1 //===- Parsing, selection, and construction of pass pipelines --*- C++ -*--===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
11 /// Interfaces for registering analysis passes, producing common pass manager
12 /// configurations, and parsing of pass pipelines.
14 //===----------------------------------------------------------------------===//
16 #ifndef LLVM_PASSES_PASSBUILDER_H
17 #define LLVM_PASSES_PASSBUILDER_H
19 #include "llvm/ADT/Optional.h"
20 #include "llvm/Analysis/CGSCCPassManager.h"
21 #include "llvm/IR/PassManager.h"
22 #include "llvm/Transforms/Scalar/LoopPassManager.h"
30 /// A struct capturing PGO tunables.
32 std::string ProfileGenFile = "";
33 std::string ProfileUseFile = "";
34 bool RunProfileGen = false;
35 bool SamplePGO = false;
38 /// \brief This class provides access to building LLVM's passes.
40 /// It's members provide the baseline state available to passes during their
41 /// construction. The \c PassRegistry.def file specifies how to construct all
42 /// of the built-in passes, and those may reference these members during
46 Optional<PGOOptions> PGOOpt;
49 /// \brief LLVM-provided high-level optimization levels.
51 /// This enumerates the LLVM-provided high-level optimization levels. Each
52 /// level has a specific goal and rationale.
53 enum OptimizationLevel {
54 /// Disable as many optimizations as possible. This doesn't completely
55 /// disable the optimizer in all cases, for example always_inline functions
56 /// can be required to be inlined for correctness.
59 /// Optimize quickly without destroying debuggability.
61 /// FIXME: The current and historical behavior of this level does *not*
62 /// agree with this goal, but we would like to move toward this goal in the
65 /// This level is tuned to produce a result from the optimizer as quickly
66 /// as possible and to avoid destroying debuggability. This tends to result
67 /// in a very good development mode where the compiled code will be
68 /// immediately executed as part of testing. As a consequence, where
69 /// possible, we would like to produce efficient-to-execute code, but not
70 /// if it significantly slows down compilation or would prevent even basic
71 /// debugging of the resulting binary.
73 /// As an example, complex loop transformations such as versioning,
74 /// vectorization, or fusion might not make sense here due to the degree to
75 /// which the executed code would differ from the source code, and the
76 /// potential compile time cost.
79 /// Optimize for fast execution as much as possible without triggering
80 /// significant incremental compile time or code size growth.
82 /// The key idea is that optimizations at this level should "pay for
83 /// themselves". So if an optimization increases compile time by 5% or
84 /// increases code size by 5% for a particular benchmark, that benchmark
85 /// should also be one which sees a 5% runtime improvement. If the compile
86 /// time or code size penalties happen on average across a diverse range of
87 /// LLVM users' benchmarks, then the improvements should as well.
89 /// And no matter what, the compile time needs to not grow superlinearly
90 /// with the size of input to LLVM so that users can control the runtime of
91 /// the optimizer in this mode.
93 /// This is expected to be a good default optimization level for the vast
94 /// majority of users.
97 /// Optimize for fast execution as much as possible.
99 /// This mode is significantly more aggressive in trading off compile time
100 /// and code size to get execution time improvements. The core idea is that
101 /// this mode should include any optimization that helps execution time on
102 /// balance across a diverse collection of benchmarks, even if it increases
103 /// code size or compile time for some benchmarks without corresponding
104 /// improvements to execution time.
106 /// Despite being willing to trade more compile time off to get improved
107 /// execution time, this mode still tries to avoid superlinear growth in
108 /// order to make even significantly slower compile times at least scale
109 /// reasonably. This does not preclude very substantial constant factor
113 /// Similar to \c O2 but tries to optimize for small code size instead of
114 /// fast execution without triggering significant incremental execution
117 /// The logic here is exactly the same as \c O2, but with code size and
118 /// execution time metrics swapped.
120 /// A consequence of the different core goal is that this should in general
121 /// produce substantially smaller executables that still run in
122 /// a reasonable amount of time.
125 /// A very specialized mode that will optimize for code size at any and all
128 /// This is useful primarily when there are absolute size limitations and
129 /// any effort taken to reduce the size is worth it regardless of the
130 /// execution time impact. You should expect this level to produce rather
131 /// slow, but very small, code.
135 explicit PassBuilder(TargetMachine *TM = nullptr,
136 Optional<PGOOptions> PGOOpt = None)
137 : TM(TM), PGOOpt(PGOOpt) {}
139 /// \brief Cross register the analysis managers through their proxies.
141 /// This is an interface that can be used to cross register each
142 // AnalysisManager with all the others analysis managers.
143 void crossRegisterProxies(LoopAnalysisManager &LAM,
144 FunctionAnalysisManager &FAM,
145 CGSCCAnalysisManager &CGAM,
146 ModuleAnalysisManager &MAM);
148 /// \brief Registers all available module analysis passes.
150 /// This is an interface that can be used to populate a \c
151 /// ModuleAnalysisManager with all registered module analyses. Callers can
152 /// still manually register any additional analyses. Callers can also
153 /// pre-register analyses and this will not override those.
