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[clang][RISCV] Add big-endian RISC-V target support #165599

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[clang][RISCV] Add big-endian RISC-V target support #165599

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[clang][RISCV] Add big-endian RISC-V target support
djtodoro Jun 9, 2025
028fbfd
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djtodoro Oct 31, 2025
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2 changes: 1 addition & 1 deletion clang/include/clang/Basic/Attr.td
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Original file line number Diff line number Diff line change
Expand Up @@ -476,7 +476,7 @@ def TargetMips32 : TargetArch<["mips", "mipsel"]>;
def TargetAnyMips : TargetArch<["mips", "mipsel", "mips64", "mips64el"]>;
def TargetMSP430 : TargetArch<["msp430"]>;
def TargetM68k : TargetArch<["m68k"]>;
def TargetRISCV : TargetArch<["riscv32", "riscv64"]>;
def TargetRISCV : TargetArch<["riscv32", "riscv64", "riscv32be", "riscv64be"]>;
def TargetX86 : TargetArch<["x86"]>;
def TargetX86_64 : TargetArch<["x86_64"]>;
def TargetAnyX86 : TargetArch<["x86", "x86_64"]>;
Expand Down
2 changes: 2 additions & 0 deletions clang/include/clang/Basic/DiagnosticDriverKinds.td
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Expand Up @@ -419,6 +419,8 @@ def warn_ignored_clang_option : Warning<"the flag '%0' has been deprecated and w
def warn_drv_unsupported_opt_for_target : Warning<
"optimization flag '%0' is not supported for target '%1'">,
InGroup<IgnoredOptimizationArgument>;
def warn_drv_riscv_be_experimental : Warning<
"big-endian RISC-V target support is experimental">;
def warn_drv_unsupported_debug_info_opt_for_target : Warning<
"debug information option '%0' is not supported for target '%1'">,
InGroup<UnsupportedTargetOpt>;
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1 change: 1 addition & 0 deletions clang/include/clang/Basic/ObjCRuntime.h
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Expand Up @@ -110,6 +110,7 @@ class ObjCRuntime {
case llvm::Triple::mips64:
return !(getVersion() >= VersionTuple(1, 9));
case llvm::Triple::riscv64:
case llvm::Triple::riscv64be:
return !(getVersion() >= VersionTuple(2, 2));
default:
return true;
Expand Down
2 changes: 2 additions & 0 deletions clang/lib/Basic/Targets.cpp
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Expand Up @@ -428,6 +428,7 @@ std::unique_ptr<TargetInfo> AllocateTarget(const llvm::Triple &Triple,
return std::make_unique<AMDGPUTargetInfo>(Triple, Opts);

case llvm::Triple::riscv32:
case llvm::Triple::riscv32be:
switch (os) {
case llvm::Triple::NetBSD:
return std::make_unique<NetBSDTargetInfo<RISCV32TargetInfo>>(Triple,
Expand All @@ -439,6 +440,7 @@ std::unique_ptr<TargetInfo> AllocateTarget(const llvm::Triple &Triple,
}

case llvm::Triple::riscv64:
case llvm::Triple::riscv64be:
switch (os) {
case llvm::Triple::FreeBSD:
return std::make_unique<FreeBSDTargetInfo<RISCV64TargetInfo>>(Triple,
Expand Down
4 changes: 4 additions & 0 deletions clang/lib/Basic/Targets/OSTargets.h
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Expand Up @@ -255,6 +255,8 @@ class LLVM_LIBRARY_VISIBILITY FreeBSDTargetInfo : public OSTargetInfo<Target> {
break;
case llvm::Triple::loongarch64:
case llvm::Triple::riscv64:
case llvm::Triple::riscv32be:
case llvm::Triple::riscv64be:
break;
}
}
Expand Down Expand Up @@ -513,6 +515,8 @@ class LLVM_LIBRARY_VISIBILITY OpenBSDTargetInfo : public OSTargetInfo<Target> {
break;
case llvm::Triple::loongarch64:
case llvm::Triple::riscv64:
case llvm::Triple::riscv32be:
case llvm::Triple::riscv64be:
break;
}
}
Expand Down
16 changes: 12 additions & 4 deletions clang/lib/Basic/Targets/RISCV.h
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Expand Up @@ -175,13 +175,17 @@ class LLVM_LIBRARY_VISIBILITY RISCV32TargetInfo : public RISCVTargetInfo {
IntPtrType = SignedInt;
PtrDiffType = SignedInt;
SizeType = UnsignedInt;
resetDataLayout("e-m:e-p:32:32-i64:64-n32-S128");
resetDataLayout((Twine(Triple.isLittleEndian() ? "e" : "E") +
"-m:e-p:32:32-i64:64-n32-S128")
.str());
}

