[Driver] -fsanitize=numerical: work with ubsan and support -shared-libsan

* `-fsanitize=numerical,undefined`: don't link in the ubsan standalone
  runtime.
* `-shared-libsan`: link against `libclang_rt.nsan.so`

The compiler-rt part will be properly fixed by #98415

Author: MaskRay

clang/lib/Driver/SanitizerArgs.cpp

@@ -285,8 +285,8 @@ bool SanitizerArgs::needsFuzzerInterceptors() const {
 
 bool SanitizerArgs::needsUbsanRt() const {
   // All of these include ubsan.
-  if (needsAsanRt() || needsMsanRt() || needsHwasanRt() || needsTsanRt() ||
-      needsDfsanRt() || needsLsanRt() || needsCfiDiagRt() ||
+  if (needsAsanRt() || needsMsanRt() || needsNsanRt() || needsHwasanRt() ||
+      needsTsanRt() || needsDfsanRt() || needsLsanRt() || needsCfiDiagRt() ||
       (needsScudoRt() && !requiresMinimalRuntime()))
     return false;
 

clang/lib/Driver/ToolChains/CommonArgs.cpp

@@ -1409,6 +1409,8 @@ collectSanitizerRuntimes(const ToolChain &TC, const ArgList &Args,
       if (!Args.hasArg(options::OPT_shared) && !TC.getTriple().isAndroid())
         HelperStaticRuntimes.push_back("memprof-preinit");
     }
+    if (SanArgs.needsNsanRt())
+      SharedRuntimes.push_back("nsan");
     if (SanArgs.needsUbsanRt()) {
       if (SanArgs.requiresMinimalRuntime())
         SharedRuntimes.push_back("ubsan_minimal");
@@ -1479,7 +1481,7 @@ collectSanitizerRuntimes(const ToolChain &TC, const ArgList &Args,
     if (SanArgs.linkCXXRuntimes())
       StaticRuntimes.push_back("msan_cxx");
   }
-  if (SanArgs.needsNsanRt())
+  if (!SanArgs.needsSharedRt() && SanArgs.needsNsanRt())
     StaticRuntimes.push_back("nsan");
   if (!SanArgs.needsSharedRt() && SanArgs.needsTsanRt()) {
     StaticRuntimes.push_back("tsan");

clang/test/Driver/sanitizer-ld.c

@@ -646,6 +646,24 @@
 // CHECK-NSAN-LINUX: libclang_rt.nsan.a"
 // CHECK-NSAN-LINUX: "-lpthread" "-lrt" "-lm" "-ldl" "-lresolv"
 
+// RUN: %clang -### %s 2>&1 --target=x86_64-unknown-linux -fuse-ld=ld -fsanitize=numerical -shared-libsan \
+// RUN:     -resource-dir=%S/Inputs/resource_dir \
+// RUN:     --sysroot=%S/Inputs/basic_linux_tree \
+// RUN:   | FileCheck --check-prefix=CHECK-NSAN-SHARED-LINUX %s
+
+// CHECK-NSAN-SHARED-LINUX: libclang_rt.nsan.so"
+// CHECK-NSAN-SHARED-LINUX-NOT: "-lpthread"
+// CHECK-NSAN-SHARED-LINUX-NOT: "-ldl"
+// CHECK-NSAN-SHARED-LINUX-NOT: "--dynamic-list
+
+// RUN: %clang -### %s 2>&1 --target=x86_64-unknown-linux -fsanitize=numerical,undefined \
+// RUN:     -resource-dir=%S/Inputs/resource_dir \
+// RUN:     --sysroot=%S/Inputs/basic_linux_tree \
+// RUN:   | FileCheck --check-prefix=CHECK-NSAN-UBSAN %s
+
+// CHECK-NSAN-UBSAN: "--whole-archive" "{{[^"]*}}libclang_rt.nsan.a" "--no-whole-archive"
+// CHECK-NSAN-UBSAN-NOT: libclang_rt.ubsan
+
 // CFI by itself does not link runtime libraries.
 // RUN: not %clang -fsanitize=cfi -### %s 2>&1 \
 // RUN:     --target=x86_64-unknown-linux -fuse-ld=ld -rtlib=platform \