PIX: Fix scope ascension for variable lookup (microsoft#6091)

In DxcPixLiveVariables.cpp,
UniqueScopeForInlinedFunctions::AscendScopeHierarchy tries to keep track
of a variable's scope and the scope at which its containing function was
inlined, if any.

This scope duo has to be the same in two places for things to work out:
the scopes inferred from dbg.declare, and then again when the scope
hierarchy is ascended in order to discover all variables accessible from
a given point in the program.

AscendScopeHierarchy was forgetting to update the inlined part of the
scope, resulting in, for example, PIX's debugger losing track of
variables outside of, for example, a for loop, even though the code can
see those variables at that point.

Just setting the inlined scope to be the same as the function scope
fixes this problem.

(In addition to these new tests, existing PIX tests exercise this
situation happily)

include/dxc/Test/HlslTestUtils.h

@@ -115,6 +115,7 @@ using namespace std;
 #endif // VERIFY_ARE_EQUAL
 
 static constexpr char whitespaceChars[] = " \t\r\n";
+static constexpr wchar_t wideWhitespaceChars[] = L" \t\r\n";
 
 inline std::string strltrim(const std::string &value) {
   size_t first = value.find_first_not_of(whitespaceChars);
@@ -157,6 +158,25 @@ strtok(const std::string &value, const char *delimiters = whitespaceChars) {
   return tokens;
 }
 
+inline std::vector<std::wstring>
+strtok(const std::wstring &value,
+       const wchar_t *delimiters = wideWhitespaceChars) {
+  size_t searchOffset = 0;
+  std::vector<std::wstring> tokens;
+  while (searchOffset != value.size()) {
+    size_t tokenStartIndex = value.find_first_not_of(delimiters, searchOffset);
+    if (tokenStartIndex == std::string::npos)
+      break;
+    size_t tokenEndIndex = value.find_first_of(delimiters, tokenStartIndex);
+    if (tokenEndIndex == std::string::npos)
+      tokenEndIndex = value.size();
+    tokens.emplace_back(
+        value.substr(tokenStartIndex, tokenEndIndex - tokenStartIndex));
+    searchOffset = tokenEndIndex;
+  }
+  return tokens;
+}
+
 // strreplace will replace all instances of lookFors with replacements at the
 // same index. Will log an error if the string is not found, unless the first
 // character is ? marking it optional.

include/dxc/WinAdapter.h

@@ -1015,6 +1015,11 @@ class CComBSTR {
     m_str = NULL;
     return s;
   }
+
+  void Empty() throw() {
+    SysFreeString(m_str);
+    m_str = NULL;
+  }
 };
 
 //===--------- Convert argv to wchar ----------------===//

lib/DxilDia/DxcPixLiveVariables.cpp

@@ -49,12 +49,19 @@ class UniqueScopeForInlinedFunctions {
     // is at file-level scope, it will return nullptr.
     if (auto Namespace = llvm::dyn_cast<llvm::DINamespace>(FunctionScope)) {
       if (auto *ContainingScope = Namespace->getScope()) {
-        FunctionScope = ContainingScope;
+        if (FunctionScope == InlinedAtScope)
+          InlinedAtScope = FunctionScope = ContainingScope;
+        else
+          FunctionScope = ContainingScope;
         return;
       }
     }
     const llvm::DITypeIdentifierMap EmptyMap;
-    FunctionScope = FunctionScope->getScope().resolve(EmptyMap);
+    if (FunctionScope == InlinedAtScope)
+      InlinedAtScope = FunctionScope =
+          FunctionScope->getScope().resolve(EmptyMap);
+    else
+      FunctionScope = FunctionScope->getScope().resolve(EmptyMap);
   }
 
   static UniqueScopeForInlinedFunctions Create(llvm::DebugLoc const &DbgLoc,