bool setABI(const std::string &Name) override {
if (Name == "ilp32e") {
ABI = Name;
resetDataLayout("e-m:e-p:32:32-i64:64-n32-S32");
resetDataLayout((Twine(getTriple().isLittleEndian() ? "e" : "E") +
"-m:e-p:32:32-i64:64-n32-S32")
.str());
return true;
}

Expand All @@ -205,13 +209,17 @@ class LLVM_LIBRARY_VISIBILITY RISCV64TargetInfo : public RISCVTargetInfo {
: RISCVTargetInfo(Triple, Opts) {
LongWidth = LongAlign = PointerWidth = PointerAlign = 64;
IntMaxType = Int64Type = SignedLong;
resetDataLayout("e-m:e-p:64:64-i64:64-i128:128-n32:64-S128");
resetDataLayout((Twine(Triple.isLittleEndian() ? "e" : "E") +
"-m:e-p:64:64-i64:64-i128:128-n32:64-S128")
.str());
}

bool setABI(const std::string &Name) override {
if (Name == "lp64e") {
ABI = Name;
resetDataLayout("e-m:e-p:64:64-i64:64-i128:128-n32:64-S64");
resetDataLayout((Twine(getTriple().isLittleEndian() ? "e" : "E") +
"-m:e-p:64:64-i64:64-i128:128-n32:64-S64")
.str());
return true;
}

Expand Down
2 changes: 2 additions & 0 deletions clang/lib/CodeGen/CGBuiltin.cpp
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Expand Up @@ -121,6 +121,8 @@ static Value *EmitTargetArchBuiltinExpr(CodeGenFunction *CGF,
return CGF->EmitHexagonBuiltinExpr(BuiltinID, E);
case llvm::Triple::riscv32:
case llvm::Triple::riscv64:
case llvm::Triple::riscv32be:
case llvm::Triple::riscv64be:
return CGF->EmitRISCVBuiltinExpr(BuiltinID, E, ReturnValue);
case llvm::Triple::spirv32:
case llvm::Triple::spirv64:
Expand Down
2 changes: 2 additions & 0 deletions clang/lib/CodeGen/CodeGenFunction.cpp
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Expand Up @@ -2989,6 +2989,8 @@ void CodeGenFunction::EmitMultiVersionResolver(
return;
case llvm::Triple::riscv32:
case llvm::Triple::riscv64:
case llvm::Triple::riscv32be:
case llvm::Triple::riscv64be:
EmitRISCVMultiVersionResolver(Resolver, Options);
return;

Expand Down
4 changes: 3 additions & 1 deletion clang/lib/CodeGen/CodeGenModule.cpp
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Expand Up @@ -223,7 +223,9 @@ createTargetCodeGenInfo(CodeGenModule &CGM) {
return createMSP430TargetCodeGenInfo(CGM);

case llvm::Triple::riscv32:
case llvm::Triple::riscv64: {
case llvm::Triple::riscv64:
case llvm::Triple::riscv32be:
case llvm::Triple::riscv64be: {
StringRef ABIStr = Target.getABI();
unsigned XLen = Target.getPointerWidth(LangAS::Default);
unsigned ABIFLen = 0;
Expand Down
26 changes: 22 additions & 4 deletions clang/lib/Driver/Driver.cpp
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Expand Up @@ -822,14 +822,30 @@ static llvm::Triple computeTargetTriple(const Driver &D,
ArchName, /*EnableExperimentalExtensions=*/true);
if (!llvm::errorToBool(ISAInfo.takeError())) {
unsigned XLen = (*ISAInfo)->getXLen();
if (XLen == 32)
Target.setArch(llvm::Triple::riscv32);
else if (XLen == 64)
Target.setArch(llvm::Triple::riscv64);
if (XLen == 32) {
if (Target.isLittleEndian())
Target.setArch(llvm::Triple::riscv32);
else
Target.setArch(llvm::Triple::riscv32be);
} else if (XLen == 64) {
if (Target.isLittleEndian())
Target.setArch(llvm::Triple::riscv64);
else
Target.setArch(llvm::Triple::riscv64be);
}
}
}
}

