makepanda: Support building with mimalloc on Windows, experimentally

Partial backport of 07545bc9e318d1799ceabe8838d04d7ad9297a45 for Windows, requires building with `--override USE_MEMORY_MIMALLOC=1 --override USE_DELETED_CHAIN=UNDEF` for optimum effect

dtool/src/dtoolbase/dtoolbase.h

@@ -387,6 +387,10 @@ typedef struct _object PyObject;
 // This specialized malloc implementation can perform the required alignment.
 #undef MEMORY_HOOK_DO_ALIGN
 
+#elif defined(USE_MEMORY_MIMALLOC)
+// This one does, too.
+#undef MEMORY_HOOK_DO_ALIGN
+
 #elif defined(USE_MEMORY_PTMALLOC2)
 // But not this one.  For some reason it crashes when we try to build it with
 // alignment 16.  So if we're using ptmalloc2, we need to enforce alignment
@@ -438,7 +442,7 @@ typedef struct _object PyObject;
 #endif
 
 /* Determine our memory-allocation requirements. */
-#if defined(USE_MEMORY_PTMALLOC2) || defined(USE_MEMORY_DLMALLOC) || defined(DO_MEMORY_USAGE) || defined(MEMORY_HOOK_DO_ALIGN)
+#if defined(USE_MEMORY_MIMALLOC) || defined(USE_MEMORY_PTMALLOC2) || defined(USE_MEMORY_DLMALLOC) || defined(DO_MEMORY_USAGE) || defined(MEMORY_HOOK_DO_ALIGN)
 /* In this case we have some custom memory management requirements. */
 #else
 /* Otherwise, if we have no custom memory management needs at all, we

dtool/src/dtoolbase/memoryHook.cxx

@@ -51,6 +51,18 @@ static_assert((MEMORY_HOOK_ALIGNMENT & (MEMORY_HOOK_ALIGNMENT - 1)) == 0,
 
 #if defined(CPPPARSER)
 
+#elif defined(USE_MEMORY_MIMALLOC)
+
+// mimalloc is a modern memory manager by Microsoft that is very fast as well
+// as thread-safe.
+
+#include "mimalloc.h"
+
+#define call_malloc mi_malloc
+#define call_realloc mi_realloc
+#define call_free mi_free
+#undef MEMORY_HOOK_MALLOC_LOCK
+
 #elif defined(USE_MEMORY_DLMALLOC)
 
 // Memory manager: DLMALLOC This is Doug Lea's memory manager.  It is very

makepanda/makepanda.py

@@ -103,6 +103,7 @@ PkgListSet(["PYTHON", "DIRECT",                        # Python support
   "PANDAPARTICLESYSTEM",                               # Built in particle system
   "CONTRIB",                                           # Experimental
   "SSE2", "NEON",                                      # Compiler features
+  "MIMALLOC",                                          # Memory allocators
 ])
 
 CheckPandaSourceTree()
@@ -767,6 +768,7 @@ if (COMPILER == "MSVC"):
     if (PkgSkip("DIRECTCAM")==0): LibName("DIRECTCAM", "quartz.lib")
     if (PkgSkip("DIRECTCAM")==0): LibName("DIRECTCAM", "odbc32.lib")
     if (PkgSkip("DIRECTCAM")==0): LibName("DIRECTCAM", "odbccp32.lib")
+    if (PkgSkip("MIMALLOC")==0): LibName("MIMALLOC", GetThirdpartyDir() + "mimalloc/lib/mimalloc-static.lib")
     if (PkgSkip("OPENSSL")==0):
         if os.path.isfile(GetThirdpartyDir() + "openssl/lib/libpandassl.lib"):
             LibName("OPENSSL", GetThirdpartyDir() + "openssl/lib/libpandassl.lib")
@@ -949,6 +951,8 @@ if (COMPILER == "MSVC"):
         LibName("BULLET", GetThirdpartyDir() + "bullet/lib/BulletSoftBody" + suffix)
 
 if (COMPILER=="GCC"):
+    PkgDisable("MIMALLOC") # no discernable benefit over glibc
+
     if GetTarget() != "darwin":
         PkgDisable("CARBON")
         PkgDisable("COCOA")
@@ -3766,7 +3770,7 @@ if GetTarget() == 'windows':
 # DIRECTORY: dtool/src/dtoolbase/
 #
 
-OPTS=['DIR:dtool/src/dtoolbase', 'BUILDING:DTOOL']
+OPTS=['DIR:dtool/src/dtoolbase', 'BUILDING:DTOOL', 'MIMALLOC']
 TargetAdd('p3dtoolbase_composite1.obj', opts=OPTS, input='p3dtoolbase_composite1.cxx')
 TargetAdd('p3dtoolbase_composite2.obj', opts=OPTS, input='p3dtoolbase_composite2.cxx')
 TargetAdd('p3dtoolbase_lookup3.obj',    opts=OPTS, input='lookup3.c')
@@ -3797,7 +3801,7 @@ TargetAdd('libp3dtool.dll', input='p3dtoolbase_composite1.obj')
 TargetAdd('libp3dtool.dll', input='p3dtoolbase_composite2.obj')
 TargetAdd('libp3dtool.dll', input='p3dtoolbase_indent.obj')
 TargetAdd('libp3dtool.dll', input='p3dtoolbase_lookup3.obj')
-TargetAdd('libp3dtool.dll', opts=['ADVAPI','WINSHELL','WINKERNEL'])
+TargetAdd('libp3dtool.dll', opts=['ADVAPI','WINSHELL','WINKERNEL','MIMALLOC'])
 
 #
 # DIRECTORY: dtool/src/cppparser/