Tools/ReducedFTL/ReducedFTL.c - WebKit - Git at Google

 /*
  * Copyright (C) 2013 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 /*
  * Simple tool that takes some LLVM bitcode as input and "JITs" it, in the
  * same way that the FTL would use LLVM to JIT the IR that it generates.
  * This is meant for use as a reduction when communicating to LLVMers
  * about bugs, and for quick "what-if" testing to see how our optimization
  * pipeline performs. Because of its use as a reduction, this tool is
  * intentionally standalone and it would be great if it continues to fit
  * in one file.
  */

 #include <getopt.h>
 #include <inttypes.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/mman.h>
 #include <sys/time.h>
 #include <unistd.h>

 #include <llvm-c/Analysis.h>
 #include <llvm-c/BitReader.h>
 #include <llvm-c/Core.h>
 #include <llvm-c/Disassembler.h>
 #include <llvm-c/ExecutionEngine.h>
 #include <llvm-c/Target.h>
 #include <llvm-c/Transforms/PassManagerBuilder.h>
 #include <llvm-c/Transforms/Scalar.h>

 static void usage()
 {
     printf("Usage: ReducedFTL <file1> [<file2> ...]\n");
     printf("\n");
     printf("Options:\n");
     printf("--verbose        Display more information, including module dumps.\n");
     printf("--timing         Measure the time it takes to compile.\n");
     printf("--disassemble    Disassemble all of the generated code at the end.\n");
     printf("--mode <mode>    Set the optimization mode (either \"simple\" or \"opt\").\n");
     printf("--contexts <arg> Set the number of contexts (either \"one\" or \"many\").\n");
     printf("--loop           Keep recompiling forever. Useful when attaching a profiler.\n");
     printf("--fast-isel      Enable the \"fast\" instruction selector.\n");
     printf("--help           Print this message.\n");
     printf("\n");
     printf("Unless you specify one of --verbose, --timing, or --disassemble, you will\n");
     printf("not see any output.\n");
     exit(1);
 }

 static double currentTime()
 {
     struct timeval now;
     gettimeofday(&now, 0);
     return now.tv_sec + now.tv_usec / 1000000.0;
 }

 struct MemorySection {
     uint8_t *start;
     size_t size;
     struct MemorySection *next;
 };

 static struct MemorySection* sectionHead;

 static size_t roundUpSize(size_t size)
 {
     size_t pageSize = getpagesize();

     return (size + pageSize - 1) & ~pageSize;
 }

 static uint8_t *mmAllocateCodeSection(
     void *opaqueState, uintptr_t size, unsigned alignment, unsigned sectionID)
 {
     uint8_t *start = mmap(
         0,  roundUpSize(size),
         PROT_WRITE | PROT_READ | PROT_EXEC,
         MAP_ANON | MAP_PRIVATE, -1, 0);
     if (start == (uint8_t*)-1) {
         fprintf(stderr, "Unable to allocate %" PRIuPTR " bytes of executable memory.\n", size);
         exit(1);
     }

     struct MemorySection *section = malloc(sizeof(struct MemorySection));
     section->start = start;
     section->size = size;
     section->next = sectionHead;
     sectionHead = section;

     return start;
 }

 static uint8_t *mmAllocateDataSection(
     void *opaqueState, uintptr_t size, unsigned alignment, unsigned sectionID,
     LLVMBool isReadOnly)
 {
     return mmAllocateCodeSection(opaqueState, size, alignment, sectionID);
 }

 static LLVMBool mmApplyPermissions(void *opaque, char **message)
 {
     return 0;
 }

 static void mmDestroy(void *opaque)
 {
 }

 static const char *symbolLookupCallback(
     void *opaque, uint64_t referenceValue, uint64_t *referenceType, uint64_t referencePC,
     const char **referenceName)
 {
     static char symbolString[20];

