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[clang][Hexagon] Add Picolibc as part of triple #169613

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@quic-k quic-k commented Nov 26, 2025

This patch adds Picolibc as part of triple so toolchains can switch the to Picolibc based on triple.
Hexagon toolchain uses the triple hexagon-none-picolibc.

@llvmbot llvmbot added backend:Hexagon clang:driver 'clang' and 'clang++' user-facing binaries. Not 'clang-cl' labels Nov 26, 2025
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llvmbot commented Nov 26, 2025

@llvm/pr-subscribers-backend-hexagon

Author: None (quic-k)

Changes

This patch adds Picolibc as part of triple so toolchains can switch the to Picolibc based on triple.
Hexagon toolchain uses the triple hexagon-none-picolibc.

Patch is 20.97 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/169613.diff

5 Files Affected:

  • (modified) clang/lib/Driver/ToolChains/Hexagon.cpp (+172-13)
  • (modified) clang/lib/Driver/ToolChains/Hexagon.h (+8)
  • (added) clang/test/Driver/hexagon-toolchain-picolibc.c (+133)
  • (modified) llvm/include/llvm/TargetParser/Triple.h (+4)
  • (modified) llvm/lib/TargetParser/Triple.cpp (+2)
diff --git a/clang/lib/Driver/ToolChains/Hexagon.cpp b/clang/lib/Driver/ToolChains/Hexagon.cpp
index 084f51721315c..151798e7e572b 100644
--- a/clang/lib/Driver/ToolChains/Hexagon.cpp
+++ b/clang/lib/Driver/ToolChains/Hexagon.cpp
@@ -273,6 +273,101 @@ void hexagon::Linker::RenderExtraToolArgs(const JobAction &JA,
                                           ArgStringList &CmdArgs) const {
 }
 
+static void constructHexagonPicolibcLinkArgs(
+    Compilation &C, const JobAction &JA,
+    const toolchains::HexagonToolChain &HTC, const InputInfo &Output,
+    const InputInfoList &Inputs, const ArgList &Args, ArgStringList &CmdArgs,
+    const char *LinkingOutput) {
+  const Driver &D = HTC.getDriver();
+  bool IsShared = Args.hasArg(options::OPT_shared);
+  bool IncStdLib = !Args.hasArg(options::OPT_nostdlib);
+  bool IncStartFiles = !Args.hasArg(options::OPT_nostartfiles);
+  bool IncDefLibs = !Args.hasArg(options::OPT_nodefaultlibs);
+  StringRef CpuVer = toolchains::HexagonToolChain::GetTargetCPUVersion(Args);
+  // Use G0 for Picolibc
+  bool UseG0 = true;
+  auto OsType = HTC.getOS();
+
+  CmdArgs.push_back("--eh-frame-hdr");
+  // Propagate arch flags to the linker when not using LLD, to match
+  // upstream Hexagon driver behavior validated by tests.
+  bool UseLLD = false;
+  const char *LinkerPath = Args.MakeArgString(HTC.GetLinkerPath(&UseLLD));
+  UseLLD = UseLLD ||
+           llvm::sys::path::filename(LinkerPath).ends_with("ld.lld") ||
+           llvm::sys::path::stem(LinkerPath).ends_with("ld.lld");
+  if (!UseLLD) {
+    CmdArgs.push_back("-march=hexagon");
+    CmdArgs.push_back(Args.MakeArgString("-mcpu=hexagon" + CpuVer));
+  }
+  CmdArgs.push_back("-o");
+  CmdArgs.push_back(Output.getFilename());
+
+  // Inputs
+  Args.addAllArgs(CmdArgs, {options::OPT_T_Group, options::OPT_s,
+                            options::OPT_t, options::OPT_u_Group});
+  AddLinkerInputs(HTC, Inputs, Args, CmdArgs, JA);
+
+  //----------------------------------------------------------------------------
+  // Start Files
+  //----------------------------------------------------------------------------
+  const std::string MCpuSuffix = "/" + CpuVer.str();
+  const std::string MCpuG0Suffix = MCpuSuffix + "/G0";
+  const std::string RootDir =
+      HTC.getHexagonTargetDir(D.Dir, D.PrefixDirs) + "/";
+  std::string NormalizedTriple =
+      HTC.getTriple().normalize(llvm::Triple::CanonicalForm::FOUR_IDENT);
+  const std::string StartSubDir =
+      NormalizedTriple + "/lib" + (UseG0 ? MCpuG0Suffix : MCpuSuffix);
+
+  if (IncStdLib && IncStartFiles) {
+    if (!IsShared) {
+      if (OsType == "none" || OsType == "unknown") {
+        std::string Crt0 = RootDir + StartSubDir + "/crt0-semihost.o";
+        CmdArgs.push_back(Args.MakeArgString(Crt0));
+      }
+    }
+  }
+
+  //----------------------------------------------------------------------------
+  // Library Search Paths
+  //----------------------------------------------------------------------------
+  const ToolChain::path_list &LibPaths = HTC.getFilePaths();
+  for (const auto &LibPath : LibPaths)
+    CmdArgs.push_back(Args.MakeArgString(StringRef("-L") + LibPath));
+  //----------------------------------------------------------------------------
+  // Libraries
+  //----------------------------------------------------------------------------
+  if (IncStdLib && IncDefLibs) {
+    if (D.CCCIsCXX()) {
+      if (HTC.ShouldLinkCXXStdlib(Args))
+        HTC.AddCXXStdlibLibArgs(Args, CmdArgs);
+      CmdArgs.push_back("-lm");
+    }
+
+    CmdArgs.push_back("--start-group");
+
+    if (!IsShared) {
+      // add OS libraries to link
+      std::vector<std::string> OsLibs{};
+      if (OsType == "none" || OsType == "unknown") {
+        OsLibs.push_back("semihost");
+      } else if (OsType == "h2") {
+        OsLibs.push_back("h2");
+      } else if (OsType == "qurt") {
+        OsLibs.push_back("qurt");
+      }
+      for (StringRef Lib : OsLibs)
+        CmdArgs.push_back(Args.MakeArgString("-l" + Lib));
+      if (!Args.hasArg(options::OPT_nolibc))
+        CmdArgs.push_back("-lc");
+    }
+    // Force compiler-rt for Picolibc
+    CmdArgs.push_back("-lclang_rt.builtins");
+    CmdArgs.push_back("--end-group");
+  }
+}
+
 static void
 constructHexagonLinkArgs(Compilation &C, const JobAction &JA,
                          const toolchains::HexagonToolChain &HTC,
@@ -437,8 +532,8 @@ constructHexagonLinkArgs(Compilation &C, const JobAction &JA,
       CmdArgs.push_back(Args.MakeArgString(Crt0));
     }
     std::string Init = UseShared
-          ? Find(RootDir, StartSubDir + "/pic", "/initS.o")
-          : Find(RootDir, StartSubDir, "/init.o");
+                           ? Find(RootDir, StartSubDir + "/pic", "/initS.o")
+                           : Find(RootDir, StartSubDir, "/init.o");
     CmdArgs.push_back(Args.MakeArgString(Init));
   }
 
