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/IR/CallingConv.h"
21 #include "llvm/IR/DataLayout.h"
22 #include "llvm/IR/Instructions.h"
23 #include "llvm/IR/IntrinsicInst.h"
24 #include "llvm/IR/Module.h"
25 #include "llvm/IR/Type.h"
26 #include "llvm/Support/CallSite.h"
27 #include "llvm/Transforms/IPO/InlinerPass.h"
33 /// \brief Inliner pass which only handles "always inline" functions.
34 class AlwaysInliner : public Inliner {
35 InlineCostAnalyzer CA;
38 // Use extremely low threshold.
39 AlwaysInliner() : Inliner(ID, -2000000000, /*InsertLifetime*/ true) {
40 initializeAlwaysInlinerPass(*PassRegistry::getPassRegistry());
43 AlwaysInliner(bool InsertLifetime)
44 : Inliner(ID, -2000000000, InsertLifetime) {
45 initializeAlwaysInlinerPass(*PassRegistry::getPassRegistry());
48 static char ID; // Pass identification, replacement for typeid
50 virtual InlineCost getInlineCost(CallSite CS);
52 using llvm::Pass::doFinalization;
53 virtual bool doFinalization(CallGraph &CG) {
54 return removeDeadFunctions(CG, /*AlwaysInlineOnly=*/ true);
57 using llvm::Pass::doInitialization;
58 virtual bool doInitialization(CallGraph &CG);
63 char AlwaysInliner::ID = 0;
64 INITIALIZE_PASS_BEGIN(AlwaysInliner, "always-inline",
65 "Inliner for always_inline functions", false, false)
66 INITIALIZE_AG_DEPENDENCY(CallGraph)
67 INITIALIZE_PASS_END(AlwaysInliner, "always-inline",
68 "Inliner for always_inline functions", false, false)
70 Pass *llvm::createAlwaysInlinerPass() { return new AlwaysInliner(); }
72 Pass *llvm::createAlwaysInlinerPass(bool InsertLifetime) {
73 return new AlwaysInliner(InsertLifetime);
76 /// \brief Get the inline cost for the always-inliner.
78 /// The always inliner *only* handles functions which are marked with the
79 /// attribute to force inlining. As such, it is dramatically simpler and avoids
80 /// using the powerful (but expensive) inline cost analysis. Instead it uses
81 /// a very simple and boring direct walk of the instructions looking for
82 /// impossible-to-inline constructs.
84 /// Note, it would be possible to go to some lengths to cache the information
85 /// computed here, but as we only expect to do this for relatively few and
86 /// small functions which have the explicit attribute to force inlining, it is
87 /// likely not worth it in practice.
88 InlineCost AlwaysInliner::getInlineCost(CallSite CS) {
89 Function *Callee = CS.getCalledFunction();
91 // Only inline direct calls to functions with always-inline attributes
92 // that are viable for inlining. FIXME: We shouldn't even get here for
94 if (Callee && !Callee->isDeclaration() &&
95 Callee->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
96 Attribute::AlwaysInline) &&
97 CA.isInlineViable(*Callee))
98 return InlineCost::getAlways();
100 return InlineCost::getNever();
103 bool AlwaysInliner::doInitialization(CallGraph &CG) {
104 CA.setDataLayout(getAnalysisIfAvailable<DataLayout>());