) << A->getAsString(Args) << B->getAsString(Args);
// Long calls create constant pool entries and have not yet been fixed up
// to play nicely with execute-only. Hence, they cannot be used in
// execute-only code for now
else if (Arg *B = Args.getLastArg(options::OPT_mlong_calls, options::OPT_mno_long_calls)) {
if (B->getOption().matches(options::OPT_mlong_calls))
D.Diag(diag::err_opt_not_valid_with_opt) << A->getAsString(Args) << B->getAsString(Args);
}
Features.push_back("+execute-only");
}
}
}
// Kernel code has more strict alignment requirements.
if (KernelOrKext)
Features.push_back("+strict-align");
else if (Arg *A = Args.getLastArg(options::OPT_mno_unaligned_access,
options::OPT_munaligned_access)) {
if (A->getOption().matches(options::OPT_munaligned_access)) {
// No v6M core supports unaligned memory access (v6M ARM ARM A3.2).
if (Triple.getSubArch() == llvm::Triple::SubArchType::ARMSubArch_v6m)
D.Diag(diag::err_target_unsupported_unaligned) << "v6m";
// v8M Baseline follows on from v6M, so doesn't support unaligned memory
// access either.
else if (Triple.getSubArch() == llvm::Triple::SubArchType::ARMSubArch_v8m_baseline)
D.Diag(diag::err_target_unsupported_unaligned) << "v8m.base";
} else
Features.push_back("+strict-align");
} else {
// Assume pre-ARMv6 doesn't support unaligned accesses.
//
// ARMv6 may or may not support unaligned accesses depending on the
// SCTLR.U bit, which is architecture-specific. We assume ARMv6
// Darwin and NetBSD targets support unaligned accesses, and others don't.
//
// ARMv7 always has SCTLR.U set to 1, but it has a new SCTLR.A bit
// which raises an alignment fault on unaligned accesses. Linux
// defaults this bit to 0 and handles it as a system-wide (not
// per-process) setting. It is therefore safe to assume that ARMv7+
// Linux targets support unaligned accesses. The same goes for NaCl.
//
// The above behavior is consistent with GCC.
int VersionNum = getARMSubArchVersionNumber(Triple);
if (Triple.isOSDarwin() || Triple.isOSNetBSD()) {
if (VersionNum < 6 ||
Triple.getSubArch() == llvm::Triple::SubArchType::ARMSubArch_v6m)
Features.push_back("+strict-align");
} else if (Triple.isOSLinux() || Triple.isOSNaCl()) {
if (VersionNum < 7)
Features.push_back("+strict-align");
} else
Features.push_back("+strict-align");
}
// llvm does not support reserving registers in general. There is support
// for reserving r9 on ARM though (defined as a platform-specific register
// in ARM EABI).
if (Args.hasArg(options::OPT_ffixed_r9))
Features.push_back("+reserve-r9");
// The kext linker doesn't know how to deal with movw/movt.
if (KernelOrKext || Args.hasArg(options::OPT_mno_movt))
Features.push_back("+no-movt");
if (Args.hasArg(options::OPT_mno_neg_immediates))
Features.push_back("+no-neg-immediates");
}
