Support for optimizing and emitting code in LLVM JIT provider.

This commit introduces the ability to actually generate code using
LLVM. In particular, this adds:

- Ability to emit code both in heavily optimized and largely
  unoptimized fashion
- Batching facility to allow functions to be defined in small
  increments, but optimized and emitted in executable form in larger
  batches (for performance and memory efficiency)
- Type and function declaration synchronization between runtime
  generated code and normal postgres code. This is critical to be able
  to access struct fields etc.
- Developer oriented jit_dump_bitcode GUC, for inspecting / debugging
  the generated code.
- per JitContext statistics of number of functions, time spent
  generating code, optimizing, and emitting it.  This will later be
  employed for EXPLAIN support.

This commit doesn't yet contain any code actually generating
functions. That'll follow in later commits.

Documentation for GUCs added, and for JIT in general, will be added in
later commits.

Author: Andres Freund, with contributions by Pierre Ducroquet
Testing-By: Thomas Munro, Peter Eisentraut
Discussion: https://postgr.es/m/20170901064131.tazjxwus3k2w3ybh@alap3.anarazel.de

.gitignore

@@ -1,6 +1,7 @@
 # Global excludes across all subdirectories
 *.o
 *.obj
+*.bc
 *.so
 *.so.[0-9]
 *.so.[0-9].[0-9]

src/Makefile.global.in

@@ -951,3 +951,24 @@ coverage-clean:
 	rm -f `find . -name '*.gcda' -print`
 
 endif # enable_coverage
+
+##########################################################################
+#
+# LLVM support
+#
+
+ifndef COMPILE.c.bc
+# -Wno-ignored-attributes added so gnu_printf doesn't trigger
+# warnings, when the main binary is compiled with C.
+COMPILE.c.bc = $(CLANG) -Wno-ignored-attributes $(BITCODE_CFLAGS) $(CPPFLAGS) -flto=thin -emit-llvm -c
+endif
+
+ifndef COMPILE.cxx.bc
+COMPILE.cxx.bc = $(CLANG) -xc++ -Wno-ignored-attributes $(BITCODE_CXXFLAGS) $(CPPFLAGS) -flto=thin -emit-llvm -c
+endif
+
+%.bc : %.c
+	$(COMPILE.c.bc) -o $@ $<
+
+%.bc : %.cpp
+	$(COMPILE.cxx.bc) -o $@ $<

src/backend/common.mk

@@ -46,3 +46,4 @@ clean-local:
 	rm -f $(subsysfilename) $(OBJS)
 
 $(call recurse,coverage)
+$(call recurse,install)

src/backend/jit/jit.c

@@ -33,6 +33,7 @@
 /* GUCs */
 bool		jit_enabled = true;
 char	   *jit_provider = "llvmjit";
+bool		jit_dump_bitcode = false;
 
 static JitProviderCallbacks provider;
 static bool provider_successfully_loaded = false;

src/backend/jit/llvm/Makefile

@@ -41,15 +41,23 @@ OBJS += llvmjit.o llvmjit_error.o llvmjit_wrap.o
 # Code generation
 OBJS +=
 
-all: all-shared-lib
+all: all-shared-lib llvmjit_types.bc
 
-install: all installdirs install-lib
+install: all installdirs install-lib install-types
 
 installdirs: installdirs-lib
 
-uninstall: uninstall-lib
+uninstall: uninstall-lib uninstall-types
+
+# Note this is intentionally not in bitcodedir, as it's not for inlining */
+install-types: llvmjit_types.bc
+	$(INSTALL_DATA) llvmjit_types.bc '$(DESTDIR)$(pkglibdir)'
+
+uninstall-types:
+	rm -f '$(DESTDIR)$(pkglibdir)/llvmjit_types.bc'
 
 include $(top_srcdir)/src/Makefile.shlib
 
 clean distclean maintainer-clean: clean-lib
 	rm -f $(OBJS)
+	rm -f llvmjit_types.bc

src/backend/jit/llvm/llvmjit.c

@@ -19,18 +19,59 @@
 
 #include "utils/memutils.h"
 #include "utils/resowner_private.h"
+#include "portability/instr_time.h"
 #include "storage/ipc.h"
 
