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//===--- ARM.cpp - ARM (not AArch64) Helpers for Tools ----------*- C++ -*-===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
#include "ARM.h"
#include "clang/Driver/Driver.h"
#include "clang/Driver/DriverDiagnostic.h"
#include "clang/Driver/Options.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/Option/ArgList.h"
#include "llvm/Support/TargetParser.h"
using namespace clang::driver;
using namespace clang::driver::tools;
using namespace clang;
using namespace llvm::opt;
// Get SubArch (vN).
int arm::getARMSubArchVersionNumber(const llvm::Triple &Triple) {
llvm::StringRef Arch = Triple.getArchName();
return llvm::ARM::parseArchVersion(Arch);
// True if M-profile.
bool arm::isARMMProfile(const llvm::Triple &Triple) {
llvm::StringRef Arch = Triple.getArchName();
return llvm::ARM::parseArchProfile(Arch) == llvm::ARM::ProfileKind::M;
// Get Arch/CPU from args.
void arm::getARMArchCPUFromArgs(const ArgList &Args, llvm::StringRef &Arch,
llvm::StringRef &CPU, bool FromAs) {
if (const Arg *A = Args.getLastArg(clang::driver::options::OPT_mcpu_EQ))
CPU = A->getValue();
if (const Arg *A = Args.getLastArg(options::OPT_march_EQ))
Arch = A->getValue();
if (!FromAs)
for (const Arg *A :
Args.filtered(options::OPT_Wa_COMMA, options::OPT_Xassembler)) {
StringRef Value = A->getValue();
if (Value.startswith("-mcpu="))
CPU = Value.substr(6);
if (Value.startswith("-march="))
Arch = Value.substr(7);
// Handle -mhwdiv=.
// FIXME: Use ARMTargetParser.
static void getARMHWDivFeatures(const Driver &D, const Arg *A,
const ArgList &Args, StringRef HWDiv,
std::vector<StringRef> &Features) {
unsigned HWDivID = llvm::ARM::parseHWDiv(HWDiv);
if (!llvm::ARM::getHWDivFeatures(HWDivID, Features))
D.Diag(clang::diag::err_drv_clang_unsupported) << A->getAsString(Args);
// Handle -mfpu=.
static void getARMFPUFeatures(const Driver &D, const Arg *A,
const ArgList &Args, StringRef FPU,
std::vector<StringRef> &Features) {
unsigned FPUID = llvm::ARM::parseFPU(FPU);
if (!llvm::ARM::getFPUFeatures(FPUID, Features))
D.Diag(clang::diag::err_drv_clang_unsupported) << A->getAsString(Args);
// Decode ARM features from string like +[no]featureA+[no]featureB+...
static bool DecodeARMFeatures(const Driver &D, StringRef text,
std::vector<StringRef> &Features) {
SmallVector<StringRef, 8> Split;
text.split(Split, StringRef("+"), -1, false);
for (StringRef Feature : Split) {
StringRef FeatureName = llvm::ARM::getArchExtFeature(Feature);
if (!FeatureName.empty())
return false;
return true;
static void DecodeARMFeaturesFromCPU(const Driver &D, StringRef CPU,
std::vector<StringRef> &Features) {
if (CPU != "generic") {
llvm::ARM::ArchKind ArchKind = llvm::ARM::parseCPUArch(CPU);
unsigned Extension = llvm::ARM::getDefaultExtensions(CPU, ArchKind);
llvm::ARM::getExtensionFeatures(Extension, Features);
// Check if -march is valid by checking if it can be canonicalised and parsed.