@@ -500,8 +595,12 @@ void hexagon::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   auto &HTC = static_cast<const toolchains::HexagonToolChain&>(getToolChain());
 
   ArgStringList CmdArgs;
-  constructHexagonLinkArgs(C, JA, HTC, Output, Inputs, Args, CmdArgs,
-                           LinkingOutput);
+  if (HTC.getTriple().isPicolibc())
+    constructHexagonPicolibcLinkArgs(C, JA, HTC, Output, Inputs, Args, CmdArgs,
+                                     LinkingOutput);
+  else
+    constructHexagonLinkArgs(C, JA, HTC, Output, Inputs, Args, CmdArgs,
+                             LinkingOutput);
 
   const char *Exec = Args.MakeArgString(HTC.GetLinkerPath());
   C.addCommand(std::make_unique<Command>(JA, *this,
@@ -583,16 +682,38 @@ void HexagonToolChain::getHexagonLibraryPaths(const ArgList &Args,
     HasG0 = *G == 0;
 
   const std::string CpuVer = GetTargetCPUVersion(Args).str();
-  for (auto &Dir : RootDirs) {
-    std::string LibDir = Dir + "/hexagon/lib";
-    std::string LibDirCpu = LibDir + '/' + CpuVer;
+  // Special-case Picolibc baremetal layout:
+  //   <install>/../target/<normalized-triple>/lib/<vXX>/G0[/pic]
+  if (getTriple().isPicolibc()) {
+    std::string SubDir = '/' + CpuVer;
+    // Force G0 for Picolibc
+    HasG0 = true;
     if (HasG0) {
       if (HasPIC)
-        LibPaths.push_back(LibDirCpu + "/G0/pic");
-      LibPaths.push_back(LibDirCpu + "/G0");
+        SubDir += "/G0/pic";
+      else
+        SubDir += "/G0";
+    }
+    if (getTriple().getOS() != llvm::Triple::Linux) {
+      for (auto &Dir : RootDirs) {
+        auto NormalizedTriple = getTriple().normalize();
+        std::string LibDir = Dir + '/' + NormalizedTriple + "/lib";
+        LibPaths.push_back(LibDir + SubDir);
+      }
+    }
+    return;
+  } else {
+    for (auto &Dir : RootDirs) {
+      std::string LibDir = Dir + "/hexagon/lib";
+      std::string LibDirCpu = LibDir + '/' + CpuVer;
+      if (HasG0) {
+        if (HasPIC)
+          LibPaths.push_back(LibDirCpu + "/G0/pic");
+        LibPaths.push_back(LibDirCpu + "/G0");
+      }
+      LibPaths.push_back(LibDirCpu);
+      LibPaths.push_back(LibDir);
     }
-    LibPaths.push_back(LibDirCpu);
-    LibPaths.push_back(LibDir);
   }
 }
 
@@ -637,7 +758,9 @@ void HexagonToolChain::AddCXXStdlibLibArgs(const ArgList &Args,
     if (Args.hasArg(options::OPT_fexperimental_library))
       CmdArgs.push_back("-lc++experimental");
     CmdArgs.push_back("-lc++abi");
-    if (UNW != ToolChain::UNW_None)
+    // For Picolibc baremetal, always link libunwind with libc++ regardless of
+    // -unwindlib setting; libunwind is the only supported unwinding library.
+    if (UNW != ToolChain::UNW_None || getTriple().isPicolibc())
       CmdArgs.push_back("-lunwind");
     break;
 
@@ -711,6 +834,16 @@ void HexagonToolChain::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
 
   const Driver &D = getDriver();
   SmallString<128> ResourceDirInclude(D.ResourceDir);
+  // Picolibc baremetal headers live under the normalized triple tree.
+  if (getTriple().isPicolibc()) {
+    if (DriverArgs.hasArg(options::OPT_nostdlibinc))
+      return;
+    std::string TargetDir = getHexagonTargetDir(D.Dir, D.PrefixDirs);
+    std::string Target = getTriple().normalize();
+    addExternCSystemInclude(DriverArgs, CC1Args,
+                            TargetDir + "/" + Target + "/include");
+    return;
+  }
   if (!IsELF) {
     llvm::sys::path::append(ResourceDirInclude, "include");
     if (!DriverArgs.hasArg(options::OPT_nobuiltininc) &&
@@ -769,11 +902,37 @@ void HexagonToolChain::addLibStdCxxIncludePaths(
                            DriverArgs, CC1Args);
 }
 
+void HexagonToolChain::AddClangCXXStdlibIncludeArgs(
+    const llvm::opt::ArgList &DriverArgs,
+    llvm::opt::ArgStringList &CC1Args) const {
+  if (DriverArgs.hasArg(options::OPT_nostdlibinc) ||
+      DriverArgs.hasArg(options::OPT_nostdincxx))
+    return;
+
+  const Driver &D = getDriver();
+  if (getTriple().getOS() != llvm::Triple::Linux) {
+    if (getTriple().isPicolibc()) {
+      StringRef InstallDir = D.Dir;
+      addExternCSystemInclude(DriverArgs, CC1Args,
+                              InstallDir + "/../target/" +
+                                  getTriple().normalize() + "/include/c++/v1");
+    } else {
+      if (getTriple().isPicolibc()) {
+        StringRef InstallDir = D.Dir;
+        addExternCSystemInclude(DriverArgs, CC1Args,
+                                InstallDir + "/../target/" +
+                                    getTriple().normalize() +
+                                    "/include/c++/v1");
+      }
+    }
+  }
+}
+
 ToolChain::CXXStdlibType
 HexagonToolChain::GetCXXStdlibType(const ArgList &Args) const {
   Arg *A = Args.getLastArg(options::OPT_stdlib_EQ);
   if (!A) {
-    if (getTriple().isMusl())
+    if (getTriple().isMusl() || getTriple().isPicolibc())
       return ToolChain::CST_Libcxx;
     else
       return ToolChain::CST_Libstdcxx;
diff --git a/clang/lib/Driver/ToolChains/Hexagon.h b/clang/lib/Driver/ToolChains/Hexagon.h
index 033d9b48cae10..446c7cea2264b 100644
--- a/clang/lib/Driver/ToolChains/Hexagon.h
+++ b/clang/lib/Driver/ToolChains/Hexagon.h
@@ -33,6 +33,11 @@ class LLVM_LIBRARY_VISIBILITY Assembler final : public Tool {
                     const InputInfo &Output, const InputInfoList &Inputs,
                     const llvm::opt::ArgList &TCArgs,
                     const char *LinkingOutput) const override;
+  void ConstructJobForPicolibc(Compilation &C, const JobAction &JA,
+                               const InputInfo &Output,
+                               const InputInfoList &Inputs,
+                               const llvm::opt::ArgList &TCArgs,
+                               const char *LinkingOutput) const;
 };
 