154 void registerModuleAnalyses(ModuleAnalysisManager &MAM);
156 /// \brief Registers all available CGSCC analysis passes.
158 /// This is an interface that can be used to populate a \c CGSCCAnalysisManager
159 /// with all registered CGSCC analyses. Callers can still manually register any
160 /// additional analyses. Callers can also pre-register analyses and this will
161 /// not override those.
162 void registerCGSCCAnalyses(CGSCCAnalysisManager &CGAM);
164 /// \brief Registers all available function analysis passes.
166 /// This is an interface that can be used to populate a \c
167 /// FunctionAnalysisManager with all registered function analyses. Callers can
168 /// still manually register any additional analyses. Callers can also
169 /// pre-register analyses and this will not override those.
170 void registerFunctionAnalyses(FunctionAnalysisManager &FAM);
172 /// \brief Registers all available loop analysis passes.
174 /// This is an interface that can be used to populate a \c LoopAnalysisManager
175 /// with all registered loop analyses. Callers can still manually register any
176 /// additional analyses.
177 void registerLoopAnalyses(LoopAnalysisManager &LAM);
179 /// Construct the core LLVM function canonicalization and simplification
182 /// This is a long pipeline and uses most of the per-function optimization
183 /// passes in LLVM to canonicalize and simplify the IR. It is suitable to run
184 /// repeatedly over the IR and is not expected to destroy important
185 /// information about the semantics of the IR.
187 /// Note that \p Level cannot be `O0` here. The pipelines produced are
188 /// only intended for use when attempting to optimize code. If frontends
189 /// require some transformations for semantic reasons, they should explicitly
192 buildFunctionSimplificationPipeline(OptimizationLevel Level,
193 bool DebugLogging = false);
195 /// Construct the core LLVM module canonicalization and simplification
198 /// This pipeline focuses on canonicalizing and simplifying the entire module
199 /// of IR. Much like the function simplification pipeline above, it is
200 /// suitable to run repeatedly over the IR and is not expected to destroy
201 /// important information. It does, however, perform inlining and other
202 /// heuristic based simplifications that are not strictly reversible.
204 /// Note that \p Level cannot be `O0` here. The pipelines produced are
205 /// only intended for use when attempting to optimize code. If frontends
206 /// require some transformations for semantic reasons, they should explicitly
209 buildModuleSimplificationPipeline(OptimizationLevel Level,
210 bool DebugLogging = false);
212 /// Construct the core LLVM module optimization pipeline.
214 /// This pipeline focuses on optimizing the execution speed of the IR. It
215 /// uses cost modeling and thresholds to balance code growth against runtime
216 /// improvements. It includes vectorization and other information destroying
217 /// transformations. It also cannot generally be run repeatedly on a module
218 /// without potentially seriously regressing either runtime performance of
219 /// the code or serious code size growth.
221 /// Note that \p Level cannot be `O0` here. The pipelines produced are
222 /// only intended for use when attempting to optimize code. If frontends
223 /// require some transformations for semantic reasons, they should explicitly
225 ModulePassManager buildModuleOptimizationPipeline(OptimizationLevel Level,
226 bool DebugLogging = false);
228 /// Build a per-module default optimization pipeline.
230 /// This provides a good default optimization pipeline for per-module
231 /// optimization and code generation without any link-time optimization. It
232 /// typically correspond to frontend "-O[123]" options for optimization
233 /// levels \c O1, \c O2 and \c O3 resp.
235 /// Note that \p Level cannot be `O0` here. The pipelines produced are
236 /// only intended for use when attempting to optimize code. If frontends
237 /// require some transformations for semantic reasons, they should explicitly
239 ModulePassManager buildPerModuleDefaultPipeline(OptimizationLevel Level,
240 bool DebugLogging = false);
242 /// Build a pre-link, ThinLTO-targeting default optimization pipeline to
245 /// This adds the pre-link optimizations tuned to prepare a module for
246 /// a ThinLTO run. It works to minimize the IR which needs to be analyzed
247 /// without making irreversible decisions which could be made better during
250 /// Note that \p Level cannot be `O0` here. The pipelines produced are
251 /// only intended for use when attempting to optimize code. If frontends
252 /// require some transformations for semantic reasons, they should explicitly
255 buildThinLTOPreLinkDefaultPipeline(OptimizationLevel Level,
256 bool DebugLogging = false);
258 /// Build an ThinLTO default optimization pipeline to a pass manager.
260 /// This provides a good default optimization pipeline for link-time
261 /// optimization and code generation. It is particularly tuned to fit well
262 /// when IR coming into the LTO phase was first run through \c
263 /// addPreLinkLTODefaultPipeline, and the two coordinate closely.
