clang/win: Add a flag to disable default-linking of compiler-rt libraries

nico · nico · commit 77877642ea58 · 2024-04-22T14:05:12.000-04:00
For ASan, users already manually have to pass in the path to the lib, and for other libraries they have to pass in the path to the libpath. With LLVM's unreliable name of the lib (due to LLVM_ENABLE_PER_TARGET_RUNTIME_DIR confusion and whatnot), it's useful to be able to opt in to just explicitly passing the paths to the libs everywhere. Follow-up of sorts to https://reviews.llvm.org/D65543, and to #81037.
diff --git a/clang/docs/UsersManual.rst b/clang/docs/UsersManual.rst
@@ -4921,6 +4921,9 @@ directory. Using the example installation above, this would mean passing
 If the user links the program with the ``clang`` or ``clang-cl`` drivers, the
 driver will pass this flag for them.
 
+The auto-linking can be disabled with -fno-rtlib-defaultlib. If that flag is
+used, pass the complete flag to required libraries as described for ASan below.
+
 If the linker cannot find the appropriate library, it will emit an error like
 this::
 
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
@@ -5502,6 +5502,14 @@ def fno_rtlib_add_rpath: Flag<["-"], "fno-rtlib-add-rpath">,
   Visibility<[ClangOption, FlangOption]>,
   HelpText<"Do not add -rpath with architecture-specific resource directory to the linker flags. "
   "When --hip-link is specified, do not add -rpath with HIP runtime library directory to the linker flags">;
+def frtlib_defaultlib : Flag<["-"], "frtlib-defaultlib">,
+                      Visibility<[ClangOption, CLOption]>,
+                      Group<f_Group>,
+                      HelpText<"On Windows, emit /defaultlib: directives to link compiler-rt libraries (default)">;
+def fno_rtlib_defaultlib : Flag<["-"], "fno-rtlib-defaultlib">,
+                      Visibility<[ClangOption, CLOption]>,
+                      Group<f_Group>,
+                      HelpText<"On Windows, do not emit /defaultlib: directives to link compiler-rt libraries">;
 def offload_add_rpath: Flag<["--"], "offload-add-rpath">,
   Flags<[NoArgumentUnused]>,
   Alias<frtlib_add_rpath>;
diff --git a/clang/lib/Driver/SanitizerArgs.cpp b/clang/lib/Driver/SanitizerArgs.cpp
@@ -1192,7 +1192,9 @@ void SanitizerArgs::addArgs(const ToolChain &TC, const llvm::opt::ArgList &Args,
                           BinaryMetadataIgnorelistFiles);
   }
 
-  if (TC.getTriple().isOSWindows() && needsUbsanRt()) {
+  if (TC.getTriple().isOSWindows() && needsUbsanRt() &&
+      Args.hasFlag(options::OPT_frtlib_defaultlib,
+                   options::OPT_fno_rtlib_defaultlib, true)) {
     // Instruct the code generator to embed linker directives in the object file
     // that cause the required runtime libraries to be linked.
     CmdArgs.push_back(
@@ -1203,7 +1205,9 @@ void SanitizerArgs::addArgs(const ToolChain &TC, const llvm::opt::ArgList &Args,
           "--dependent-lib=" +
           TC.getCompilerRTBasename(Args, "ubsan_standalone_cxx")));
   }
-  if (TC.getTriple().isOSWindows() && needsStatsRt()) {
+  if (TC.getTriple().isOSWindows() && needsStatsRt() &&
+      Args.hasFlag(options::OPT_frtlib_defaultlib,
+                   options::OPT_fno_rtlib_defaultlib, true)) {
     CmdArgs.push_back(Args.MakeArgString(
         "--dependent-lib=" + TC.getCompilerRTBasename(Args, "stats_client")));
 
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -637,7 +637,9 @@ static void addPGOAndCoverageFlags(const ToolChain &TC, Compilation &C,
                                            ProfileGenerateArg->getValue()));
     // The default is to use Clang Instrumentation.
     CmdArgs.push_back("-fprofile-instrument=clang");
-    if (TC.getTriple().isWindowsMSVCEnvironment()) {
+    if (TC.getTriple().isWindowsMSVCEnvironment() &&
+        Args.hasFlag(options::OPT_frtlib_defaultlib,
+                     options::OPT_fno_rtlib_defaultlib, true)) {
       // Add dependent lib for clang_rt.profile
       CmdArgs.push_back(Args.MakeArgString(
           "--dependent-lib=" + TC.getCompilerRTBasename(Args, "profile")));
@@ -656,7 +658,9 @@ static void addPGOAndCoverageFlags(const ToolChain &TC, Compilation &C,
     CmdArgs.push_back("-fprofile-instrument=csllvm");
   }
   if (PGOGenArg) {
-    if (TC.getTriple().isWindowsMSVCEnvironment()) {
+    if (TC.getTriple().isWindowsMSVCEnvironment() &&
+        Args.hasFlag(options::OPT_frtlib_defaultlib,
+                     options::OPT_fno_rtlib_defaultlib, true)) {
       // Add dependent lib for clang_rt.profile
       CmdArgs.push_back(Args.MakeArgString(
           "--dependent-lib=" + TC.getCompilerRTBasename(Args, "profile")));
diff --git a/clang/test/Driver/cl-options.c b/clang/test/Driver/cl-options.c
@@ -70,12 +70,16 @@
 // fsanitize_address: -fsanitize=address
 
