[Driver] Support UBSan multilib

[phosek]

Summary

This is analogous to the existing ASan multilib.

[leonardchan]

LGTM

[mcgrathr]

clang/cmake/caches/Fuchsia-stage2.cmake

214–215

Don't you need plain +ubsan instances of these like for +asan above?

216–217

Standalone ubsan doesn't replace the allocator, so these shouldn't be overridden for it like they are for asan.

clang/lib/Driver/ToolChains/Fuchsia.cpp

205

This being the case, should we be adding -fsanitize=undefined to the libc++ (et al) build for asan?
I guess that's an orthogonal change, really.

217

This is getting to be a lot of individual ordered integer constants to maintain.
Can we just define a local enum to represent the ordering and use symbolic names in each call?

clang/cmake/caches/Fuchsia-stage2.cmake

foreach(target x86_64;aarch64)
 
     set(RUNTIMES_${target}-unknown-fuchsia+asan+noexcept_LLVM_BUILD_COMPILER_RT OFF CACHE BOOL "")
     set(RUNTIMES_${target}-unknown-fuchsia+asan+noexcept_LLVM_USE_SANITIZER "Address" CACHE STRING "")
     set(RUNTIMES_${target}-unknown-fuchsia+asan+noexcept_LIBCXXABI_ENABLE_NEW_DELETE_DEFINITIONS OFF CACHE BOOL "")
     set(RUNTIMES_${target}-unknown-fuchsia+asan+noexcept_LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS OFF CACHE BOOL "")
     set(RUNTIMES_${target}-unknown-fuchsia+asan+noexcept_LIBCXXABI_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
     set(RUNTIMES_${target}-unknown-fuchsia+asan+noexcept_LIBCXX_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
 
+    set(RUNTIMES_${target}-unknown-fuchsia+ubsan+noexcept_LLVM_BUILD_COMPILER_RT OFF CACHE BOOL "")
+    set(RUNTIMES_${target}-unknown-fuchsia+ubsan+noexcept_LLVM_USE_SANITIZER "Undefined" CACHE STRING "")
+    set(RUNTIMES_${target}-unknown-fuchsia+ubsan+noexcept_LIBCXXABI_ENABLE_NEW_DELETE_DEFINITIONS OFF CACHE BOOL "")
+    set(RUNTIMES_${target}-unknown-fuchsia+ubsan+noexcept_LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS OFF CACHE BOOL "")
+    set(RUNTIMES_${target}-unknown-fuchsia+ubsan+noexcept_LIBCXXABI_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
+    set(RUNTIMES_${target}-unknown-fuchsia+ubsan+noexcept_LIBCXX_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
+
     # Use .build-id link.
     list(APPEND RUNTIME_BUILD_ID_LINK "${target}-unknown-fuchsia")
   endforeach()
 
-  set(LLVM_RUNTIME_MULTILIBS "asan;noexcept;asan+noexcept" CACHE STRING "")
+  set(LLVM_RUNTIME_MULTILIBS "asan;noexcept;asan+noexcept;ubsan;ubsan+noexcept" CACHE STRING "")
   set(LLVM_RUNTIME_MULTILIB_asan_TARGETS "x86_64-unknown-fuchsia;aarch64-unknown-fuchsia" CACHE STRING "")
   set(LLVM_RUNTIME_MULTILIB_noexcept_TARGETS "x86_64-unknown-fuchsia;aarch64-unknown-fuchsia" CACHE STRING "")
   set(LLVM_RUNTIME_MULTILIB_asan+noexcept_TARGETS "x86_64-unknown-fuchsia;aarch64-unknown-fuchsia" CACHE STRING "")
+  set(LLVM_RUNTIME_MULTILIB_ubsan_TARGETS "x86_64-unknown-fuchsia;aarch64-unknown-fuchsia" CACHE STRING "")
+  set(LLVM_RUNTIME_MULTILIB_ubsan+noexcept_TARGETS "x86_64-unknown-fuchsia;aarch64-unknown-fuchsia" CACHE STRING "")
 endif()
 
 set(LLVM_BUILTIN_TARGETS "${BUILTIN_TARGETS}" CACHE STRING "")
 set(LLVM_RUNTIME_TARGETS "${RUNTIME_TARGETS}" CACHE STRING "")
 set(LLVM_RUNTIME_BUILD_ID_LINK_TARGETS "${RUNTIME_BUILD_ID_LINK}" CACHE STRING "")
 
