commit a5cacb5ba7f1f18e7bb6f6709e42683eeb7e6470
Author: Sterling Augustine <saugustine@google.com>
Date:   Tue Mar 19 20:01:59 2019 +0000

    Add --unwindlib=[libgcc|compiler-rt] to parallel --rtlib= [take 2]
    
    "clang++ hello.cc --rtlib=compiler-rt"
    
    now can works without specifying additional unwind or exception
    handling libraries.
    
    This reworked version of the feature no longer modifies today's default
    unwind library for compiler-rt: which is nothing. Rather, a user
    can specify -DCLANG_DEFAULT_UNWINDLIB=libunwind when configuring
    the compiler.
    
    This should address the issues from the previous version.
    
    Update tests for new --unwindlib semantics.
    
    Differential Revision: https://reviews.llvm.org/D59109
    
    llvm-svn: 356508

diff --git clang/CMakeLists.txt clang/CMakeLists.txt
index 52b881939499..2c3fb62f6e73 100644
--- clang/CMakeLists.txt
+++ clang/CMakeLists.txt
@@ -244,6 +244,24 @@ if (NOT(CLANG_DEFAULT_RTLIB STREQUAL "" OR
     "Default runtime library to use (\"libgcc\" or \"compiler-rt\", empty for platform default)" FORCE)
 endif()
 
+set(CLANG_DEFAULT_UNWINDLIB "" CACHE STRING
+  "Default unwind library to use (\"none\" \"libgcc\" or \"libunwind\", empty to match runtime library.)")
+if (CLANG_DEFAULT_UNWINDLIB STREQUAL "")
+  if (CLANG_DEFAULT_RTLIB STREQUAL "libgcc")
+    set (CLANG_DEFAULT_UNWINDLIB "libgcc" CACHE STRING "" FORCE)
+  elseif (CLANG_DEFAULT_RTLIBS STREQUAL "libunwind")
+    set (CLANG_DEFAULT_UNWINDLIB "none" CACHE STRING "" FORCE)
+  endif()
+endif()
+
+if (NOT(CLANG_DEFAULT_UNWINDLIB STREQUAL "none" OR
+        CLANG_DEFAULT_UNWINDLIB STREQUAL "libgcc" OR
+        CLANG_DEFAULT_UNWINDLIB STREQUAL "libunwind"))
+  message(WARNING "Resetting default unwindlib to use platform default")
+  set(CLANG_DEFAULT_UNWINDLIB "" CACHE STRING
+    "Default unwind library to use (\"none\" \"libgcc\" or \"libunwind\", empty for none)" FORCE)
+endif()
+
 set(CLANG_DEFAULT_OBJCOPY "objcopy" CACHE STRING
   "Default objcopy executable to use.")
 
diff --git clang/include/clang/Basic/DiagnosticDriverKinds.td clang/include/clang/Basic/DiagnosticDriverKinds.td
index 7f75f45c6578..7e1bb33b5cef 100644
--- clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -52,6 +52,10 @@ def err_drv_invalid_rtlib_name : Error<
   "invalid runtime library name in argument '%0'">;
 def err_drv_unsupported_rtlib_for_platform : Error<
   "unsupported runtime library '%0' for platform '%1'">;
+def err_drv_invalid_unwindlib_name : Error<
+  "invalid unwind library name in argument '%0'">;
+def err_drv_incompatible_unwindlib : Error<
+  "--rtlib=libgcc requires --unwindlib=libgcc">;
 def err_drv_invalid_stdlib_name : Error<
   "invalid library name in argument '%0'">;
 def err_drv_invalid_output_with_multiple_archs : Error<
diff --git clang/include/clang/Config/config.h.cmake clang/include/clang/Config/config.h.cmake
index 1d624450b9d9..2d4cb747e87e 100644
--- clang/include/clang/Config/config.h.cmake
+++ clang/include/clang/Config/config.h.cmake
@@ -23,6 +23,9 @@
 /* Default runtime library to use. */
 #define CLANG_DEFAULT_RTLIB "${CLANG_DEFAULT_RTLIB}"
 
