1 //===-- Passes.cpp - Target independent code generation passes ------------===//
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 //===----------------------------------------------------------------------===//
10 // This file defines interfaces to access the target independent code
11 // generation passes provided by the LLVM backend.
13 //===---------------------------------------------------------------------===//
15 #include "llvm/Analysis/Passes.h"
16 #include "llvm/Analysis/Verifier.h"
17 #include "llvm/Transforms/Scalar.h"
18 #include "llvm/PassManager.h"
19 #include "llvm/CodeGen/GCStrategy.h"
20 #include "llvm/CodeGen/MachineFunctionPass.h"
21 #include "llvm/CodeGen/Passes.h"
22 #include "llvm/CodeGen/RegAllocRegistry.h"
23 #include "llvm/Target/TargetLowering.h"
24 #include "llvm/Target/TargetOptions.h"
25 #include "llvm/Assembly/PrintModulePass.h"
26 #include "llvm/Support/CommandLine.h"
27 #include "llvm/Support/Debug.h"
28 #include "llvm/Support/ErrorHandling.h"
32 static cl::opt<bool> DisablePostRA("disable-post-ra", cl::Hidden,
33 cl::desc("Disable Post Regalloc"));
34 static cl::opt<bool> DisableBranchFold("disable-branch-fold", cl::Hidden,
35 cl::desc("Disable branch folding"));
36 static cl::opt<bool> DisableTailDuplicate("disable-tail-duplicate", cl::Hidden,
37 cl::desc("Disable tail duplication"));
38 static cl::opt<bool> DisableEarlyTailDup("disable-early-taildup", cl::Hidden,
39 cl::desc("Disable pre-register allocation tail duplication"));
40 static cl::opt<bool> EnableBlockPlacement("enable-block-placement",
41 cl::Hidden, cl::desc("Enable probability-driven block placement"));
42 static cl::opt<bool> EnableBlockPlacementStats("enable-block-placement-stats",
43 cl::Hidden, cl::desc("Collect probability-driven block placement stats"));
44 static cl::opt<bool> DisableCodePlace("disable-code-place", cl::Hidden,
45 cl::desc("Disable code placement"));
46 static cl::opt<bool> DisableSSC("disable-ssc", cl::Hidden,
47 cl::desc("Disable Stack Slot Coloring"));
48 static cl::opt<bool> DisableMachineDCE("disable-machine-dce", cl::Hidden,
49 cl::desc("Disable Machine Dead Code Elimination"));
50 static cl::opt<bool> DisableMachineLICM("disable-machine-licm", cl::Hidden,
51 cl::desc("Disable Machine LICM"));
52 static cl::opt<bool> DisableMachineCSE("disable-machine-cse", cl::Hidden,
53 cl::desc("Disable Machine Common Subexpression Elimination"));
54 static cl::opt<bool> DisablePostRAMachineLICM("disable-postra-machine-licm",
56 cl::desc("Disable Machine LICM"));
57 static cl::opt<bool> DisableMachineSink("disable-machine-sink", cl::Hidden,
58 cl::desc("Disable Machine Sinking"));
59 static cl::opt<bool> DisableLSR("disable-lsr", cl::Hidden,
60 cl::desc("Disable Loop Strength Reduction Pass"));
61 static cl::opt<bool> DisableCGP("disable-cgp", cl::Hidden,
62 cl::desc("Disable Codegen Prepare"));
63 static cl::opt<bool> DisableCopyProp("disable-copyprop", cl::Hidden,
64 cl::desc("Disable Copy Propagation pass"));
65 static cl::opt<bool> PrintLSR("print-lsr-output", cl::Hidden,
66 cl::desc("Print LLVM IR produced by the loop-reduce pass"));
67 static cl::opt<bool> PrintISelInput("print-isel-input", cl::Hidden,
68 cl::desc("Print LLVM IR input to isel pass"));
69 static cl::opt<bool> PrintGCInfo("print-gc", cl::Hidden,
70 cl::desc("Dump garbage collector data"));
71 static cl::opt<bool> VerifyMachineCode("verify-machineinstrs", cl::Hidden,
72 cl::desc("Verify generated machine code"),
73 cl::init(getenv("LLVM_VERIFY_MACHINEINSTRS")!=NULL));
75 //===---------------------------------------------------------------------===//
77 //===---------------------------------------------------------------------===//
79 INITIALIZE_PASS(TargetPassConfig, "targetpassconfig",
80 "Target Pass Configuration", false, false)
81 char TargetPassConfig::ID = 0;
83 // Out of line virtual method.
