lib/base-compiler.js - compiler-explorer - Rivoreo Source Code Repositories

 // Copyright (c) 2012-2017, Matt Godbolt
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are met:
 //
 //     * Redistributions of source code must retain the above copyright notice,
 //       this list of conditions and the following disclaimer.
 //     * 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 THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE COPYRIGHT HOLDER 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.

 /*jslint node: true */
 "use strict";

 var child_process = require('child_process'),
     temp = require('temp'),
     path = require('path'),
     fs = require('fs-extra'),
     Promise = require('promise'), // jshint ignore:line
     asm = require('./asm'),
     utils = require('./utils'),
     _ = require('underscore-node'),
     exec = require('./exec'),
     logger = require('./logger').logger,
     compilerOptInfo = require("compiler-opt-info"),
     argumentParsers = require("./compilers/argument-parsers"),
     cfg = require('./cfg');
 var node_util = require("util");

 function Compile(compiler, env) {
     this.compiler = compiler;
     this.env = env;
     this.asm = new asm.AsmParser(env.compilerProps);
 }

 // AP: Create directory in specified tmpDir. tmpDir on Windows volume is required for WSL execution.
 // NPM temp package: https://www.npmjs.com/package/temp, see Affixes
 Compile.prototype.newTempDir = function () {
     return new Promise(function (resolve, reject) {
        // temp.mkdir('compiler-explorer-compiler', function (err, dirPath) {
        temp.mkdir({prefix: 'compiler-explorer-compiler', dir: process.env.tmpDir}, function (err, dirPath) {
             if (err)
                 reject("Unable to open temp file: " + err);
             else
                 resolve(dirPath);
         });
     });
 };

 Compile.prototype.writeFile = Promise.denodeify(fs.writeFile);
 Compile.prototype.readFile = Promise.denodeify(fs.readFile);
 Compile.prototype.stat = Promise.denodeify(fs.stat);

 Compile.prototype.optOutputRequested = function (options) {
     return options.some((x) => x === "-fsave-optimization-record");
 };

 Compile.prototype.getRemote = function () {
     if (this.compiler.exe === null && this.compiler.remote)
         return this.compiler.remote;
     return false;
 };

 Compile.prototype.exec = function (compiler, args, options) {
     // Here only so can be overridden by compiler implementations.
     return exec.execute(compiler, args, options);
 };

 Compile.prototype.getDefaultExecOptions = function () {
     return {
         timeoutMs: this.env.gccProps("compileTimeoutMs", 100),
         maxErrorOutput: this.env.gccProps("max-error-output", 5000),
         env: this.env.getEnv(this.compiler.needsMulti),
         wrapper: this.env.compilerProps("compiler-wrapper")
     };
 };

 Compile.prototype.runCompiler = function (compiler, options, inputFilename, execOptions) {
     if (!execOptions) {
         execOptions = this.getDefaultExecOptions();
     }

     return this.exec(compiler, options, execOptions).then(function (result) {
         result.stdout = utils.parseOutput(result.stdout, inputFilename);
         result.stderr = utils.parseOutput(result.stderr, inputFilename);
         return result;
     });
 };

 Compile.prototype.supportsObjdump = function () {
     return this.compiler.objdumper !== "";
 };

 Compile.prototype.objdump = function (outputFilename, result, maxSize, intelAsm, demangle) {
     var args = ["-d", outputFilename, "-l", "--insn-width=16"];
     if (demangle) args = args.concat("-C");
     if (intelAsm) args = args.concat(["-M", "intel"]);
     return this.exec(this.compiler.objdumper, args, {maxOutput: maxSize})
         .then(function (objResult) {
 				if(objResult.signal) {
 					result.asm = node_util.format("<objdump failed due to %s>", objResult.signal);
 				} else if (objResult.status !== 0) {
 					result.asm = node_util.format("<objdump exited with status %d>", objResult.status);
 				} else {
 					result.asm = objResult.stdout;
 				}
 				return result;
 			});
 };

 Compile.prototype.execBinary = function (executable, result, maxSize) {
     return exec.sandbox(executable, [], {
         maxOutput: maxSize,
         timeoutMs: 2000
     })  // TODO make config
         .then(function (execResult) {
             execResult.stdout = utils.parseOutput(execResult.stdout);
             execResult.stderr = utils.parseOutput(execResult.stderr);
             result.execResult = execResult;
             return result;
         }).catch(function (e) {
 				// TODO: is this the best way? Perhaps
 				// failures in sandbox shouldn't reject with
 				// "results", but instead should play on?
 				result.execResult = {
 					stdout:[],
 					stderr:e.message,
 					status:null,
 					signal:null
 				};
 				return result;
 			});
 };

 Compile.prototype.filename = function (fn) {
     return fn;
 };

 Compile.prototype.optionsForFilter = function (filters, outputFilename, userOptions) {
     var options = ['-g', '-o', this.filename(outputFilename)];
     if (this.compiler.intelAsm && filters.intel && !filters.binary) {
         options = options.concat(this.compiler.intelAsm.split(" "));
     }
     if (filters.binary) {
 		if(!filters.link) options = options.concat("-c");
     } else {
 		options = options.concat("-S");
     }
     return options;
 };

