1 //===- InlineSimple.cpp - Code to perform simple function inlining --------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements bottom-up inlining of functions into callees.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #define DEBUG_TYPE "inline"
15 #include "llvm/CallingConv.h"
16 #include "llvm/Instructions.h"
17 #include "llvm/IntrinsicInst.h"
18 #include "llvm/Module.h"
19 #include "llvm/Type.h"
20 #include "llvm/Analysis/CallGraph.h"
21 #include "llvm/Support/CallSite.h"
22 #include "llvm/Support/Compiler.h"
23 #include "llvm/Transforms/IPO.h"
24 #include "llvm/Transforms/IPO/InlinerPass.h"
25 #include "llvm/Transforms/Utils/InlineCost.h"
26 #include "llvm/ADT/SmallPtrSet.h"
27 
28 using namespace llvm;
29 
30 namespace {
31 
32   class VISIBILITY_HIDDEN SimpleInliner : public Inliner {
33     // Functions that are never inlined
34     SmallPtrSet<const Function*, 16> NeverInline;
35     InlineCostAnalyzer CA;
36   public:
37     SimpleInliner() : Inliner(&ID) {}
38     SimpleInliner(int Threshold) : Inliner(&ID, Threshold) {}
39     static char ID; // Pass identification, replacement for typeid
40     InlineCost getInlineCost(CallSite CS) {
41       return CA.getInlineCost(CS, NeverInline);
42     }
43     float getInlineFudgeFactor(CallSite CS) {
44       return CA.getInlineFudgeFactor(CS);
45     }
46     void resetCachedCostInfo(Function *Caller) {
47       CA.resetCachedCostInfo(Caller);
48     }
49     virtual bool doInitialization(CallGraph &CG);
50   };
51 }
52 
53 char SimpleInliner::ID = 0;
54 static RegisterPass<SimpleInliner>
55 X("inline", "Function Integration/Inlining");
56 
57 Pass *llvm::createFunctionInliningPass() { return new SimpleInliner(); }
58 
59 Pass *llvm::createFunctionInliningPass(int Threshold) {
60   return new SimpleInliner(Threshold);
61 }
62 
63 // doInitialization - Initializes the vector of functions that have been
64 // annotated with the noinline attribute.
65 bool SimpleInliner::doInitialization(CallGraph &CG) {
66 
67   Module &M = CG.getModule();
68 
69   for (Module::iterator I = M.begin(), E = M.end();
70        I != E; ++I)
71     if (!I->isDeclaration() && I->hasFnAttr(Attribute::NoInline))
72       NeverInline.insert(I);
73 
74   // Get llvm.noinline
75   GlobalVariable *GV = M.getNamedGlobal("llvm.noinline");
76 
77   if (GV == 0)
78     return false;
79 
80   // Don't crash on invalid code
81   if (!GV->hasInitializer())
82     return false;
83 
84   const ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
85 
86   if (InitList == 0)
87     return false;
88 
89   // Iterate over each element and add to the NeverInline set
90   for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
91 
92     // Get Source
93     const Constant *Elt = InitList->getOperand(i);
94 
95     if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(Elt))
96       if (CE->getOpcode() == Instruction::BitCast)
97         Elt = CE->getOperand(0);
98 
99     // Insert into set of functions to never inline
100     if (const Function *F = dyn_cast<Function>(Elt))
101       NeverInline.insert(F);
102   }
103 
104   return false;
105 }
106 
107