+/* Default unwind library to use. */
+#define CLANG_DEFAULT_UNWINDLIB "${CLANG_DEFAULT_UNWINDLIB}"
+
 /* Default objcopy to use */
 #define CLANG_DEFAULT_OBJCOPY "${CLANG_DEFAULT_OBJCOPY}"
 
diff --git clang/include/clang/Driver/Options.td clang/include/clang/Driver/Options.td
index 601aa8744967..0e74a2d36dea 100644
--- clang/include/clang/Driver/Options.td
+++ clang/include/clang/Driver/Options.td
@@ -2428,6 +2428,8 @@ def std_EQ : Joined<["-", "--"], "std=">, Flags<[CC1Option]>,
   }]>;
 def stdlib_EQ : Joined<["-", "--"], "stdlib=">, Flags<[CC1Option]>,
   HelpText<"C++ standard library to use">, Values<"libc++,libstdc++,platform">;
+def unwindlib_EQ : Joined<["-", "--"], "unwindlib=">, Flags<[CC1Option]>,
+  HelpText<"Unwind library to use">, Values<"libgcc,unwindlib,platform">;
 def sub__library : JoinedOrSeparate<["-"], "sub_library">;
 def sub__umbrella : JoinedOrSeparate<["-"], "sub_umbrella">;
 def system_header_prefix : Joined<["--"], "system-header-prefix=">,
diff --git clang/include/clang/Driver/ToolChain.h clang/include/clang/Driver/ToolChain.h
index 2f9c2c190e32..d5b131bcf112 100644
--- clang/include/clang/Driver/ToolChain.h
+++ clang/include/clang/Driver/ToolChain.h
@@ -99,6 +99,12 @@ public:
     RLT_Libgcc
   };
 
+  enum UnwindLibType {
+    UNW_None,
+    UNW_CompilerRT,
+    UNW_Libgcc
+  };
+
   enum RTTIMode {
     RM_Enabled,
     RM_Disabled,
@@ -352,6 +358,10 @@ public:
     return ToolChain::CST_Libstdcxx;
   }
 
+  virtual UnwindLibType GetDefaultUnwindLibType() const {
+    return ToolChain::UNW_None;
+  }
+
   virtual std::string getCompilerRTPath() const;
 
   virtual std::string getCompilerRT(const llvm::opt::ArgList &Args,
@@ -484,6 +494,10 @@ public:
   // given compilation arguments.
   virtual CXXStdlibType GetCXXStdlibType(const llvm::opt::ArgList &Args) const;
 
+  // GetUnwindLibType - Determine the unwind library type to use with the
+  // given compilation arguments.
+  virtual UnwindLibType GetUnwindLibType(const llvm::opt::ArgList &Args) const;
+
   /// AddClangCXXStdlibIncludeArgs - Add the clang -cc1 level arguments to set
   /// the include paths to use for the given C++ standard library type.
   virtual void
diff --git clang/lib/Driver/ToolChain.cpp clang/lib/Driver/ToolChain.cpp
index cf3db34688df..d980dd5d23fb 100644
--- clang/lib/Driver/ToolChain.cpp
+++ clang/lib/Driver/ToolChain.cpp
@@ -665,6 +665,33 @@ ToolChain::RuntimeLibType ToolChain::GetRuntimeLibType(
   return GetDefaultRuntimeLibType();
 }
 
