Formalize FreeBSD support of compiler rt

[trixirt]

Summary

FreeBSD's libgcc and libgcc_p are symlinks to libcompiler_rt and libcompiler_rt_p
Start using the compiler rt libs directly.

[bsdjhb]

My only question is if we want an OS version check as the FreeBSD driver does now for libc++ vs libstdc++? FreeBSD started using libcompiler_rt for libgcc.a in 9.0.

[krytarowski]

What's wrong with the symlink approach?

[trixirt]

I think it is overkill to look for fbsd 8, it was eol-ed 2015, and 9 in 2016.
A native build of clang 7 on fbsd 8 would be difficult to pull off, needing at least 1-3 intermediate clang's/gcc's

[trixirt]

The symlinks were useful in the transition from gcc to clang.
Now they don't serve any purpose.
Clang uses libcompiler_rt, not libgcc.

lib/Driver/ToolChains/CommonArgs.cpp

 
 void tools::AddRunTimeLibs(const ToolChain &TC, const Driver &D,
                            ArgStringList &CmdArgs, const ArgList &Args) {
   // Make use of compiler-rt if --rtlib option is used
   ToolChain::RuntimeLibType RLT = TC.GetRuntimeLibType(Args);
 
   switch (RLT) {
   case ToolChain::RLT_CompilerRT:
-    CmdArgs.push_back(TC.getCompilerRTArgString(Args, "builtins"));
+    if (llvm::Triple::FreeBSD == TC.getTriple().getOS()) {
+      if (Args.hasArg(options::OPT_pg))
+        CmdArgs.push_back("-lcompiler_rt_p");
+      else
+        CmdArgs.push_back("-lcompiler_rt");
+    } else {
+      CmdArgs.push_back(TC.getCompilerRTArgString(Args, "builtins"));
+    }
     break;
   case ToolChain::RLT_Libgcc:
     // Make sure libgcc is not used under MSVC environment by default
     if (TC.getTriple().isKnownWindowsMSVCEnvironment()) {
       // Issue error diagnostic if libgcc is explicitly specified
       // through command line as --rtlib option argument.
       if (Args.hasArg(options::OPT_rtlib_EQ)) {
         TC.getDriver().Diag(diag::err_drv_unsupported_rtlib_for_platform)

lib/Driver/ToolChains/FreeBSD.h

public:
   llvm::ExceptionHandling GetExceptionModel(
       const llvm::opt::ArgList &Args) const override;
   bool isPIEDefault() const override;
   SanitizerMask getSupportedSanitizers() const override;
   unsigned GetDefaultDwarfVersion() const override { return 2; }
   // Until dtrace (via CTF) and LLDB can deal with distributed debug info,
   // FreeBSD defaults to standalone/full debug info.
   bool GetDefaultStandaloneDebug() const override { return true; }
-
+  RuntimeLibType GetDefaultRuntimeLibType() const override { return ToolChain::RLT_CompilerRT; }
 protected:
   Tool *buildAssembler() const override;
   Tool *buildLinker() const override;
 };
 
 } // end namespace toolchains
 } // end namespace driver
 } // end namespace clang
 
 #endif // LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_FREEBSD_H

lib/Driver/ToolChains/FreeBSD.cpp

         CmdArgs.push_back("-lm_p");
       else
         CmdArgs.push_back("-lm");
     }
     if (NeedsSanitizerDeps)
       linkSanitizerRuntimeDeps(ToolChain, CmdArgs);
     // FIXME: For some reason GCC passes -lgcc and -lgcc_s before adding
     // the default system libraries. Just mimic this for now.
-    if (Args.hasArg(options::OPT_pg))
-      CmdArgs.push_back("-lgcc_p");
-    else
-      CmdArgs.push_back("-lgcc");
+    AddRunTimeLibs(ToolChain, D, CmdArgs, Args);
+
     if (Args.hasArg(options::OPT_static)) {
       CmdArgs.push_back("-lgcc_eh");
     } else if (Args.hasArg(options::OPT_pg)) {
       CmdArgs.push_back("-lgcc_eh_p");
     } else {
       CmdArgs.push_back("--as-needed");
       CmdArgs.push_back("-lgcc_s");
       CmdArgs.push_back("--no-as-needed");
     }
 
