1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
|
//===- LoopExtractor.cpp - Extract each loop into a new function ----------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// A pass wrapper around the ExtractLoop() scalar transformation to extract each
// top-level loop into its own new function. If the loop is the ONLY loop in a
// given function, it is not touched. This is a pass most useful for debugging
// via bugpoint.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/IPO.h"
#include "llvm/iTerminators.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/FunctionUtils.h"
#include "Support/Statistic.h"
using namespace llvm;
namespace {
Statistic<> NumExtracted("loop-extract", "Number of loops extracted");
// FIXME: This is not a function pass, but the PassManager doesn't allow
// Module passes to require FunctionPasses, so we can't get loop info if we're
// not a function pass.
struct LoopExtractor : public FunctionPass {
unsigned NumLoops;
LoopExtractor(unsigned numLoops = ~0) : NumLoops(numLoops) {}
virtual bool runOnFunction(Function &F);
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequiredID(BreakCriticalEdgesID);
AU.addRequiredID(LoopSimplifyID);
AU.addRequired<DominatorSet>();
AU.addRequired<LoopInfo>();
}
};
RegisterOpt<LoopExtractor>
X("loop-extract", "Extract loops into new functions");
/// SingleLoopExtractor - For bugpoint.
struct SingleLoopExtractor : public LoopExtractor {
SingleLoopExtractor() : LoopExtractor(1) {}
};
RegisterOpt<SingleLoopExtractor>
Y("loop-extract-single", "Extract at most one loop into a new function");
} // End anonymous namespace
bool LoopExtractor::runOnFunction(Function &F) {
LoopInfo &LI = getAnalysis<LoopInfo>();
// If this function has no loops, there is nothing to do.
if (LI.begin() == LI.end())
return false;
DominatorSet &DS = getAnalysis<DominatorSet>();
// If there is more than one top-level loop in this function, extract all of
// the loops.
bool Changed = false;
if (LI.end()-LI.begin() > 1) {
for (LoopInfo::iterator i = LI.begin(), e = LI.end(); i != e; ++i) {
if (NumLoops == 0) return Changed;
--NumLoops;
Changed |= ExtractLoop(DS, *i) != 0;
++NumExtracted;
}
} else {
// Otherwise there is exactly one top-level loop. If this function is more
// than a minimal wrapper around the loop, extract the loop.
Loop *TLL = *LI.begin();
bool ShouldExtractLoop = false;
// Extract the loop if the entry block doesn't branch to the loop header.
TerminatorInst *EntryTI = F.getEntryBlock().getTerminator();
if (!isa<BranchInst>(EntryTI) ||
!cast<BranchInst>(EntryTI)->isUnconditional() ||
EntryTI->getSuccessor(0) != TLL->getHeader())
ShouldExtractLoop = true;
else {
// Check to see if any exits from the loop are more than just return
// blocks.
std::vector<BasicBlock*> ExitBlocks;
TLL->getExitBlocks(ExitBlocks);
for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i)
if (!isa<ReturnInst>(ExitBlocks[i]->getTerminator())) {
ShouldExtractLoop = true;
break;
}
}
if (ShouldExtractLoop) {
if (NumLoops == 0) return Changed;
--NumLoops;
Changed |= ExtractLoop(DS, TLL) != 0;
++NumExtracted;
} else {
// Okay, this function is a minimal container around the specified loop.
// If we extract the loop, we will continue to just keep extracting it
// infinitely... so don't extract it. However, if the loop contains any
// subloops, extract them.
for (Loop::iterator i = TLL->begin(), e = TLL->end(); i != e; ++i) {
if (NumLoops == 0) return Changed;
--NumLoops;
Changed |= ExtractLoop(DS, *i) != 0;
++NumExtracted;
}
}
}
return Changed;
}
// createSingleLoopExtractorPass - This pass extracts one natural loop from the
// program into a function if it can. This is used by bugpoint.
//
Pass *llvm::createSingleLoopExtractorPass() {
return new SingleLoopExtractor();
}
|
