[clang] [Clang][Solaris] Support --ld-path in Solaris driver (PR #163000)

Daniel Levin via cfe-commits cfe-commits at lists.llvm.org
Sat Oct 11 07:10:11 PDT 2025


https://github.com/daniel-levin updated https://github.com/llvm/llvm-project/pull/163000

>From c0ce9634a737a47b63dc3552bb7a15498b059c24 Mon Sep 17 00:00:00 2001
From: Daniel Levin <daniellevin2607 at gmail.com>
Date: Fri, 10 Oct 2025 14:54:03 +0000
Subject: [PATCH] [Clang][Solaris] Support --ld-path in Solaris driver

---
 clang/include/clang/Driver/ToolChain.h     |   2 +
 clang/lib/Driver/ToolChains/CommonArgs.cpp |   8 +-
 clang/lib/Driver/ToolChains/Solaris.cpp    | 119 ++++++++++++++-------
 clang/lib/Driver/ToolChains/Solaris.h      |  31 +++++-
 4 files changed, 119 insertions(+), 41 deletions(-)

diff --git a/clang/include/clang/Driver/ToolChain.h b/clang/include/clang/Driver/ToolChain.h
index 1425714d34110..753742067fe8c 100644
--- a/clang/include/clang/Driver/ToolChain.h
+++ b/clang/include/clang/Driver/ToolChain.h
@@ -491,6 +491,8 @@ class ToolChain {
   }
 
   /// GetDefaultLinker - Get the default linker to use.
+  /// Note: this is distinct from the 'preferred' linker, which is optionally
+  /// set at compile time using CLANG_DEFAULT_LINKER.
   virtual const char *getDefaultLinker() const { return "ld"; }
 
   /// GetDefaultRuntimeLibType - Get the default runtime library variant to use.
diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 16cc1db0a2235..87a6f9a89b904 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1480,11 +1480,11 @@ static void addSanitizerRuntime(const ToolChain &TC, const ArgList &Args,
 static bool addSanitizerDynamicList(const ToolChain &TC, const ArgList &Args,
                                     ArgStringList &CmdArgs,
                                     StringRef Sanitizer) {
-  bool LinkerIsGnuLd = solaris::isLinkerGnuLd(TC, Args);
+  bool LinkerIsSolarisLinkEditor = solaris::isLinkerSolarisLinkEditor(TC, Args);
 
   // Solaris ld defaults to --export-dynamic behaviour but doesn't support
   // the option, so don't try to pass it.
-  if (TC.getTriple().isOSSolaris() && !LinkerIsGnuLd)
+  if (TC.getTriple().isOSSolaris() && LinkerIsSolarisLinkEditor)
     return true;
   SmallString<128> SanRT(TC.getCompilerRT(Args, Sanitizer));
   if (llvm::sys::fs::exists(SanRT + ".syms")) {
@@ -1500,14 +1500,14 @@ void tools::addAsNeededOption(const ToolChain &TC,
                               bool as_needed) {
   assert(!TC.getTriple().isOSAIX() &&
          "AIX linker does not support any form of --as-needed option yet.");
-  bool LinkerIsGnuLd = solaris::isLinkerGnuLd(TC, Args);
+  bool LinkerIsSolarisLinkEditor = solaris::isLinkerSolarisLinkEditor(TC, Args);
 
   // While the Solaris 11.2 ld added --as-needed/--no-as-needed as aliases
   // for the native forms -z ignore/-z record, they are missing in Illumos,
   // so always use the native form.
   // GNU ld doesn't support -z ignore/-z record, so don't use them even on
   // Solaris.
-  if (TC.getTriple().isOSSolaris() && !LinkerIsGnuLd) {
+  if (TC.getTriple().isOSSolaris() && LinkerIsSolarisLinkEditor) {
     CmdArgs.push_back("-z");
     CmdArgs.push_back(as_needed ? "ignore" : "record");
   } else {
diff --git a/clang/lib/Driver/ToolChains/Solaris.cpp b/clang/lib/Driver/ToolChains/Solaris.cpp
index 02aa59817449d..edd794d19cbe5 100644
--- a/clang/lib/Driver/ToolChains/Solaris.cpp
+++ b/clang/lib/Driver/ToolChains/Solaris.cpp
@@ -36,11 +36,12 @@ void solaris::Assembler::ConstructJob(Compilation &C, const JobAction &JA,
   gnutools::Assembler::ConstructJob(C, JA, Output, Inputs, Args, LinkingOutput);
 }
 
-bool solaris::isLinkerGnuLd(const ToolChain &TC, const ArgList &Args) {
-  // Only used if targetting Solaris.
-  const Arg *A = Args.getLastArg(options::OPT_fuse_ld_EQ);
-  StringRef UseLinker = A ? A->getValue() : TC.getDriver().getPreferredLinker();
-  return UseLinker == "bfd" || UseLinker == "gld";
+bool solaris::isLinkerSolarisLinkEditor(const ToolChain &TC,
+                                        const ArgList &Args) {
+  auto Determination =
+      solaris::LinkerDetermination::make(TC, Args, /* EmitDiagnostics */ false);
+  return Determination.Expectations ==
+         solaris::LinkerExpectations::SolarisLinkEditor;
 }
 
 static bool getPIE(const ArgList &Args, const ToolChain &TC) {
@@ -52,30 +53,11 @@ static bool getPIE(const ArgList &Args, const ToolChain &TC) {
                       TC.isPIEDefault(Args));
 }
 