265 /// Note that \p Level cannot be `O0` here. The pipelines produced are
266 /// only intended for use when attempting to optimize code. If frontends
267 /// require some transformations for semantic reasons, they should explicitly
269 ModulePassManager buildThinLTODefaultPipeline(OptimizationLevel Level,
270 bool DebugLogging = false);
272 /// Build a pre-link, LTO-targeting default optimization pipeline to a pass
275 /// This adds the pre-link optimizations tuned to work well with a later LTO
276 /// run. It works to minimize the IR which needs to be analyzed without
277 /// making irreversible decisions which could be made better during the LTO
280 /// Note that \p Level cannot be `O0` here. The pipelines produced are
281 /// only intended for use when attempting to optimize code. If frontends
282 /// require some transformations for semantic reasons, they should explicitly
284 ModulePassManager buildLTOPreLinkDefaultPipeline(OptimizationLevel Level,
285 bool DebugLogging = false);
287 /// Build an LTO default optimization pipeline to a pass manager.
289 /// This provides a good default optimization pipeline for link-time
290 /// optimization and code generation. It is particularly tuned to fit well
291 /// when IR coming into the LTO phase was first run through \c
292 /// addPreLinkLTODefaultPipeline, and the two coordinate closely.
294 /// Note that \p Level cannot be `O0` here. The pipelines produced are
295 /// only intended for use when attempting to optimize code. If frontends
296 /// require some transformations for semantic reasons, they should explicitly
298 ModulePassManager buildLTODefaultPipeline(OptimizationLevel Level,
299 bool DebugLogging = false);
301 /// Build the default `AAManager` with the default alias analysis pipeline
303 AAManager buildDefaultAAPipeline();
305 /// \brief Parse a textual pass pipeline description into a \c ModulePassManager.
307 /// The format of the textual pass pipeline description looks something like:
309 /// module(function(instcombine,sroa),dce,cgscc(inliner,function(...)),...)
311 /// Pass managers have ()s describing the nest structure of passes. All passes
312 /// are comma separated. As a special shortcut, if the very first pass is not
313 /// a module pass (as a module pass manager is), this will automatically form
314 /// the shortest stack of pass managers that allow inserting that first pass.
315 /// So, assuming function passes 'fpassN', CGSCC passes 'cgpassN', and loop passes
316 /// 'lpassN', all of these are valid:
318 /// fpass1,fpass2,fpass3
319 /// cgpass1,cgpass2,cgpass3
320 /// lpass1,lpass2,lpass3
322 /// And they are equivalent to the following (resp.):
324 /// module(function(fpass1,fpass2,fpass3))
325 /// module(cgscc(cgpass1,cgpass2,cgpass3))
326 /// module(function(loop(lpass1,lpass2,lpass3)))
328 /// This shortcut is especially useful for debugging and testing small pass
329 /// combinations. Note that these shortcuts don't introduce any other magic. If
330 /// the sequence of passes aren't all the exact same kind of pass, it will be
331 /// an error. You cannot mix different levels implicitly, you must explicitly
332 /// form a pass manager in which to nest passes.
333 bool parsePassPipeline(ModulePassManager &MPM, StringRef PipelineText,
334 bool VerifyEachPass = true, bool DebugLogging = false);
336 /// Parse a textual alias analysis pipeline into the provided AA manager.
338 /// The format of the textual AA pipeline is a comma separated list of AA
341 /// basic-aa,globals-aa,...
343 /// The AA manager is set up such that the provided alias analyses are tried
344 /// in the order specified. See the \c AAManaager documentation for details
345 /// about the logic used. This routine just provides the textual mapping
346 /// between AA names and the analyses to register with the manager.
348 /// Returns false if the text cannot be parsed cleanly. The specific state of
349 /// the \p AA manager is unspecified if such an error is encountered and this
351 bool parseAAPipeline(AAManager &AA, StringRef PipelineText);
354 /// A struct to capture parsed pass pipeline names.
355 struct PipelineElement {
357 std::vector<PipelineElement> InnerPipeline;
360 static Optional<std::vector<PipelineElement>>
361 parsePipelineText(StringRef Text);
363 bool parseModulePass(ModulePassManager &MPM, const PipelineElement &E,
364 bool VerifyEachPass, bool DebugLogging);
365 bool parseCGSCCPass(CGSCCPassManager &CGPM, const PipelineElement &E,
366 bool VerifyEachPass, bool DebugLogging);
367 bool parseFunctionPass(FunctionPassManager &FPM, const PipelineElement &E,
368 bool VerifyEachPass, bool DebugLogging);
369 bool parseLoopPass(LoopPassManager &LPM, const PipelineElement &E,
370 bool VerifyEachPass, bool DebugLogging);
371 bool parseAAPassName(AAManager &AA, StringRef Name);
373 bool parseLoopPassPipeline(LoopPassManager &LPM,
374 ArrayRef<PipelineElement> Pipeline,
375 bool VerifyEachPass, bool DebugLogging);
376 bool parseFunctionPassPipeline(FunctionPassManager &FPM,
377 ArrayRef<PipelineElement> Pipeline,
378 bool VerifyEachPass, bool DebugLogging);
379 bool parseCGSCCPassPipeline(CGSCCPassManager &CGPM,
380 ArrayRef<PipelineElement> Pipeline,
381 bool VerifyEachPass, bool DebugLogging);
382 bool parseModulePassPipeline(ModulePassManager &MPM,
383 ArrayRef<PipelineElement> Pipeline,
384 bool VerifyEachPass, bool DebugLogging);