 Compile.prototype.prepareArguments = function (userOptions, filters, backendOptions, inputFilename, outputFilename) {
     var options = this.optionsForFilter(filters, outputFilename, userOptions);
     backendOptions = backendOptions || {};

     if (this.compiler.options) {
         options = options.concat(this.compiler.options.split(" "));
     }

     if (this.compiler.supportsOptOutput && backendOptions.produceOptInfo) {
         options = options.concat(this.compiler.optArg);
     }

     return options.concat(userOptions || []).concat([this.filename(inputFilename)]);
 };

 Compile.prototype.generateAST = function (inputFilename, options) {
     // These options make Clang produce an AST dump
     var newOptions = options.concat(["-Xclang", "-ast-dump", "-fsyntax-only"]);

     let execOptions = this.getDefaultExecOptions();
     // A higher max output is needed for when the user includes headers
     execOptions.maxOutput = 1024 * 1024 * 1024;

     return this.runCompiler(this.compiler.exe, newOptions, this.filename(inputFilename), execOptions)
         .then(this.processAstOutput);
 };

 Compile.prototype.compile = function (source, options, backendOptions, filters) {
     var self = this;
     var optionsError = self.checkOptions(options);
     if (optionsError) return Promise.reject(optionsError);
     var sourceError = self.checkSource(source);
     if (sourceError) return Promise.reject(sourceError);

     // Don't run binary for unsupported compilers, even if we're asked.
     if (filters.binary && !self.compiler.supportsBinary) {
         delete filters.binary;
     }

     var key = JSON.stringify({
         compiler: this.compiler,
         source: source,
         options: options,
         backendOptions: backendOptions,
         filters: filters
     });

     var cached = this.env.cacheGet(key);
     if (cached) {
         return Promise.resolve(cached);
     }

     if (filters.binary && !source.match(this.env.compilerProps("stubRe"))) {
         source += "\n" + this.env.compilerProps("stubText") + "\n";
     }
     return self.env.enqueue(function () {
         var tempFileAndDirPromise = Promise.resolve().then(function () {
             return self.newTempDir().then(function (dirPath) {
                 var inputFilename = path.join(dirPath, self.env.compilerProps("compileFilename"));
                 return self.writeFile(inputFilename, source).then(function () {
                     return {inputFilename: inputFilename, dirPath: dirPath};
                 });
             });
         });

         var compileToAsmPromise = tempFileAndDirPromise.then(function (info) {
             var inputFilename = info.inputFilename;
             var dirPath = info.dirPath;
             var outputFilebase = "output";
             var outputFilename = path.join(dirPath, outputFilebase); // NB keep lower case as ldc compiler `tolower`s the output name
             options = self.prepareArguments(options, filters, backendOptions, inputFilename, outputFilename);

             options = options.filter(_.identity);

             var asmPromise = self.runCompiler(self.compiler.exe, options, self.filename(inputFilename));

             var astPromise;
             if (backendOptions && backendOptions.produceAst) {
                 if (self.couldSupportASTDump(options, self.compiler.version)) {
                     astPromise = self.generateAST(inputFilename, options);
                 }
                 else {
                     astPromise = Promise.resolve("AST output is only supported in Clang >= 3.3");
                 }
             }
             else {
                 astPromise = Promise.resolve("");
             }

             return Promise.all([asmPromise, astPromise])
                 .then(function (results) {
                     var asmResult = results[0];
                     var astResult = results[1];

                     asmResult.dirPath = dirPath;
                     if (asmResult.signal || asmResult.status !== 0) {
                         asmResult.asm = "<Compilation failed>";
                         return asmResult;
                     }
                     asmResult.output_file_path = outputFilename;
                     asmResult.hasOptOutput = false;
                     if (self.compiler.supportsOptOutput && self.optOutputRequested(options)) {
                         asmResult.hasOptOutput = false;
                         const optPath = path.join(dirPath, outputFilebase + ".opt.yaml");
                         if (fs.existsSync(optPath)) {
                             asmResult.hasOptOutput = true;
                             asmResult.optPath = optPath;
                         }
                     }
                     if (astResult) {
                         asmResult.hasAstOutput = true;
                         asmResult.astOutput = astResult;
                     }

                     return self.postProcess(asmResult, outputFilename, filters);
                 });
         });

         return compileToAsmPromise
             .then(function (results) {
                 //TODO(jared): this isn't ideal. Rethink
                 var result;
                 var optOutput;
                 if (results.length) {
                     result = results[0];
                     optOutput = results[1];
                 } else {
                     result = results;
                 }
                 if (result.okToCache) {
                     result.asm = self.asm.process(result.asm, filters);
                 } else {
                     result.asm = {text: result.asm};
                     if (result.dirPath) {
                         fs.remove(result.dirPath);
                         result.dirPath = undefined;
                     }
                 }
                 if (result.hasOptOutput) {
                     result.optPath = undefined;
                     result.optOutput = optOutput;
                 }
                 return result;
             })
             .then(function (result) {
                 return filters.demangle ? _.bind(self.postProcessAsm, self, result)() : result;
             })
             .then(function (result) {
                 result.supportsCfg = false;
                 if (result.status === 0 && !filters.binary && self.isCfgCompiler(self.compiler.version)) {
                     var cfg_ = new cfg.ControlFlowGraph(self.compiler.version);
                     result.cfg = cfg_.generateCfgStructure(result.asm);
                     result.supportsCfg = true;
                 }
                 return result;
             })
             .then(function (result) {
                 if (result.okToCache) self.env.cachePut(key, result);
                 return result;
             });
     });
 };