 
+#include <llvm-c/Analysis.h>
+#include <llvm-c/BitReader.h>
+#include <llvm-c/BitWriter.h>
+#include <llvm-c/Core.h>
+#include <llvm-c/OrcBindings.h>
+#include <llvm-c/Support.h>
 #include <llvm-c/Target.h>
+#include <llvm-c/Transforms/IPO.h>
+#include <llvm-c/Transforms/PassManagerBuilder.h>
+#include <llvm-c/Transforms/Scalar.h>
+
+
+/* Handle of a module emitted via ORC JIT */
+typedef struct LLVMJitHandle
+{
+	LLVMOrcJITStackRef stack;
+	LLVMOrcModuleHandle orc_handle;
+} LLVMJitHandle;
+
+
+/* types & functions commonly needed for JITing */
+LLVMTypeRef TypeSizeT;
+
+LLVMValueRef AttributeTemplate;
+LLVMValueRef FuncStrlen;
 
 
 static bool llvm_session_initialized = false;
+static size_t llvm_generation = 0;
+static const char *llvm_triple = NULL;
+static const char *llvm_layout = NULL;
+
+
+static LLVMTargetMachineRef llvm_opt0_targetmachine;
+static LLVMTargetMachineRef llvm_opt3_targetmachine;
+
+static LLVMTargetRef llvm_targetref;
+static LLVMOrcJITStackRef llvm_opt0_orc;
+static LLVMOrcJITStackRef llvm_opt3_orc;
 
 
 static void llvm_release_context(JitContext *context);
 static void llvm_session_initialize(void);
 static void llvm_shutdown(int code, Datum arg);
+static void llvm_compile_module(LLVMJitContext *context);
+static void llvm_optimize_module(LLVMJitContext *context, LLVMModuleRef module);
+
+static void llvm_create_types(void);
+static uint64_t llvm_resolve_symbol(const char *name, void *ctx);
 
