Address PR feedback

* Simply use F.getName() for function name.
* Fix llvm/test/CodeGen/Generic/ms-hotpatch-direct-global-access.ll
* Add negative testing for functions that are not supposed to be hotpatched

Author: sivadeilra

clang/test/CodeGen/ms-hotpatch-cpp.cpp

@@ -0,0 +1,22 @@
+// This verifies that hotpatch function attributes are correctly propagated when compiling directly to OBJ,
+// and that name mangling works as expected.
+//
+// RUN: %clang_cl -c --target=x86_64-windows-msvc -O2 /Z7 -fms-hotpatch-functions-list=?this_gets_hotpatched@@YAHXZ /Fo%t.obj %s
+// RUN: llvm-readobj --codeview %t.obj | FileCheck %s
+
+void this_might_have_side_effects();
+
+int __declspec(noinline) this_gets_hotpatched() {
+    this_might_have_side_effects();
+    return 42;
+}
+
+// CHECK: Kind: S_HOTPATCHFUNC (0x1169)
+// CHECK-NEXT: Function: this_gets_hotpatched
+// CHECK-NEXT: Name: ?this_gets_hotpatched@@YAHXZ
+
+extern "C" int __declspec(noinline) this_does_not_get_hotpatched() {
+    return this_gets_hotpatched() + 100;
+}
+
+// CHECK-NOT: S_HOTPATCHFUNC

clang/test/CodeGen/ms-hotpatch.c

@@ -2,8 +2,6 @@
 //
 // RUN: %clang_cl -c --target=x86_64-windows-msvc -O2 /Z7 -fms-hotpatch-functions-file=%S/ms-hotpatch-functions.txt /Fo%t.obj %s
 // RUN: llvm-readobj --codeview %t.obj | FileCheck %s
-// CHECK: Kind: S_HOTPATCHFUNC (0x1169)
-// CHECK-NEXT: Function: this_gets_hotpatched
 
 void this_might_have_side_effects();
 
@@ -12,6 +10,11 @@ int __declspec(noinline) this_gets_hotpatched() {
     return 42;
 }
 
+// CHECK: Kind: S_HOTPATCHFUNC (0x1169)
+// CHECK-NEXT: Function: this_gets_hotpatched
+
 int __declspec(noinline) this_does_not_get_hotpatched() {
     return this_gets_hotpatched() + 100;
 }
+
+// CHECK-NOT: S_HOTPATCHFUNC

llvm/include/llvm/IR/Attributes.td

@@ -398,7 +398,7 @@ def MarkedForWindowsHotPatching
 /// decl, not the hotpatched function.
 def AllowDirectAccessInHotPatchFunction
     : EnumAttr<"allow_direct_access_in_hot_patch_function",
-               IntersectPreserve, []>;
+               IntersectPreserve, [FnAttr]>;
 
 /// Target-independent string attributes.
 def LessPreciseFPMAD : StrBoolAttr<"less-precise-fpmad">;

llvm/lib/CodeGen/WindowsHotPatch.cpp

@@ -130,16 +130,7 @@ bool WindowsHotPatch::runOnModule(Module &M) {
         continue;
       }
 
-      llvm::StringRef FuncName{};
-      if (auto *SP = F.getSubprogram(); SP != nullptr) {
-        FuncName = SP->getLinkageName();
-        if (FuncName.empty()) {
-          FuncName = F.getName();
-        }
-      } else {
-        FuncName = F.getName();
-      }
-      if (HotPatchFunctionsSet.contains(FuncName)) {
+      if (HotPatchFunctionsSet.contains(F.getName())) {
         F.addFnAttr(Attribute::MarkedForWindowsHotPatching);
       }
     }