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, 24 insertions, 3 deletions

diff --git a/source/core/slang-string.h b/source/core/slang-string.h
index 65fd3a315..3f401b7bb 100644
--- a/source/core/slang-string.h
+++ b/source/core/slang-string.h
@@ -10,8 +10,10 @@
 #include "slang-common.h"
 #include "slang-hash.h"
 #include "slang-secure-crt.h"
+#include "slang-stable-hash.h"
 
 #include <new>
+#include <type_traits>
 
 namespace Slang
 {
@@ -32,8 +34,10 @@ namespace Slang
         }
     }
     template<typename IntType>
-    inline int intToAscii(char* buffer, IntType val, int radix)
+    inline int intToAscii(char* buffer, IntType val, int radix, int padTo = 0)
     {
+        static_assert(std::is_integral_v<IntType>);
+
         int i = 0;
         IntType sign;
         
@@ -52,6 +56,9 @@ namespace Slang
                 buffer[i++] = (char)(digit - 10 + 'A');
         } while ((val /= radix) > 0);
 
+        while(i < padTo)
+            buffer[i++] = '0';
+
         if (sign < 0)
             buffer[i++] = '-';
 
@@ -189,7 +196,8 @@ namespace Slang
             /// Trims any horizonatl whitespace from start and returns as a substring
         UnownedStringSlice trimStart() const;
 
-        HashCode getHashCode() const
+        static constexpr bool kHasUniformHash = true;
+        HashCode64 getHashCode() const
         {
             return Slang::getHashCode(m_begin, size_t(m_end - m_begin)); 
         }
@@ -508,6 +516,10 @@ namespace Slang
         void append(float val, const char* format = "%g");
         void append(double val, const char* format = "%g");
 
+        // Padded hex representations
+        void append(StableHashCode32 val);
+        void append(StableHashCode64 val);
+
         void append(char const* str);
         void append(char const* str, size_t len);
         void append(const char* textBegin, char const* textEnd);
@@ -549,6 +561,14 @@ namespace Slang
         {
             append(val, radix);
         }
+        explicit String(StableHashCode32 val)
+        {
+            append(val);
+        }
+        explicit String(StableHashCode64 val)
+        {
+            append(val);
+        }
         explicit String(float val, const char* format = "%g")
         {
             append(val, format);
@@ -869,7 +889,8 @@ namespace Slang
             return contains(str.begin());
         }
 
-        HashCode getHashCode() const
+        static constexpr bool kHasUniformHash = true;
+        HashCode64 getHashCode() const
         {
             return Slang::getHashCode(StringRepresentation::asSlice(m_buffer));
         }