     switch (*referenceType) {
     case LLVMDisassembler_ReferenceType_InOut_None:
         return 0;
     case LLVMDisassembler_ReferenceType_In_Branch:
         *referenceName = 0;
         *referenceType = LLVMDisassembler_ReferenceType_InOut_None;
         snprintf(
             symbolString, sizeof(symbolString), "0x%lx",
             (unsigned long)referenceValue);
         return symbolString;
     default:
         fprintf(stderr, "Unexpected reference type!\n");
         exit(1);
         return 0;
     }
 }

 void webkit_osr_exit()
 {
     abort();
 }

 int main(int c, char **v)
 {
     LLVMContextRef *contexts;
     LLVMModuleRef *modules;
     char *error;
     const char *mode = "opt";
     const char **filenames;
     unsigned numFiles;
     unsigned i;
     bool moreOptions;
     static int verboseFlag = 0;
     static int timingFlag = 0;
     static int disassembleFlag = 0;
     bool manyContexts = true;
     bool loop = false;
     double beforeAll;
     bool fastIsel = false;
     int jitOptLevel = 2;
     struct MemorySection *section;

     if (c == 1)
         usage();

     moreOptions = true;
     while (moreOptions) {
         static struct option longOptions[] = {
             {"verbose", no_argument, &verboseFlag, 1},
             {"timing", no_argument, &timingFlag, 1},
             {"disassemble", no_argument, &disassembleFlag, 1},
             {"mode", required_argument, 0, 0},
             {"contexts", required_argument, 0, 0},
             {"loop", no_argument, 0, 0},
             {"fast-isel", no_argument, 0, 0},
             {"jit-opt", required_argument, 0, 0},
             {"help", no_argument, 0, 0}
         };

         int optionIndex;
         int optionValue;

         optionValue = getopt_long(c, v, "", longOptions, &optionIndex);

         switch (optionValue) {
         case -1:
             moreOptions = false;
             break;

         case 0: {
             const char* thisOption = longOptions[optionIndex].name;
             if (!strcmp(thisOption, "help"))
                 usage();
             if (!strcmp(thisOption, "loop"))
                 loop = true;
             if (!strcmp(thisOption, "fast-isel"))
                 fastIsel = true;
             if (!strcmp(thisOption, "contexts")) {
                 if (!strcasecmp(optarg, "one"))
                     manyContexts = false;
                 else if (!strcasecmp(optarg, "many"))
                     manyContexts = true;
                 else {
                     fprintf(stderr, "Invalid argument for --contexts.\n");
                     exit(1);
                 }
                 break;
             }
             if (!strcmp(thisOption, "jit-opt")) {
                 if (sscanf(optarg, "%d", &jitOptLevel) != 1) {
                     fprintf(stderr, "Invalid argument for --jit-opt.\n");
                     exit(1);
                 }
                 break;
             }
             if (!strcmp(thisOption, "mode")) {
                 mode = strdup(optarg);
                 break;
             }
             break;
         }

         case '?':
             exit(0);
             break;

         default:
             printf("optionValue = %d\n", optionValue);
             abort();
             break;
         }
     }

     LLVMLinkInMCJIT();
     LLVMInitializeNativeTarget();
     LLVMInitializeX86AsmPrinter();
     LLVMInitializeX86Disassembler();

     filenames = (const char **)(v + optind);
     numFiles = c - optind;

     if (!numFiles)
         return 0;

     do {
         contexts = malloc(sizeof(LLVMContextRef) * numFiles);
         modules = malloc(sizeof(LLVMModuleRef) * numFiles);

         if (manyContexts) {
             for (i = 0; i < numFiles; ++i)
                 contexts[i] = LLVMContextCreate();
         } else {
             LLVMContextRef context = LLVMContextCreate();
             for (i = 0; i < numFiles; ++i)
                 contexts[i] = context;
         }

         for (i = 0; i < numFiles; ++i) {
             LLVMMemoryBufferRef buffer;
             const char* filename = filenames[i];

             if (LLVMCreateMemoryBufferWithContentsOfFile(filename, &buffer, &error)) {
                 fprintf(stderr, "Error reading file %s: %s\n", filename, error);
                 exit(1);
             }

             if (LLVMParseBitcodeInContext(contexts[i], buffer, modules + i, &error)) {
                 fprintf(stderr, "Error parsing file %s: %s\n", filename, error);
                 exit(1);
             }