 class LLVM_LIBRARY_VISIBILITY Linker final : public Tool {
@@ -78,6 +83,9 @@ class LLVM_LIBRARY_VISIBILITY HexagonToolChain : public Linux {
   void
   AddClangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
                             llvm::opt::ArgStringList &CC1Args) const override;
+  void AddClangCXXStdlibIncludeArgs(
+      const llvm::opt::ArgList &DriverArgs,
+      llvm::opt::ArgStringList &CC1Args) const override;
   void addLibStdCxxIncludePaths(
       const llvm::opt::ArgList &DriverArgs,
       llvm::opt::ArgStringList &CC1Args) const override;
diff --git a/clang/test/Driver/hexagon-toolchain-picolibc.c b/clang/test/Driver/hexagon-toolchain-picolibc.c
new file mode 100644
index 0000000000000..00b092358006b
--- /dev/null
+++ b/clang/test/Driver/hexagon-toolchain-picolibc.c
@@ -0,0 +1,133 @@
+// UNSUPPORTED: system-windows
+// REQUIRES: hexagon-registered-target
+
+// -----------------------------------------------------------------------------
+// Test standard include paths
+// -----------------------------------------------------------------------------
+// RUN: %clang -### --target=hexagon-none-picolibc \
+// RUN:   -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin %s 2>&1 | FileCheck -check-prefix=CHECK-C-INCLUDES %s
+// CHECK-C-INCLUDES: "-cc1" {{.*}} "-internal-externc-isystem" "{{.*}}/Inputs/hexagon_tree/Tools/bin/../target/hexagon-unknown-none-picolibc/include"
+
+// RUN: %clangxx -### --target=hexagon-none-picolibc \
+// RUN:   -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin %s 2>&1 | FileCheck -check-prefix=CHECK-CXX-INCLUDES %s
+// CHECK-CXX-INCLUDES: "-cc1" {{.*}} "-internal-externc-isystem" "{{.*}}/Inputs/hexagon_tree/Tools/bin/../target/hexagon-unknown-none-picolibc/include/c++/v1"
+// CHECK-CXX-INCLUDES: "-internal-externc-isystem" "{{.*}}/Inputs/hexagon_tree/Tools/bin/../target/hexagon-unknown-none-picolibc/include"
+// -----------------------------------------------------------------------------
+// Passing start files for Picolibc
+// -----------------------------------------------------------------------------
+// RUN: %clang -target hexagon-none-picolibc -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-STARTUP
+// CHECK-STARTUP: "{{.*}}crt0-semihost.o"
+//
+// RUN: %clang -target hexagon-none-picolibc -nostartfiles -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-NOSTART
+// CHECK-NOSTART-NOT: "{{.*}}crt0-semihost.o"
+// -----------------------------------------------------------------------------
+// Passing  -nostdlib, -nostartfiles, -nodefaultlibs, -nolibc
+// -----------------------------------------------------------------------------
+// RUN: %clangxx -### --target=hexagon-none-picolibc \
+// RUN:   -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin \
+// RUN:   -mcpu=hexagonv60 \
+// RUN:   -nostdlib %s 2>&1 | FileCheck -check-prefix=CHECK-NOSTDLIB %s
+// CHECK-NOSTDLIB: "-cc1"
+// CHECK-NOSTDLIB: {{hexagon-link|ld}}
+// CHECK-NOSTDLIB-NOT: {{.*}}crt0-semihost.o
+// CHECK-NOSTDLIB-NOT: "-lc++"
+// CHECK-NOSTDLIB-NOT: "-lm"
+// CHECK-NOSTDLIB-NOT: "--start-group"
+// CHECK-NOSTDLIB-NOT: "-lsemihost"
+// CHECK-NOSTDLIB-NOT: "-lc"
+// CHECK-NOSTDLIB-NOT: "-lclang_rt.builtins"
+// CHECK-NOSTDLIB-NOT: "--end-group"
+
+// RUN: %clangxx -### --target=hexagon-none-picolibc \
+// RUN:   -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin \
+// RUN:   -mcpu=hexagonv60 \
+// RUN:   -nostartfiles %s 2>&1 | FileCheck -check-prefix=CHECK-NOSTARTFILES %s
+// CHECK-NOSTARTFILES: "-cc1"
+// CHECK-NOSTARTFILES: {{hexagon-link|ld}}
+// CHECK-NOSTARTFILES-NOT: {{.*}}crt0-semihost.o
+// CHECK-NOSTARTFILES: "-lc++" "-lc++abi" "-lunwind" "-lm" "--start-group" "-lsemihost" "-lc" "-lclang_rt.builtins" "--end-group"
+
+// RUN: %clangxx -### --target=hexagon-none-picolibc \
+// RUN:   -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin \
+// RUN:   -mcpu=hexagonv60 \
+// RUN:   -nodefaultlibs %s 2>&1 | FileCheck -check-prefix=CHECK-NODEFAULTLIBS %s
+// CHECK-NODEFAULTLIBS: "-cc1"
+// CHECK-NODEFAULTLIBS: {{hexagon-link|ld}}
+// CHECK-NODEFAULTLIBS: "{{.*}}crt0-semihost.o"
+// CHECK-NODEFAULTLIBS-NOT: "-lc++"
+// CHECK-NODEFAULTLIBS-NOT: "-lm"
+// CHECK-NODEFAULTLIBS-NOT: "--start-group"
+// CHECK-NODEFAULTLIBS-NOT: "-lsemihost"
+// CHECK-NODEFAULTLIBS-NOT: "-lc"
+// CHECK-NODEFAULTLIBS-NOT: "-lclang_rt.builtins"
+// CHECK-NODEFAULTLIBS-NOT: "--end-group"
+
+// RUN: %clangxx -### --target=hexagon-none-picolibc \
+// RUN:   -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin -mcpu=hexagonv60 \
+// RUN:   -nolibc %s 2>&1 | FileCheck -check-prefix=CHECK-NOLIBC %s
+// CHECK-NOLIBC: "-cc1"
+// CHECK-NOLIBC: hexagon-link
+// CHECK-NOLIBC-SAME: "{{.*}}crt0-semihost.o"
+// CHECK-NOLIBC-SAME: "-lc++"
+// CHECK-NOLIBC-SAME: "-lm"
+// CHECK-NOLIBC-SAME: "--start-group"
+// CHECK-NOLIBC-SAME: "-lsemihost"
+// CHECK-NOLIBC-NOT: "-lc"
+// CHECK-NOLIBC-SAME: "-lclang_rt.builtins"
+// CHECK-NOLIBC-SAME: "--end-group"
+// -----------------------------------------------------------------------------
+// Force compiler-rt when Picolibc is selected
+// -----------------------------------------------------------------------------
+// RUN: %clang -target hexagon-none-picolibc -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-RTLIB
+// RUN: %clangxx -target hexagon-none-picolibc -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-RTLIB
+// CHECK-RTLIB: "-lclang_rt.builtins"
+// -----------------------------------------------------------------------------
+// Force libunwind when Picolibc is selected
+// -----------------------------------------------------------------------------
+// RUN: %clang -target hexagon-none-picolibc -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-C-UNWIND
+// RUN: %clangxx -target hexagon-none-picolibc -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-CXX-UNWIND
+// CHECK-C-UNWIND-NOT: "-lunwind"
+// CHECK-CXX-UNWIND: "-lunwind"
+// -----------------------------------------------------------------------------
+// Force G0 for Picolibc
+// -----------------------------------------------------------------------------
+// RUN: %clang -target hexagon-none-picolibc -### \
+// RUN:   -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin \
+// RUN:   -mcpu=hexagonv68 %s 2>&1 | FileCheck %s --check-prefix=CHECK-G0
+// RUN: %clangxx -target hexagon-none-picolibc -### \
+// RUN:   -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin \
+// RUN:   -mcpu=hexagonv68 %s 2>&1 | FileCheck %s --check-prefix=CHECK-G0
+// CHECK-G0: "{{.*}}/G0/crt0-semihost.o"
+// CHECK-G0-SAME: "-L{{.*}}/Inputs/hexagon_tree/Tools/bin/../target/hexagon-unknown-none-picolibc/lib/v68/G0"
+// -----------------------------------------------------------------------------
+// Libc++ experimental library linkage
+// -----------------------------------------------------------------------------
+// RUN: %clangxx -### --target=hexagon-none-picolibc -fexperimental-library %s 2>&1 | FileCheck %s --check-prefix=CHECK-EXPERIMENTAL
+// CHECK-EXPERIMENTAL: "-lc++experimental"
+// -----------------------------------------------------------------------------
+// Custom -L forwarding
+// -----------------------------------------------------------------------------
+// RUN: %clang -### --target=hexagon-none-picolibc -L/foo/bar %s 2>&1 | FileCheck %s --check-prefix=CHECK-CUSTOM-L
+// CHECK-CUSTOM-L: "-L/foo/bar"
+// -----------------------------------------------------------------------------
+// Link arch flags propagation
+// -----------------------------------------------------------------------------
+// RUN: %clang -### --target=hexagon-none-picolibc -mcpu=hexagonv68 %s 2>&1 | FileCheck %s --check-prefix=CHECK-LINK-ARCH
+// CHECK-LINK-ARCH: "-march=hexagon"
+// CHECK-LINK-ARCH: "-mcpu=hexagonv68"
+// -----------------------------------------------------------------------------
+// No standard includes when -nostdinc (C only); -nostdinc++ blocks C++ headers
+// -----------------------------------------------------------------------------
+// RUN: %clang -### --target=hexagon-none-picolibc \
+// RUN:   -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin -nostdinc %s 2>&1 | FileCheck %s --check-prefix=CHECK-NOSTDINC-C
+// CHECK-NOSTDINC-C-NOT: "{{.*}}/Inputs/hexagon_tree/Tools/bin/../target/hexagon-unknown-none-picolibc/include"
+// RUN: %clangxx -### --target=hexagon-none-picolibc \
+// RUN:   -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin -nostdinc++ %s 2>&1 | FileCheck %s --check-prefix=CHECK-NOSTDINCXX
+// CHECK-NOSTDINCXX-NOT: "{{.*}}/Inputs/hexagon_tree/Tools/bin/../target/hexagon-unknown-none-picolibc/include/c++/v1"
+// CHECK-NOSTDINCXX: "-internal-externc-isystem" "{{.*}}/Inputs/hexagon_tree/Tools/bin/../target/hexagon-unknown-none-picolibc/include"
+// -----------------------------------------------------------------------------
+// C linking does not include -lm by default
+// -----------------------------------------------------------------------------
+// RUN: %clang -### --target=hexagon-none-picolibc %s 2>&1 | FileCheck %s --check-prefix=CHECK-C-NO-LM
+// CHECK-C-NO-LM-NOT: "-lm"
+// -----------------------------------------------------------------------------
diff --git a/llvm/include/llvm/TargetParser/Triple.h b/llvm/include/llvm/TargetParser/Triple.h
index 11b76cd183108..06fbc9cddfe36 100644
--- a/llvm/include/llvm/TargetParser/Triple.h
+++ b/llvm/include/llvm/TargetParser/Triple.h
@@ -311,6 +311,7 @@ class Triple {
     OpenCL,
     OpenHOS,
     Mlibc,
+    Picolibc,
 
