-//===- FunctionInlining.cpp - Code to perform function inlining -----------===//
+//===- InlineSimple.cpp - Code to perform simple function inlining --------===//
//
-// This file implements inlining of functions.
+// The LLVM Compiler Infrastructure
//
-// Specifically, this:
-// * Exports functionality to inline any function call
-// * Inlines functions that consist of a single basic block
-// * Is able to inline ANY function call
-// . Has a smart heuristic for when to inline a function
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
-// Notice that:
-// * This pass opens up a lot of opportunities for constant propogation. It
-// is a good idea to to run a constant propogation pass, then a DCE pass
-// sometime after running this pass.
+//===----------------------------------------------------------------------===//
//
-// FIXME: This pass should transform alloca instructions in the called function
-// into malloc/free pairs!
+// This file implements bottom-up inlining of functions into callees.
//
//===----------------------------------------------------------------------===//
+#define DEBUG_TYPE "inline"
#include "llvm/Transforms/IPO.h"
-#include "llvm/Transforms/Utils/Cloning.h"
-#include "llvm/Module.h"
-#include "llvm/Pass.h"
-#include "llvm/iTerminators.h"
-#include "llvm/iPHINode.h"
-#include "llvm/iOther.h"
-#include "llvm/Type.h"
-#include "Support/Statistic.h"
-#include <algorithm>
-
-static Statistic<> NumInlined("inline", "Number of functions inlined");
-using std::cerr;
-
-// InlineFunction - This function forcibly inlines the called function into the
-// basic block of the caller. This returns false if it is not possible to
-// inline this call. The program is still in a well defined state if this
-// occurs though.
-//
-// Note that this only does one level of inlining. For example, if the
-// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now
-// exists in the instruction stream. Similiarly this will inline a recursive
-// function by one level.
-//
-bool InlineFunction(CallInst *CI) {
- assert(isa<CallInst>(CI) && "InlineFunction only works on CallInst nodes");
- assert(CI->getParent() && "Instruction not embedded in basic block!");
- assert(CI->getParent()->getParent() && "Instruction not in function!");
-
- const Function *CalledFunc = CI->getCalledFunction();
- if (CalledFunc == 0 || // Can't inline external function or indirect call!
- CalledFunc->isExternal()) return false;
-
- //cerr << "Inlining " << CalledFunc->getName() << " into "
- // << CurrentMeth->getName() << "\n";
-
- BasicBlock *OrigBB = CI->getParent();
-
- // Call splitBasicBlock - The original basic block now ends at the instruction
- // immediately before the call. The original basic block now ends with an
- // unconditional branch to NewBB, and NewBB starts with the call instruction.
- //
- BasicBlock *NewBB = OrigBB->splitBasicBlock(CI);
- NewBB->setName("InlinedFunctionReturnNode");
-
- // Remove (unlink) the CallInst from the start of the new basic block.
- NewBB->getInstList().remove(CI);
-
- // If we have a return value generated by this call, convert it into a PHI
- // node that gets values from each of the old RET instructions in the original
- // function.
- //
- PHINode *PHI = 0;
- if (!CI->use_empty()) {
- // The PHI node should go at the front of the new basic block to merge all
- // possible incoming values.
- //
- PHI = new PHINode(CalledFunc->getReturnType(), CI->getName(),
- NewBB->begin());
-
- // Anything that used the result of the function call should now use the PHI
- // node as their operand.
- //
- CI->replaceAllUsesWith(PHI);
- }
-
- // Get a pointer to the last basic block in the function, which will have the
- // new function inlined after it.
- //
- Function::iterator LastBlock = &OrigBB->getParent()->back();
-
- // Calculate the vector of arguments to pass into the function cloner...
- std::vector<Value*> ArgVector;
- for (unsigned i = 1, e = CI->getNumOperands(); i != e; ++i)
- ArgVector.push_back(CI->getOperand(i));
-
- // Since we are now done with the CallInst, we can delete it.
- delete CI;
+#include "llvm/Analysis/CallGraph.h"
+#include "llvm/Analysis/InlineCost.h"
+#include "llvm/IR/CallingConv.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/Type.h"
+#include "llvm/Support/CallSite.h"
+#include "llvm/Transforms/IPO/InlinerPass.h"
+
+using namespace llvm;
- // Make a vector to capture the return instructions in the cloned function...
- std::vector<ReturnInst*> Returns;
-
- // Do all of the hard part of cloning the callee into the caller...
- CloneFunctionInto(OrigBB->getParent(), CalledFunc, ArgVector, Returns, ".i");
-
- // Loop over all of the return instructions, turning them into unconditional
- // branches to the merge point now...
- for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
- ReturnInst *RI = Returns[i];
- BasicBlock *BB = RI->getParent();
-
- // Add a branch to the merge point where the PHI node would live...