             LLVMDisposeMemoryBuffer(buffer);

             if (verboseFlag) {
                 printf("Module #%u (%s) after parsing:\n", i, filename);
                 LLVMDumpModule(modules[i]);
             }
         }

         if (verboseFlag)
             printf("Generating code for modules...\n");

         if (timingFlag)
             beforeAll = currentTime();
         for (i = 0; i < numFiles; ++i) {
             LLVMModuleRef module;
             LLVMExecutionEngineRef engine;
             struct LLVMMCJITCompilerOptions options;
             LLVMValueRef value;
             LLVMPassManagerRef functionPasses = 0;
             LLVMPassManagerRef modulePasses = 0;

             double before;

             if (timingFlag)
                 before = currentTime();

             module = modules[i];

             LLVMInitializeMCJITCompilerOptions(&options, sizeof(options));
             options.OptLevel = jitOptLevel;
             options.EnableFastISel = fastIsel;
             options.MCJMM = LLVMCreateSimpleMCJITMemoryManager(
                 0, mmAllocateCodeSection, mmAllocateDataSection, mmApplyPermissions, mmDestroy);

             if (LLVMCreateMCJITCompilerForModule(&engine, module, &options, sizeof(options), &error)) {
                 fprintf(stderr, "Error building MCJIT: %s\n", error);
                 exit(1);
             }

             if (!strcasecmp(mode, "simple")) {
                 modulePasses = LLVMCreatePassManager();
                 LLVMAddTargetData(LLVMGetExecutionEngineTargetData(engine), modulePasses);
                 LLVMAddPromoteMemoryToRegisterPass(modulePasses);
                 LLVMAddConstantPropagationPass(modulePasses);
                 LLVMAddInstructionCombiningPass(modulePasses);
                 LLVMAddBasicAliasAnalysisPass(modulePasses);
                 LLVMAddTypeBasedAliasAnalysisPass(modulePasses);
                 LLVMAddGVNPass(modulePasses);
                 LLVMAddCFGSimplificationPass(modulePasses);
                 LLVMRunPassManager(modulePasses, module);
             } else if (!strcasecmp(mode, "opt")) {
                 LLVMPassManagerBuilderRef passBuilder;

                 passBuilder = LLVMPassManagerBuilderCreate();
                 LLVMPassManagerBuilderSetOptLevel(passBuilder, 2);
                 LLVMPassManagerBuilderSetSizeLevel(passBuilder, 0);

                 functionPasses = LLVMCreateFunctionPassManagerForModule(module);
                 modulePasses = LLVMCreatePassManager();

                 LLVMAddTargetData(LLVMGetExecutionEngineTargetData(engine), modulePasses);

                 LLVMPassManagerBuilderPopulateFunctionPassManager(passBuilder, functionPasses);
                 LLVMPassManagerBuilderPopulateModulePassManager(passBuilder, modulePasses);

                 LLVMPassManagerBuilderDispose(passBuilder);

                 LLVMInitializeFunctionPassManager(functionPasses);
                 for (value = LLVMGetFirstFunction(module); value; value = LLVMGetNextFunction(value))
                     LLVMRunFunctionPassManager(functionPasses, value);
                 LLVMFinalizeFunctionPassManager(functionPasses);

                 LLVMRunPassManager(modulePasses, module);
             } else {
                 fprintf(stderr, "Bad optimization mode: %s.\n", mode);
                 fprintf(stderr, "Valid modes are: \"simple\" or \"opt\".\n");
                 exit(1);
             }

             if (verboseFlag) {
                 printf("Module #%d (%s) after optimization:\n", i, filenames[i]);
                 LLVMDumpModule(module);
             }

             for (value = LLVMGetFirstFunction(module); value; value = LLVMGetNextFunction(value)) {
                 if (LLVMIsDeclaration(value))
                     continue;
                 LLVMGetPointerToGlobal(engine, value);
             }

             if (functionPasses)
                 LLVMDisposePassManager(functionPasses);
             if (modulePasses)
                 LLVMDisposePassManager(modulePasses);