     PAuthTest,
     MTIA,
@@ -866,6 +867,9 @@ class Triple {
            getEnvironment() == Triple::OpenHOS || isOSLiteOS();
   }
 
+  // Tests whether the environment is picolibc
+  bool isPicolibc() const { return getEnvironment() == Triple::Picolibc; }
+
   /// Tests whether the target is OHOS
   /// LiteOS default enviroment is also OHOS, but omited on triple.
   bool isO...
[truncated]

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llvmbot commented Nov 26, 2025

@llvm/pr-subscribers-clang-driver

Author: None (quic-k)

Changes

This patch adds Picolibc as part of triple so toolchains can switch the to Picolibc based on triple.
Hexagon toolchain uses the triple hexagon-none-picolibc.

Patch is 20.97 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/169613.diff

5 Files Affected:

  • (modified) clang/lib/Driver/ToolChains/Hexagon.cpp (+172-13)
  • (modified) clang/lib/Driver/ToolChains/Hexagon.h (+8)
  • (added) clang/test/Driver/hexagon-toolchain-picolibc.c (+133)
  • (modified) llvm/include/llvm/TargetParser/Triple.h (+4)
  • (modified) llvm/lib/TargetParser/Triple.cpp (+2)
diff --git a/clang/lib/Driver/ToolChains/Hexagon.cpp b/clang/lib/Driver/ToolChains/Hexagon.cpp
index 084f51721315c..151798e7e572b 100644
--- a/clang/lib/Driver/ToolChains/Hexagon.cpp
+++ b/clang/lib/Driver/ToolChains/Hexagon.cpp
@@ -273,6 +273,101 @@ void hexagon::Linker::RenderExtraToolArgs(const JobAction &JA,
                                           ArgStringList &CmdArgs) const {
 }
 
+static void constructHexagonPicolibcLinkArgs(
+    Compilation &C, const JobAction &JA,
+    const toolchains::HexagonToolChain &HTC, const InputInfo &Output,
+    const InputInfoList &Inputs, const ArgList &Args, ArgStringList &CmdArgs,
+    const char *LinkingOutput) {
+  const Driver &D = HTC.getDriver();
+  bool IsShared = Args.hasArg(options::OPT_shared);
+  bool IncStdLib = !Args.hasArg(options::OPT_nostdlib);
+  bool IncStartFiles = !Args.hasArg(options::OPT_nostartfiles);
+  bool IncDefLibs = !Args.hasArg(options::OPT_nodefaultlibs);
+  StringRef CpuVer = toolchains::HexagonToolChain::GetTargetCPUVersion(Args);
+  // Use G0 for Picolibc
+  bool UseG0 = true;
+  auto OsType = HTC.getOS();
+
+  CmdArgs.push_back("--eh-frame-hdr");
+  // Propagate arch flags to the linker when not using LLD, to match
+  // upstream Hexagon driver behavior validated by tests.
+  bool UseLLD = false;
+  const char *LinkerPath = Args.MakeArgString(HTC.GetLinkerPath(&UseLLD));
+  UseLLD = UseLLD ||
+           llvm::sys::path::filename(LinkerPath).ends_with("ld.lld") ||
+           llvm::sys::path::stem(LinkerPath).ends_with("ld.lld");
+  if (!UseLLD) {
+    CmdArgs.push_back("-march=hexagon");
+    CmdArgs.push_back(Args.MakeArgString("-mcpu=hexagon" + CpuVer));
+  }
+  CmdArgs.push_back("-o");
+  CmdArgs.push_back(Output.getFilename());
+
+  // Inputs
+  Args.addAllArgs(CmdArgs, {options::OPT_T_Group, options::OPT_s,
+                            options::OPT_t, options::OPT_u_Group});
+  AddLinkerInputs(HTC, Inputs, Args, CmdArgs, JA);
+
+  //----------------------------------------------------------------------------
+  // Start Files
+  //----------------------------------------------------------------------------
+  const std::string MCpuSuffix = "/" + CpuVer.str();
+  const std::string MCpuG0Suffix = MCpuSuffix + "/G0";
+  const std::string RootDir =
+      HTC.getHexagonTargetDir(D.Dir, D.PrefixDirs) + "/";
+  std::string NormalizedTriple =
+      HTC.getTriple().normalize(llvm::Triple::CanonicalForm::FOUR_IDENT);
+  const std::string StartSubDir =
+      NormalizedTriple + "/lib" + (UseG0 ? MCpuG0Suffix : MCpuSuffix);
+
+  if (IncStdLib && IncStartFiles) {
+    if (!IsShared) {
+      if (OsType == "none" || OsType == "unknown") {
+        std::string Crt0 = RootDir + StartSubDir + "/crt0-semihost.o";
+        CmdArgs.push_back(Args.MakeArgString(Crt0));
+      }
+    }
+  }
+
+  //----------------------------------------------------------------------------
+  // Library Search Paths
+  //----------------------------------------------------------------------------
+  const ToolChain::path_list &LibPaths = HTC.getFilePaths();
+  for (const auto &LibPath : LibPaths)
+    CmdArgs.push_back(Args.MakeArgString(StringRef("-L") + LibPath));
+  //----------------------------------------------------------------------------
+  // Libraries
+  //----------------------------------------------------------------------------
+  if (IncStdLib && IncDefLibs) {
+    if (D.CCCIsCXX()) {
+      if (HTC.ShouldLinkCXXStdlib(Args))
+        HTC.AddCXXStdlibLibArgs(Args, CmdArgs);
+      CmdArgs.push_back("-lm");
+    }
+
+    CmdArgs.push_back("--start-group");
+
+    if (!IsShared) {
+      // add OS libraries to link
+      std::vector<std::string> OsLibs{};
+      if (OsType == "none" || OsType == "unknown") {
+        OsLibs.push_back("semihost");
+      } else if (OsType == "h2") {
+        OsLibs.push_back("h2");
+      } else if (OsType == "qurt") {
+        OsLibs.push_back("qurt");
+      }
+      for (StringRef Lib : OsLibs)
+        CmdArgs.push_back(Args.MakeArgString("-l" + Lib));
+      if (!Args.hasArg(options::OPT_nolibc))
+        CmdArgs.push_back("-lc");
+    }
+    // Force compiler-rt for Picolibc
+    CmdArgs.push_back("-lclang_rt.builtins");
+    CmdArgs.push_back("--end-group");
+  }
+}
+
 static void
 constructHexagonLinkArgs(Compilation &C, const JobAction &JA,
                          const toolchains::HexagonToolChain &HTC,
@@ -437,8 +532,8 @@ constructHexagonLinkArgs(Compilation &C, const JobAction &JA,
       CmdArgs.push_back(Args.MakeArgString(Crt0));
     }
     std::string Init = UseShared
-          ? Find(RootDir, StartSubDir + "/pic", "/initS.o")
-          : Find(RootDir, StartSubDir, "/init.o");
+                           ? Find(RootDir, StartSubDir + "/pic", "/initS.o")
+                           : Find(RootDir, StartSubDir, "/init.o");
     CmdArgs.push_back(Args.MakeArgString(Init));
   }
 
@@ -500,8 +595,12 @@ void hexagon::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   auto &HTC = static_cast<const toolchains::HexagonToolChain&>(getToolChain());
 