// getARMArch is used here instead of just checking the -march value in order
// to handle -march=native correctly.
static void checkARMArchName(const Driver &D, const Arg *A, const ArgList &Args,
llvm::StringRef ArchName,
std::vector<StringRef> &Features,
const llvm::Triple &Triple) {
std::pair<StringRef, StringRef> Split = ArchName.split("+");
std::string MArch = arm::getARMArch(ArchName, Triple);
if (llvm::ARM::parseArch(MArch) == llvm::ARM::ArchKind::INVALID ||
(Split.second.size() && !DecodeARMFeatures(D, Split.second, Features)))
D.Diag(clang::diag::err_drv_clang_unsupported) << A->getAsString(Args);
// Check -mcpu=. Needs ArchName to handle -mcpu=generic.
static void checkARMCPUName(const Driver &D, const Arg *A, const ArgList &Args,
llvm::StringRef CPUName, llvm::StringRef ArchName,
std::vector<StringRef> &Features,
const llvm::Triple &Triple) {
std::pair<StringRef, StringRef> Split = CPUName.split("+");
std::string CPU = arm::getARMTargetCPU(CPUName, ArchName, Triple);
if (arm::getLLVMArchSuffixForARM(CPU, ArchName, Triple).empty() ||
(Split.second.size() && !DecodeARMFeatures(D, Split.second, Features)))
D.Diag(clang::diag::err_drv_clang_unsupported) << A->getAsString(Args);
bool arm::useAAPCSForMachO(const llvm::Triple &T) {
// The backend is hardwired to assume AAPCS for M-class processors, ensure
// the frontend matches that.
return T.getEnvironment() == llvm::Triple::EABI ||
T.getOS() == llvm::Triple::UnknownOS || isARMMProfile(T);
// Select mode for reading thread pointer (-mtp=soft/cp15).
arm::ReadTPMode arm::getReadTPMode(const ToolChain &TC, const ArgList &Args) {
if (Arg *A = Args.getLastArg(options::OPT_mtp_mode_EQ)) {
const Driver &D = TC.getDriver();
arm::ReadTPMode ThreadPointer =
.Case("cp15", ReadTPMode::Cp15)
.Case("soft", ReadTPMode::Soft)
if (ThreadPointer != ReadTPMode::Invalid)
return ThreadPointer;
if (StringRef(A->getValue()).empty())
D.Diag(diag::err_drv_missing_arg_mtp) << A->getAsString(Args);
D.Diag(diag::err_drv_invalid_mtp) << A->getAsString(Args);
return ReadTPMode::Invalid;
return ReadTPMode::Soft;
// Select the float ABI as determined by -msoft-float, -mhard-float, and
// -mfloat-abi=.
arm::FloatABI arm::getARMFloatABI(const ToolChain &TC, const ArgList &Args) {
const Driver &D = TC.getDriver();
const llvm::Triple &Triple = TC.getEffectiveTriple();
auto SubArch = getARMSubArchVersionNumber(Triple);
arm::FloatABI ABI = FloatABI::Invalid;
if (Arg *A =
Args.getLastArg(options::OPT_msoft_float, options::OPT_mhard_float,
options::OPT_mfloat_abi_EQ)) {
if (A->getOption().matches(options::OPT_msoft_float)) {
ABI = FloatABI::Soft;
} else if (A->getOption().matches(options::OPT_mhard_float)) {
ABI = FloatABI::Hard;
} else {
ABI = llvm::StringSwitch<arm::FloatABI>(A->getValue())
.Case("soft", FloatABI::Soft)
.Case("softfp", FloatABI::SoftFP)
.Case("hard", FloatABI::Hard)
if (ABI == FloatABI::Invalid && !StringRef(A->getValue()).empty()) {
D.Diag(diag::err_drv_invalid_mfloat_abi) << A->getAsString(Args);
ABI = FloatABI::Soft;
// It is incorrect to select hard float ABI on MachO platforms if the ABI is
// "apcs-gnu".
if (Triple.isOSBinFormatMachO() && !useAAPCSForMachO(Triple) &&
ABI == FloatABI::Hard) {
D.Diag(diag::err_drv_unsupported_opt_for_target) << A->getAsString(Args)
<< Triple.getArchName();
// If unspecified, choose the default based on the platform.
if (ABI == FloatABI::Invalid) {
switch (Triple.getOS()) {
case llvm::Triple::Darwin:
case llvm::Triple::MacOSX:
case llvm::Triple::IOS:
case llvm::Triple::TvOS: {
// Darwin defaults to "softfp" for v6 and v7.