 Compile.prototype.postProcessAsm = function (result) {
     if (!result.okToCache) return result;
     var demangler = this.compiler.demangler;
     if (!demangler) return result;
     return this.exec(demangler, [], {input: _.pluck(result.asm, 'text').join("\n")})
         .then(_.bind(function (demangleResult) {
             var lines = utils.splitLines(demangleResult.stdout);
             for (var i = 0; i < result.asm.length; ++i)
                 result.asm[i].text = lines[i];
             return result;
         }, this));
 };
 Compile.prototype.processOptOutput = function (hasOptOutput, optPath) {
     var output = [],
         //if we have no compileFilename for whatever reason
         //let everything through
         inputFile = this.env.compilerProps("compileFilename", "");
     return new Promise(
         function (resolve) {
             fs.createReadStream(optPath, {encoding: "utf-8"})
                 .pipe(new compilerOptInfo.LLVMOptTransformer())
                 .on("data", function (opt) {
                     if (opt.DebugLoc &&
                         opt.DebugLoc.File &&
                         opt.DebugLoc.File.indexOf(inputFile) > -1) {

                         output.push(opt);
                     }
                 }.bind(this))
                 .on("end", function () {
                     if (this.compiler.demangler) {
                         var result = JSON.stringify(output, null, 4);
                         this.exec(this.compiler.demangler, ["-n", "-p"], {input: result})
                             .then(function (demangleResult) {
                                 output = JSON.parse(demangleResult.stdout);
                                 resolve(output);
                             }.bind(this))
                             .catch(function (exception) {
                                 logger.warn("Caught exception " + exception + " during opt demangle parsing");
                                 resolve(output);
                             }.bind(this));
                     } else {
                         resolve(output);
                     }
                 }.bind(this));
         }.bind(this));
 };

 Compile.prototype.couldSupportASTDump = function (options, version) {
     var versionRegex = /version (\d.\d+)/;
     var versionMatch = versionRegex.exec(version);

     if (versionMatch) {
         var versionNum = parseFloat(versionMatch[1]);
         return version.toLowerCase().indexOf("clang") > -1 && versionNum >= 3.3;
     }

     return false;
 };

 Compile.prototype.isCfgCompiler = function (compilerVersion) {
     return compilerVersion.includes("clang") || compilerVersion.indexOf("g++") === 0;
 };

 Compile.prototype.processAstOutput = function (output) {
     output = output.stdout;
     output = output.map(function (x) {
         return x.text;
     });

     // Top level decls start with |- or `-
     var topLevelRegex = /^(\||`)-/;

     // Refers to the user's source file rather than a system header
     var sourceRegex = /<source>/g;

     // Refers to whatever the most recent file specified was
     var lineRegex = /<line:/;

     var mostRecentIsSource = false;

     // Remove all AST nodes which aren't directly from the user's source code
     for (var i = 0; i < output.length; ++i) {
         if (output[i].match(topLevelRegex)) {
             if (output[i].match(lineRegex) && mostRecentIsSource) {
                 //do nothing
             }
             // This is a system header or implicit definition,
             // remove everything up to the next top level decl
             else if (!output[i].match(sourceRegex)) {
                 // Top level decls with invalid sloc as the file don't change the most recent file
                 let slocRegex = /<<invalid sloc>>/;
                 if (!output[i].match(slocRegex)) {
                     mostRecentIsSource = false;
                 }

                 var spliceMax = i + 1;
                 while (output[spliceMax] && !output[spliceMax].match(topLevelRegex)) {
                     spliceMax++;
                 }
                 output.splice(i, spliceMax - i);
                 --i;
             }
             else {
                 mostRecentIsSource = true;
             }
         }
     }

     output = output.join('\n');

     // Filter out the symbol addresses
     var addressRegex = /^([^A-Za-z]*[A-Za-z]+) 0x[a-z0-9]+/mg;
     output = output.replace(addressRegex, '$1');

     // Filter out <invalid sloc> and <<invalid sloc>>
     let slocRegex = / ?<?<invalid sloc>>?/g;
     output = output.replace(slocRegex, '');

     // Unify file references
     output = output.replace(sourceRegex, 'line');

     return output;
 };

