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     void growCachedCostInfo(Function* Caller, Function* Callee) {
49       CA.growCachedCostInfo(Caller, Callee);
50     }
51     virtual bool doInitialization(CallGraph &CG);
52   };
53 }
54 
55 char SimpleInliner::ID = 0;
56 static RegisterPass<SimpleInliner>
57 X("inline", "Function Integration/Inlining");
58 
59 Pass *llvm::createFunctionInliningPass() { return new SimpleInliner(); }
60 
61 Pass *llvm::createFunctionInliningPass(int Threshold) {
62   return new SimpleInliner(Threshold);
63 }
64 
65 // doInitialization - Initializes the vector of functions that have been
66 // annotated with the noinline attribute.
67 bool SimpleInliner::doInitialization(CallGraph &CG) {
68 
69   Module &M = CG.getModule();
70 
71   for (Module::iterator I = M.begin(), E = M.end();
72        I != E; ++I)
73     if (!I->isDeclaration() && I->hasFnAttr(Attribute::NoInline))
74       NeverInline.insert(I);
75 
76   // Get llvm.noinline
77   GlobalVariable *GV = M.getNamedGlobal("llvm.noinline");
78 
79   if (GV == 0)
80     return false;
81 
82   // Don't crash on invalid code
83   if (!GV->hasDefinitiveInitializer())
84     return false;
85 
86   const ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
87 
88   if (InitList == 0)
89     return false;
90 
91   // Iterate over each element and add to the NeverInline set
92   for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
93 
94     // Get Source
95     const Constant *Elt = InitList->getOperand(i);
96 
97     if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(Elt))
98       if (CE->getOpcode() == Instruction::BitCast)
99         Elt = CE->getOperand(0);
100 
101     // Insert into set of functions to never inline
102     if (const Function *F = dyn_cast<Function>(Elt))
103       NeverInline.insert(F);
104   }
105 
106   return false;
107 }
108 
109