84 TargetPassConfig::~TargetPassConfig() {}
86 // Out of line constructor provides default values for pass options and
87 // registers all common codegen passes.
88 TargetPassConfig::TargetPassConfig(TargetMachine *tm, PassManagerBase &pm)
89 : ImmutablePass(ID), TM(tm), PM(pm), Initialized(false),
91 EnableTailMerge(true) {
93 // Register all target independent codegen passes to activate their PassIDs,
94 // including this pass itself.
95 initializeCodeGen(*PassRegistry::getPassRegistry());
98 /// createPassConfig - Create a pass configuration object to be used by
99 /// addPassToEmitX methods for generating a pipeline of CodeGen passes.
101 /// Targets may override this to extend TargetPassConfig.
102 TargetPassConfig *LLVMTargetMachine::createPassConfig(PassManagerBase &PM) {
103 return new TargetPassConfig(this, PM);
106 TargetPassConfig::TargetPassConfig()
107 : ImmutablePass(ID), PM(*(PassManagerBase*)0) {
108 llvm_unreachable("TargetPassConfig should not be constructed on-the-fly");
111 // Helper to verify the analysis is really immutable.
112 void TargetPassConfig::setOpt(bool &Opt, bool Val) {
113 assert(!Initialized && "PassConfig is immutable");
117 void TargetPassConfig::addPass(char &ID) {
118 // FIXME: check user overrides
119 Pass *P = Pass::createPass(ID);
121 llvm_unreachable("Pass ID not registered");
125 void TargetPassConfig::printNoVerify(const char *Banner) const {
126 if (TM->shouldPrintMachineCode())
127 PM.add(createMachineFunctionPrinterPass(dbgs(), Banner));
130 void TargetPassConfig::printAndVerify(const char *Banner) const {
131 if (TM->shouldPrintMachineCode())
132 PM.add(createMachineFunctionPrinterPass(dbgs(), Banner));
134 if (VerifyMachineCode)
135 PM.add(createMachineVerifierPass(Banner));
138 /// Add common target configurable passes that perform LLVM IR to IR transforms
139 /// following machine independent optimization.
140 void TargetPassConfig::addIRPasses() {
141 // Basic AliasAnalysis support.
142 // Add TypeBasedAliasAnalysis before BasicAliasAnalysis so that
143 // BasicAliasAnalysis wins if they disagree. This is intended to help
144 // support "obvious" type-punning idioms.
145 PM.add(createTypeBasedAliasAnalysisPass());
146 PM.add(createBasicAliasAnalysisPass());
148 // Before running any passes, run the verifier to determine if the input
149 // coming from the front-end and/or optimizer is valid.
151 PM.add(createVerifierPass());
153 // Run loop strength reduction before anything else.
154 if (getOptLevel() != CodeGenOpt::None && !DisableLSR) {
155 PM.add(createLoopStrengthReducePass(getTargetLowering()));
157 PM.add(createPrintFunctionPass("\n\n*** Code after LSR ***\n", &dbgs()));
160 PM.add(createGCLoweringPass());
162 // Make sure that no unreachable blocks are instruction selected.
163 PM.add(createUnreachableBlockEliminationPass());
166 /// Add common passes that perform LLVM IR to IR transforms in preparation for
167 /// instruction selection.
168 void TargetPassConfig::addISelPrepare() {
169 if (getOptLevel() != CodeGenOpt::None && !DisableCGP)
170 PM.add(createCodeGenPreparePass(getTargetLowering()));
172 PM.add(createStackProtectorPass(getTargetLowering()));
177 PM.add(createPrintFunctionPass("\n\n"
178 "*** Final LLVM Code input to ISel ***\n",
181 // All passes which modify the LLVM IR are now complete; run the verifier
182 // to ensure that the IR is valid.