   ArgStringList CmdArgs;
-  constructHexagonLinkArgs(C, JA, HTC, Output, Inputs, Args, CmdArgs,
-                           LinkingOutput);
+  if (HTC.getTriple().isPicolibc())
+    constructHexagonPicolibcLinkArgs(C, JA, HTC, Output, Inputs, Args, CmdArgs,
+                                     LinkingOutput);
+  else
+    constructHexagonLinkArgs(C, JA, HTC, Output, Inputs, Args, CmdArgs,
+                             LinkingOutput);
 
   const char *Exec = Args.MakeArgString(HTC.GetLinkerPath());
   C.addCommand(std::make_unique<Command>(JA, *this,
@@ -583,16 +682,38 @@ void HexagonToolChain::getHexagonLibraryPaths(const ArgList &Args,
     HasG0 = *G == 0;
 
   const std::string CpuVer = GetTargetCPUVersion(Args).str();
-  for (auto &Dir : RootDirs) {
-    std::string LibDir = Dir + "/hexagon/lib";
-    std::string LibDirCpu = LibDir + '/' + CpuVer;
+  // Special-case Picolibc baremetal layout:
+  //   <install>/../target/<normalized-triple>/lib/<vXX>/G0[/pic]
+  if (getTriple().isPicolibc()) {
+    std::string SubDir = '/' + CpuVer;
+    // Force G0 for Picolibc
+    HasG0 = true;
     if (HasG0) {
       if (HasPIC)
-        LibPaths.push_back(LibDirCpu + "/G0/pic");
-      LibPaths.push_back(LibDirCpu + "/G0");
+        SubDir += "/G0/pic";
+      else
+        SubDir += "/G0";
+    }
+    if (getTriple().getOS() != llvm::Triple::Linux) {
+      for (auto &Dir : RootDirs) {
+        auto NormalizedTriple = getTriple().normalize();
+        std::string LibDir = Dir + '/' + NormalizedTriple + "/lib";
+        LibPaths.push_back(LibDir + SubDir);
+      }
+    }
+    return;
+  } else {
+    for (auto &Dir : RootDirs) {
+      std::string LibDir = Dir + "/hexagon/lib";
+      std::string LibDirCpu = LibDir + '/' + CpuVer;
+      if (HasG0) {
+        if (HasPIC)
+          LibPaths.push_back(LibDirCpu + "/G0/pic");
+        LibPaths.push_back(LibDirCpu + "/G0");
+      }
+      LibPaths.push_back(LibDirCpu);
+      LibPaths.push_back(LibDir);
     }
-    LibPaths.push_back(LibDirCpu);
-    LibPaths.push_back(LibDir);
   }
 }
 
@@ -637,7 +758,9 @@ void HexagonToolChain::AddCXXStdlibLibArgs(const ArgList &Args,
     if (Args.hasArg(options::OPT_fexperimental_library))
       CmdArgs.push_back("-lc++experimental");
     CmdArgs.push_back("-lc++abi");
-    if (UNW != ToolChain::UNW_None)
+    // For Picolibc baremetal, always link libunwind with libc++ regardless of
+    // -unwindlib setting; libunwind is the only supported unwinding library.
+    if (UNW != ToolChain::UNW_None || getTriple().isPicolibc())
       CmdArgs.push_back("-lunwind");
     break;
 
@@ -711,6 +834,16 @@ void HexagonToolChain::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
 
   const Driver &D = getDriver();
   SmallString<128> ResourceDirInclude(D.ResourceDir);
+  // Picolibc baremetal headers live under the normalized triple tree.
+  if (getTriple().isPicolibc()) {
+    if (DriverArgs.hasArg(options::OPT_nostdlibinc))
+      return;
+    std::string TargetDir = getHexagonTargetDir(D.Dir, D.PrefixDirs);
+    std::string Target = getTriple().normalize();
+    addExternCSystemInclude(DriverArgs, CC1Args,
+                            TargetDir + "/" + Target + "/include");
+    return;
+  }
   if (!IsELF) {
     llvm::sys::path::append(ResourceDirInclude, "include");
     if (!DriverArgs.hasArg(options::OPT_nobuiltininc) &&
@@ -769,11 +902,37 @@ void HexagonToolChain::addLibStdCxxIncludePaths(
                            DriverArgs, CC1Args);
 }
 
+void HexagonToolChain::AddClangCXXStdlibIncludeArgs(
+    const llvm::opt::ArgList &DriverArgs,
+    llvm::opt::ArgStringList &CC1Args) const {
+  if (DriverArgs.hasArg(options::OPT_nostdlibinc) ||
+      DriverArgs.hasArg(options::OPT_nostdincxx))
+    return;
+
+  const Driver &D = getDriver();
+  if (getTriple().getOS() != llvm::Triple::Linux) {
+    if (getTriple().isPicolibc()) {
+      StringRef InstallDir = D.Dir;
+      addExternCSystemInclude(DriverArgs, CC1Args,
+                              InstallDir + "/../target/" +
+                                  getTriple().normalize() + "/include/c++/v1");
+    } else {
+      if (getTriple().isPicolibc()) {
+        StringRef InstallDir = D.Dir;
+        addExternCSystemInclude(DriverArgs, CC1Args,
+                                InstallDir + "/../target/" +
+                                    getTriple().normalize() +
+                                    "/include/c++/v1");
+      }
+    }
+  }
+}
+
 ToolChain::CXXStdlibType
 HexagonToolChain::GetCXXStdlibType(const ArgList &Args) const {
   Arg *A = Args.getLastArg(options::OPT_stdlib_EQ);
   if (!A) {
-    if (getTriple().isMusl())
+    if (getTriple().isMusl() || getTriple().isPicolibc())
       return ToolChain::CST_Libcxx;
     else
       return ToolChain::CST_Libstdcxx;
diff --git a/clang/lib/Driver/ToolChains/Hexagon.h b/clang/lib/Driver/ToolChains/Hexagon.h
index 033d9b48cae10..446c7cea2264b 100644
--- a/clang/lib/Driver/ToolChains/Hexagon.h
+++ b/clang/lib/Driver/ToolChains/Hexagon.h
@@ -33,6 +33,11 @@ class LLVM_LIBRARY_VISIBILITY Assembler final : public Tool {
                     const InputInfo &Output, const InputInfoList &Inputs,
                     const llvm::opt::ArgList &TCArgs,
                     const char *LinkingOutput) const override;
+  void ConstructJobForPicolibc(Compilation &C, const JobAction &JA,
+                               const InputInfo &Output,
+                               const InputInfoList &Inputs,
+                               const llvm::opt::ArgList &TCArgs,
+                               const char *LinkingOutput) const;
 };
 
