1 //===- LoopPassManager.cpp - Loop pass management -------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #include "llvm/Support/TimeProfiler.h"
10 #include "llvm/Transforms/Scalar/LoopPassManager.h"
11 #include "llvm/Analysis/LoopInfo.h"
12
13 using namespace llvm;
14
15 // Explicit template instantiations and specialization defininitions for core
16 // template typedefs.
17 namespace llvm {
18 template class PassManager<Loop, LoopAnalysisManager,
19 LoopStandardAnalysisResults &, LPMUpdater &>;
20
21 /// Explicitly specialize the pass manager's run method to handle loop nest
22 /// structure updates.
23 template <>
24 PreservedAnalyses
25 PassManager<Loop, LoopAnalysisManager, LoopStandardAnalysisResults &,
run(Loop & L,LoopAnalysisManager & AM,LoopStandardAnalysisResults & AR,LPMUpdater & U)26 LPMUpdater &>::run(Loop &L, LoopAnalysisManager &AM,
27 LoopStandardAnalysisResults &AR, LPMUpdater &U) {
28 PreservedAnalyses PA = PreservedAnalyses::all();
29
30 if (DebugLogging)
31 dbgs() << "Starting Loop pass manager run.\n";
32
33 // Request PassInstrumentation from analysis manager, will use it to run
34 // instrumenting callbacks for the passes later.
35 PassInstrumentation PI = AM.getResult<PassInstrumentationAnalysis>(L, AR);
36 for (auto &Pass : Passes) {
37 // Check the PassInstrumentation's BeforePass callbacks before running the
38 // pass, skip its execution completely if asked to (callback returns false).
39 if (!PI.runBeforePass<Loop>(*Pass, L))
40 continue;
41
42 if (DebugLogging)
43 dbgs() << "Running pass: " << Pass->name() << " on " << L;
44
45 PreservedAnalyses PassPA;
46 {
47 TimeTraceScope TimeScope(Pass->name(), L.getName());
48 PassPA = Pass->run(L, AM, AR, U);
49 }
50
51 // do not pass deleted Loop into the instrumentation
52 if (U.skipCurrentLoop())
53 PI.runAfterPassInvalidated<Loop>(*Pass);
54 else
55 PI.runAfterPass<Loop>(*Pass, L);
56
57 // If the loop was deleted, abort the run and return to the outer walk.
58 if (U.skipCurrentLoop()) {
59 PA.intersect(std::move(PassPA));
60 break;
61 }
62
63 #ifndef NDEBUG
64 // Verify the loop structure and LCSSA form before visiting the loop.
65 L.verifyLoop();
66 assert(L.isRecursivelyLCSSAForm(AR.DT, AR.LI) &&
67 "Loops must remain in LCSSA form!");
68 #endif
69
70 // Update the analysis manager as each pass runs and potentially
71 // invalidates analyses.
72 AM.invalidate(L, PassPA);
73
74 // Finally, we intersect the final preserved analyses to compute the
75 // aggregate preserved set for this pass manager.
76 PA.intersect(std::move(PassPA));
77
78 // FIXME: Historically, the pass managers all called the LLVM context's
79 // yield function here. We don't have a generic way to acquire the
80 // context and it isn't yet clear what the right pattern is for yielding
81 // in the new pass manager so it is currently omitted.
82 // ...getContext().yield();
83 }
84
85 // Invalidation for the current loop should be handled above, and other loop
86 // analysis results shouldn't be impacted by runs over this loop. Therefore,
87 // the remaining analysis results in the AnalysisManager are preserved. We
88 // mark this with a set so that we don't need to inspect each one
89 // individually.
90 // FIXME: This isn't correct! This loop and all nested loops' analyses should
91 // be preserved, but unrolling should invalidate the parent loop's analyses.
92 PA.preserveSet<AllAnalysesOn<Loop>>();
93
94 if (DebugLogging)
95 dbgs() << "Finished Loop pass manager run.\n";
96
97 return PA;
98 }
99 }
100
PrintLoopPass()101 PrintLoopPass::PrintLoopPass() : OS(dbgs()) {}
PrintLoopPass(raw_ostream & OS,const std::string & Banner)102 PrintLoopPass::PrintLoopPass(raw_ostream &OS, const std::string &Banner)
103 : OS(OS), Banner(Banner) {}
104
run(Loop & L,LoopAnalysisManager &,LoopStandardAnalysisResults &,LPMUpdater &)105 PreservedAnalyses PrintLoopPass::run(Loop &L, LoopAnalysisManager &,
106 LoopStandardAnalysisResults &,
107 LPMUpdater &) {
108 printLoop(L, OS, Banner);
109 return PreservedAnalyses::all();
110 }
111