 
 PG_MODULE_MAGIC;
@@ -81,6 +122,359 @@ llvm_create_context(int jitFlags)
 static void
 llvm_release_context(JitContext *context)
 {
+	LLVMJitContext *llvm_context = (LLVMJitContext *) context;
+
+	llvm_enter_fatal_on_oom();
+
+	/*
+	 * When this backend is exiting, don't clean up LLVM. As an error might
+	 * have occurred from within LLVM, we do not want to risk reentering. All
+	 * resource cleanup is going to happen through process exit.
+	 */
+	if (!proc_exit_inprogress)
+	{
+		if (llvm_context->module)
+		{
+			LLVMDisposeModule(llvm_context->module);
+			llvm_context->module = NULL;
+		}
+
+		while (llvm_context->handles != NIL)
+		{
+			LLVMJitHandle *jit_handle;
+
+			jit_handle = (LLVMJitHandle *) linitial(llvm_context->handles);
+			llvm_context->handles = list_delete_first(llvm_context->handles);
+
+			LLVMOrcRemoveModule(jit_handle->stack, jit_handle->orc_handle);
+			pfree(jit_handle);
+		}
+	}
+}
+
+/*
+ * Return module which may be modified, e.g. by creating new functions.
+ */
+LLVMModuleRef
+llvm_mutable_module(LLVMJitContext *context)
+{
+	llvm_assert_in_fatal_section();
+
+	/*
+	 * If there's no in-progress module, create a new one.
+	 */
+	if (!context->module)
+	{
+		context->compiled = false;
+		context->module_generation = llvm_generation++;
+		context->module = LLVMModuleCreateWithName("pg");
+		LLVMSetTarget(context->module, llvm_triple);
+		LLVMSetDataLayout(context->module, llvm_layout);
+	}
+
+	return context->module;
+}
+
+/*
+ * Expand function name to be non-conflicting. This should be used by code
+ * generating code, when adding new externally visible function definitions to
+ * a Module.
+ */
+char *
+llvm_expand_funcname(struct LLVMJitContext *context, const char *basename)
+{
+	Assert(context->module != NULL);
+
+	context->base.created_functions++;
+
+	/*
+	 * Previously we used dots to separate, but turns out some tools, e.g.
+	 * GDB, don't like that and truncate name.
+	 */
+	return psprintf("%s_%zu_%d",
+					basename,
+					context->module_generation,
+					context->counter++);
+}
+
+/*
+ * Return pointer to function funcname, which has to exist. If there's pending
+ * code to be optimized and emitted, do so first.
+ */
+void *
+llvm_get_function(LLVMJitContext *context, const char *funcname)
+{
+	LLVMOrcTargetAddress addr = 0;
+#if defined(HAVE_DECL_LLVMORCGETSYMBOLADDRESSIN) && HAVE_DECL_LLVMORCGETSYMBOLADDRESSIN
+	ListCell   *lc;
+#endif
+
+	llvm_assert_in_fatal_section();
+
+	/*
+	 * If there is a pending / not emitted module, compile and emit now.
+	 * Otherwise we migh not find the [correct] function.
+	 */
+	if (!context->compiled)
+	{
+		llvm_compile_module(context);
+	}
+
+	/*
+	 * ORC's symbol table is of *unmangled* symbols. Therefore we don't need
+	 * to mangle here.
+	 */
+
+#if defined(HAVE_DECL_LLVMORCGETSYMBOLADDRESSIN) && HAVE_DECL_LLVMORCGETSYMBOLADDRESSIN
+	foreach(lc, context->handles)
+	{
+		LLVMJitHandle *handle = (LLVMJitHandle *) lfirst(lc);
+
+		addr = 0;
+		if (LLVMOrcGetSymbolAddressIn(handle->stack, &addr, handle->orc_handle, funcname))
+			elog(ERROR, "failed to lookup symbol \"%s\"", funcname);
+		if (addr)
+			return (void *) (uintptr_t) addr;
+	}
+
+#else
+
+#if LLVM_VERSION_MAJOR < 5
+	if ((addr = LLVMOrcGetSymbolAddress(llvm_opt0_orc, funcname)))
+		return (void *) (uintptr_t) addr;