     if (Args.hasArg(options::OPT_pthread)) {
       if (Args.hasArg(options::OPT_pg))
         CmdArgs.push_back("-lpthread_p");
       else
         CmdArgs.push_back("-lpthread");
     }
 
     if (Args.hasArg(options::OPT_pg)) {
       if (Args.hasArg(options::OPT_shared))
         CmdArgs.push_back("-lc");
       else
         CmdArgs.push_back("-lc_p");
-      CmdArgs.push_back("-lgcc_p");
     } else {
       CmdArgs.push_back("-lc");
-      CmdArgs.push_back("-lgcc");
     }
 
+    AddRunTimeLibs(ToolChain, D, CmdArgs, Args);
+
     if (Args.hasArg(options::OPT_static)) {
       CmdArgs.push_back("-lgcc_eh");
     } else if (Args.hasArg(options::OPT_pg)) {
       CmdArgs.push_back("-lgcc_eh_p");
     } else {
       CmdArgs.push_back("--as-needed");
       CmdArgs.push_back("-lgcc_s");
       CmdArgs.push_back("--no-as-needed");

test/Driver/freebsd.c

 // RUN: %clang -no-canonical-prefixes \
 // RUN:   -target aarch64-pc-freebsd11 %s                              \
 // RUN:   --sysroot=%S/Inputs/basic_freebsd64_tree -### 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-ARM64 %s
 // CHECK-ARM64: "-cc1" "-triple" "aarch64-pc-freebsd11"
 // CHECK-ARM64: ld{{.*}}" "--sysroot=[[SYSROOT:[^"]+]]"
-// CHECK-ARM64: "--eh-frame-hdr" "-dynamic-linker" "{{.*}}ld-elf{{.*}}" "-o" "a.out" "{{.*}}crt1.o" "{{.*}}crti.o" "{{.*}}crtbegin.o" "-L[[SYSROOT]]/usr/lib" "{{.*}}.o" "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed" "-lc" "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed" "{{.*}}crtend.o" "{{.*}}crtn.o"
+// CHECK-ARM64: "--eh-frame-hdr" "-dynamic-linker" "{{.*}}ld-elf{{.*}}" "-o" "a.out" "{{.*}}crt1.o" "{{.*}}crti.o" "{{.*}}crtbegin.o" "-L[[SYSROOT]]/usr/lib" "{{.*}}.o" "-lcompiler_rt" "--as-needed" "-lgcc_s" "--no-as-needed" "-lc" "-lcompiler_rt" "--as-needed" "-lgcc_s" "--no-as-needed" "{{.*}}crtend.o" "{{.*}}crtn.o"
+// RUN: %clang -no-canonical-prefixes \
+// RUN:   -target aarch64-pc-freebsd11 %s                              \
+// RUN:   --sysroot=%S/Inputs/basic_freebsd64_tree -### -pg 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-ARM64_PG %s
+// CHECK-ARM64_PG: "-cc1" "-triple" "aarch64-pc-freebsd11"
+// CHECK-ARM64_PG: ld{{.*}}" "--sysroot=[[SYSROOT:[^"]+]]"
+// CHECK-ARM64_PG: "--eh-frame-hdr" "-dynamic-linker" "{{.*}}ld-elf{{.*}}" "-o" "a.out" "{{.*}}crt1.o" "{{.*}}crti.o" "{{.*}}crtbegin.o" "-L[[SYSROOT]]/usr/lib" "{{.*}}.o" "-lcompiler_rt_p" "-lgcc_eh_p" "-lc_p" "-lcompiler_rt_p" "-lgcc_eh_p" "{{.*}}crtend.o" "{{.*}}crtn.o"
+//
+// RUN: %clang -no-canonical-prefixes \
+// RUN:   -target aarch64-pc-freebsd11 %s                              \
+// RUN:   --sysroot=%S/Inputs/basic_freebsd64_tree -### -pg -static 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-ARM64_PG_STATIC %s