ABI = (SubArch == 6 || SubArch == 7) ? FloatABI::SoftFP : FloatABI::Soft;
ABI = Triple.isWatchABI() ? FloatABI::Hard : ABI;
case llvm::Triple::WatchOS:
ABI = FloatABI::Hard;
// FIXME: this is invalid for WindowsCE
case llvm::Triple::Win32:
ABI = FloatABI::Hard;
case llvm::Triple::NetBSD:
switch (Triple.getEnvironment()) {
case llvm::Triple::EABIHF:
case llvm::Triple::GNUEABIHF:
ABI = FloatABI::Hard;
ABI = FloatABI::Soft;
case llvm::Triple::FreeBSD:
switch (Triple.getEnvironment()) {
case llvm::Triple::GNUEABIHF:
ABI = FloatABI::Hard;
// FreeBSD defaults to soft float
ABI = FloatABI::Soft;
case llvm::Triple::OpenBSD:
ABI = FloatABI::SoftFP;
switch (Triple.getEnvironment()) {
case llvm::Triple::GNUEABIHF:
case llvm::Triple::MuslEABIHF:
case llvm::Triple::EABIHF:
ABI = FloatABI::Hard;
case llvm::Triple::GNUEABI:
case llvm::Triple::MuslEABI:
case llvm::Triple::EABI:
// EABI is always AAPCS, and if it was not marked 'hard', it's softfp
ABI = FloatABI::SoftFP;
case llvm::Triple::Android:
ABI = (SubArch == 7) ? FloatABI::SoftFP : FloatABI::Soft;
// Assume "soft", but warn the user we are guessing.
if (Triple.isOSBinFormatMachO() &&
Triple.getSubArch() == llvm::Triple::ARMSubArch_v7em)
ABI = FloatABI::Hard;
ABI = FloatABI::Soft;
if (Triple.getOS() != llvm::Triple::UnknownOS ||
D.Diag(diag::warn_drv_assuming_mfloat_abi_is) << "soft";
assert(ABI != FloatABI::Invalid && "must select an ABI");
return ABI;
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);
arm::ReadTPMode ThreadPointer = arm::getReadTPMode(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)
// Use software floating point argument passing?
if (ABI != arm::FloatABI::Hard)
} 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;
if (ThreadPointer == arm::ReadTPMode::Cp15)
// Check -march. ClangAs gives preference to -Wa,-march=.
const Arg *ArchArg = Args.getLastArg(options::OPT_march_EQ);
StringRef ArchName;
if (WaArch) {
if (ArchArg)
<< 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)
<< 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)
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)
<< FPUArg->getAsString(Args);
getARMFPUFeatures(D, WaFPU, Args, StringRef(WaFPU->getValue()).substr(6),
} 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)
<< 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/-mfloat-abi=soft effectively disables the FPU (GCC
// ignores the -mfpu options in this case).
// Note that the ABI can also be set implicitly by the target selected.
if (ABI == arm::FloatABI::Soft) {
llvm::ARM::getFPUFeatures(llvm::ARM::FK_NONE, Features);
// Disable hardware FP features which have been enabled.
// FIXME: Disabling vfp2 and neon should be enough as all the other
// features are dependent on these 2 features in LLVM. However
// there is currently no easy way to test this in clang, so for
// now just be explicit and disable all known dependent features
// as well.
for (std::string Feature : {"vfp2", "vfp3", "vfp4", "fp-armv8", "fullfp16",
"neon", "crypto", "dotprod"})
if (std::find(std::begin(Features), std::end(Features), "+" + Feature) != std::end(Features))
Features.push_back(Args.MakeArgString("-" + Feature));
// En/disable crc code generation.
if (Arg *A = Args.getLastArg(options::OPT_mcrc, options::OPT_mnocrc)) {
if (A->getOption().matches(options::OPT_mcrc))
// 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))
} else if (KernelOrKext && (!Triple.isiOS() || Triple.isOSVersionLT(6)) &&
!Triple.isWatchOS()) {
// 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);
// Kernel code has more strict alignment requirements.