 Compile.prototype.postProcess = function (result, outputFilename, filters) {
     var postProcess = this.compiler.postProcess.filter(_.identity);
     var maxSize = this.env.gccProps("max-asm-size", 8 * 1024 * 1024);
     var optPromise, asmPromise, execPromise;
     if (result.hasOptOutput) {
         optPromise = this.processOptOutput(result.hasOptOutput, result.optPath);
     } else {
         optPromise = Promise.resolve("");
     }

     if (filters.binary && this.supportsObjdump()) {
         asmPromise = this.objdump(outputFilename, result, maxSize, filters.intel, filters.demangle);
     } else {
         asmPromise = this.stat(outputFilename).then(_.bind(function (stat) {
                 if (stat.size >= maxSize) {
                     result.asm = "<No output: generated assembly was too large (" + stat.size + " > " + maxSize + " bytes)>";
                     return result;
                 }
                 if (postProcess.length) {
                     const postCommand = 'cat "' + outputFilename + '" | ' + postProcess.join(" | ");
                     return this.exec("bash", ["-c", postCommand], {maxOutput: maxSize})
                         .then((postResult) => {
                             return this.handlePostProcessResult(result, postResult);
                         });
                 } else {
                     return this.readFile(outputFilename).then(function (contents) {
                         result.asm = contents.toString();
                         return Promise.resolve(result);
                     });
                 }
             }, this),
             function () {
                 result.asm = "<No output file>";
                 return result;
             }
         );
     }
     if (this.compiler.supportsExecute && filters.binary && filters.link && filters.execute) {
         var maxExecOutputSize = this.env.gccProps("max-executable-output-size", 32 * 1024);
         execPromise = this.execBinary(outputFilename, result, maxExecOutputSize);
     } else {
         execPromise = Promise.resolve("");
     }

     return Promise.all([asmPromise, optPromise, execPromise]);
 };

 Compile.prototype.handlePostProcessResult = function (result, postResult) {
 	if(postResult.signal) {
 		result.asm = "<Error during post processing: " + postResult.signal + ">";
 		logger.error("Error during post-processing", result);
 	} else if (postResult.status !== 0) {
 		result.asm = node_util.format("<Error during post processing: status %d>",
 			postResult.status);
 		logger.error("Error during post-processing", result);
 	} else {
 		result.asm = postResult.stdout;
 	}
 	return result;
 };

 Compile.prototype.checkOptions = function (options) {
     var error = this.env.findBadOptions(options);
     if (error.length > 0) return "Bad options: " + error.join(", ");
     return null;
 };

 // This check for arbitrary user-controlled preprocessor inclusions
 // can be circumvented in more than one way. The goal here is to respond
 // to simple attempts with a clear diagnostic; the service still needs to
 // assume that malicious actors can make the compiler open arbitrary files.
 Compile.prototype.checkSource = function (source) {
     var re = /^\s*#\s*i(nclude|mport)(_next)?\s+["<"](\/|.*\.\.)/;
     var failed = [];
     utils.splitLines(source).forEach(function (line, index) {
         if (line.match(re)) {
             failed.push("<stdin>:" + (index + 1) + ":1: no absolute or relative includes please");
         }
     });
     if (failed.length > 0) return failed.join("\n");
     return null;
 };

 Compile.prototype.getArgumentParser = function () {
     let exe = this.compiler.exe.toLowerCase();
     if (exe.indexOf("clang") >= 0) {  // check this first as "clang++" matches "g++"
         return argumentParsers.clang;
     } else if (exe.indexOf("g++") >= 0 || exe.indexOf("gcc") >= 0) {
         return argumentParsers.gcc;
     }
     //there is a lot of code around that makes this assumption.
     //probably not the best thing to do :D
     return argumentParsers.gcc;
 };

 Compile.prototype.initialise = function () {
     if (this.getRemote()) return Promise.resolve(this);
     let argumentParser = this.getArgumentParser();
     var compiler = this.compiler.exe;
     var versionFlag = this.compiler.versionFlag || '--version';
     var versionRe = new RegExp(this.compiler.versionRe || '.*');
     logger.info("Gathering version information on", compiler);
     return this.exec(compiler, [versionFlag]).then(_.bind(function (result) {
 			if(result.signal) {
 				logger.error("Unable to get version for compiler '%s': %s", compiler, result.signal);
 				return null;
 			}
 			if(result.status !== 0) {
 				logger.error("Unable to get version for compiler '%s': status %d", compiler, result.status);
 				return null;
 			}
                 var version = "";
                 _.each(utils.splitLines(result.stdout + result.stderr), function (line) {
                     if (version) return;
                     var match = line.match(versionRe);
                     if (match) version = match[0];
                 });
                 if (!version) {
                     logger.error("Unable to find compiler version for '" + compiler + "':", result,
                         'with re', versionRe);
                     return null;
                 }
                 logger.info(compiler + " is version '" + version + "'");
                 this.compiler.version = version;
                 return argumentParser(this).then(function (compiler) {
                     delete compiler.compiler.supportedOptions;
                     return compiler;
                 });
             }, this),
             _.bind(function (err) {
                 logger.error("Unable to get version for compiler '" + compiler + "' - " + err);
                 return null;
             }, this));
 };

 Compile.prototype.getInfo = function () {
     return this.compiler;
 };

 Compile.prototype.getDefaultFilters = function () {
     // TODO; propagate to UI?
     return {
         intel: true,
         commentOnly: true,
         directives: true,
         labels: true,
         optOutput: false
     };
 };

 module.exports = Compile;
	// Copyright (c) 2012-2017, Matt Godbolt
	// All rights reserved.
	//
	// Redistribution and use in source and binary forms, with or without
	// modification, are permitted provided that the following conditions are met:
	//
	// * Redistributions of source code must retain the above copyright notice,
	// this list of conditions and the following disclaimer.
	// * 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 THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE COPYRIGHT HOLDER 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.