             LLVMDisposeExecutionEngine(engine);

             if (timingFlag) {
                 double after = currentTime();
                 printf("Module #%d (%s) took %lf ms.\n", i, filenames[i], (after - before) * 1000);
             }
         }

         if (manyContexts) {
             for (i = 0; i < numFiles; ++i)
                 LLVMContextDispose(contexts[i]);
         } else
             LLVMContextDispose(contexts[0]);

         if (timingFlag) {
             double after = currentTime();
             printf("Compilation took a total of %lf ms.\n", (after - beforeAll) * 1000);
         }

         if (disassembleFlag) {
             LLVMDisasmContextRef disassembler;

             disassembler = LLVMCreateDisasm("x86_64-apple-darwin", 0, 0, 0, symbolLookupCallback);
             if (!disassembler) {
                 fprintf(stderr, "Error building disassembler.\n");
                 exit(1);
             }

             for (section = sectionHead; section; section = section->next) {
                 printf("Disassembly for section %p:\n", section);

                 char pcString[20];
                 char instructionString[1000];
                 uint8_t *pc;
                 uint8_t *end;

                 pc = section->start;
                 end = pc + section->size;

                 while (pc < end) {
                     snprintf(
                         pcString, sizeof(pcString), "0x%lx",
                         (unsigned long)(uintptr_t)pc);

                     size_t instructionSize = LLVMDisasmInstruction(
                         disassembler, pc, end - pc, (uintptr_t)pc,
                         instructionString, sizeof(instructionString));

                     if (!instructionSize)
                         snprintf(instructionString, sizeof(instructionString), ".byte 0x%02x", *pc++);
                     else
                         pc += instructionSize;

                     printf("    %16s: %s\n", pcString, instructionString);
                 }
             }
         }

         for (section = sectionHead; section;) {
             struct MemorySection* nextSection = section->next;

             munmap(section->start, roundUpSize(section->size));
             free(section);

             section = nextSection;
         }
         sectionHead = 0;

     } while (loop);

     return 0;
 }
	/*
	* Copyright (C) 2013 Apple Inc. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
	* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
	* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
	* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
	* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
	* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
	* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	/*
	* Simple tool that takes some LLVM bitcode as input and "JITs" it, in the
	* same way that the FTL would use LLVM to JIT the IR that it generates.
	* This is meant for use as a reduction when communicating to LLVMers
	* about bugs, and for quick "what-if" testing to see how our optimization
	* pipeline performs. Because of its use as a reduction, this tool is
	* intentionally standalone and it would be great if it continues to fit
	* in one file.
	*/

	#include <getopt.h>
	#include <inttypes.h>
	#include <stdbool.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <sys/mman.h>
	#include <sys/time.h>
	#include <unistd.h>

	#include <llvm-c/Analysis.h>
	#include <llvm-c/BitReader.h>
	#include <llvm-c/Core.h>
	#include <llvm-c/Disassembler.h>
	#include <llvm-c/ExecutionEngine.h>
	#include <llvm-c/Target.h>
	#include <llvm-c/Transforms/PassManagerBuilder.h>
	#include <llvm-c/Transforms/Scalar.h>

	static void usage()
	{
	printf("Usage: ReducedFTL <file1> [<file2> ...]\n");
	printf("\n");
	printf("Options:\n");
	printf("--verbose Display more information, including module dumps.\n");
	printf("--timing Measure the time it takes to compile.\n");
	printf("--disassemble Disassemble all of the generated code at the end.\n");
	printf("--mode <mode> Set the optimization mode (either \"simple\" or \"opt\").\n");
	printf("--contexts <arg> Set the number of contexts (either \"one\" or \"many\").\n");
	printf("--loop Keep recompiling forever. Useful when attaching a profiler.\n");
	printf("--fast-isel Enable the \"fast\" instruction selector.\n");
	printf("--help Print this message.\n");
	printf("\n");
	printf("Unless you specify one of --verbose, --timing, or --disassemble, you will\n");
	printf("not see any output.\n");
	exit(1);
	}