+	if ((addr = LLVMOrcGetSymbolAddress(llvm_opt3_orc, funcname)))
+		return (void *) (uintptr_t) addr;
+#else
+	if (LLVMOrcGetSymbolAddress(llvm_opt0_orc, &addr, funcname))
+		elog(ERROR, "failed to lookup symbol \"%s\"", funcname);
+	if (addr)
+		return (void *) (uintptr_t) addr;
+	if (LLVMOrcGetSymbolAddress(llvm_opt3_orc, &addr, funcname))
+		elog(ERROR, "failed to lookup symbol \"%s\"", funcname);
+	if (addr)
+		return (void *) (uintptr_t) addr;
+#endif							/* LLVM_VERSION_MAJOR */
+
+#endif							/* HAVE_DECL_LLVMORCGETSYMBOLADDRESSIN */
+
+	elog(ERROR, "failed to JIT: %s", funcname);
+
+	return NULL;
+}
+
+/*
+ * Return declaration for passed function, adding it to the module if
+ * necessary.
+ *
+ * This is used to make functions imported by llvm_create_types() known to the
+ * module that's currently being worked on.
+ */
+LLVMValueRef
+llvm_get_decl(LLVMModuleRef mod, LLVMValueRef v_src)
+{
+	LLVMValueRef v_fn;
+
+	/* don't repeatedly add function */
+	v_fn = LLVMGetNamedFunction(mod, LLVMGetValueName(v_src));
+	if (v_fn)
+		return v_fn;
+
+	v_fn = LLVMAddFunction(mod,
+						   LLVMGetValueName(v_src),
+						   LLVMGetElementType(LLVMTypeOf(v_src)));
+	llvm_copy_attributes(v_src, v_fn);
+
+	return v_fn;
+}
+
+/*
+ * Copy attributes from one function to another.
+ */
+void
+llvm_copy_attributes(LLVMValueRef v_from, LLVMValueRef v_to)
+{
+	int			num_attributes;
+	int			attno;
+	LLVMAttributeRef *attrs;
+
+	num_attributes =
+		LLVMGetAttributeCountAtIndex(v_from, LLVMAttributeFunctionIndex);
+
+	attrs = palloc(sizeof(LLVMAttributeRef) * num_attributes);
+	LLVMGetAttributesAtIndex(v_from, LLVMAttributeFunctionIndex, attrs);
+
+	for (attno = 0; attno < num_attributes; attno++)
+	{
+		LLVMAddAttributeAtIndex(v_to, LLVMAttributeFunctionIndex,
+								attrs[attno]);
+	}
+}
+
+/*
+ * Optimize code in module using the flags set in context.
+ */
+static void
+llvm_optimize_module(LLVMJitContext *context, LLVMModuleRef module)
+{
+	LLVMPassManagerBuilderRef llvm_pmb;
+	LLVMPassManagerRef llvm_mpm;
+	LLVMPassManagerRef llvm_fpm;
+	LLVMValueRef func;
+	int			compile_optlevel;
+
+	if (context->base.flags & PGJIT_OPT3)
+		compile_optlevel = 3;
+	else
+		compile_optlevel = 0;
+
+	/*
+	 * Have to create a new pass manager builder every pass through, as the
+	 * inliner has some per-builder state. Otherwise one ends up only inlining
+	 * a function the first time though.
+	 */
+	llvm_pmb = LLVMPassManagerBuilderCreate();
+	LLVMPassManagerBuilderSetOptLevel(llvm_pmb, compile_optlevel);
+	llvm_fpm = LLVMCreateFunctionPassManagerForModule(module);
+
+	if (context->base.flags & PGJIT_OPT3)
+	{
+		/* TODO: Unscientifically determined threshhold */
+		LLVMPassManagerBuilderUseInlinerWithThreshold(llvm_pmb, 512);
+	}
+	else
+	{
+		/* we rely on mem2reg heavily, so emit even in the O0 case */
+		LLVMAddPromoteMemoryToRegisterPass(llvm_fpm);
+	}
+
+	LLVMPassManagerBuilderPopulateFunctionPassManager(llvm_pmb, llvm_fpm);
+
+	/*
+	 * Do function level optimization. This could be moved to the point where
+	 * functions are emitted, to reduce memory usage a bit.
+	 */
+	LLVMInitializeFunctionPassManager(llvm_fpm);
+	for (func = LLVMGetFirstFunction(context->module);
+		 func != NULL;
+		 func = LLVMGetNextFunction(func))
+		LLVMRunFunctionPassManager(llvm_fpm, func);
