gallivm: add cache interface to mcjit

MCJIT uses an ObjectCache object to implement the cache,
this creates and instances of it and adds it to the MCJIT
instances, it stores the cached object for later use by
the outer layers.

Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5049>

src/gallium/auxiliary/gallivm/lp_bld_init.c

@@ -212,6 +212,7 @@ gallivm_free_ir(struct gallivm_state *gallivm)
    }
 
    if (gallivm->cache) {
+      lp_free_objcache(gallivm->cache->jit_obj_cache);
       free(gallivm->cache->data);
    }
    FREE(gallivm->module_name);

src/gallium/auxiliary/gallivm/lp_bld_misc.cpp

@@ -62,7 +62,7 @@
 #include <llvm/Support/CommandLine.h>
 #include <llvm/Support/Host.h>
 #include <llvm/Support/PrettyStackTrace.h>
-
+#include <llvm/ExecutionEngine/ObjectCache.h>
 #include <llvm/Support/TargetSelect.h>
 
 #if LLVM_VERSION_MAJOR < 11
@@ -289,6 +289,36 @@ class ShaderMemoryManager : public DelegatingJITMemoryManager {
       }
 };
 
+class LPObjectCache : public llvm::ObjectCache {
+private:
+   bool has_object;
+   struct lp_cached_code *cache_out;
+public:
+   LPObjectCache(struct lp_cached_code *cache) {
+      cache_out = cache;
+      has_object = false;
+   }
+
+   ~LPObjectCache() {
+   }
+   void notifyObjectCompiled(const llvm::Module *M, llvm::MemoryBufferRef Obj) {
+      const std::string ModuleID = M->getModuleIdentifier();
+      if (has_object)
+         fprintf(stderr, "CACHE ALREADY HAS MODULE OBJECT\n");
+      has_object = true;
+      cache_out->data_size = Obj.getBufferSize();
+      cache_out->data = malloc(cache_out->data_size);
+      memcpy(cache_out->data, Obj.getBufferStart(), cache_out->data_size);
+   }
+
+   virtual std::unique_ptr<llvm::MemoryBuffer> getObject(const llvm::Module *M) {
+      if (cache_out->data_size) {
+         return llvm::MemoryBuffer::getMemBuffer(llvm::StringRef((const char *)cache_out->data, cache_out->data_size));
+      }
+      return NULL;
+   }
+
+};
 
 /**
  * Same as LLVMCreateJITCompilerForModule, but:
@@ -502,6 +532,13 @@ lp_build_create_jit_compiler_for_module(LLVMExecutionEngineRef *OutJIT,
    ExecutionEngine *JIT;
 
    JIT = builder.create();
+
+   if (cache_out) {
+      LPObjectCache *objcache = new LPObjectCache(cache_out);
+      JIT->setObjectCache(objcache);
+      cache_out->jit_obj_cache = (void *)objcache;
+   }
+
 #if LLVM_USE_INTEL_JITEVENTS
    JITEventListener *JEL = JITEventListener::createIntelJITEventListener();
    JIT->RegisterJITEventListener(JEL);
@@ -541,6 +578,13 @@ lp_free_memory_manager(LLVMMCJITMemoryManagerRef memorymgr)
    delete reinterpret_cast<BaseMemoryManager*>(memorymgr);
 }
 
+extern "C" void
+lp_free_objcache(void *objcache_ptr)
+{
+   LPObjectCache *objcache = (LPObjectCache *)objcache_ptr;
+   delete objcache;
+}
+
 extern "C" LLVMValueRef
 lp_get_called_value(LLVMValueRef call)
 {

src/gallium/auxiliary/gallivm/lp_bld_misc.h

@@ -50,6 +50,7 @@ struct lp_cached_code {
    void *data;
    size_t data_size;
    bool dont_cache;
+   void *jit_obj_cache;
 };
 
 struct lp_generated_code;
@@ -88,6 +89,8 @@ lp_get_called_value(LLVMValueRef call);
 extern bool
 lp_is_function(LLVMValueRef v);
 
+void
+lp_free_objcache(void *objcache);
 #ifdef __cplusplus
 }
 #endif