-// FIXME: Need to handle PreferredLinker here?
 std::string solaris::Linker::getLinkerPath(const ArgList &Args) const {
-  const ToolChain &ToolChain = getToolChain();
-  if (const Arg *A = Args.getLastArg(options::OPT_fuse_ld_EQ)) {
-    StringRef UseLinker = A->getValue();
-    if (!UseLinker.empty()) {
-      if (llvm::sys::path::is_absolute(UseLinker) &&
-          llvm::sys::fs::can_execute(UseLinker))
-        return std::string(UseLinker);
-
-      // Accept 'bfd' and 'gld' as aliases for the GNU linker.
-      if (UseLinker == "bfd" || UseLinker == "gld")
-        // FIXME: Could also use /usr/bin/gld here.
-        return "/usr/gnu/bin/ld";
+  auto Determination =
+      solaris::LinkerDetermination::make(getToolChain(), Args, true);
 
-      // Accept 'ld' as alias for the default linker
-      if (UseLinker != "ld")
-        ToolChain.getDriver().Diag(diag::err_drv_invalid_linker_name)
-            << A->getAsString(Args);
-    }
-  }
-
-  // getDefaultLinker() always returns an absolute path.
-  return ToolChain.getDefaultLinker();
+  return Determination.Linker;
 }
 
 void solaris::Linker::ConstructJob(Compilation &C, const JobAction &JA,
@@ -87,11 +69,11 @@ void solaris::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   const Driver &D = ToolChain.getDriver();
   const llvm::Triple::ArchType Arch = ToolChain.getArch();
   const bool IsPIE = getPIE(Args, ToolChain);
-  const bool LinkerIsGnuLd = isLinkerGnuLd(ToolChain, Args);
+  const bool LinkerIsSolarisLd = isLinkerSolarisLinkEditor(ToolChain, Args);
   ArgStringList CmdArgs;
 
   // Demangle C++ names in errors.  GNU ld already defaults to --demangle.
-  if (!LinkerIsGnuLd)
+  if (LinkerIsSolarisLd)
     CmdArgs.push_back("-C");
 
   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_shared,
@@ -101,7 +83,7 @@ void solaris::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   }
 
   if (IsPIE) {
-    if (LinkerIsGnuLd) {
+    if (!LinkerIsSolarisLd) {
       CmdArgs.push_back("-pie");
     } else {
       CmdArgs.push_back("-z");
@@ -122,7 +104,7 @@ void solaris::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     Args.ClaimAllArgs(options::OPT_pthreads);
   }
 
-  if (LinkerIsGnuLd) {
+  if (!LinkerIsSolarisLd) {
     // Set the correct linker emulation for 32- and 64-bit Solaris.
     switch (Arch) {
     case llvm::Triple::x86:
@@ -256,7 +238,7 @@ void solaris::Linker::ConstructJob(Compilation &C, const JobAction &JA,
       if (Arch == llvm::Triple::x86_64 &&
           (SA.needsAsanRt() || SA.needsStatsRt() ||
            (SA.needsUbsanRt() && !SA.requiresMinimalRuntime())) &&
-          !LinkerIsGnuLd) {
+          LinkerIsSolarisLd) {
         CmdArgs.push_back("-z");
         CmdArgs.push_back("relax=transtls");
       }
@@ -344,10 +326,10 @@ SanitizerMask Solaris::getSupportedSanitizers() const {
 }
 
 const char *Solaris::getDefaultLinker() const {
-  // FIXME: Only handle Solaris ld and GNU ld here.
-  return llvm::StringSwitch<const char *>(getDriver().getPreferredLinker())
-      .Cases("bfd", "gld", "/usr/gnu/bin/ld")
-      .Default("/usr/bin/ld");
+  // The default linker on Solaris is _always_ the Solaris Link Editor.
+  // Recall that the driver's _default_ linker is distinct from the compile-time
+  // _preferred_ linker setting CLANG_DEFAULT_LINKER, which may even be empty.
+  return "/usr/bin/ld";
 }
 