+	LLVMFinalizeFunctionPassManager(llvm_fpm);
+	LLVMDisposePassManager(llvm_fpm);
+
+	/*
+	 * Perform module level optimization. We do so even in the non-optimized
+	 * case, so always-inline functions etc get inlined. It's cheap enough.
+	 */
+	llvm_mpm = LLVMCreatePassManager();
+	LLVMPassManagerBuilderPopulateModulePassManager(llvm_pmb,
+													llvm_mpm);
+	/* always use always-inliner pass */
+	if (!(context->base.flags & PGJIT_OPT3))
+		LLVMAddAlwaysInlinerPass(llvm_mpm);
+	LLVMRunPassManager(llvm_mpm, context->module);
+	LLVMDisposePassManager(llvm_mpm);
+
+	LLVMPassManagerBuilderDispose(llvm_pmb);
+}
+
+/*
+ * Emit code for the currently pending module.
+ */
+static void
+llvm_compile_module(LLVMJitContext *context)
+{
+	LLVMOrcModuleHandle orc_handle;
+	MemoryContext oldcontext;
+	static LLVMOrcJITStackRef compile_orc;
+	instr_time	starttime;
+	instr_time	endtime;
+
+	if (context->base.flags & PGJIT_OPT3)
+		compile_orc = llvm_opt3_orc;
+	else
+		compile_orc = llvm_opt0_orc;
+
+	if (jit_dump_bitcode)
+	{
+		char	   *filename;
+
+		filename = psprintf("%u.%zu.bc",
+							MyProcPid,
+							context->module_generation);
+		LLVMWriteBitcodeToFile(context->module, filename);
+		pfree(filename);
+	}
+
+
+	/* optimize according to the chosen optimization settings */
+	INSTR_TIME_SET_CURRENT(starttime);
+	llvm_optimize_module(context, context->module);
+	INSTR_TIME_SET_CURRENT(endtime);
+	INSTR_TIME_ACCUM_DIFF(context->base.optimization_counter,
+						  endtime, starttime);
+
+	if (jit_dump_bitcode)
+	{
+		char	   *filename;
+
+		filename = psprintf("%u.%zu.optimized.bc",
+							MyProcPid,
+							context->module_generation);
+		LLVMWriteBitcodeToFile(context->module, filename);
+		pfree(filename);
+	}
+
+	/*
+	 * Emit the code. Note that this can, depending on the optimization
+	 * settings, take noticeable resources as code emission executes low-level
+	 * instruction combining/selection passes etc. Without optimization a
+	 * faster instruction selection mechanism is used.
+	 */
+	INSTR_TIME_SET_CURRENT(starttime);
+#if LLVM_VERSION_MAJOR < 5
+	{
+		orc_handle = LLVMOrcAddEagerlyCompiledIR(compile_orc, context->module,
+												 llvm_resolve_symbol, NULL);
+	}
+#else
+	{
+		LLVMSharedModuleRef smod;
+
+		smod = LLVMOrcMakeSharedModule(context->module);
+		if (LLVMOrcAddEagerlyCompiledIR(compile_orc, &orc_handle, smod,
+										llvm_resolve_symbol, NULL))
+		{
+			elog(ERROR, "failed to jit module");
+		}
+		LLVMOrcDisposeSharedModuleRef(smod);
+	}
+#endif
+	INSTR_TIME_SET_CURRENT(endtime);
+	INSTR_TIME_ACCUM_DIFF(context->base.emission_counter,
+						  endtime, starttime);
+
+	context->module = NULL;
+	context->compiled = true;
+
+	/* remember emitted code for cleanup and lookups */
+	oldcontext = MemoryContextSwitchTo(TopMemoryContext);
+	{
+		LLVMJitHandle *handle;
+
+		handle = (LLVMJitHandle *) palloc(sizeof(LLVMJitHandle));
+		handle->stack = compile_orc;
+		handle->orc_handle = orc_handle;
+
+		context->handles = lappend(context->handles, handle);
+	}
+	MemoryContextSwitchTo(oldcontext);
+
+	ereport(DEBUG1,
+			(errmsg("time to opt: %.3fs, emit: %.3fs",
+					INSTR_TIME_GET_DOUBLE(context->base.optimization_counter),
+					INSTR_TIME_GET_DOUBLE(context->base.emission_counter)),
+			 errhidestmt(true),
+			 errhidecontext(true)));
 }
 