	static double currentTime()
	{
	struct timeval now;
	gettimeofday(&now, 0);
	return now.tv_sec + now.tv_usec / 1000000.0;
	}

	struct MemorySection {
	uint8_t *start;
	size_t size;
	struct MemorySection *next;
	};

	static struct MemorySection* sectionHead;

	static size_t roundUpSize(size_t size)
	{
	size_t pageSize = getpagesize();

	return (size + pageSize - 1) & ~pageSize;
	}

	static uint8_t *mmAllocateCodeSection(
	void *opaqueState, uintptr_t size, unsigned alignment, unsigned sectionID)
	{
	uint8_t *start = mmap(
	0, roundUpSize(size),
	PROT_WRITE \| PROT_READ \| PROT_EXEC,
	MAP_ANON \| MAP_PRIVATE, -1, 0);
	if (start == (uint8_t*)-1) {
	fprintf(stderr, "Unable to allocate %" PRIuPTR " bytes of executable memory.\n", size);
	exit(1);
	}

	struct MemorySection *section = malloc(sizeof(struct MemorySection));
	section->start = start;
	section->size = size;
	section->next = sectionHead;
	sectionHead = section;

	return start;
	}

	static uint8_t *mmAllocateDataSection(
	void *opaqueState, uintptr_t size, unsigned alignment, unsigned sectionID,
	LLVMBool isReadOnly)
	{
	return mmAllocateCodeSection(opaqueState, size, alignment, sectionID);
	}

	static LLVMBool mmApplyPermissions(void opaque, char *message)
	{
	return 0;
	}

	static void mmDestroy(void *opaque)
	{
	}

	static const char *symbolLookupCallback(
	void opaque, uint64_t referenceValue, uint64_t referenceType, uint64_t referencePC,
	const char **referenceName)
	{
	static char symbolString[20];

	switch (*referenceType) {
	case LLVMDisassembler_ReferenceType_InOut_None:
	return 0;
	case LLVMDisassembler_ReferenceType_In_Branch:
	*referenceName = 0;
	*referenceType = LLVMDisassembler_ReferenceType_InOut_None;
	snprintf(
	symbolString, sizeof(symbolString), "0x%lx",
	(unsigned long)referenceValue);
	return symbolString;
	default:
	fprintf(stderr, "Unexpected reference type!\n");
	exit(1);
	return 0;
	}
	}

	void webkit_osr_exit()
	{
	abort();
	}

	int main(int c, char **v)
	{
	LLVMContextRef *contexts;
	LLVMModuleRef *modules;
	char *error;
	const char *mode = "opt";
	const char **filenames;
	unsigned numFiles;
	unsigned i;
	bool moreOptions;
	static int verboseFlag = 0;
	static int timingFlag = 0;
	static int disassembleFlag = 0;
	bool manyContexts = true;
	bool loop = false;
	double beforeAll;
	bool fastIsel = false;
	int jitOptLevel = 2;
	struct MemorySection *section;

	if (c == 1)
	usage();

	moreOptions = true;
	while (moreOptions) {
	static struct option longOptions[] = {
	{"verbose", no_argument, &verboseFlag, 1},
	{"timing", no_argument, &timingFlag, 1},
	{"disassemble", no_argument, &disassembleFlag, 1},
	{"mode", required_argument, 0, 0},
	{"contexts", required_argument, 0, 0},
	{"loop", no_argument, 0, 0},
	{"fast-isel", no_argument, 0, 0},
	{"jit-opt", required_argument, 0, 0},
	{"help", no_argument, 0, 0}
	};

	int optionIndex;
	int optionValue;

	optionValue = getopt_long(c, v, "", longOptions, &optionIndex);

	switch (optionValue) {
	case -1:
	moreOptions = false;
	break;