+// CHECK-ARM64_PG_STATIC: "-cc1" "-triple" "aarch64-pc-freebsd11"
+// CHECK-ARM64_PG_STATIC: ld{{.*}}" "--sysroot=[[SYSROOT:[^"]+]]"
+// CHECK-ARM64_PG_STATIC: "--eh-frame-hdr" "-Bstatic" "-o" "a.out" "{{.*}}crt1.o" "{{.*}}crti.o" "{{.*}}crtbeginT.o" "-L[[SYSROOT]]/usr/lib" "{{.*}}.o" "-lcompiler_rt_p" "-lgcc_eh" "-lc_p" "-lcompiler_rt_p" "-lgcc_eh" "{{.*}}crtend.o" "{{.*}}crtn.o"
 //
 // RUN: %clang -no-canonical-prefixes \
 // RUN:   -target powerpc-pc-freebsd8 %s    \
 // RUN:   --sysroot=%S/Inputs/basic_freebsd_tree -### 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-PPC %s
 // CHECK-PPC: "-cc1" "-triple" "powerpc-pc-freebsd8"
 // CHECK-PPC: ld{{.*}}" "--sysroot=[[SYSROOT:[^"]+]]"
-// CHECK-PPC: "--eh-frame-hdr" "-dynamic-linker" "{{.*}}ld-elf{{.*}}" "-o" "a.out" "{{.*}}crt1.o" "{{.*}}crti.o" "{{.*}}crtbegin.o" "-L[[SYSROOT]]/usr/lib" "{{.*}}.o" "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed" "-lc" "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed" "{{.*}}crtend.o" "{{.*}}crtn.o"
+// CHECK-PPC: "--eh-frame-hdr" "-dynamic-linker" "{{.*}}ld-elf{{.*}}" "-o" "a.out" "{{.*}}crt1.o" "{{.*}}crti.o" "{{.*}}crtbegin.o" "-L[[SYSROOT]]/usr/lib" "{{.*}}.o" "-lcompiler_rt" "--as-needed" "-lgcc_s" "--no-as-needed" "-lc" "-lcompiler_rt" "--as-needed" "-lgcc_s" "--no-as-needed" "{{.*}}crtend.o" "{{.*}}crtn.o"
 //
 // RUN: %clang -no-canonical-prefixes \
 // RUN:   -target powerpc64-pc-freebsd8 %s                              \
 // RUN:   --sysroot=%S/Inputs/basic_freebsd64_tree -### 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-PPC64 %s
 // CHECK-PPC64: "-cc1" "-triple" "powerpc64-pc-freebsd8"
 // CHECK-PPC64: ld{{.*}}" "--sysroot=[[SYSROOT:[^"]+]]"
-// CHECK-PPC64: "--eh-frame-hdr" "-dynamic-linker" "{{.*}}ld-elf{{.*}}" "-o" "a.out" "{{.*}}crt1.o" "{{.*}}crti.o" "{{.*}}crtbegin.o" "-L[[SYSROOT]]/usr/lib" "{{.*}}.o" "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed" "-lc" "-lgcc" "--as-needed" "-lgcc_s" "--no-as-needed" "{{.*}}crtend.o" "{{.*}}crtn.o"
+// CHECK-PPC64: "--eh-frame-hdr" "-dynamic-linker" "{{.*}}ld-elf{{.*}}" "-o" "a.out" "{{.*}}crt1.o" "{{.*}}crti.o" "{{.*}}crtbegin.o" "-L[[SYSROOT]]/usr/lib" "{{.*}}.o" "-lcompiler_rt" "--as-needed" "-lgcc_s" "--no-as-needed" "-lc" "-lcompiler_rt" "--as-needed" "-lgcc_s" "--no-as-needed" "{{.*}}crtend.o" "{{.*}}crtn.o"
 //
 //
 // Check that -m32 properly adjusts the toolchain flags.
 //
 // RUN: %clang -no-canonical-prefixes -target x86_64-pc-freebsd8 -m32 %s \
 // RUN:   --sysroot=%S/Inputs/multiarch_freebsd64_tree -### 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-LIB32 %s
 // CHECK-LIB32: "-cc1" "-triple" "i386-pc-freebsd8"