- new BranchInst(NewBB, RI);
-
- if (PHI) { // The PHI node should include this value!
- assert(RI->getReturnValue() && "Ret should have value!");
- assert(RI->getReturnValue()->getType() == PHI->getType() &&
- "Ret value not consistent in function!");
- PHI->addIncoming(RI->getReturnValue(), BB);
- }
+namespace {
- // Delete the return instruction now
- BB->getInstList().erase(RI);
+/// \brief Actual inliner pass implementation.
+///
+/// The common implementation of the inlining logic is shared between this
+/// inliner pass and the always inliner pass. The two passes use different cost
+/// analyses to determine when to inline.
+class SimpleInliner : public Inliner {
+ InlineCostAnalysis *ICA;
+
+public:
+ SimpleInliner() : Inliner(ID), ICA(0) {
+ initializeSimpleInlinerPass(*PassRegistry::getPassRegistry());
}
- // Check to see if the PHI node only has one argument. This is a common
- // case resulting from there only being a single return instruction in the
- // function call. Because this is so common, eliminate the PHI node.
- //
- if (PHI && PHI->getNumIncomingValues() == 1) {
- PHI->replaceAllUsesWith(PHI->getIncomingValue(0));
- PHI->getParent()->getInstList().erase(PHI);
+ SimpleInliner(int Threshold)
+ : Inliner(ID, Threshold, /*InsertLifetime*/ true), ICA(0) {
+ initializeSimpleInlinerPass(*PassRegistry::getPassRegistry());
}
- // Change the branch that used to go to NewBB to branch to the first basic
- // block of the inlined function.
- //
- TerminatorInst *Br = OrigBB->getTerminator();
- assert(Br && Br->getOpcode() == Instruction::Br &&
- "splitBasicBlock broken!");
- Br->setOperand(0, ++LastBlock);
- return true;
-}
+ static char ID; // Pass identification, replacement for typeid
-static inline bool ShouldInlineFunction(const CallInst *CI, const Function *F) {
- assert(CI->getParent() && CI->getParent()->getParent() &&
- "Call not embedded into a function!");
+ InlineCost getInlineCost(CallSite CS) {
+ return ICA->getInlineCost(CS, getInlineThreshold(CS));
+ }
- // Don't inline a recursive call.
- if (CI->getParent()->getParent() == F) return false;
+ virtual bool runOnSCC(CallGraphSCC &SCC);
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const;
+};
- // Don't inline something too big. This is a really crappy heuristic
- if (F->size() > 3) return false;
+} // end anonymous namespace
- // Don't inline into something too big. This is a **really** crappy heuristic
- if (CI->getParent()->getParent()->size() > 10) return false;
+char SimpleInliner::ID = 0;
+INITIALIZE_PASS_BEGIN(SimpleInliner, "inline",
+ "Function Integration/Inlining", false, false)
+INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(InlineCostAnalysis)
+INITIALIZE_PASS_END(SimpleInliner, "inline",
+ "Function Integration/Inlining", false, false)
- // Go ahead and try just about anything else.
- return true;
-}
+Pass *llvm::createFunctionInliningPass() { return new SimpleInliner(); }
-
-static inline bool DoFunctionInlining(BasicBlock *BB) {
- for (BasicBlock::iterator I = BB->begin(); I != BB->end(); ++I) {
- if (CallInst *CI = dyn_cast<CallInst>(&*I)) {
- // Check to see if we should inline this function
- Function *F = CI->getCalledFunction();
- if (F && ShouldInlineFunction(CI, F)) {
- return InlineFunction(CI);
- }
- }
- }
- return false;
+Pass *llvm::createFunctionInliningPass(int Threshold) {
+ return new SimpleInliner(Threshold);
}
-// doFunctionInlining - Use a heuristic based approach to inline functions that
-// seem to look good.
-//
-static bool doFunctionInlining(Function &F) {
- bool Changed = false;
-
- // Loop through now and inline instructions a basic block at a time...
- for (Function::iterator I = F.begin(); I != F.end(); )
- if (DoFunctionInlining(I)) {
- ++NumInlined;
- Changed = true;
- } else {
- ++I;
- }
-
- return Changed;
+bool SimpleInliner::runOnSCC(CallGraphSCC &SCC) {
+ ICA = &getAnalysis<InlineCostAnalysis>();
+ return Inliner::runOnSCC(SCC);
}
-namespace {
- struct FunctionInlining : public FunctionPass {
- virtual bool runOnFunction(Function &F) {
- return doFunctionInlining(F);
- }
- };
- RegisterOpt<FunctionInlining> X("inline", "Function Integration/Inlining");
+void SimpleInliner::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<InlineCostAnalysis>();
+ Inliner::getAnalysisUsage(AU);
}
-
-Pass *createFunctionInliningPass() { return new FunctionInlining(); }
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