 // RUN: %clang_cl -### /FA -fprofile-instr-generate -- %s 2>&1 | FileCheck -check-prefix=CHECK-PROFILE-INSTR-GENERATE %s
+// RUN: %clang_cl -### /FA -fprofile-instr-generate -fno-rtlib-defaultlib -frtlib-defaultlib -- %s 2>&1 | FileCheck -check-prefix=CHECK-PROFILE-INSTR-GENERATE %s
 // RUN: %clang_cl -### /FA -fprofile-instr-generate=/tmp/somefile.profraw -- %s 2>&1 | FileCheck -check-prefix=CHECK-PROFILE-INSTR-GENERATE-FILE %s
 // RUN: %clang_cl -### /FAcsu -fprofile-instr-generate -- %s 2>&1 | FileCheck -check-prefix=CHECK-PROFILE-INSTR-GENERATE %s
 // RUN: %clang_cl -### /FAcsu -fprofile-instr-generate=/tmp/somefile.profraw -- %s 2>&1 | FileCheck -check-prefix=CHECK-PROFILE-INSTR-GENERATE-FILE %s
 // CHECK-PROFILE-INSTR-GENERATE: "-fprofile-instrument=clang" "--dependent-lib=clang_rt.profile{{[^"]*}}.lib"
 // CHECK-PROFILE-INSTR-GENERATE-FILE: "-fprofile-instrument-path=/tmp/somefile.profraw"
 
+// RUN: %clang_cl -### /FA -fprofile-instr-generate -fno-rtlib-defaultlib -- %s 2>&1 | FileCheck -check-prefix=CHECK-PROFILE-INSTR-GENERATE-NODEF %s
+// CHECK-PROFILE-INSTR-GENERATE-NODEF-NOT: "--dependent-lib=clang_rt.profile{{[^"]*}}.lib"
+
 // RUN: %clang_cl -### /FA -fprofile-generate -- %s 2>&1 | FileCheck -check-prefix=CHECK-PROFILE-GENERATE %s
 // RUN: %clang_cl -### /FAcsu -fprofile-generate -- %s 2>&1 | FileCheck -check-prefix=CHECK-PROFILE-GENERATE %s
 // CHECK-PROFILE-GENERATE: "-fprofile-instrument=llvm" "--dependent-lib=clang_rt.profile{{[^"]*}}.lib"
diff --git a/clang/test/Driver/sanitizer-ld.c b/clang/test/Driver/sanitizer-ld.c
@@ -802,10 +802,24 @@
 // RUN:     --target=i686-pc-windows \
 // RUN:     --sysroot=%S/Inputs/basic_linux_tree \
 // RUN:   | FileCheck --check-prefix=CHECK-CFI-STATS-WIN32 %s
+// RUN: not %clang -fsanitize=cfi -fsanitize-stats -### %s 2>&1 \
+// RUN:     --target=i686-pc-windows \
+// RUN:     -fno-rtlib-defaultlib \
+// RUN:     -frtlib-defaultlib \
+// RUN:     --sysroot=%S/Inputs/basic_linux_tree \
+// RUN:   | FileCheck --check-prefix=CHECK-CFI-STATS-WIN32 %s
 // CHECK-CFI-STATS-WIN32: "--dependent-lib=clang_rt.stats_client{{(-i386)?}}.lib"
 // CHECK-CFI-STATS-WIN32: "--dependent-lib=clang_rt.stats{{(-i386)?}}.lib"
 // CHECK-CFI-STATS-WIN32: "--linker-option=/include:___sanitizer_stats_register"
 
+// RUN: not %clang -fsanitize=cfi -fsanitize-stats -### %s 2>&1 \
+// RUN:     --target=i686-pc-windows \
+// RUN:     -fno-rtlib-defaultlib \
+// RUN:     --sysroot=%S/Inputs/basic_linux_tree \
+// RUN:   | FileCheck --check-prefix=CHECK-CFI-STATS-WIN32-NODEF %s
+// CHECK-CFI-STATS-WIN32-NODEF-NOT: "--dependent-lib=clang_rt.stats_client{{(-i386)?}}.lib"
+// CHECK-CFI-STATS-WIN32-NODEF-NOT: "--dependent-lib=clang_rt.stats{{(-i386)?}}.lib"
+
 // RUN: %clang -### %s 2>&1 \
 // RUN:     --target=arm-linux-androideabi -fuse-ld=ld -fsanitize=safe-stack \
 // RUN:     --sysroot=%S/Inputs/basic_android_tree \