if (KernelOrKext)
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
} 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)
} else if (Triple.isOSLinux() || Triple.isOSNaCl()) {
if (VersionNum < 7)
} else
// 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))
// The kext linker doesn't know how to deal with movw/movt.
if (KernelOrKext || Args.hasArg(options::OPT_mno_movt))
if (Args.hasArg(options::OPT_mno_neg_immediates))
const std::string arm::getARMArch(StringRef Arch, const llvm::Triple &Triple) {
std::string MArch;
if (!Arch.empty())
MArch = Arch;
MArch = Triple.getArchName();
MArch = StringRef(MArch).split("+").first.lower();
// Handle -march=native.
if (MArch == "native") {
std::string CPU = llvm::sys::getHostCPUName();
if (CPU != "generic") {
// Translate the native cpu into the architecture suffix for that CPU.
StringRef Suffix = arm::getLLVMArchSuffixForARM(CPU, MArch, Triple);
// If there is no valid architecture suffix for this CPU we don't know how
// to handle it, so return no architecture.
if (Suffix.empty())
MArch = "";
MArch = std::string("arm") + Suffix.str();
return MArch;
/// Get the (LLVM) name of the minimum ARM CPU for the arch we are targeting.
StringRef arm::getARMCPUForMArch(StringRef Arch, const llvm::Triple &Triple) {
std::string MArch = getARMArch(Arch, Triple);
// getARMCPUForArch defaults to the triple if MArch is empty, but empty MArch
// here means an -march=native that we can't handle, so instead return no CPU.
if (MArch.empty())
return StringRef();
// We need to return an empty string here on invalid MArch values as the
// various places that call this function can't cope with a null result.
return Triple.getARMCPUForArch(MArch);
/// getARMTargetCPU - Get the (LLVM) name of the ARM cpu we are targeting.
std::string arm::getARMTargetCPU(StringRef CPU, StringRef Arch,
const llvm::Triple &Triple) {
// FIXME: Warn on inconsistent use of -mcpu and -march.
// If we have -mcpu=, use that.
if (!CPU.empty()) {
std::string MCPU = StringRef(CPU).split("+").first.lower();
// Handle -mcpu=native.
if (MCPU == "native")
return llvm::sys::getHostCPUName();
return MCPU;
return getARMCPUForMArch(Arch, Triple);
/// getLLVMArchSuffixForARM - Get the LLVM arch name to use for a particular
/// CPU (or Arch, if CPU is generic).
// FIXME: This is redundant with -mcpu, why does LLVM use this.
StringRef arm::getLLVMArchSuffixForARM(StringRef CPU, StringRef Arch,
const llvm::Triple &Triple) {
llvm::ARM::ArchKind ArchKind;
if (CPU == "generic") {
std::string ARMArch = tools::arm::getARMArch(Arch, Triple);
ArchKind = llvm::ARM::parseArch(ARMArch);
if (ArchKind == llvm::ARM::ArchKind::INVALID)
// In case of generic Arch, i.e. "arm",
// extract arch from default cpu of the Triple
ArchKind = llvm::ARM::parseCPUArch(Triple.getARMCPUForArch(ARMArch));
} else {
// FIXME: horrible hack to get around the fact that Cortex-A7 is only an
// armv7k triple if it's actually been specified via "-arch armv7k".
ArchKind = (Arch == "armv7k" || Arch == "thumbv7k")
? llvm::ARM::ArchKind::ARMV7K
: llvm::ARM::parseCPUArch(CPU);
if (ArchKind == llvm::ARM::ArchKind::INVALID)
return "";
return llvm::ARM::getSubArch(ArchKind);
void arm::appendEBLinkFlags(const ArgList &Args, ArgStringList &CmdArgs,
const llvm::Triple &Triple) {
if (Args.hasArg(options::OPT_r))
// ARMv7 (and later) and ARMv6-M do not support BE-32, so instruct the linker
// to generate BE-8 executables.
if (arm::getARMSubArchVersionNumber(Triple) >= 7 || arm::isARMMProfile(Triple))