 /*
@@ -90,6 +484,9 @@ static void
 llvm_session_initialize(void)
 {
 	MemoryContext oldcontext;
+	char	   *error = NULL;
+	char	   *cpu = NULL;
+	char	   *features = NULL;
 
 	if (llvm_session_initialized)
 		return;
@@ -100,6 +497,50 @@ llvm_session_initialize(void)
 	LLVMInitializeNativeAsmPrinter();
 	LLVMInitializeNativeAsmParser();
 
+	/*
+	 * Synchronize types early, as that also includes inferring the target
+	 * triple.
+	 */
+	llvm_create_types();
+
+	if (LLVMGetTargetFromTriple(llvm_triple, &llvm_targetref, &error) != 0)
+	{
+		elog(FATAL, "failed to query triple %s\n", error);
+	}
+
+	/*
+	 * We want the generated code to use all available features. Therefore
+	 * grab the host CPU string and detect features of the current CPU. The
+	 * latter is needed because some CPU architectures default to enabling
+	 * features not all CPUs have (weird, huh).
+	 */
+	cpu = LLVMGetHostCPUName();
+	features = LLVMGetHostCPUFeatures();
+	elog(DEBUG2, "LLVMJIT detected CPU \"%s\", with features \"%s\"",
+		 cpu, features);
+
+	llvm_opt0_targetmachine =
+		LLVMCreateTargetMachine(llvm_targetref, llvm_triple, cpu, features,
+								LLVMCodeGenLevelNone,
+								LLVMRelocDefault,
+								LLVMCodeModelJITDefault);
+	llvm_opt3_targetmachine =
+		LLVMCreateTargetMachine(llvm_targetref, llvm_triple, cpu, features,
+								LLVMCodeGenLevelAggressive,
+								LLVMRelocDefault,
+								LLVMCodeModelJITDefault);
+
+	LLVMDisposeMessage(cpu);
+	cpu = NULL;
+	LLVMDisposeMessage(features);
+	features = NULL;
+
+	/* force symbols in main binary to be loaded */
+	LLVMLoadLibraryPermanently(NULL);
+
+	llvm_opt0_orc = LLVMOrcCreateInstance(llvm_opt0_targetmachine);
+	llvm_opt3_orc = LLVMOrcCreateInstance(llvm_opt3_targetmachine);
+
 	before_shmem_exit(llvm_shutdown, 0);
 
 	llvm_session_initialized = true;
@@ -111,3 +552,150 @@ static void
 llvm_shutdown(int code, Datum arg)
 {
 }
+
+/* helper for llvm_create_types */
+static LLVMTypeRef
+load_type(LLVMModuleRef mod, const char *name)
+{
+	LLVMValueRef value;
+	LLVMTypeRef typ;
+
+	/* this'll return a *pointer* to the global */
+	value = LLVMGetNamedGlobal(mod, name);
+	if (!value)
+		elog(ERROR, "type %s is unknown", name);
+
+	/* therefore look at the contained type and return that */
+	typ = LLVMTypeOf(value);
+	Assert(typ != NULL);
+	typ = LLVMGetElementType(typ);
+	Assert(typ != NULL);
+	return typ;
+}
+
+/*
+ * Load required information, types, function signatures from llvmjit_types.c
+ * and make them available in global variables.
+ *
+ * Those global variables are then used while emitting code.
+ */
+static void
+llvm_create_types(void)
+{
+	char		path[MAXPGPATH];
+	LLVMMemoryBufferRef buf;
+	char	   *msg;
+	LLVMModuleRef mod = NULL;
+
+	snprintf(path, MAXPGPATH, "%s/%s", pkglib_path, "llvmjit_types.bc");
+
+	/* open file */
+	if (LLVMCreateMemoryBufferWithContentsOfFile(path, &buf, &msg))
+	{
+		elog(ERROR, "LLVMCreateMemoryBufferWithContentsOfFile(%s) failed: %s",
+			 path, msg);
+	}
+
+	/* eagerly load contents, going to need it all */
+	if (LLVMParseBitcode2(buf, &mod))
+	{
+		elog(ERROR, "LLVMParseBitcode2 of %s failed", path);
+	}
+	LLVMDisposeMemoryBuffer(buf);
+
+	/*
+	 * Load triple & layout from clang emitted file so we're guaranteed to be
+	 * compatible.
+	 */
+	llvm_triple = pstrdup(LLVMGetTarget(mod));
+	llvm_layout = pstrdup(LLVMGetDataLayoutStr(mod));
+
+	TypeSizeT = load_type(mod, "TypeSizeT");
+
+	AttributeTemplate = LLVMGetNamedFunction(mod, "AttributeTemplate");
+	FuncStrlen = LLVMGetNamedFunction(mod, "strlen");
+
+	/*
+	 * Leave the module alive, otherwise references to function would be
+	 * dangling.
+	 */
+
+	return;
+}
+
+/*
+ * Split a symbol into module / function parts.  If the function is in the
+ * main binary (or an external library) *modname will be NULL.
+ */
+void
+llvm_split_symbol_name(const char *name, char **modname, char **funcname)
+{
+	*modname = NULL;
+	*funcname = NULL;
+
+	/*
+	 * Module function names are pgextern.$module.$funcname
+	 */
+	if (strncmp(name, "pgextern.", strlen("pgextern.")) == 0)
+	{
+		/*
+		 * Symbol names cannot contain a ., therefore we can split based on
+		 * first and last occurance of one.
+		 */
+		*funcname = rindex(name, '.');
+		(*funcname)++;			/* jump over . */
+
+		*modname = pnstrdup(name + strlen("pgextern."),
+							*funcname - name - strlen("pgextern.") - 1);
+		Assert(funcname);
+
+		*funcname = pstrdup(*funcname);
+	}
+	else
+	{
+		*modname = NULL;
+		*funcname = pstrdup(name);
+	}
+}
+
+/*
+ * Attempt to resolve symbol, so LLVM can emit a reference to it.
+ */
+static uint64_t
+llvm_resolve_symbol(const char *symname, void *ctx)
+{
+	uintptr_t	addr;
+	char	   *funcname;
+	char	   *modname;
+
+	/*
+	 * OSX prefixes all object level symbols with an underscore. But neither
+	 * dlsym() nor PG's inliner expect that. So undo.
+	 */
+#if defined(__darwin__)
+	if (symname[0] != '_')
+		elog(ERROR, "expected prefixed symbol name, but got \"%s\"", symname);
+	symname++;
+#endif
+
+	llvm_split_symbol_name(symname, &modname, &funcname);
+
+	/* functions that aren't resolved to names shouldn't ever get here */
+	Assert(funcname);
+
+	if (modname)
+		addr = (uintptr_t) load_external_function(modname, funcname,
+												  true, NULL);
+	else
+		addr = (uintptr_t) LLVMSearchForAddressOfSymbol(symname);
+
+	pfree(funcname);
+	if (modname)
+		pfree(modname);
+
+	/* let LLVM will error out - should never happen */
+	if (!addr)
+		elog(WARNING, "failed to resolve name %s", symname);
+
+	return (uint64_t) addr;
+}

