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/Analysis/InlineCost.h"
22 #include "llvm/Support/CallSite.h"
23 #include "llvm/Transforms/IPO.h"
24 #include "llvm/Transforms/IPO/InlinerPass.h"
25 #include "llvm/ADT/SmallPtrSet.h"
26 
27 using namespace llvm;
28 
29 namespace {
30 
31   class SimpleInliner : public Inliner {
32     // Functions that are never inlined
33     SmallPtrSet<const Function*, 16> NeverInline;
34     InlineCostAnalyzer CA;
35   public:
36     SimpleInliner() : Inliner(&ID) {}
37     SimpleInliner(int Threshold) : Inliner(&ID, Threshold) {}
38     static char ID; // Pass identification, replacement for typeid
39     InlineCost getInlineCost(CallSite CS) {
40       return CA.getInlineCost(CS, NeverInline);
41     }
42     float getInlineFudgeFactor(CallSite CS) {
43       return CA.getInlineFudgeFactor(CS);
44     }
45     void resetCachedCostInfo(Function *Caller) {
46       CA.resetCachedCostInfo(Caller);
47     }
48     virtual bool doInitialization(CallGraph &CG);
49   };
50 }
51 
52 char SimpleInliner::ID = 0;
53 static RegisterPass<SimpleInliner>
54 X("inline", "Function Integration/Inlining");
55 
56 Pass *llvm::createFunctionInliningPass() { return new SimpleInliner(); }
57 
58 Pass *llvm::createFunctionInliningPass(int Threshold) {
59   return new SimpleInliner(Threshold);
60 }
61 
62 // doInitialization - Initializes the vector of functions that have been
63 // annotated with the noinline attribute.
64 bool SimpleInliner::doInitialization(CallGraph &CG) {
65 
66   Module &M = CG.getModule();
67 
68   for (Module::iterator I = M.begin(), E = M.end();
69        I != E; ++I)
70     if (!I->isDeclaration() && I->hasFnAttr(Attribute::NoInline))
71       NeverInline.insert(I);
72 
73   // Get llvm.noinline
74   GlobalVariable *GV = M.getNamedGlobal("llvm.noinline");
75 
76   if (GV == 0)
77     return false;
78 
79   // Don't crash on invalid code
80   if (!GV->hasDefinitiveInitializer())
81     return false;
82 
83   const ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
84 
85   if (InitList == 0)
86     return false;
87 
88   // Iterate over each element and add to the NeverInline set
89   for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
90 
91     // Get Source
92     const Constant *Elt = InitList->getOperand(i);
93 
94     if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(Elt))
95       if (CE->getOpcode() == Instruction::BitCast)
96         Elt = CE->getOperand(0);
97 
98     // Insert into set of functions to never inline
99     if (const Function *F = dyn_cast<Function>(Elt))
100       NeverInline.insert(F);
101   }
102 
103   return false;
104 }
105 
106