	case 0: {
	const char* thisOption = longOptions[optionIndex].name;
	if (!strcmp(thisOption, "help"))
	usage();
	if (!strcmp(thisOption, "loop"))
	loop = true;
	if (!strcmp(thisOption, "fast-isel"))
	fastIsel = true;
	if (!strcmp(thisOption, "contexts")) {
	if (!strcasecmp(optarg, "one"))
	manyContexts = false;
	else if (!strcasecmp(optarg, "many"))
	manyContexts = true;
	else {
	fprintf(stderr, "Invalid argument for --contexts.\n");
	exit(1);
	}
	break;
	}
	if (!strcmp(thisOption, "jit-opt")) {
	if (sscanf(optarg, "%d", &jitOptLevel) != 1) {
	fprintf(stderr, "Invalid argument for --jit-opt.\n");
	exit(1);
	}
	break;
	}
	if (!strcmp(thisOption, "mode")) {
	mode = strdup(optarg);
	break;
	}
	break;
	}

	case '?':
	exit(0);
	break;

	default:
	printf("optionValue = %d\n", optionValue);
	abort();
	break;
	}
	}

	LLVMLinkInMCJIT();
	LLVMInitializeNativeTarget();
	LLVMInitializeX86AsmPrinter();
	LLVMInitializeX86Disassembler();

	filenames = (const char **)(v + optind);
	numFiles = c - optind;

	if (!numFiles)
	return 0;

	do {
	contexts = malloc(sizeof(LLVMContextRef) * numFiles);
	modules = malloc(sizeof(LLVMModuleRef) * numFiles);

	if (manyContexts) {
	for (i = 0; i < numFiles; ++i)
	contexts[i] = LLVMContextCreate();
	} else {
	LLVMContextRef context = LLVMContextCreate();
	for (i = 0; i < numFiles; ++i)
	contexts[i] = context;
	}

	for (i = 0; i < numFiles; ++i) {
	LLVMMemoryBufferRef buffer;
	const char* filename = filenames[i];

	if (LLVMCreateMemoryBufferWithContentsOfFile(filename, &buffer, &error)) {
	fprintf(stderr, "Error reading file %s: %s\n", filename, error);
	exit(1);
	}

	if (LLVMParseBitcodeInContext(contexts[i], buffer, modules + i, &error)) {
	fprintf(stderr, "Error parsing file %s: %s\n", filename, error);
	exit(1);
	}

	LLVMDisposeMemoryBuffer(buffer);

	if (verboseFlag) {
	printf("Module #%u (%s) after parsing:\n", i, filename);
	LLVMDumpModule(modules[i]);
	}
	}

	if (verboseFlag)
	printf("Generating code for modules...\n");

	if (timingFlag)
	beforeAll = currentTime();
	for (i = 0; i < numFiles; ++i) {
	LLVMModuleRef module;
	LLVMExecutionEngineRef engine;
	struct LLVMMCJITCompilerOptions options;
	LLVMValueRef value;
	LLVMPassManagerRef functionPasses = 0;
	LLVMPassManagerRef modulePasses = 0;

	double before;

	if (timingFlag)
	before = currentTime();

	module = modules[i];

	LLVMInitializeMCJITCompilerOptions(&options, sizeof(options));
	options.OptLevel = jitOptLevel;
	options.EnableFastISel = fastIsel;
	options.MCJMM = LLVMCreateSimpleMCJITMemoryManager(
	0, mmAllocateCodeSection, mmAllocateDataSection, mmApplyPermissions, mmDestroy);

	if (LLVMCreateMCJITCompilerForModule(&engine, module, &options, sizeof(options), &error)) {
	fprintf(stderr, "Error building MCJIT: %s\n", error);
	exit(1);
	}

	if (!strcasecmp(mode, "simple")) {
	modulePasses = LLVMCreatePassManager();
	LLVMAddTargetData(LLVMGetExecutionEngineTargetData(engine), modulePasses);
	LLVMAddPromoteMemoryToRegisterPass(modulePasses);
	LLVMAddConstantPropagationPass(modulePasses);
	LLVMAddInstructionCombiningPass(modulePasses);
	LLVMAddBasicAliasAnalysisPass(modulePasses);
	LLVMAddTypeBasedAliasAnalysisPass(modulePasses);
	LLVMAddGVNPass(modulePasses);
	LLVMAddCFGSimplificationPass(modulePasses);
	LLVMRunPassManager(modulePasses, module);
	} else if (!strcasecmp(mode, "opt")) {
	LLVMPassManagerBuilderRef passBuilder;