if (Target.getArch() == llvm::Triple::riscv32be ||
Target.getArch() == llvm::Triple::riscv64be) {
static bool WarnedRISCVBE = false;
if (!WarnedRISCVBE) {
D.Diag(diag::warn_drv_riscv_be_experimental);
WarnedRISCVBE = true;
}
}

return Target;
}

Expand Down Expand Up @@ -6957,6 +6973,8 @@ const ToolChain &Driver::getToolChain(const ArgList &Args,
break;
case llvm::Triple::riscv32:
case llvm::Triple::riscv64:
case llvm::Triple::riscv32be:
case llvm::Triple::riscv64be:
TC = std::make_unique<toolchains::BareMetal>(*this, Target, Args);
break;
case llvm::Triple::ve:
Expand Down
2 changes: 2 additions & 0 deletions clang/lib/Driver/ToolChain.cpp
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Expand Up @@ -370,6 +370,8 @@ ToolChain::getMultilibFlags(const llvm::opt::ArgList &Args) const {
break;
case llvm::Triple::riscv32:
case llvm::Triple::riscv64:
case llvm::Triple::riscv32be:
case llvm::Triple::riscv64be:
getRISCVMultilibFlags(D, Triple, Args, Result);
break;
default:
Expand Down
3 changes: 2 additions & 1 deletion clang/lib/Driver/ToolChains/BareMetal.cpp
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Expand Up @@ -714,7 +714,8 @@ SanitizerMask BareMetal::getSupportedSanitizers() const {
const bool IsX86_64 = getTriple().getArch() == llvm::Triple::x86_64;
const bool IsAArch64 = getTriple().getArch() == llvm::Triple::aarch64 ||
getTriple().getArch() == llvm::Triple::aarch64_be;
const bool IsRISCV64 = getTriple().getArch() == llvm::Triple::riscv64;
const bool IsRISCV64 = getTriple().getArch() == llvm::Triple::riscv64 ||
getTriple().getArch() == llvm::Triple::riscv64be;
SanitizerMask Res = ToolChain::getSupportedSanitizers();
Res |= SanitizerKind::Address;
Res |= SanitizerKind::KernelAddress;
Expand Down
9 changes: 8 additions & 1 deletion clang/lib/Driver/ToolChains/Clang.cpp
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Expand Up @@ -1195,6 +1195,8 @@ static bool isSignedCharDefault(const llvm::Triple &Triple) {
case llvm::Triple::ppc64le:
case llvm::Triple::riscv32:
case llvm::Triple::riscv64:
case llvm::Triple::riscv32be:
case llvm::Triple::riscv64be:
case llvm::Triple::systemz:
case llvm::Triple::xcore:
case llvm::Triple::xtensa:
Expand Down Expand Up @@ -1593,6 +1595,8 @@ void Clang::RenderTargetOptions(const llvm::Triple &EffectiveTriple,

case llvm::Triple::riscv32:
case llvm::Triple::riscv64:
case llvm::Triple::riscv32be:
case llvm::Triple::riscv64be:
AddRISCVTargetArgs(Args, CmdArgs);
break;

Expand Down Expand Up @@ -5644,7 +5648,8 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
} else if (Name == "SLEEF" || Name == "ArmPL") {
if (Triple.getArch() != llvm::Triple::aarch64 &&
Triple.getArch() != llvm::Triple::aarch64_be &&
Triple.getArch() != llvm::Triple::riscv64)
Triple.getArch() != llvm::Triple::riscv64 &&
Triple.getArch() != llvm::Triple::riscv64be)
D.Diag(diag::err_drv_unsupported_opt_for_target)
<< Name << Triple.getArchName();
}
Expand Down Expand Up @@ -8718,6 +8723,8 @@ void ClangAs::ConstructJob(Compilation &C, const JobAction &JA,

case llvm::Triple::riscv32:
case llvm::Triple::riscv64:
case llvm::Triple::riscv32be:
case llvm::Triple::riscv64be:
AddRISCVTargetArgs(Args, CmdArgs);
break;