	/jslint node: true /
	"use strict";

	var child_process = require('child_process'),
	temp = require('temp'),
	path = require('path'),
	fs = require('fs-extra'),
	Promise = require('promise'), // jshint ignore:line
	asm = require('./asm'),
	utils = require('./utils'),
	_ = require('underscore-node'),
	exec = require('./exec'),
	logger = require('./logger').logger,
	compilerOptInfo = require("compiler-opt-info"),
	argumentParsers = require("./compilers/argument-parsers"),
	cfg = require('./cfg');
	var node_util = require("util");

	function Compile(compiler, env) {
	this.compiler = compiler;
	this.env = env;
	this.asm = new asm.AsmParser(env.compilerProps);
	}

	// AP: Create directory in specified tmpDir. tmpDir on Windows volume is required for WSL execution.
	// NPM temp package: https://www.npmjs.com/package/temp, see Affixes
	Compile.prototype.newTempDir = function () {
	return new Promise(function (resolve, reject) {
	// temp.mkdir('compiler-explorer-compiler', function (err, dirPath) {
	temp.mkdir({prefix: 'compiler-explorer-compiler', dir: process.env.tmpDir}, function (err, dirPath) {
	if (err)
	reject("Unable to open temp file: " + err);
	else
	resolve(dirPath);
	});
	});
	};

	Compile.prototype.writeFile = Promise.denodeify(fs.writeFile);
	Compile.prototype.readFile = Promise.denodeify(fs.readFile);
	Compile.prototype.stat = Promise.denodeify(fs.stat);

	Compile.prototype.optOutputRequested = function (options) {
	return options.some((x) => x === "-fsave-optimization-record");
	};

	Compile.prototype.getRemote = function () {
	if (this.compiler.exe === null && this.compiler.remote)
	return this.compiler.remote;
	return false;
	};

	Compile.prototype.exec = function (compiler, args, options) {
	// Here only so can be overridden by compiler implementations.
	return exec.execute(compiler, args, options);
	};

	Compile.prototype.getDefaultExecOptions = function () {
	return {
	timeoutMs: this.env.gccProps("compileTimeoutMs", 100),
	maxErrorOutput: this.env.gccProps("max-error-output", 5000),
	env: this.env.getEnv(this.compiler.needsMulti),
	wrapper: this.env.compilerProps("compiler-wrapper")
	};
	};

	Compile.prototype.runCompiler = function (compiler, options, inputFilename, execOptions) {
	if (!execOptions) {
	execOptions = this.getDefaultExecOptions();
	}

	return this.exec(compiler, options, execOptions).then(function (result) {
	result.stdout = utils.parseOutput(result.stdout, inputFilename);
	result.stderr = utils.parseOutput(result.stderr, inputFilename);
	return result;
	});
	};

	Compile.prototype.supportsObjdump = function () {
	return this.compiler.objdumper !== "";
	};

	Compile.prototype.objdump = function (outputFilename, result, maxSize, intelAsm, demangle) {
	var args = ["-d", outputFilename, "-l", "--insn-width=16"];
	if (demangle) args = args.concat("-C");
	if (intelAsm) args = args.concat(["-M", "intel"]);
	return this.exec(this.compiler.objdumper, args, {maxOutput: maxSize})
	.then(function (objResult) {
	if(objResult.signal) {
	result.asm = node_util.format("<objdump failed due to %s>", objResult.signal);
	} else if (objResult.status !== 0) {
	result.asm = node_util.format("<objdump exited with status %d>", objResult.status);
	} else {
	result.asm = objResult.stdout;
	}
	return result;
	});
	};

	Compile.prototype.execBinary = function (executable, result, maxSize) {
	return exec.sandbox(executable, [], {
	maxOutput: maxSize,
	timeoutMs: 2000
	}) // TODO make config
	.then(function (execResult) {
	execResult.stdout = utils.parseOutput(execResult.stdout);
	execResult.stderr = utils.parseOutput(execResult.stderr);
	result.execResult = execResult;
	return result;
	}).catch(function (e) {
	// TODO: is this the best way? Perhaps
	// failures in sandbox shouldn't reject with
	// "results", but instead should play on?
	result.execResult = {
	stdout:[],
	stderr:e.message,
	status:null,
	signal:null
	};
	return result;
	});
	};

	Compile.prototype.filename = function (fn) {
	return fn;
	};