 class LLVM_LIBRARY_VISIBILITY Linker final : public Tool {
@@ -78,6 +83,9 @@ class LLVM_LIBRARY_VISIBILITY HexagonToolChain : public Linux {
   void
   AddClangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
                             llvm::opt::ArgStringList &CC1Args) const override;
+  void AddClangCXXStdlibIncludeArgs(
+      const llvm::opt::ArgList &DriverArgs,
+      llvm::opt::ArgStringList &CC1Args) const override;
   void addLibStdCxxIncludePaths(
       const llvm::opt::ArgList &DriverArgs,
       llvm::opt::ArgStringList &CC1Args) const override;
diff --git a/clang/test/Driver/hexagon-toolchain-picolibc.c b/clang/test/Driver/hexagon-toolchain-picolibc.c
new file mode 100644
index 0000000000000..00b092358006b
--- /dev/null
+++ b/clang/test/Driver/hexagon-toolchain-picolibc.c
@@ -0,0 +1,133 @@
+// UNSUPPORTED: system-windows
+// REQUIRES: hexagon-registered-target
+
+// -----------------------------------------------------------------------------
+// Test standard include paths
+// -----------------------------------------------------------------------------
+// RUN: %clang -### --target=hexagon-none-picolibc \
+// RUN:   -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin %s 2>&1 | FileCheck -check-prefix=CHECK-C-INCLUDES %s
+// CHECK-C-INCLUDES: "-cc1" {{.*}} "-internal-externc-isystem" "{{.*}}/Inputs/hexagon_tree/Tools/bin/../target/hexagon-unknown-none-picolibc/include"
+
+// RUN: %clangxx -### --target=hexagon-none-picolibc \
+// RUN:   -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin %s 2>&1 | FileCheck -check-prefix=CHECK-CXX-INCLUDES %s
+// CHECK-CXX-INCLUDES: "-cc1" {{.*}} "-internal-externc-isystem" "{{.*}}/Inputs/hexagon_tree/Tools/bin/../target/hexagon-unknown-none-picolibc/include/c++/v1"
+// CHECK-CXX-INCLUDES: "-internal-externc-isystem" "{{.*}}/Inputs/hexagon_tree/Tools/bin/../target/hexagon-unknown-none-picolibc/include"
+// -----------------------------------------------------------------------------
+// Passing start files for Picolibc
+// -----------------------------------------------------------------------------
+// RUN: %clang -target hexagon-none-picolibc -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-STARTUP
+// CHECK-STARTUP: "{{.*}}crt0-semihost.o"
+//
+// RUN: %clang -target hexagon-none-picolibc -nostartfiles -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-NOSTART
+// CHECK-NOSTART-NOT: "{{.*}}crt0-semihost.o"
+// -----------------------------------------------------------------------------
+// Passing  -nostdlib, -nostartfiles, -nodefaultlibs, -nolibc
+// -----------------------------------------------------------------------------
+// RUN: %clangxx -### --target=hexagon-none-picolibc \
+// RUN:   -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin \
+// RUN:   -mcpu=hexagonv60 \
+// RUN:   -nostdlib %s 2>&1 | FileCheck -check-prefix=CHECK-NOSTDLIB %s
+// CHECK-NOSTDLIB: "-cc1"
+// CHECK-NOSTDLIB: {{hexagon-link|ld}}
+// CHECK-NOSTDLIB-NOT: {{.*}}crt0-semihost.o
+// CHECK-NOSTDLIB-NOT: "-lc++"
+// CHECK-NOSTDLIB-NOT: "-lm"
+// CHECK-NOSTDLIB-NOT: "--start-group"
+// CHECK-NOSTDLIB-NOT: "-lsemihost"
+// CHECK-NOSTDLIB-NOT: "-lc"
+// CHECK-NOSTDLIB-NOT: "-lclang_rt.builtins"
+// CHECK-NOSTDLIB-NOT: "--end-group"
+
+// RUN: %clangxx -### --target=hexagon-none-picolibc \
+// RUN:   -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin \
+// RUN:   -mcpu=hexagonv60 \
+// RUN:   -nostartfiles %s 2>&1 | FileCheck -check-prefix=CHECK-NOSTARTFILES %s
+// CHECK-NOSTARTFILES: "-cc1"
+// CHECK-NOSTARTFILES: {{hexagon-link|ld}}
+// CHECK-NOSTARTFILES-NOT: {{.*}}crt0-semihost.o
+// CHECK-NOSTARTFILES: "-lc++" "-lc++abi" "-lunwind" "-lm" "--start-group" "-lsemihost" "-lc" "-lclang_rt.builtins" "--end-group"
+
+// RUN: %clangxx -### --target=hexagon-none-picolibc \
+// RUN:   -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin \
+// RUN:   -mcpu=hexagonv60 \
+// RUN:   -nodefaultlibs %s 2>&1 | FileCheck -check-prefix=CHECK-NODEFAULTLIBS %s
+// CHECK-NODEFAULTLIBS: "-cc1"
+// CHECK-NODEFAULTLIBS: {{hexagon-link|ld}}
+// CHECK-NODEFAULTLIBS: "{{.*}}crt0-semihost.o"
+// CHECK-NODEFAULTLIBS-NOT: "-lc++"
+// CHECK-NODEFAULTLIBS-NOT: "-lm"
+// CHECK-NODEFAULTLIBS-NOT: "--start-group"
+// CHECK-NODEFAULTLIBS-NOT: "-lsemihost"
+// CHECK-NODEFAULTLIBS-NOT: "-lc"
+// CHECK-NODEFAULTLIBS-NOT: "-lclang_rt.builtins"
+// CHECK-NODEFAULTLIBS-NOT: "--end-group"
+
+// RUN: %clangxx -### --target=hexagon-none-picolibc \
+// RUN:   -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin -mcpu=hexagonv60 \
+// RUN:   -nolibc %s 2>&1 | FileCheck -check-prefix=CHECK-NOLIBC %s
+// CHECK-NOLIBC: "-cc1"
+// CHECK-NOLIBC: hexagon-link
+// CHECK-NOLIBC-SAME: "{{.*}}crt0-semihost.o"
+// CHECK-NOLIBC-SAME: "-lc++"
+// CHECK-NOLIBC-SAME: "-lm"