Expand Down
10 changes: 10 additions & 0 deletions clang/lib/Driver/ToolChains/CommonArgs.cpp
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Expand Up @@ -90,6 +90,8 @@ static bool useFramePointerForTargetByDefault(const llvm::opt::ArgList &Args,
case llvm::Triple::ppc64le:
case llvm::Triple::riscv32:
case llvm::Triple::riscv64:
case llvm::Triple::riscv32be:
case llvm::Triple::riscv64be:
case llvm::Triple::sparc:
case llvm::Triple::sparcel:
case llvm::Triple::sparcv9:
Expand Down Expand Up @@ -590,6 +592,10 @@ const char *tools::getLDMOption(const llvm::Triple &T, const ArgList &Args) {
return "elf32lriscv";
case llvm::Triple::riscv64:
return "elf64lriscv";
case llvm::Triple::riscv32be:
return "elf32briscv";
case llvm::Triple::riscv64be:
return "elf64briscv";
case llvm::Triple::sparc:
case llvm::Triple::sparcel:
return "elf32_sparc";
Expand Down Expand Up @@ -767,6 +773,8 @@ std::string tools::getCPUName(const Driver &D, const ArgList &Args,
return "ck810";
case llvm::Triple::riscv32:
case llvm::Triple::riscv64:
case llvm::Triple::riscv32be:
case llvm::Triple::riscv64be:
return riscv::getRISCVTargetCPU(Args, T);

case llvm::Triple::bpfel:
Expand Down Expand Up @@ -848,6 +856,8 @@ void tools::getTargetFeatures(const Driver &D, const llvm::Triple &Triple,
break;
case llvm::Triple::riscv32:
case llvm::Triple::riscv64:
case llvm::Triple::riscv32be:
case llvm::Triple::riscv64be:
riscv::getRISCVTargetFeatures(D, Triple, Args, Features);
break;
case llvm::Triple::systemz:
Expand Down
8 changes: 8 additions & 0 deletions clang/lib/Driver/ToolChains/FreeBSD.cpp
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Expand Up @@ -212,6 +212,14 @@ void freebsd::Linker::ConstructJob(Compilation &C, const JobAction &JA,
CmdArgs.push_back("-m");
CmdArgs.push_back("elf64lriscv");
break;
case llvm::Triple::riscv32be:
CmdArgs.push_back("-m");
CmdArgs.push_back("elf32briscv");
break;
case llvm::Triple::riscv64be:
CmdArgs.push_back("-m");
CmdArgs.push_back("elf64briscv");
break;
case llvm::Triple::loongarch64:
CmdArgs.push_back("-m");
CmdArgs.push_back("elf64loongarch");
Expand Down
40 changes: 35 additions & 5 deletions clang/lib/Driver/ToolChains/Gnu.cpp
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Expand Up @@ -672,7 +672,9 @@ void tools::gnutools::Assembler::ConstructJob(Compilation &C,
break;
}
case llvm::Triple::riscv32:
case llvm::Triple::riscv64: {
case llvm::Triple::riscv64:
case llvm::Triple::riscv32be:
case llvm::Triple::riscv64be: {
StringRef ABIName = riscv::getRISCVABI(Args, getToolChain().getTriple());
CmdArgs.push_back("-mabi");
CmdArgs.push_back(ABIName.data());
Expand Down Expand Up @@ -1732,16 +1734,20 @@ static void findRISCVBareMetalMultilibs(const Driver &D,
.flag(Twine("-march=", Element.march).str())
.flag(Twine("-mabi=", Element.mabi).str()));
}

std::string EndiannessSuffix = TargetTriple.isLittleEndian() ? "" : "be";
MultilibSet RISCVMultilibs =
MultilibSetBuilder()
.Either(Ms)
.makeMultilibSet()
.FilterOut(NonExistent)
.setFilePathsCallback([](const Multilib &M) {
.setFilePathsCallback([EndiannessSuffix](const Multilib &M) {
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@efriedma-quic efriedma-quic Oct 31, 2025