	Compile.prototype.optionsForFilter = function (filters, outputFilename, userOptions) {
	var options = ['-g', '-o', this.filename(outputFilename)];
	if (this.compiler.intelAsm && filters.intel && !filters.binary) {
	options = options.concat(this.compiler.intelAsm.split(" "));
	}
	if (filters.binary) {
	if(!filters.link) options = options.concat("-c");
	} else {
	options = options.concat("-S");
	}
	return options;
	};

	Compile.prototype.prepareArguments = function (userOptions, filters, backendOptions, inputFilename, outputFilename) {
	var options = this.optionsForFilter(filters, outputFilename, userOptions);
	backendOptions = backendOptions \|\| {};

	if (this.compiler.options) {
	options = options.concat(this.compiler.options.split(" "));
	}

	if (this.compiler.supportsOptOutput && backendOptions.produceOptInfo) {
	options = options.concat(this.compiler.optArg);
	}

	return options.concat(userOptions \|\| []).concat([this.filename(inputFilename)]);
	};

	Compile.prototype.generateAST = function (inputFilename, options) {
	// These options make Clang produce an AST dump
	var newOptions = options.concat(["-Xclang", "-ast-dump", "-fsyntax-only"]);

	let execOptions = this.getDefaultExecOptions();
	// A higher max output is needed for when the user includes headers
	execOptions.maxOutput = 1024 * 1024 * 1024;

	return this.runCompiler(this.compiler.exe, newOptions, this.filename(inputFilename), execOptions)
	.then(this.processAstOutput);
	};

	Compile.prototype.compile = function (source, options, backendOptions, filters) {
	var self = this;
	var optionsError = self.checkOptions(options);
	if (optionsError) return Promise.reject(optionsError);
	var sourceError = self.checkSource(source);
	if (sourceError) return Promise.reject(sourceError);

	// Don't run binary for unsupported compilers, even if we're asked.
	if (filters.binary && !self.compiler.supportsBinary) {
	delete filters.binary;
	}

	var key = JSON.stringify({
	compiler: this.compiler,
	source: source,
	options: options,
	backendOptions: backendOptions,
	filters: filters
	});

	var cached = this.env.cacheGet(key);
	if (cached) {
	return Promise.resolve(cached);
	}

	if (filters.binary && !source.match(this.env.compilerProps("stubRe"))) {
	source += "\n" + this.env.compilerProps("stubText") + "\n";
	}
	return self.env.enqueue(function () {
	var tempFileAndDirPromise = Promise.resolve().then(function () {
	return self.newTempDir().then(function (dirPath) {
	var inputFilename = path.join(dirPath, self.env.compilerProps("compileFilename"));
	return self.writeFile(inputFilename, source).then(function () {
	return {inputFilename: inputFilename, dirPath: dirPath};
	});
	});
	});

	var compileToAsmPromise = tempFileAndDirPromise.then(function (info) {
	var inputFilename = info.inputFilename;
	var dirPath = info.dirPath;
	var outputFilebase = "output";
	var outputFilename = path.join(dirPath, outputFilebase); // NB keep lower case as ldc compiler `tolower`s the output name
	options = self.prepareArguments(options, filters, backendOptions, inputFilename, outputFilename);

	options = options.filter(_.identity);

	var asmPromise = self.runCompiler(self.compiler.exe, options, self.filename(inputFilename));

	var astPromise;
	if (backendOptions && backendOptions.produceAst) {
	if (self.couldSupportASTDump(options, self.compiler.version)) {
	astPromise = self.generateAST(inputFilename, options);
	}
	else {
	astPromise = Promise.resolve("AST output is only supported in Clang >= 3.3");
	}
	}
	else {
	astPromise = Promise.resolve("");
	}

	return Promise.all([asmPromise, astPromise])
	.then(function (results) {
	var asmResult = results[0];
	var astResult = results[1];

	asmResult.dirPath = dirPath;
	if (asmResult.signal \|\| asmResult.status !== 0) {
	asmResult.asm = "<Compilation failed>";
	return asmResult;
	}
	asmResult.output_file_path = outputFilename;
	asmResult.hasOptOutput = false;
	if (self.compiler.supportsOptOutput && self.optOutputRequested(options)) {
	asmResult.hasOptOutput = false;
	const optPath = path.join(dirPath, outputFilebase + ".opt.yaml");
	if (fs.existsSync(optPath)) {
	asmResult.hasOptOutput = true;
	asmResult.optPath = optPath;
	}
	}
	if (astResult) {
	asmResult.hasAstOutput = true;
	asmResult.astOutput = astResult;
	}

	return self.postProcess(asmResult, outputFilename, filters);
	});
	});

	return compileToAsmPromise
	.then(function (results) {
	//TODO(jared): this isn't ideal. Rethink
	var result;
	var optOutput;
	if (results.length) {
	result = results[0];
	optOutput = results[1];
	} else {
	result = results;
	}
	if (result.okToCache) {
	result.asm = self.asm.process(result.asm, filters);
	} else {
	result.asm = {text: result.asm};
	if (result.dirPath) {
	fs.remove(result.dirPath);
	result.dirPath = undefined;
	}
	}
	if (result.hasOptOutput) {
	result.optPath = undefined;
	result.optOutput = optOutput;
	}
	return result;
	})
	.then(function (result) {
	return filters.demangle ? _.bind(self.postProcessAsm, self, result)() : result;
	})
	.then(function (result) {
	result.supportsCfg = false;
	if (result.status === 0 && !filters.binary && self.isCfgCompiler(self.compiler.version)) {
	var cfg_ = new cfg.ControlFlowGraph(self.compiler.version);
	result.cfg = cfg_.generateCfgStructure(result.asm);
	result.supportsCfg = true;
	}
	return result;
	})
	.then(function (result) {
	if (result.okToCache) self.env.cachePut(key, result);
	return result;
	});
	});
	};