+ToolChain::UnwindLibType ToolChain::GetUnwindLibType(
+    const ArgList &Args) const {
+  const Arg *A = Args.getLastArg(options::OPT_unwindlib_EQ);
+  StringRef LibName = A ? A->getValue() : CLANG_DEFAULT_UNWINDLIB;
+
+  if (LibName == "none")
+    return ToolChain::UNW_None;
+  else if (LibName == "platform" || LibName == "") {
+    ToolChain::RuntimeLibType RtLibType = GetRuntimeLibType(Args);
+    if (RtLibType == ToolChain::RLT_CompilerRT)
+      return ToolChain::UNW_None;
+    else if (RtLibType == ToolChain::RLT_Libgcc)
+      return ToolChain::UNW_Libgcc;
+  } else if (LibName == "libunwind") {
+    if (GetRuntimeLibType(Args) == RLT_Libgcc)
+      getDriver().Diag(diag::err_drv_incompatible_unwindlib);
+    return ToolChain::UNW_CompilerRT;
+  } else if (LibName == "libgcc")
+    return ToolChain::UNW_Libgcc;
+
+  if (A)
+    getDriver().Diag(diag::err_drv_invalid_unwindlib_name)
+        << A->getAsString(Args);
+
+  return GetDefaultUnwindLibType();
+}
+
 ToolChain::CXXStdlibType ToolChain::GetCXXStdlibType(const ArgList &Args) const{
   const Arg *A = Args.getLastArg(options::OPT_stdlib_EQ);
   StringRef LibName = A ? A->getValue() : CLANG_DEFAULT_CXX_STDLIB;
diff --git clang/test/Driver/compiler-rt-unwind.c clang/test/Driver/compiler-rt-unwind.c
new file mode 100644
index 000000000000..00024dfa7ed3
--- /dev/null
+++ clang/test/Driver/compiler-rt-unwind.c
@@ -0,0 +1,49 @@
+// General tests that the driver handles combinations of --rtlib=XXX and
+// --unwindlib=XXX properly.
+//
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
+// RUN:     --target=x86_64-unknown-linux \
+// RUN:     --gcc-toolchain="" \
+// RUN:   | FileCheck --check-prefix=RTLIB-EMPTY %s
+// RTLIB-EMPTY: "{{.*}}lgcc"
+// RTLIB-EMPTY: "{{.*}}-lgcc_s"
+//
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
+// RUN:     --target=x86_64-unknown-linux -rtlib=libgcc \
+// RUN:     --gcc-toolchain="" \
+// RUN:   | FileCheck --check-prefix=RTLIB-GCC %s
+// RTLIB-GCC: "{{.*}}lgcc"
+// RTLIB-GCC: "{{.*}}lgcc_s"
+//
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
+// RUN:     --target=x86_64-unknown-linux -rtlib=libgcc --unwindlib=libunwind \
+// RUN:     --gcc-toolchain="" \
+// RUN:   | FileCheck --check-prefix=RTLIB-GCC-UNWINDLIB-COMPILER-RT %s
+// RTLIB-GCC-UNWINDLIB-COMPILER-RT: "{{.*}}lgcc"
+// RTLIB-GCC-UNWINDLIB-COMPILER-RT: "{{.*}}lunwind"
+//
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1   \
+// RUN:     --target=x86_64-unknown-linux -rtlib=compiler-rt \
+// RUN:     --gcc-toolchain="" \
+// RUN:   | FileCheck --check-prefix=RTLIB-COMPILER-RT %s
+// RTLIB-COMPILER-RT: "{{.*}}libclang_rt.builtins-x86_64.a"
+//
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1   \
+// RUN:     --target=x86_64-unknown-linux -rtlib=compiler-rt --unwindlib=libgcc \
+// RUN:     --gcc-toolchain="" \
+// RUN:   | FileCheck --check-prefix=RTLIB-COMPILER-RT-UNWINDLIB-GCC %s
+// RTLIB-COMPILER-RT-UNWINDLIB-GCC: "{{.*}}libclang_rt.builtins-x86_64.a"
+// RTLIB-COMPILER-RT-UNWINDLIB-GCC: "{{.*}}lgcc_s"
+//
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1              \
+// RUN:     --target=x86_64-unknown-linux -rtlib=compiler-rt --unwindlib=libgcc \
+// RUN:     -static --gcc-toolchain="" \
+// RUN:   | FileCheck --check-prefix=RTLIB-COMPILER-RT-UNWINDLIB-GCC-STATIC %s
+// RTLIB-COMPILER-RT-UNWINDLIB-GCC-STATIC: "{{.*}}libclang_rt.builtins-x86_64.a"
+// RTLIB-COMPILER-RT-UNWINDLIB-GCC-STATIC: "{{.*}}lgcc_eh"
+//
+// RUN: not %clang -no-canonical-prefixes %s -o %t.o 2> %t.err              \
+// RUN:     --target=x86_64-unknown-linux -rtlib=libgcc --unwindlib=libunwind \
+// RUN:     --gcc-toolchain="" \
+// RUN: FileCheck --input-file=%t.err --check-prefix=RTLIB-GCC-UNWINDLIB-COMPILER_RT %s
+// RTLIB-GCC-UNWINDLIB-COMPILER_RT: "{{[.|\\\n]*}}--rtlib=libgcc requires --unwindlib=libgcc"