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Suggested change
.setFilePathsCallback([EndiannessSuffix](const Multilib &M) {
.setFilePathsCallback([&EndiannessSuffix](const Multilib &M) {

return std::vector<std::string>(
{M.gccSuffix(),
"/../../../../riscv64-unknown-elf/lib" + M.gccSuffix(),
"/../../../../riscv32-unknown-elf/lib" + M.gccSuffix()});
"/../../../../riscv64" + EndiannessSuffix +
"-unknown-elf/lib" + M.gccSuffix(),
"/../../../../riscv32" + EndiannessSuffix +
"-unknown-elf/lib" + M.gccSuffix()});
});

Multilib::flags_list Flags;
Expand Down Expand Up @@ -1789,7 +1795,8 @@ static void findRISCVMultilibs(const Driver &D,
.FilterOut(NonExistent);

Multilib::flags_list Flags;
bool IsRV64 = TargetTriple.getArch() == llvm::Triple::riscv64;
bool IsRV64 = (TargetTriple.getArch() == llvm::Triple::riscv64 ||
TargetTriple.getArch() == llvm::Triple::riscv64be);
StringRef ABIName = tools::riscv::getRISCVABI(Args, TargetTriple);

addMultilibFlag(!IsRV64, "-m32", Flags);
Expand Down Expand Up @@ -2431,6 +2438,15 @@ void Generic_GCC::GCCInstallationDetector::AddDefaultGCCPrefixes(
static const char *const RISCV64Triples[] = {"riscv64-unknown-linux-gnu",
"riscv64-unknown-elf"};

static const char *const RISCV32beLibDirs[] = {"/lib32", "/lib"};
static const char *const RISCV32beTriples[] = {"riscv32be-unknown-linux-gnu",
"riscv32be-linux-gnu",
"riscv32be-unknown-elf"};
static const char *const RISCV64beLibDirs[] = {"/lib64", "/lib"};
static const char *const RISCV64beTriples[] = {"riscv64be-unknown-linux-gnu",
"riscv64be-linux-gnu",
"riscv64be-unknown-elf"};

static const char *const SPARCv8LibDirs[] = {"/lib32", "/lib"};
static const char *const SPARCv8Triples[] = {"sparc-linux-gnu",
"sparcv8-linux-gnu"};
Expand Down Expand Up @@ -2723,6 +2739,18 @@ void Generic_GCC::GCCInstallationDetector::AddDefaultGCCPrefixes(
BiarchLibDirs.append(begin(RISCV32LibDirs), end(RISCV32LibDirs));
BiarchTripleAliases.append(begin(RISCV32Triples), end(RISCV32Triples));
break;
case llvm::Triple::riscv32be:
LibDirs.append(begin(RISCV32beLibDirs), end(RISCV32beLibDirs));
TripleAliases.append(begin(RISCV32beTriples), end(RISCV32beTriples));
BiarchLibDirs.append(begin(RISCV64beLibDirs), end(RISCV64beLibDirs));
BiarchTripleAliases.append(begin(RISCV64beTriples), end(RISCV64beTriples));
break;
case llvm::Triple::riscv64be:
LibDirs.append(begin(RISCV64beLibDirs), end(RISCV64beLibDirs));
TripleAliases.append(begin(RISCV64beTriples), end(RISCV64beTriples));
BiarchLibDirs.append(begin(RISCV32beLibDirs), end(RISCV32beLibDirs));
BiarchTripleAliases.append(begin(RISCV32beTriples), end(RISCV32beTriples));
break;
case llvm::Triple::sparc:
case llvm::Triple::sparcel:
LibDirs.append(begin(SPARCv8LibDirs), end(SPARCv8LibDirs));
Expand Down Expand Up @@ -3038,6 +3066,8 @@ Generic_GCC::getDefaultUnwindTableLevel(const ArgList &Args) const {
case llvm::Triple::ppc64le:
case llvm::Triple::riscv32:
case llvm::Triple::riscv64:
case llvm::Triple::riscv32be:
case llvm::Triple::riscv64be:
case llvm::Triple::x86:
case llvm::Triple::x86_64:
return UnwindTableLevel::Asynchronous;
Expand Down
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