[X86] Link safestacksepseg runtime

[mlemay-intel]

Summary

When SafeStack and the separate-stack-seg feature are both enabled, link the
safestacksepseg runtime library.

[mlemay-intel]

Only link safestacksepseg, not safestack. I changed the build configuration for safestacksepseg to also include the files in safestack.

[mlemay-intel]

Added test.

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())
+  if (SanArgs.needsSafeStackRt()) {
+    if (Args.hasFlag(options::OPT_mseparate_stack_seg, options::OPT_mno_separate_stack_seg, false))
+      StaticRuntimes.push_back("safestacksepseg");
+    else
       StaticRuntimes.push_back("safestack");
+  }
   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()) {

test/Driver/sanitizer-ld.c

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