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, 11 insertions, 15 deletions

diff --git a/source/slang/slang-check-decl.cpp b/source/slang/slang-check-decl.cpp
index 6385e5f57..8c9ca2936 100644
--- a/source/slang/slang-check-decl.cpp
+++ b/source/slang/slang-check-decl.cpp
@@ -2006,11 +2006,11 @@ namespace Slang
         // Once things are done, we will install the satisfying values
         // into the witness table for the requirements.
         //
-        for( auto p : mapRequiredToSatisfyingAccessorDeclRef )
+        for( const auto& [key, value] : mapRequiredToSatisfyingAccessorDeclRef )
         {
             witnessTable->add(
-                p.key.getDecl(),
-                RequirementWitness(p.value));
+                key.getDecl(),
+                RequirementWitness(value));
         }
         //
         // Note: the property declaration itself isn't something that
@@ -2559,10 +2559,10 @@ namespace Slang
                 // 
                 if (auto typeParamDecl = as<DeclRefType>(constraintDecl->sub.type)->getDeclRef().as<GenericTypeParamDecl>().getDecl())
                 {  
-                    auto synTypeParamDecl = mapOrigToSynTypeParams[typeParamDecl];
+                    auto synTypeParamDecl = mapOrigToSynTypeParams.getValue(typeParamDecl);
 
                     // Construct a DeclRefExpr from the type parameter.
-                    auto synTypeParamDeclRef = makeDeclRef(synTypeParamDecl.getValue());
+                    auto synTypeParamDeclRef = makeDeclRef(synTypeParamDecl);
 
                     auto synTypeParamDeclRefExpr = m_astBuilder->create<VarExpr>();
                     synTypeParamDeclRefExpr->declRef = synTypeParamDeclRef;
@@ -3262,9 +3262,9 @@ namespace Slang
         // difference between our synthetic property and a hand-written
         // one with the same behavior.
         //
-        for(auto p : mapRequiredAccessorToSynAccessor)
+        for(auto& [key, value] : mapRequiredAccessorToSynAccessor)
         {
-            witnessTable->add(p.key.getDecl(), RequirementWitness(makeDeclRef(p.value)));
+            witnessTable->add(key.getDecl(), RequirementWitness(makeDeclRef(value)));
         }
         witnessTable->add(requiredMemberDeclRef.getDecl(),
             RequirementWitness(makeDeclRef(synPropertyDecl)));
@@ -3531,7 +3531,6 @@ namespace Slang
             {
                 case SynthesisPattern::AllInductive:
                 {
-                    int paramIndex = 0;
                     for (auto arg : synArgs)
                     {
                         auto memberExpr = m_astBuilder->create<MemberExpr>();
@@ -3541,8 +3540,6 @@ namespace Slang
                         memberExpr->name = varMember->getName();
                         paramFields.add(memberExpr);
                         inductiveArgMask.add(true);
-
-                        paramIndex++;
                     }
                     break;
                 }
@@ -5460,9 +5457,8 @@ namespace Slang
             _addTargetModifiers(newDecl, newTargets);
 
             bool hasConflict = false;
-            for (auto& pair : newTargets)
+            for (auto& [target, value] : newTargets)
             {
-                Name* target = pair.key;
                 auto found = currentTargets.tryGetValue(target);
                 if (found)
                 {
@@ -6666,10 +6662,10 @@ namespace Slang
     
     void SharedSemanticsContext::_addCandidateExtensionsFromModule(ModuleDecl* moduleDecl)
     {
-        for( auto& entry : moduleDecl->mapTypeToCandidateExtensions )
+        for( auto& [entryKey, entryValue] : moduleDecl->mapTypeToCandidateExtensions )
         {
-            auto& list = _getCandidateExtensionList(entry.key, m_mapTypeDeclToCandidateExtensions);
-            list.addRange(entry.value->candidateExtensions);
+            auto& list = _getCandidateExtensionList(entryKey, m_mapTypeDeclToCandidateExtensions);
+            list.addRange(entryValue->candidateExtensions);
         }
     }