forked from OSchip/llvm-project
157 lines
5.8 KiB
C++
157 lines
5.8 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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#include "llvm/Transforms/IPO/AlwaysInliner.h"
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#include "llvm/ADT/SetVector.h"
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#include "llvm/Analysis/AssumptionCache.h"
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#include "llvm/Analysis/InlineCost.h"
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#include "llvm/Analysis/TargetLibraryInfo.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/Module.h"
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#include "llvm/IR/Type.h"
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#include "llvm/Transforms/IPO.h"
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#include "llvm/Transforms/IPO/Inliner.h"
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#include "llvm/Transforms/Utils/Cloning.h"
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#include "llvm/Transforms/Utils/ModuleUtils.h"
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using namespace llvm;
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#define DEBUG_TYPE "inline"
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PreservedAnalyses AlwaysInlinerPass::run(Module &M, ModuleAnalysisManager &) {
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InlineFunctionInfo IFI;
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SmallSetVector<CallSite, 16> Calls;
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bool Changed = false;
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SmallVector<Function *, 16> InlinedFunctions;
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for (Function &F : M)
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if (!F.isDeclaration() && F.hasFnAttribute(Attribute::AlwaysInline) &&
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isInlineViable(F)) {
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Calls.clear();
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for (User *U : F.users())
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if (auto CS = CallSite(U))
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if (CS.getCalledFunction() == &F)
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Calls.insert(CS);
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for (CallSite CS : Calls)
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// FIXME: We really shouldn't be able to fail to inline at this point!
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// We should do something to log or check the inline failures here.
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Changed |=
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InlineFunction(CS, IFI, /*CalleeAAR=*/nullptr, InsertLifetime);
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// Remember to try and delete this function afterward. This both avoids
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// re-walking the rest of the module and avoids dealing with any iterator
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// invalidation issues while deleting functions.
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InlinedFunctions.push_back(&F);
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}
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// Remove any live functions.
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erase_if(InlinedFunctions, [&](Function *F) {
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F->removeDeadConstantUsers();
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return !F->isDefTriviallyDead();
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});
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// Delete the non-comdat ones from the module and also from our vector.
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auto NonComdatBegin = partition(
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InlinedFunctions, [&](Function *F) { return F->hasComdat(); });
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for (Function *F : make_range(NonComdatBegin, InlinedFunctions.end()))
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M.getFunctionList().erase(F);
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InlinedFunctions.erase(NonComdatBegin, InlinedFunctions.end());
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if (!InlinedFunctions.empty()) {
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// Now we just have the comdat functions. Filter out the ones whose comdats
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// are not actually dead.
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filterDeadComdatFunctions(M, InlinedFunctions);
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// The remaining functions are actually dead.
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for (Function *F : InlinedFunctions)
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M.getFunctionList().erase(F);
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}
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return Changed ? PreservedAnalyses::none() : PreservedAnalyses::all();
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}
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namespace {
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/// Inliner pass which only handles "always inline" functions.
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///
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/// Unlike the \c AlwaysInlinerPass, this uses the more heavyweight \c Inliner
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/// base class to provide several facilities such as array alloca merging.
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class AlwaysInlinerLegacyPass : public LegacyInlinerBase {
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public:
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AlwaysInlinerLegacyPass() : LegacyInlinerBase(ID, /*InsertLifetime*/ true) {
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initializeAlwaysInlinerLegacyPassPass(*PassRegistry::getPassRegistry());
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}
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AlwaysInlinerLegacyPass(bool InsertLifetime)
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: LegacyInlinerBase(ID, InsertLifetime) {
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initializeAlwaysInlinerLegacyPassPass(*PassRegistry::getPassRegistry());
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}
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/// Main run interface method. We override here to avoid calling skipSCC().
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bool runOnSCC(CallGraphSCC &SCC) override { return inlineCalls(SCC); }
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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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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 AlwaysInlinerLegacyPass::ID = 0;
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INITIALIZE_PASS_BEGIN(AlwaysInlinerLegacyPass, "always-inline",
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"Inliner for always_inline functions", false, false)
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INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
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INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)
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INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)
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INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
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INITIALIZE_PASS_END(AlwaysInlinerLegacyPass, "always-inline",
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"Inliner for always_inline functions", false, false)
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Pass *llvm::createAlwaysInlinerLegacyPass(bool InsertLifetime) {
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return new AlwaysInlinerLegacyPass(InsertLifetime);
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}
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/// 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 AlwaysInlinerLegacyPass::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) && isInlineViable(*Callee))
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return InlineCost::getAlways();
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return InlineCost::getNever();
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}
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