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86953b5795
a dynamic analysis done on each call to the routine. However, now it can use the standard pass infrastructure to reference other analyses, instead of a silly setter method. This will become more interesting as I teach it about more analysis passes. This updates the two inliner passes to use the inline cost analysis. Doing so highlights how utterly redundant these two passes are. Either we should find a cheaper way to do always inlining, or we should merge the two and just fiddle with the thresholds to get the desired behavior. I'm leaning increasingly toward the latter as it would also remove the Inliner sub-class split. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173030 91177308-0d34-0410-b5e6-96231b3b80d8
113 lines
3.8 KiB
C++
113 lines
3.8 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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#define DEBUG_TYPE "inline"
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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/CallGraph.h"
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#include "llvm/Analysis/InlineCost.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/Support/CallSite.h"
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#include "llvm/Transforms/IPO/InlinerPass.h"
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using namespace llvm;
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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), ICA(0) {
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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(0) {
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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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virtual InlineCost getInlineCost(CallSite CS);
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virtual void getAnalysisUsage(AnalysisUsage &AU) const;
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virtual bool runOnSCC(CallGraphSCC &SCC);
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using llvm::Pass::doFinalization;
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virtual bool doFinalization(CallGraph &CG) {
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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(CallGraph)
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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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Callee->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
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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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