 Tool *Solaris::buildAssembler() const {
@@ -423,3 +405,68 @@ void Solaris::addLibStdCxxIncludePaths(
                            TripleStr, Multilib.includeSuffix(), DriverArgs,
                            CC1Args);
 }
+
+solaris::LinkerDetermination
+solaris::LinkerDetermination::make(const ToolChain &TC, const ArgList &Args,
+                                   bool EmitDiagnostics) {
+  // First, check --ld-path, then -fuse-ld, then the compile-time
+  // preferred linker (CLANG_DEFAULT_LINKER), then finally fall back to the
+  // platform's default - the Solaris Link Editor. This behavior is consonant
+  // with the other platforms' drivers.
+
+  auto InferExpectations =
+      [](const std::string &s) -> solaris::LinkerExpectations {
+    if (s == "ld" || s == "/bin/ld" || s == "/usr/bin/ld")
+      return solaris::LinkerExpectations::SolarisLinkEditor;
+    return solaris::LinkerExpectations::GnuLdCompatibleArgParser;
+  };
+
+  if (const Arg *A = Args.getLastArg(options::OPT_ld_path_EQ)) {
+    StringRef UseLinker = A->getValue();
+    if (!UseLinker.empty()) {
+      auto LinkerPath = std::string(UseLinker);
+      if (llvm::sys::fs::can_execute(LinkerPath))
+        return solaris::LinkerDetermination(LinkerPath,
+                                            InferExpectations(LinkerPath));
+    }
+    if (EmitDiagnostics)
+      TC.getDriver().Diag(diag::err_drv_invalid_linker_name)
+          << A->getAsString(Args);
+  } else if (const Arg *A = Args.getLastArg(options::OPT_fuse_ld_EQ)) {
+    StringRef UseLinker = A->getValue();
+    if (!UseLinker.empty()) {
+      if (llvm::sys::path::is_absolute(UseLinker) &&
+          llvm::sys::fs::can_execute(UseLinker)) {
+        auto LinkerPath = std::string(UseLinker);
+        return solaris::LinkerDetermination(LinkerPath,
+                                            InferExpectations(LinkerPath));
+      }
+
+      // Accept 'bfd' and 'gld' as aliases for the GNU linker.
+      if (UseLinker == "bfd" || UseLinker == "gld")
+        return solaris::LinkerDetermination(
+            "/usr/gnu/bin/ld",
+            solaris::LinkerExpectations::GnuLdCompatibleArgParser);
+
+      // Accept 'ld' as an alias for the default linker
+      if (UseLinker == "ld")
+        return solaris::LinkerDetermination(
+            "/usr/bin/ld", solaris::LinkerExpectations::SolarisLinkEditor);
+
+      if (EmitDiagnostics)
+        TC.getDriver().Diag(diag::err_drv_invalid_linker_name)
+            << A->getAsString(Args);
+    }
+  }
+
+  auto CompileTimePreferredLinker = TC.getDriver().getPreferredLinker();
+  if (!CompileTimePreferredLinker.empty()) {
+    auto LinkerPath = std::string(CompileTimePreferredLinker);
+    return solaris::LinkerDetermination(LinkerPath,
+                                        InferExpectations(LinkerPath));
+  }
+
+  return solaris::LinkerDetermination(
+      std::string("/usr/bin/ld"),
+      solaris::LinkerExpectations::SolarisLinkEditor);
+}
diff --git a/clang/lib/Driver/ToolChains/Solaris.h b/clang/lib/Driver/ToolChains/Solaris.h
index 9ec83b773da44..0d3a78ff09189 100644
--- a/clang/lib/Driver/ToolChains/Solaris.h
+++ b/clang/lib/Driver/ToolChains/Solaris.h
@@ -31,7 +31,8 @@ class LLVM_LIBRARY_VISIBILITY Assembler final : public gnutools::Assembler {
                     const char *LinkingOutput) const override;
 };
 
-bool isLinkerGnuLd(const ToolChain &TC, const llvm::opt::ArgList &Args);
+bool isLinkerSolarisLinkEditor(const ToolChain &TC,
+                               const llvm::opt::ArgList &Args);
 
 class LLVM_LIBRARY_VISIBILITY Linker final : public Tool {
 public:
@@ -46,6 +47,34 @@ class LLVM_LIBRARY_VISIBILITY Linker final : public Tool {
                     const llvm::opt::ArgList &TCArgs,
                     const char *LinkingOutput) const override;
 };
+
+enum class LinkerExpectations {
+  GnuLdCompatibleArgParser,
+  /// The formal name for the built-in ld on Solaris.
+  SolarisLinkEditor,
+};
+
+/// We use Solaris's built-in linker by default. It has a unique command line
+/// syntax and specific limitations. By contrast, other linkers such as lld,
+/// Mold, and Wild are compatible with GNU ld's command line syntax. Knowing
+/// _which_ linker to use is sufficient to determine the expectations of that
+/// linker. Rather than spread ad-hoc string comparisons all over the driver, we
+/// encapsulate the details of differences in the chosen linker here.
+class LinkerDetermination final {
+  LinkerDetermination(std::string Linker, LinkerExpectations Expectations)
+      : Linker(Linker), Expectations(Expectations) {}
+
+public:
+  std::string Linker;
+  LinkerExpectations Expectations;
+
+  /// Choose the correct linker based on arguments and compile-time options
+  /// recorded in the ToolChain.
+  static LinkerDetermination make(const ToolChain &TC,
+                                  const llvm::opt::ArgList &Args,
+                                  bool EmitDiagnostics);
+};
+
 } // end namespace solaris
 } // end namespace tools
 



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