184 PM.add(createVerifierPass());
187 /// Add the complete set of target-independent postISel code generator passes.
189 /// This can be read as the standard order of major LLVM CodeGen stages. Stages
190 /// with nontrivial configuration or multiple passes are broken out below in
191 /// add%Stage routines.
193 /// Any TargetPassConfig::addXX routine may be overriden by the Target. The
194 /// addPre/Post methods with empty header implementations allow injecting
195 /// target-specific fixups just before or after major stages. Additionally,
196 /// targets have the flexibility to change pass order within a stage by
197 /// overriding default implementation of add%Stage routines below. Each
198 /// technique has maintainability tradeoffs because alternate pass orders are
199 /// not well supported. addPre/Post works better if the target pass is easily
200 /// tied to a common pass. But if it has subtle dependencies on multiple passes,
201 /// overriding the stage instead.
203 /// TODO: We could use a single addPre/Post(ID) hook to allow pass injection
204 /// before/after any target-independent pass. But it's currently overkill.
205 void TargetPassConfig::addMachinePasses() {
206 // Print the instruction selected machine code...
207 printAndVerify("After Instruction Selection");
209 // Expand pseudo-instructions emitted by ISel.
210 addPass(ExpandISelPseudosID);
212 // Add passes that optimize machine instructions in SSA form.
213 if (getOptLevel() != CodeGenOpt::None) {
214 addMachineSSAOptimization();
217 // If the target requests it, assign local variables to stack slots relative
218 // to one another and simplify frame index references where possible.
219 addPass(LocalStackSlotAllocationID);
222 // Run pre-ra passes.
223 if (addPreRegAlloc())
224 printAndVerify("After PreRegAlloc passes");
226 // Run register allocation and passes that are tightly coupled with it,
227 // including phi elimination and scheduling.
230 // Run post-ra passes.
231 if (addPostRegAlloc())
232 printAndVerify("After PostRegAlloc passes");
234 // Insert prolog/epilog code. Eliminate abstract frame index references...
235 addPass(PrologEpilogCodeInserterID);
236 printAndVerify("After PrologEpilogCodeInserter");
238 /// Add passes that optimize machine instructions after register allocation.
239 if (getOptLevel() != CodeGenOpt::None)
240 addMachineLateOptimization();
242 // Expand pseudo instructions before second scheduling pass.
243 addPass(ExpandPostRAPseudosID);
244 printNoVerify("After ExpandPostRAPseudos");
246 // Run pre-sched2 passes.
248 printNoVerify("After PreSched2 passes");
250 // Second pass scheduler.
251 if (getOptLevel() != CodeGenOpt::None && !DisablePostRA) {
252 addPass(PostRASchedulerID);
253 printNoVerify("After PostRAScheduler");
257 addPass(GCMachineCodeAnalysisID);
259 PM.add(createGCInfoPrinter(dbgs()));
261 // Basic block placement.
262 if (getOptLevel() != CodeGenOpt::None && !DisableCodePlace)
265 if (addPreEmitPass())
266 printNoVerify("After PreEmit passes");
269 /// Add passes that optimize machine instructions in SSA form.
270 void TargetPassConfig::addMachineSSAOptimization() {
271 // Pre-ra tail duplication.
272 if (!DisableEarlyTailDup) {
273 addPass(TailDuplicateID);
274 printAndVerify("After Pre-RegAlloc TailDuplicate");
277 // Optimize PHIs before DCE: removing dead PHI cycles may make more
278 // instructions dead.
279 addPass(OptimizePHIsID);
281 // If the target requests it, assign local variables to stack slots relative
282 // to one another and simplify frame index references where possible.
283 addPass(LocalStackSlotAllocationID);
285 // With optimization, dead code should already be eliminated. However
286 // there is one known exception: lowered code for arguments that are only
287 // used by tail calls, where the tail calls reuse the incoming stack
288 // arguments directly (see t11 in test/CodeGen/X86/sibcall.ll).
