Driver: Do not link safestack with --whole-archive.

[pcc]

Summary

This allows it to be used with the other sanitizers.

clang/lib/Driver/Tools.cpp

if (SanArgs.needsTsanRt()) {
     if (SanArgs.linkCXXRuntimes())
       StaticRuntimes.push_back("tsan_cxx");
   }
   if (SanArgs.needsUbsanRt()) {
     StaticRuntimes.push_back("ubsan_standalone");
     if (SanArgs.linkCXXRuntimes())
       StaticRuntimes.push_back("ubsan_standalone_cxx");
   }
-  if (SanArgs.needsSafeStackRt())
-    StaticRuntimes.push_back("safestack");
+  if (SanArgs.needsSafeStackRt()) {
+    NonWholeStaticRuntimes.push_back("safestack");
+    RequiredSymbols.push_back("__safestack_init");
+  }
   if (SanArgs.needsCfiRt())
     StaticRuntimes.push_back("cfi");
   if (SanArgs.needsCfiDiagRt()) {
     StaticRuntimes.push_back("cfi_diag");
     if (SanArgs.linkCXXRuntimes())
       StaticRuntimes.push_back("ubsan_standalone_cxx");
   }
   if (SanArgs.needsStatsRt()) {
static bool addSanitizerRuntimes(const ToolChain &TC, const ArgList &Args,
   // to be dynamic to be sure we export sanitizer interface functions.
   if (AddExportDynamic)
     CmdArgs.push_back("-export-dynamic");
 
   const SanitizerArgs &SanArgs = TC.getSanitizerArgs();
   if (SanArgs.hasCrossDsoCfi() && !AddExportDynamic)
     CmdArgs.push_back("-export-dynamic-symbol=__cfi_check");
 
-  return !StaticRuntimes.empty();
+  return !StaticRuntimes.empty() || !NonWholeStaticRuntimes.empty();
 }
 
 static bool addXRayRuntime(const ToolChain &TC, const ArgList &Args,
                            ArgStringList &CmdArgs) {
   if (Args.hasFlag(options::OPT_fxray_instrument,
                    options::OPT_fnoxray_instrument, false)) {
     CmdArgs.push_back("-whole-archive");
     CmdArgs.push_back(TC.getCompilerRTArgString(Args, "xray", false));

clang/test/Driver/sanitizer-ld.c

 
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -target x86_64-unknown-linux -fuse-ld=ld -fsanitize=safe-stack \
 // RUN:     --sysroot=%S/Inputs/basic_linux_tree \
 // RUN:   | FileCheck --check-prefix=CHECK-SAFESTACK-LINUX %s
 //
 // CHECK-SAFESTACK-LINUX: "{{(.*[^-.0-9A-Z_a-z])?}}ld{{(.exe)?}}"
 // CHECK-SAFESTACK-LINUX-NOT: "-lc"
+// CHECK-SAFESTACK-LINUX-NOT: whole-archive
 // CHECK-SAFESTACK-LINUX: libclang_rt.safestack-x86_64.a"
+// CHECK-SAFESTACK-LINUX: "-u" "__safestack_init"
 // CHECK-SAFESTACK-LINUX: "-lpthread"
 // CHECK-SAFESTACK-LINUX: "-ldl"
 
 // RUN: %clang -fsanitize=cfi -fsanitize-stats %s -### -o %t.o 2>&1 \
 // RUN:     -target x86_64-unknown-linux -fuse-ld=ld \
 // RUN:     --sysroot=%S/Inputs/basic_linux_tree \
 // RUN:   | FileCheck --check-prefix=CHECK-CFI-STATS-LINUX %s
 // CHECK-CFI-STATS-LINUX: "{{.*}}ld{{(.exe)?}}"