	passBuilder = LLVMPassManagerBuilderCreate();
	LLVMPassManagerBuilderSetOptLevel(passBuilder, 2);
	LLVMPassManagerBuilderSetSizeLevel(passBuilder, 0);

	functionPasses = LLVMCreateFunctionPassManagerForModule(module);
	modulePasses = LLVMCreatePassManager();

	LLVMAddTargetData(LLVMGetExecutionEngineTargetData(engine), modulePasses);

	LLVMPassManagerBuilderPopulateFunctionPassManager(passBuilder, functionPasses);
	LLVMPassManagerBuilderPopulateModulePassManager(passBuilder, modulePasses);

	LLVMPassManagerBuilderDispose(passBuilder);

	LLVMInitializeFunctionPassManager(functionPasses);
	for (value = LLVMGetFirstFunction(module); value; value = LLVMGetNextFunction(value))
	LLVMRunFunctionPassManager(functionPasses, value);
	LLVMFinalizeFunctionPassManager(functionPasses);

	LLVMRunPassManager(modulePasses, module);
	} else {
	fprintf(stderr, "Bad optimization mode: %s.\n", mode);
	fprintf(stderr, "Valid modes are: \"simple\" or \"opt\".\n");
	exit(1);
	}

	if (verboseFlag) {
	printf("Module #%d (%s) after optimization:\n", i, filenames[i]);
	LLVMDumpModule(module);
	}

	for (value = LLVMGetFirstFunction(module); value; value = LLVMGetNextFunction(value)) {
	if (LLVMIsDeclaration(value))
	continue;
	LLVMGetPointerToGlobal(engine, value);
	}

	if (functionPasses)
	LLVMDisposePassManager(functionPasses);
	if (modulePasses)
	LLVMDisposePassManager(modulePasses);

	LLVMDisposeExecutionEngine(engine);

	if (timingFlag) {
	double after = currentTime();
	printf("Module #%d (%s) took %lf ms.\n", i, filenames[i], (after - before) * 1000);
	}
	}

	if (manyContexts) {
	for (i = 0; i < numFiles; ++i)
	LLVMContextDispose(contexts[i]);
	} else
	LLVMContextDispose(contexts[0]);

	if (timingFlag) {
	double after = currentTime();
	printf("Compilation took a total of %lf ms.\n", (after - beforeAll) * 1000);
	}

	if (disassembleFlag) {
	LLVMDisasmContextRef disassembler;

	disassembler = LLVMCreateDisasm("x86_64-apple-darwin", 0, 0, 0, symbolLookupCallback);
	if (!disassembler) {
	fprintf(stderr, "Error building disassembler.\n");
	exit(1);
	}

	for (section = sectionHead; section; section = section->next) {
	printf("Disassembly for section %p:\n", section);

	char pcString[20];
	char instructionString[1000];
	uint8_t *pc;
	uint8_t *end;

	pc = section->start;
	end = pc + section->size;

	while (pc < end) {
	snprintf(
	pcString, sizeof(pcString), "0x%lx",
	(unsigned long)(uintptr_t)pc);

	size_t instructionSize = LLVMDisasmInstruction(
	disassembler, pc, end - pc, (uintptr_t)pc,
	instructionString, sizeof(instructionString));

	if (!instructionSize)
	snprintf(instructionString, sizeof(instructionString), ".byte 0x%02x", *pc++);
	else
	pc += instructionSize;

	printf(" %16s: %s\n", pcString, instructionString);
	}
	}
	}

	for (section = sectionHead; section;) {
	struct MemorySection* nextSection = section->next;

	munmap(section->start, roundUpSize(section->size));
	free(section);

	section = nextSection;
	}
	sectionHead = 0;

	} while (loop);

	return 0;
	}