+// CHECK-NOLIBC-SAME: "--start-group"
+// CHECK-NOLIBC-SAME: "-lsemihost"
+// CHECK-NOLIBC-NOT: "-lc"
+// CHECK-NOLIBC-SAME: "-lclang_rt.builtins"
+// CHECK-NOLIBC-SAME: "--end-group"
+// -----------------------------------------------------------------------------
+// Force compiler-rt when Picolibc is selected
+// -----------------------------------------------------------------------------
+// RUN: %clang -target hexagon-none-picolibc -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-RTLIB
+// RUN: %clangxx -target hexagon-none-picolibc -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-RTLIB
+// CHECK-RTLIB: "-lclang_rt.builtins"
+// -----------------------------------------------------------------------------
+// Force libunwind when Picolibc is selected
+// -----------------------------------------------------------------------------
+// RUN: %clang -target hexagon-none-picolibc -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-C-UNWIND
+// RUN: %clangxx -target hexagon-none-picolibc -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-CXX-UNWIND
+// CHECK-C-UNWIND-NOT: "-lunwind"
+// CHECK-CXX-UNWIND: "-lunwind"
+// -----------------------------------------------------------------------------
+// Force G0 for Picolibc
+// -----------------------------------------------------------------------------
+// RUN: %clang -target hexagon-none-picolibc -### \
+// RUN:   -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin \
+// RUN:   -mcpu=hexagonv68 %s 2>&1 | FileCheck %s --check-prefix=CHECK-G0
+// RUN: %clangxx -target hexagon-none-picolibc -### \
+// RUN:   -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin \
+// RUN:   -mcpu=hexagonv68 %s 2>&1 | FileCheck %s --check-prefix=CHECK-G0
+// CHECK-G0: "{{.*}}/G0/crt0-semihost.o"
+// CHECK-G0-SAME: "-L{{.*}}/Inputs/hexagon_tree/Tools/bin/../target/hexagon-unknown-none-picolibc/lib/v68/G0"
+// -----------------------------------------------------------------------------
+// Libc++ experimental library linkage
+// -----------------------------------------------------------------------------
+// RUN: %clangxx -### --target=hexagon-none-picolibc -fexperimental-library %s 2>&1 | FileCheck %s --check-prefix=CHECK-EXPERIMENTAL
+// CHECK-EXPERIMENTAL: "-lc++experimental"
+// -----------------------------------------------------------------------------
+// Custom -L forwarding
+// -----------------------------------------------------------------------------
+// RUN: %clang -### --target=hexagon-none-picolibc -L/foo/bar %s 2>&1 | FileCheck %s --check-prefix=CHECK-CUSTOM-L
+// CHECK-CUSTOM-L: "-L/foo/bar"
+// -----------------------------------------------------------------------------
+// Link arch flags propagation
+// -----------------------------------------------------------------------------
+// RUN: %clang -### --target=hexagon-none-picolibc -mcpu=hexagonv68 %s 2>&1 | FileCheck %s --check-prefix=CHECK-LINK-ARCH
+// CHECK-LINK-ARCH: "-march=hexagon"
+// CHECK-LINK-ARCH: "-mcpu=hexagonv68"
+// -----------------------------------------------------------------------------
+// No standard includes when -nostdinc (C only); -nostdinc++ blocks C++ headers
+// -----------------------------------------------------------------------------
+// RUN: %clang -### --target=hexagon-none-picolibc \
+// RUN:   -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin -nostdinc %s 2>&1 | FileCheck %s --check-prefix=CHECK-NOSTDINC-C
+// CHECK-NOSTDINC-C-NOT: "{{.*}}/Inputs/hexagon_tree/Tools/bin/../target/hexagon-unknown-none-picolibc/include"
+// RUN: %clangxx -### --target=hexagon-none-picolibc \
+// RUN:   -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin -nostdinc++ %s 2>&1 | FileCheck %s --check-prefix=CHECK-NOSTDINCXX
+// CHECK-NOSTDINCXX-NOT: "{{.*}}/Inputs/hexagon_tree/Tools/bin/../target/hexagon-unknown-none-picolibc/include/c++/v1"
+// CHECK-NOSTDINCXX: "-internal-externc-isystem" "{{.*}}/Inputs/hexagon_tree/Tools/bin/../target/hexagon-unknown-none-picolibc/include"
+// -----------------------------------------------------------------------------
+// C linking does not include -lm by default
+// -----------------------------------------------------------------------------
+// RUN: %clang -### --target=hexagon-none-picolibc %s 2>&1 | FileCheck %s --check-prefix=CHECK-C-NO-LM
+// CHECK-C-NO-LM-NOT: "-lm"
+// -----------------------------------------------------------------------------
diff --git a/llvm/include/llvm/TargetParser/Triple.h b/llvm/include/llvm/TargetParser/Triple.h
index 11b76cd183108..06fbc9cddfe36 100644
--- a/llvm/include/llvm/TargetParser/Triple.h
+++ b/llvm/include/llvm/TargetParser/Triple.h
@@ -311,6 +311,7 @@ class Triple {
     OpenCL,
     OpenHOS,
     Mlibc,
+    Picolibc,
 
