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

4 files changed, 8 insertions, 0 deletions

diff --git a/build/visual-studio/core/core.vcxproj b/build/visual-studio/core/core.vcxproj
index abecd620a..80a791a13 100644
--- a/build/visual-studio/core/core.vcxproj
+++ b/build/visual-studio/core/core.vcxproj
@@ -320,6 +320,7 @@
     <ClInclude Include="..\..\..\source\core\slang-short-list.h" />

     <ClInclude Include="..\..\..\source\core\slang-signal.h" />

     <ClInclude Include="..\..\..\source\core\slang-smart-pointer.h" />

+    <ClInclude Include="..\..\..\source\core\slang-stable-hash.h" />

     <ClInclude Include="..\..\..\source\core\slang-std-writers.h" />

     <ClInclude Include="..\..\..\source\core\slang-stream.h" />

     <ClInclude Include="..\..\..\source\core\slang-string-escape-util.h" />

diff --git a/build/visual-studio/core/core.vcxproj.filters b/build/visual-studio/core/core.vcxproj.filters
index 607e9451e..0c06e36f2 100644
--- a/build/visual-studio/core/core.vcxproj.filters
+++ b/build/visual-studio/core/core.vcxproj.filters
@@ -174,6 +174,9 @@
     <ClInclude Include="..\..\..\source\core\slang-smart-pointer.h">

       <Filter>Header Files</Filter>

     </ClInclude>

+    <ClInclude Include="..\..\..\source\core\slang-stable-hash.h">

+      <Filter>Header Files</Filter>

+    </ClInclude>

     <ClInclude Include="..\..\..\source\core\slang-std-writers.h">

       <Filter>Header Files</Filter>

     </ClInclude>

diff --git a/build/visual-studio/slang-rt/slang-rt.vcxproj b/build/visual-studio/slang-rt/slang-rt.vcxproj
index 09d27d621..bd972fd6b 100644
--- a/build/visual-studio/slang-rt/slang-rt.vcxproj
+++ b/build/visual-studio/slang-rt/slang-rt.vcxproj
@@ -332,6 +332,7 @@
     <ClInclude Include="..\..\..\source\core\slang-short-list.h" />

     <ClInclude Include="..\..\..\source\core\slang-signal.h" />

     <ClInclude Include="..\..\..\source\core\slang-smart-pointer.h" />

+    <ClInclude Include="..\..\..\source\core\slang-stable-hash.h" />

     <ClInclude Include="..\..\..\source\core\slang-std-writers.h" />

     <ClInclude Include="..\..\..\source\core\slang-stream.h" />

     <ClInclude Include="..\..\..\source\core\slang-string-escape-util.h" />

diff --git a/build/visual-studio/slang-rt/slang-rt.vcxproj.filters b/build/visual-studio/slang-rt/slang-rt.vcxproj.filters
index 2dcb22999..3b9e2b59e 100644
--- a/build/visual-studio/slang-rt/slang-rt.vcxproj.filters
+++ b/build/visual-studio/slang-rt/slang-rt.vcxproj.filters
@@ -174,6 +174,9 @@
     <ClInclude Include="..\..\..\source\core\slang-smart-pointer.h">

       <Filter>Header Files</Filter>

     </ClInclude>

+    <ClInclude Include="..\..\..\source\core\slang-stable-hash.h">

+      <Filter>Header Files</Filter>

+    </ClInclude>

     <ClInclude Include="..\..\..\source\core\slang-std-writers.h">

       <Filter>Header Files</Filter>

     </ClInclude>