	Compile.prototype.postProcessAsm = function (result) {
	if (!result.okToCache) return result;
	var demangler = this.compiler.demangler;
	if (!demangler) return result;
	return this.exec(demangler, [], {input: _.pluck(result.asm, 'text').join("\n")})
	.then(_.bind(function (demangleResult) {
	var lines = utils.splitLines(demangleResult.stdout);
	for (var i = 0; i < result.asm.length; ++i)
	result.asm[i].text = lines[i];
	return result;
	}, this));
	};
	Compile.prototype.processOptOutput = function (hasOptOutput, optPath) {
	var output = [],
	//if we have no compileFilename for whatever reason
	//let everything through
	inputFile = this.env.compilerProps("compileFilename", "");
	return new Promise(
	function (resolve) {
	fs.createReadStream(optPath, {encoding: "utf-8"})
	.pipe(new compilerOptInfo.LLVMOptTransformer())
	.on("data", function (opt) {
	if (opt.DebugLoc &&
	opt.DebugLoc.File &&
	opt.DebugLoc.File.indexOf(inputFile) > -1) {

	output.push(opt);
	}
	}.bind(this))
	.on("end", function () {
	if (this.compiler.demangler) {
	var result = JSON.stringify(output, null, 4);
	this.exec(this.compiler.demangler, ["-n", "-p"], {input: result})
	.then(function (demangleResult) {
	output = JSON.parse(demangleResult.stdout);
	resolve(output);
	}.bind(this))
	.catch(function (exception) {
	logger.warn("Caught exception " + exception + " during opt demangle parsing");
	resolve(output);
	}.bind(this));
	} else {
	resolve(output);
	}
	}.bind(this));
	}.bind(this));
	};

	Compile.prototype.couldSupportASTDump = function (options, version) {
	var versionRegex = /version (\d.\d+)/;
	var versionMatch = versionRegex.exec(version);

	if (versionMatch) {
	var versionNum = parseFloat(versionMatch[1]);
	return version.toLowerCase().indexOf("clang") > -1 && versionNum >= 3.3;
	}

	return false;
	};

	Compile.prototype.isCfgCompiler = function (compilerVersion) {
	return compilerVersion.includes("clang") \|\| compilerVersion.indexOf("g++") === 0;
	};

	Compile.prototype.processAstOutput = function (output) {
	output = output.stdout;
	output = output.map(function (x) {
	return x.text;
	});

	// Top level decls start with \|- or `-
	var topLevelRegex = /^(\\|\|`)-/;

	// Refers to the user's source file rather than a system header
	var sourceRegex = /<source>/g;

	// Refers to whatever the most recent file specified was
	var lineRegex = /<line:/;

	var mostRecentIsSource = false;

	// Remove all AST nodes which aren't directly from the user's source code
	for (var i = 0; i < output.length; ++i) {
	if (output[i].match(topLevelRegex)) {
	if (output[i].match(lineRegex) && mostRecentIsSource) {
	//do nothing
	}
	// This is a system header or implicit definition,
	// remove everything up to the next top level decl
	else if (!output[i].match(sourceRegex)) {
	// Top level decls with invalid sloc as the file don't change the most recent file
	let slocRegex = /<<invalid sloc>>/;
	if (!output[i].match(slocRegex)) {
	mostRecentIsSource = false;
	}

	var spliceMax = i + 1;
	while (output[spliceMax] && !output[spliceMax].match(topLevelRegex)) {
	spliceMax++;
	}
	output.splice(i, spliceMax - i);
	--i;
	}
	else {
	mostRecentIsSource = true;
	}
	}
	}

	output = output.join('\n');

	// Filter out the symbol addresses
	var addressRegex = /^([^A-Za-z]*[A-Za-z]+) 0x[a-z0-9]+/mg;
	output = output.replace(addressRegex, '$1');

	// Filter out <invalid sloc> and <<invalid sloc>>
	let slocRegex = / ?<?<invalid sloc>>?/g;
	output = output.replace(slocRegex, '');

	// Unify file references
	output = output.replace(sourceRegex, 'line');

	return output;
	};