     PAuthTest,
     MTIA,
@@ -866,6 +867,9 @@ class Triple {
            getEnvironment() == Triple::OpenHOS || isOSLiteOS();
   }
 
+  // Tests whether the environment is picolibc
+  bool isPicolibc() const { return getEnvironment() == Triple::Picolibc; }
+
   /// Tests whether the target is OHOS
   /// LiteOS default enviroment is also OHOS, but omited on triple.
   bool isO...
[truncated]

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github-actions bot commented Nov 26, 2025 •
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✅ With the latest revision this PR passed the C/C++ code formatter.

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🐧 Linux x64 Test Results

  • 193020 tests passed
  • 6209 tests skipped

@quic-k
Add Picolibc as part of triple
5172ab3 
This patch adds Picolibc as part of triple so toolchains can switch
the to Picolibc based on triple.
Hexagon toolchain uses the triple hexagon-none-picolibc.

Signed-off-by: Kushal Pal <kushpal@qti.qualcomm.com>
androm3da
androm3da reviewed Nov 26, 2025
View reviewed changes
clang/lib/Driver/ToolChains/Hexagon.cpp
for (auto &Dir : RootDirs) {
std::string LibDir = Dir + "/hexagon/lib";
std::string LibDirCpu = LibDir + '/' + CpuVer;
// Special-case Picolibc baremetal layout:
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@androm3da androm3da Nov 26, 2025

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Once picolibc stabilizes, maybe we could consider migrating other targets to use this and make it the general case.

androm3da
androm3da reviewed Nov 26, 2025
View reviewed changes
clang/lib/Driver/ToolChains/Hexagon.cpp
case ToolChain::CST_Libstdcxx:
addLibStdCxxIncludePaths(DriverArgs, CC1Args);
break;
}
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The default case here should be handled (perhaps LLVM_UNREACHABLE?).

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quic-seaswara commented Nov 26, 2025

@MaskRay can you please take a look ?

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@quic-k @llvmbot @quic-seaswara @androm3da