1 //===- InlineAlways.cpp - Code to inline always_inline functions ----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements a custom inliner that handles only functions that
11 // are marked as "always inline".
13 //===----------------------------------------------------------------------===//
15 #define DEBUG_TYPE "inline"
16 #include "llvm/Transforms/IPO.h"
17 #include "llvm/ADT/SmallPtrSet.h"
18 #include "llvm/Analysis/CallGraph.h"
19 #include "llvm/Analysis/InlineCost.h"
20 #include "llvm/CallingConv.h"
21 #include "llvm/DataLayout.h"
22 #include "llvm/Instructions.h"
23 #include "llvm/IntrinsicInst.h"
24 #include "llvm/Module.h"
25 #include "llvm/Support/CallSite.h"
26 #include "llvm/Transforms/IPO/InlinerPass.h"
27 #include "llvm/Type.h"
33 // AlwaysInliner only inlines functions that are mark as "always inline".
34 class AlwaysInliner : public Inliner {
35 InlineCostAnalyzer CA;
37 // Use extremely low threshold.
38 AlwaysInliner() : Inliner(ID, -2000000000, /*InsertLifetime*/true) {
39 initializeAlwaysInlinerPass(*PassRegistry::getPassRegistry());
41 AlwaysInliner(bool InsertLifetime) : Inliner(ID, -2000000000,
43 initializeAlwaysInlinerPass(*PassRegistry::getPassRegistry());
45 static char ID; // Pass identification, replacement for typeid
46 virtual InlineCost getInlineCost(CallSite CS);
47 virtual bool doFinalization(CallGraph &CG) {
48 return removeDeadFunctions(CG, /*AlwaysInlineOnly=*/true);
50 virtual bool doInitialization(CallGraph &CG);
54 char AlwaysInliner::ID = 0;
55 INITIALIZE_PASS_BEGIN(AlwaysInliner, "always-inline",
56 "Inliner for always_inline functions", false, false)
57 INITIALIZE_AG_DEPENDENCY(CallGraph)
58 INITIALIZE_PASS_END(AlwaysInliner, "always-inline",
59 "Inliner for always_inline functions", false, false)
61 Pass *llvm::createAlwaysInlinerPass() { return new AlwaysInliner(); }
63 Pass *llvm::createAlwaysInlinerPass(bool InsertLifetime) {
64 return new AlwaysInliner(InsertLifetime);
67 /// \brief Get the inline cost for the always-inliner.
69 /// The always inliner *only* handles functions which are marked with the
70 /// attribute to force inlining. As such, it is dramatically simpler and avoids
71 /// using the powerful (but expensive) inline cost analysis. Instead it uses
72 /// a very simple and boring direct walk of the instructions looking for
73 /// impossible-to-inline constructs.
75 /// Note, it would be possible to go to some lengths to cache the information
76 /// computed here, but as we only expect to do this for relatively few and
77 /// small functions which have the explicit attribute to force inlining, it is
78 /// likely not worth it in practice.
79 InlineCost AlwaysInliner::getInlineCost(CallSite CS) {
80 Function *Callee = CS.getCalledFunction();
82 // Only inline direct calls to functions with always-inline attributes
83 // that are viable for inlining. FIXME: We shouldn't even get here for
85 if (Callee && !Callee->isDeclaration() &&
86 Callee->getFnAttributes().hasAttribute(Attributes::AlwaysInline) &&
87 CA.isInlineViable(*Callee))
88 return InlineCost::getAlways();
90 return InlineCost::getNever();
93 // doInitialization - Initializes the vector of functions that have not
94 // been annotated with the "always inline" attribute.
95 bool AlwaysInliner::doInitialization(CallGraph &CG) {
96 CA.setDataLayout(getAnalysisIfAvailable<DataLayout>());