 # Setup toolchain.
 set(LLVM_INSTALL_TOOLCHAIN_ONLY ON CACHE BOOL "")

clang/lib/Driver/ToolChains/Fuchsia.cpp

auto FilePaths = [&](const Multilib &M) -> std::vector<std::string> {
     return FP;
   };
 
   Multilibs.push_back(Multilib());
   // Use the noexcept variant with -fno-exceptions to avoid the extra overhead.
   Multilibs.push_back(Multilib("noexcept", {}, {}, 1)
                           .flag("-fexceptions")
                           .flag("+fno-exceptions"));
+  // UBSan has lower priority than ASan so we pick the latter when both are set.
+  Multilibs.push_back(Multilib("ubsan", {}, {}, 2)
+                          .flag("+fsanitize=undefined"));
+  // Use the ubsan+noexcept variant with UBSan and -fno-exceptions.
+  Multilibs.push_back(Multilib("ubsan+noexcept", {}, {}, 3)
+                          .flag("+fsanitize=undefined")
+                          .flag("-fexceptions")
+                          .flag("+fno-exceptions"));
   // ASan has higher priority because we always want the instrumentated version.
-  Multilibs.push_back(Multilib("asan", {}, {}, 2)
+  Multilibs.push_back(Multilib("asan", {}, {}, 4)
                           .flag("+fsanitize=address"));
   // Use the asan+noexcept variant with ASan and -fno-exceptions.
-  Multilibs.push_back(Multilib("asan+noexcept", {}, {}, 3)
+  Multilibs.push_back(Multilib("asan+noexcept", {}, {}, 5)
                           .flag("+fsanitize=address")
                           .flag("-fexceptions")
                           .flag("+fno-exceptions"));
   Multilibs.FilterOut([&](const Multilib &M) {
     std::vector<std::string> RD = FilePaths(M);
     return std::all_of(RD.begin(), RD.end(), [&](std::string P) {
       return !getVFS().exists(P);
     });
   });
 
   Multilib::flags_list Flags;
   addMultilibFlag(
       Args.hasFlag(options::OPT_fexceptions, options::OPT_fno_exceptions, true),
       "fexceptions", Flags);
+  addMultilibFlag(getSanitizerArgs().needsUbsanRt(), "fsanitize=undefined", Flags);
   addMultilibFlag(getSanitizerArgs().needsAsanRt(), "fsanitize=address", Flags);
   Multilibs.setFilePathsCallback(FilePaths);
 
   if (Multilibs.select(Flags, SelectedMultilib))
     if (!SelectedMultilib.isDefault())
       if (const auto &PathsCallback = Multilibs.filePathsCallback())
         for (const auto &Path : PathsCallback(SelectedMultilib))
           // Prepend the multilib path to ensure it takes the precedence.

clang/test/Driver/fuchsia.cpp

 // CHECK-NOSTDLIBXX-NOT: "-lm"
 // CHECK-NOSTDLIBXX: "-lc"
 