	Compile.prototype.postProcess = function (result, outputFilename, filters) {
	var postProcess = this.compiler.postProcess.filter(_.identity);
	var maxSize = this.env.gccProps("max-asm-size", 8 * 1024 * 1024);
	var optPromise, asmPromise, execPromise;
	if (result.hasOptOutput) {
	optPromise = this.processOptOutput(result.hasOptOutput, result.optPath);
	} else {
	optPromise = Promise.resolve("");
	}

	if (filters.binary && this.supportsObjdump()) {
	asmPromise = this.objdump(outputFilename, result, maxSize, filters.intel, filters.demangle);
	} else {
	asmPromise = this.stat(outputFilename).then(_.bind(function (stat) {
	if (stat.size >= maxSize) {
	result.asm = "<No output: generated assembly was too large (" + stat.size + " > " + maxSize + " bytes)>";
	return result;
	}
	if (postProcess.length) {
	const postCommand = 'cat "' + outputFilename + '" \| ' + postProcess.join(" \| ");
	return this.exec("bash", ["-c", postCommand], {maxOutput: maxSize})
	.then((postResult) => {
	return this.handlePostProcessResult(result, postResult);
	});
	} else {
	return this.readFile(outputFilename).then(function (contents) {
	result.asm = contents.toString();
	return Promise.resolve(result);
	});
	}
	}, this),
	function () {
	result.asm = "<No output file>";
	return result;
	}
	);
	}
	if (this.compiler.supportsExecute && filters.binary && filters.link && filters.execute) {
	var maxExecOutputSize = this.env.gccProps("max-executable-output-size", 32 * 1024);
	execPromise = this.execBinary(outputFilename, result, maxExecOutputSize);
	} else {
	execPromise = Promise.resolve("");
	}

	return Promise.all([asmPromise, optPromise, execPromise]);
	};

	Compile.prototype.handlePostProcessResult = function (result, postResult) {
	if(postResult.signal) {
	result.asm = "<Error during post processing: " + postResult.signal + ">";
	logger.error("Error during post-processing", result);
	} else if (postResult.status !== 0) {
	result.asm = node_util.format("<Error during post processing: status %d>",
	postResult.status);
	logger.error("Error during post-processing", result);
	} else {
	result.asm = postResult.stdout;
	}
	return result;
	};

	Compile.prototype.checkOptions = function (options) {
	var error = this.env.findBadOptions(options);
	if (error.length > 0) return "Bad options: " + error.join(", ");
	return null;
	};

	// This check for arbitrary user-controlled preprocessor inclusions
	// can be circumvented in more than one way. The goal here is to respond
	// to simple attempts with a clear diagnostic; the service still needs to
	// assume that malicious actors can make the compiler open arbitrary files.
	Compile.prototype.checkSource = function (source) {
	var re = /^\s#\si(nclude\|mport)(_next)?\s+["<"](\/\|.*\.\.)/;
	var failed = [];
	utils.splitLines(source).forEach(function (line, index) {
	if (line.match(re)) {
	failed.push("<stdin>:" + (index + 1) + ":1: no absolute or relative includes please");
	}
	});
	if (failed.length > 0) return failed.join("\n");
	return null;
	};

	Compile.prototype.getArgumentParser = function () {
	let exe = this.compiler.exe.toLowerCase();
	if (exe.indexOf("clang") >= 0) { // check this first as "clang++" matches "g++"
	return argumentParsers.clang;
	} else if (exe.indexOf("g++") >= 0 \|\| exe.indexOf("gcc") >= 0) {
	return argumentParsers.gcc;
	}
	//there is a lot of code around that makes this assumption.
	//probably not the best thing to do :D
	return argumentParsers.gcc;
	};

	Compile.prototype.initialise = function () {
	if (this.getRemote()) return Promise.resolve(this);
	let argumentParser = this.getArgumentParser();
	var compiler = this.compiler.exe;
	var versionFlag = this.compiler.versionFlag \|\| '--version';
	var versionRe = new RegExp(this.compiler.versionRe \|\| '.*');
	logger.info("Gathering version information on", compiler);
	return this.exec(compiler, [versionFlag]).then(_.bind(function (result) {
	if(result.signal) {
	logger.error("Unable to get version for compiler '%s': %s", compiler, result.signal);
	return null;
	}
	if(result.status !== 0) {
	logger.error("Unable to get version for compiler '%s': status %d", compiler, result.status);
	return null;
	}
	var version = "";
	_.each(utils.splitLines(result.stdout + result.stderr), function (line) {
	if (version) return;
	var match = line.match(versionRe);
	if (match) version = match[0];
	});
	if (!version) {
	logger.error("Unable to find compiler version for '" + compiler + "':", result,
	'with re', versionRe);
	return null;
	}
	logger.info(compiler + " is version '" + version + "'");
	this.compiler.version = version;
	return argumentParser(this).then(function (compiler) {
	delete compiler.compiler.supportedOptions;
	return compiler;
	});
	}, this),
	_.bind(function (err) {
	logger.error("Unable to get version for compiler '" + compiler + "' - " + err);
	return null;
	}, this));
	};

	Compile.prototype.getInfo = function () {
	return this.compiler;
	};

	Compile.prototype.getDefaultFilters = function () {
	// TODO; propagate to UI?
	return {
	intel: true,
	commentOnly: true,
	directives: true,
	labels: true,
	optOutput: false
	};
	};

	module.exports = Compile;