src/backend/jit/llvm/llvmjit_types.c

@@ -0,0 +1,60 @@
+/*-------------------------------------------------------------------------
+ *
+ * llvmjit_types.c
+ *	  List of types needed by JIT emitting code.
+ *
+ * JIT emitting code often needs to access struct elements, create functions
+ * with the correct signature etc. To allow synchronizing these types with a
+ * low chance of definitions getting out of sync, this file lists types and
+ * functions that directly need to be accessed from LLVM.
+ *
+ * When LlVM is first used in a backend, a bitcode version of this file, will
+ * be loaded. The needed types and signatures will be stored into Struct*,
+ * Type*, Func* variables.
+ *
+ * NB: This file will not be linked into the server, it's just converted to
+ * bitcode.
+ *
+ *
+ * Copyright (c) 2016-2018, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/lib/llvmjit_types.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "fmgr.h"
+
+/*
+ * List of types needed for JITing. These have to be non-static, otherwise
+ * clang/LLVM will omit them.  As this file will never be linked into
+ * anything, that's harmless.
+ */
+size_t		TypeSizeT;
+
+
+/*
+ * To determine which attributes functions need to have (depends e.g. on
+ * compiler version and settings) to be compatible for inlining, we simply
+ * copy the attributes of this function.
+ */
+extern Datum AttributeTemplate(PG_FUNCTION_ARGS);
+Datum
+AttributeTemplate(PG_FUNCTION_ARGS)
+{
+	PG_RETURN_NULL();
+}
+
+
+/*
+ * To force signatures of functions used during JITing to be present,
+ * reference the functions required. This again has to be non-static, to avoid
+ * being removed as unnecessary.
+ */
+void	   *referenced_functions[] =
+{
+	strlen
+};

src/backend/utils/misc/guc.c

@@ -1734,6 +1734,17 @@ static struct config_bool ConfigureNamesBool[] =
 		NULL, NULL, NULL
 	},
 