 // RUN: %clangxx %s -### --target=x86_64-fuchsia \
 // RUN:     -ccc-install-dir %S/Inputs/basic_fuchsia_tree/bin \
 // RUN:     -resource-dir=%S/Inputs/resource_dir_with_per_target_subdir \
 // RUN:     -fuse-ld=lld 2>&1\
 // RUN:     | FileCheck %s -check-prefixes=CHECK-MULTILIB-X86
-// RUN: %clangxx %s -### --target=x86_64-fuchsia -fsanitize=address \
+// RUN: %clangxx %s -### --target=x86_64-fuchsia -fno-exceptions \
 // RUN:     -ccc-install-dir %S/Inputs/basic_fuchsia_tree/bin \
 // RUN:     -resource-dir=%S/Inputs/resource_dir_with_per_target_subdir \
 // RUN:     -fuse-ld=lld 2>&1\
-// RUN:     | FileCheck %s -check-prefixes=CHECK-MULTILIB-X86,CHECK-MULTILIB-ASAN-X86
-// RUN: %clangxx %s -### --target=x86_64-fuchsia -fno-exceptions \
+// RUN:     | FileCheck %s -check-prefixes=CHECK-MULTILIB-X86,CHECK-MULTILIB-NOEXCEPT-X86
+// RUN: %clangxx %s -### --target=x86_64-fuchsia -fsanitize=address \
 // RUN:     -ccc-install-dir %S/Inputs/basic_fuchsia_tree/bin \
 // RUN:     -resource-dir=%S/Inputs/resource_dir_with_per_target_subdir \
 // RUN:     -fuse-ld=lld 2>&1\
-// RUN:     | FileCheck %s -check-prefixes=CHECK-MULTILIB-X86,CHECK-MULTILIB-NOEXCEPT-X86
+// RUN:     | FileCheck %s -check-prefixes=CHECK-MULTILIB-X86,CHECK-MULTILIB-ASAN-X86
 // RUN: %clangxx %s -### --target=x86_64-fuchsia -fsanitize=address -fno-exceptions \
 // RUN:     -ccc-install-dir %S/Inputs/basic_fuchsia_tree/bin \
 // RUN:     -resource-dir=%S/Inputs/resource_dir_with_per_target_subdir \
 // RUN:     -fuse-ld=lld 2>&1\
 // RUN:     | FileCheck %s -check-prefixes=CHECK-MULTILIB-X86,CHECK-MULTILIB-ASAN-NOEXCEPT-X86
+// RUN: %clangxx %s -### --target=x86_64-fuchsia -fsanitize=undefined \
+// RUN:     -ccc-install-dir %S/Inputs/basic_fuchsia_tree/bin \
+// RUN:     -resource-dir=%S/Inputs/resource_dir_with_per_target_subdir \
+// RUN:     -fuse-ld=lld 2>&1\
+// RUN:     | FileCheck %s -check-prefixes=CHECK-MULTILIB-X86,CHECK-MULTILIB-UBSAN-X86
+// RUN: %clangxx %s -### --target=x86_64-fuchsia -fsanitize=undefined -fno-exceptions \
+// RUN:     -ccc-install-dir %S/Inputs/basic_fuchsia_tree/bin \
+// RUN:     -resource-dir=%S/Inputs/resource_dir_with_per_target_subdir \
+// RUN:     -fuse-ld=lld 2>&1\
+// RUN:     | FileCheck %s -check-prefixes=CHECK-MULTILIB-X86,CHECK-MULTILIB-UBSAN-NOEXCEPT-X86
 // CHECK-MULTILIB-X86: "-resource-dir" "[[RESOURCE_DIR:[^"]+]]"
+// CHECK-MULTILIB-ASAN-NOEXCEPT-X86: "-L{{.*}}{{/|\\\\}}..{{/|\\\\}}lib{{/|\\\\}}x86_64-fuchsia{{/|\\\\}}c++{{/|\\\\}}asan+noexcept"
 // CHECK-MULTILIB-ASAN-X86: "-L{{.*}}{{/|\\\\}}..{{/|\\\\}}lib{{/|\\\\}}x86_64-fuchsia{{/|\\\\}}c++{{/|\\\\}}asan"
+// CHECK-MULTILIB-UBSAN-NOEXCEPT-X86: "-L{{.*}}{{/|\\\\}}..{{/|\\\\}}lib{{/|\\\\}}x86_64-fuchsia{{/|\\\\}}c++{{/|\\\\}}ubsan+noexcept"
+// CHECK-MULTILIB-UBSAN-X86: "-L{{.*}}{{/|\\\\}}..{{/|\\\\}}lib{{/|\\\\}}x86_64-fuchsia{{/|\\\\}}c++{{/|\\\\}}ubsan"
 // CHECK-MULTILIB-NOEXCEPT-X86: "-L{{.*}}{{/|\\\\}}..{{/|\\\\}}lib{{/|\\\\}}x86_64-fuchsia{{/|\\\\}}c++{{/|\\\\}}noexcept"
-// CHECK-MULTILIB-ASAN-NOEXCEPT-X86: "-L{{.*}}{{/|\\\\}}..{{/|\\\\}}lib{{/|\\\\}}x86_64-fuchsia{{/|\\\\}}c++{{/|\\\\}}asan+noexcept"
 // CHECK-MULTILIB-X86: "-L{{.*}}{{/|\\\\}}..{{/|\\\\}}lib{{/|\\\\}}x86_64-fuchsia{{/|\\\\}}c++"