289 if (!DisableMachineDCE)
290 addPass(DeadMachineInstructionElimID);
291 printAndVerify("After codegen DCE pass");
293 if (!DisableMachineLICM)
294 addPass(MachineLICMID);
295 if (!DisableMachineCSE)
296 addPass(MachineCSEID);
297 if (!DisableMachineSink)
298 addPass(MachineSinkingID);
299 printAndVerify("After Machine LICM, CSE and Sinking passes");
301 addPass(PeepholeOptimizerID);
302 printAndVerify("After codegen peephole optimization pass");
305 //===---------------------------------------------------------------------===//
306 /// Register Allocation Pass Configuration
307 //===---------------------------------------------------------------------===//
309 /// RegisterRegAlloc's global Registry tracks allocator registration.
310 MachinePassRegistry RegisterRegAlloc::Registry;
312 /// A dummy default pass factory indicates whether the register allocator is
313 /// overridden on the command line.
314 static FunctionPass *createDefaultRegisterAllocator() { return 0; }
315 static RegisterRegAlloc
316 defaultRegAlloc("default",
317 "pick register allocator based on -O option",
318 createDefaultRegisterAllocator);
320 /// -regalloc=... command line option.
321 static cl::opt<RegisterRegAlloc::FunctionPassCtor, false,
322 RegisterPassParser<RegisterRegAlloc> >
324 cl::init(&createDefaultRegisterAllocator),
325 cl::desc("Register allocator to use"));
328 /// createRegisterAllocator - choose the appropriate register allocator.
329 FunctionPass *llvm::createRegisterAllocator(CodeGenOpt::Level OptLevel) {
330 RegisterRegAlloc::FunctionPassCtor Ctor = RegisterRegAlloc::getDefault();
334 RegisterRegAlloc::setDefault(RegAlloc);
337 if (Ctor != createDefaultRegisterAllocator)
340 // When the 'default' allocator is requested, pick one based on OptLevel.
342 case CodeGenOpt::None:
343 return createFastRegisterAllocator();
345 return createGreedyRegisterAllocator();
349 /// Add standard target-independent passes that are tightly coupled with
350 /// register allocation, including coalescing, machine instruction scheduling,
351 /// and register allocation itself.
353 /// FIXME: This will become the register allocation "super pass" pipeline.
354 void TargetPassConfig::addRegAlloc() {
355 // Perform register allocation.
356 PM.add(createRegisterAllocator(getOptLevel()));
357 printAndVerify("After Register Allocation");
359 // Perform stack slot coloring and post-ra machine LICM.
360 if (getOptLevel() != CodeGenOpt::None) {
361 // FIXME: Re-enable coloring with register when it's capable of adding
364 addPass(StackSlotColoringID);
366 // Run post-ra machine LICM to hoist reloads / remats.
368 // FIXME: can this move into MachineLateOptimization?
369 if (!DisablePostRAMachineLICM)
370 addPass(MachineLICMID);
372 printAndVerify("After StackSlotColoring and postra Machine LICM");
376 //===---------------------------------------------------------------------===//
377 /// Post RegAlloc Pass Configuration
378 //===---------------------------------------------------------------------===//
380 /// Add passes that optimize machine instructions after register allocation.
381 void TargetPassConfig::addMachineLateOptimization() {
382 // Branch folding must be run after regalloc and prolog/epilog insertion.
383 if (!DisableBranchFold) {
384 addPass(BranchFolderPassID);
385 printNoVerify("After BranchFolding");
389 if (!DisableTailDuplicate) {
390 addPass(TailDuplicateID);
391 printNoVerify("After TailDuplicate");
395 if (!DisableCopyProp) {
396 addPass(MachineCopyPropagationID);
397 printNoVerify("After copy propagation pass");
401 /// Add standard basic block placement passes.
402 void TargetPassConfig::addBlockPlacement() {
403 if (EnableBlockPlacement) {
404 // MachineBlockPlacement is an experimental pass which is disabled by
405 // default currently. Eventually it should subsume CodePlacementOpt, so
406 // when enabled, the other is disabled.
407 addPass(MachineBlockPlacementID);
408 printNoVerify("After MachineBlockPlacement");
410 addPass(CodePlacementOptID);
411 printNoVerify("After CodePlacementOpt");
414 // Run a separate pass to collect block placement statistics.
415 if (EnableBlockPlacementStats) {
416 addPass(MachineBlockPlacementStatsID);
417 printNoVerify("After MachineBlockPlacementStats");