+	{
+		{"jit_dump_bitcode", PGC_SUSET, DEVELOPER_OPTIONS,
+			gettext_noop("Write out LLVM bitcode to facilitate JIT debugging."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&jit_dump_bitcode,
+		false,
+		NULL, NULL, NULL
+	},
+
 	/* End-of-list marker */
 	{
 		{NULL, 0, 0, NULL, NULL}, NULL, false, NULL, NULL, NULL

src/include/jit/jit.h

@@ -11,14 +11,34 @@
 #ifndef JIT_H
 #define JIT_H
 
+#include "executor/instrument.h"
 #include "utils/resowner.h"
 
 
+/* Flags deterimining what kind of JIT operations to perform */
+#define PGJIT_NONE     0
+#define PGJIT_PERFORM  1 << 0
+#define PGJIT_OPT3     1 << 1
+
+
 typedef struct JitContext
 {
+	/* see PGJIT_* above */
 	int			flags;
 
 	ResourceOwner resowner;
+
+	/* number of emitted functions */
+	size_t		created_functions;
+
+	/* accumulated time to generate code */
+	instr_time	generation_counter;
+
+	/* accumulated time for optimization */
+	instr_time	optimization_counter;
+
+	/* accumulated time for code emission */
+	instr_time	emission_counter;
 } JitContext;
 
 typedef struct JitProviderCallbacks JitProviderCallbacks;
@@ -38,6 +58,7 @@ struct JitProviderCallbacks
 /* GUCs */
 extern bool jit_enabled;
 extern char *jit_provider;
+extern bool jit_dump_bitcode;
 
 
 extern void jit_reset_after_error(void);

src/include/jit/llvmjit.h

@@ -30,19 +30,49 @@ extern "C"
 
 
 #include "jit/jit.h"
+#include "nodes/pg_list.h"
 
 
 typedef struct LLVMJitContext
 {
 	JitContext	base;
+
+	/* number of modules created */
+	size_t		module_generation;
+
+	/* current, "open for write", module */
+	LLVMModuleRef module;
+
+	/* is there any pending code that needs to be emitted */
+	bool		compiled;
+
+	/* # of objects emitted, used to generate non-conflicting names */
+	int			counter;
+
+	/* list of handles for code emitted via Orc */
+	List	   *handles;
 } LLVMJitContext;
 
+
+/* type and struct definitions */
+extern LLVMTypeRef TypeSizeT;
+
+extern LLVMValueRef AttributeTemplate;
+extern LLVMValueRef FuncStrlen;
+
+
 extern void llvm_enter_fatal_on_oom(void);
 extern void llvm_leave_fatal_on_oom(void);
 extern void llvm_reset_after_error(void);
 extern void llvm_assert_in_fatal_section(void);
 
 extern LLVMJitContext *llvm_create_context(int jitFlags);
+extern LLVMModuleRef llvm_mutable_module(LLVMJitContext *context);
+extern char *llvm_expand_funcname(LLVMJitContext *context, const char *basename);
+extern void *llvm_get_function(LLVMJitContext *context, const char *funcname);
+extern void llvm_split_symbol_name(const char *name, char **modname, char **funcname);
+extern LLVMValueRef llvm_get_decl(LLVMModuleRef mod, LLVMValueRef f);
+extern void llvm_copy_attributes(LLVMValueRef from, LLVMValueRef to);
 
 
 /*

src/tools/pgindent/typedefs.list

@@ -1103,6 +1103,9 @@ LDAPURLDesc
 LDAP_TIMEVAL
 LINE
 LLVMJitContext
+LLVMJitHandle
+LLVMTypeRef
+LLVMValueRef
 LOCALLOCK
 LOCALLOCKOWNER
 LOCALLOCKTAG