forked from OSchip/llvm-project
118 lines
4.0 KiB
C++
118 lines
4.0 KiB
C++
//===- InlineAlways.cpp - Code to inline always_inline functions ----------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements a custom inliner that handles only functions that
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// are marked as "always inline".
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/IPO.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/Analysis/AliasAnalysis.h"
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#include "llvm/Analysis/AssumptionCache.h"
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#include "llvm/Analysis/CallGraph.h"
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#include "llvm/Analysis/InlineCost.h"
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#include "llvm/IR/CallSite.h"
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#include "llvm/IR/CallingConv.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/IntrinsicInst.h"
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#include "llvm/IR/Module.h"
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#include "llvm/IR/Type.h"
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#include "llvm/Transforms/IPO/InlinerPass.h"
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using namespace llvm;
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#define DEBUG_TYPE "inline"
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namespace {
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/// \brief Inliner pass which only handles "always inline" functions.
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class AlwaysInliner : public Inliner {
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InlineCostAnalysis *ICA;
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public:
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// Use extremely low threshold.
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AlwaysInliner() : Inliner(ID, -2000000000, /*InsertLifetime*/ true),
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ICA(nullptr) {
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initializeAlwaysInlinerPass(*PassRegistry::getPassRegistry());
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}
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AlwaysInliner(bool InsertLifetime)
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: Inliner(ID, -2000000000, InsertLifetime), ICA(nullptr) {
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initializeAlwaysInlinerPass(*PassRegistry::getPassRegistry());
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}
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static char ID; // Pass identification, replacement for typeid
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InlineCost getInlineCost(CallSite CS) override;
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void getAnalysisUsage(AnalysisUsage &AU) const override;
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bool runOnSCC(CallGraphSCC &SCC) override;
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using llvm::Pass::doFinalization;
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bool doFinalization(CallGraph &CG) override {
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return removeDeadFunctions(CG, /*AlwaysInlineOnly=*/ true);
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}
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};
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}
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char AlwaysInliner::ID = 0;
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INITIALIZE_PASS_BEGIN(AlwaysInliner, "always-inline",
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"Inliner for always_inline functions", false, false)
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INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
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INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
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INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)
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INITIALIZE_PASS_DEPENDENCY(InlineCostAnalysis)
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INITIALIZE_PASS_END(AlwaysInliner, "always-inline",
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"Inliner for always_inline functions", false, false)
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Pass *llvm::createAlwaysInlinerPass() { return new AlwaysInliner(); }
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Pass *llvm::createAlwaysInlinerPass(bool InsertLifetime) {
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return new AlwaysInliner(InsertLifetime);
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}
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/// \brief Get the inline cost for the always-inliner.
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///
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/// The always inliner *only* handles functions which are marked with the
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/// attribute to force inlining. As such, it is dramatically simpler and avoids
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/// using the powerful (but expensive) inline cost analysis. Instead it uses
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/// a very simple and boring direct walk of the instructions looking for
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/// impossible-to-inline constructs.
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///
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/// Note, it would be possible to go to some lengths to cache the information
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/// computed here, but as we only expect to do this for relatively few and
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/// small functions which have the explicit attribute to force inlining, it is
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/// likely not worth it in practice.
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InlineCost AlwaysInliner::getInlineCost(CallSite CS) {
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Function *Callee = CS.getCalledFunction();
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// Only inline direct calls to functions with always-inline attributes
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// that are viable for inlining. FIXME: We shouldn't even get here for
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// declarations.
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if (Callee && !Callee->isDeclaration() &&
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CS.hasFnAttr(Attribute::AlwaysInline) &&
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ICA->isInlineViable(*Callee))
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return InlineCost::getAlways();
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return InlineCost::getNever();
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}
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bool AlwaysInliner::runOnSCC(CallGraphSCC &SCC) {
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ICA = &getAnalysis<InlineCostAnalysis>();
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return Inliner::runOnSCC(SCC);
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}
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void AlwaysInliner::getAnalysisUsage(AnalysisUsage &AU) const {
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AU.addRequired<InlineCostAnalysis>();
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Inliner::getAnalysisUsage(AU);
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}
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