Use ankerl/unordered_dense as a hashmap implementation (#3036)

* Correct namespace for getClockFrequency

* missing const

* Add missing assignment operator

* Remove unused variables

* Return correct modified variable

* Use stable hash code for file system identity

* terse static_assert

* Structured binding for map iteration

* Make (==) and getHashCode const on many structs

* Add ConstIterator for LinkedList

* Replace uses of ItemProxy::getValue with Dictionary::at

* Extract list of loads from gradientsMap before updating it

* Const correctness in type layout

* Add unordered_dense hashmap submodule

* Use wyhash or getHashCode in slang-hash.h

* refactor slang-hash.h

* Use ankerl/unordered_dense as a hashmap implementation

Notable changes:
- The subscript operator returns a reference directly to the value,
  rather than a lazy ItemProxy (pair of dict pointer and key)

slang-profile time (95% over 10 runs):

- Before: 6.3913906 (±0.0746)
- After:  5.9276123 (±0.0964)

* 64 bit hash for strings

So they have the same hash as char buffers with the same contents

* Narrowing warnings for gcc to match msvc

* revert back to c++17

* Correct c++ version for msvc

* Use path to unordered_dense which keeps tests happy

* Do not assign to and read from map in same expression

* Remove redundant map operations in primal-hoist

* Split out stable hash functions into slang-stable-hash.h

* 64 bit hash by default

* regenerate vs projects

* Correct return type from HashSetBase::getCount()

* correct width for call to Dictionary::reserve

* Use stable hash for obfuscated module ids

* Signed int for reserve

* clearer variable naming

* Parameterize Dictionary on hash and equality functors

* Allow heterogenous lookup for Dictionary

* missing const

* Use set over operator[] in some places

* Remove unused function

* s/at/getValue

1 files changed, 5 insertions, 14 deletions

diff --git a/source/core/slang-file-system.cpp b/source/core/slang-file-system.cpp
index e6d84cac1..7c3cd83bb 100644
--- a/source/core/slang-file-system.cpp
+++ b/source/core/slang-file-system.cpp
@@ -319,11 +319,8 @@ CacheFileSystem::CacheFileSystem(ISlangFileSystem* fileSystem, UniqueIdentityMod
 
 CacheFileSystem::~CacheFileSystem()
 {
-    for (const auto& pair : m_uniqueIdentityMap)
-    {
-        PathInfo* pathInfo = pair.value;
+    for (const auto& [_, pathInfo] : m_uniqueIdentityMap)
         delete pathInfo;
-    }
 }
 
 void CacheFileSystem::setInnerFileSystem(ISlangFileSystem* fileSystem, UniqueIdentityMode uniqueIdentityMode, PathStyle pathStyle)
@@ -374,11 +371,8 @@ void CacheFileSystem::setInnerFileSystem(ISlangFileSystem* fileSystem, UniqueIde
 
 void CacheFileSystem::clearCache()
 {
-    for (const auto& pair : m_uniqueIdentityMap)
-    {
-        PathInfo* pathInfo = pair.value;
+    for (const auto& [_, pathInfo] : m_uniqueIdentityMap)
         delete pathInfo;
-    }
 
     m_uniqueIdentityMap.clear();
     m_pathMap.clear();
@@ -434,11 +428,10 @@ SlangResult CacheFileSystem::enumeratePathContents(const char* path, FileSystemC
         simplifiedPath = "";
     }
 
-    for (auto& pair : m_pathMap)
+    for (const auto& [currentPath, pathInfo] : m_pathMap)
     {
         // NOTE! The currentPath can be a *non* simplified path (the m_pathMap is the cache of paths simplified and other to a file/directory)
         // Also note that there will always be the simplified version of the path in cache.
-        const String& currentPath = pair.key;
 
         // If it doesn't start with simplified path, then it can't be a hit
         if (!currentPath.startsWith(simplifiedPath))
@@ -468,8 +461,6 @@ SlangResult CacheFileSystem::enumeratePathContents(const char* path, FileSystemC
         // Let's check that fact...
         SLANG_ASSERT(foundPath[remaining.getLength()] == 0);
 
-        PathInfo* pathInfo = pair.value;
-
         SlangPathType pathType;
         if (SLANG_FAILED(_getPathType(pathInfo, currentPath.getBuffer(), &pathType)))
         {
@@ -548,7 +539,7 @@ SlangResult CacheFileSystem::_calcUniqueIdentity(const String& path, String& out
             }
  
             // Calculate the hash on the contents
-            const uint64_t hash = getHashCode64((const char*)outFileContents->getBufferPointer(), outFileContents->getBufferSize());
+            const StableHashCode64 hash = getStableHashCode64((const char*)outFileContents->getBufferPointer(), outFileContents->getBufferSize());
 
             String hashString = Path::getFileName(path);
             hashString = hashString.toLower();
@@ -556,7 +547,7 @@ SlangResult CacheFileSystem::_calcUniqueIdentity(const String& path, String& out
             hashString.append(':');
 
             // The uniqueIdentity is a combination of name and hash
-            hashString.append(hash, 16);
+            hashString.append(hash);
 
             outUniqueIdentity = hashString;
             return SLANG_OK;