1 //===- InlineAlways.cpp - Code to inline always_inline functions ----------===//
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 a custom inliner that handles only functions that
11 // are marked as "always inline".
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #define DEBUG_TYPE "inline"
16 #include "llvm/CallingConv.h"
17 #include "llvm/Instructions.h"
18 #include "llvm/IntrinsicInst.h"
19 #include "llvm/Module.h"
20 #include "llvm/Type.h"
21 #include "llvm/Analysis/CallGraph.h"
22 #include "llvm/Analysis/InlineCost.h"
23 #include "llvm/Support/CallSite.h"
24 #include "llvm/Transforms/IPO.h"
25 #include "llvm/Transforms/IPO/InlinerPass.h"
26 #include "llvm/Target/TargetData.h"
27 #include "llvm/ADT/SmallPtrSet.h"
28 
29 using namespace llvm;
30 
31 namespace {
32 
33   // AlwaysInliner only inlines functions that are mark as "always inline".
34   class AlwaysInliner : public Inliner {
35     // Functions that are never inlined
36     SmallPtrSet<const Function*, 16> NeverInline;
37     InlineCostAnalyzer CA;
38   public:
39     // Use extremely low threshold.
40     AlwaysInliner() : Inliner(ID, -2000000000) {
41       initializeAlwaysInlinerPass(*PassRegistry::getPassRegistry());
42     }
43     static char ID; // Pass identification, replacement for typeid
44     InlineCost getInlineCost(CallSite CS) {
45       return CA.getInlineCost(CS, NeverInline);
46     }
47     float getInlineFudgeFactor(CallSite CS) {
48       return CA.getInlineFudgeFactor(CS);
49     }
50     void resetCachedCostInfo(Function *Caller) {
51       CA.resetCachedCostInfo(Caller);
52     }
53     void growCachedCostInfo(Function* Caller, Function* Callee) {
54       CA.growCachedCostInfo(Caller, Callee);
55     }
56     virtual bool doFinalization(CallGraph &CG) {
57       return removeDeadFunctions(CG, &NeverInline);
58     }
59     virtual bool doInitialization(CallGraph &CG);
60     void releaseMemory() {
61       CA.clear();
62     }
63   };
64 }
65 
66 char AlwaysInliner::ID = 0;
67 INITIALIZE_PASS_BEGIN(AlwaysInliner, "always-inline",
68                 "Inliner for always_inline functions", false, false)
69 INITIALIZE_AG_DEPENDENCY(CallGraph)
70 INITIALIZE_PASS_END(AlwaysInliner, "always-inline",
71                 "Inliner for always_inline functions", false, false)
72 
73 Pass *llvm::createAlwaysInlinerPass() { return new AlwaysInliner(); }
74 
75 // doInitialization - Initializes the vector of functions that have not
76 // been annotated with the "always inline" attribute.
77 bool AlwaysInliner::doInitialization(CallGraph &CG) {
78   CA.setTargetData(getAnalysisIfAvailable<TargetData>());
79 
80   Module &M = CG.getModule();
81 
82   for (Module::iterator I = M.begin(), E = M.end();
83        I != E; ++I)
84     if (!I->isDeclaration() && !I->hasFnAttr(Attribute::AlwaysInline))
85       NeverInline.insert(I);
86 
87   return false;
88 }
89