-//===- 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.
//
//===----------------------------------------------------------------------===//
-#include "llvm/Transforms/IPO.h"
-#include "llvm/Transforms/Utils/Cloning.h"
+#define DEBUG_TYPE "inline"
+#include "llvm/CallingConv.h"
+#include "llvm/Instructions.h"
+#include "llvm/IntrinsicInst.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;
+#include "llvm/Analysis/CallGraph.h"
+#include "llvm/Support/CallSite.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Transforms/IPO.h"
+#include "llvm/Transforms/IPO/InlinerPass.h"
+#include "llvm/Transforms/Utils/InlineCost.h"
+#include "llvm/ADT/SmallPtrSet.h"
-// RemapInstruction - Convert the instruction operands from referencing the
-// current values into those specified by ValueMap.
-//
-static inline void RemapInstruction(Instruction *I,
- std::map<const Value *, Value*> &ValueMap) {
+using namespace llvm;
- for (unsigned op = 0, E = I->getNumOperands(); op != E; ++op) {
- const Value *Op = I->getOperand(op);
- Value *V = ValueMap[Op];
- if (!V && (isa<GlobalValue>(Op) || isa<Constant>(Op)))
- continue; // Globals and constants don't get relocated
+namespace {
- if (!V) {
- cerr << "Val = \n" << Op << "Addr = " << (void*)Op;
- cerr << "\nInst = " << I;
+ class VISIBILITY_HIDDEN SimpleInliner : public Inliner {
+ // Functions that are never inlined
+ SmallPtrSet<const Function*, 16> NeverInline;
+ InlineCostAnalyzer CA;
+ public:
+ SimpleInliner() : Inliner(&ID) {}
+ static char ID; // Pass identification, replacement for typeid
+ int getInlineCost(CallSite CS) {
+ return CA.getInlineCost(CS, NeverInline);
}
- assert(V && "Referenced value not in value map!");
- I->setOperand(op, V);
- }
+ virtual bool doInitialization(CallGraph &CG);
+ };
+ char SimpleInliner::ID = 0;
+ RegisterPass<SimpleInliner> X("inline", "Function Integration/Inlining");
}
-// 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();
+Pass *llvm::createFunctionInliningPass() { return new SimpleInliner(); }
- // 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 (CalledFunc->getReturnType() != Type::VoidTy) {
- // 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);
- }
-
- // Keep a mapping between the original function's values and the new
- // duplicated code's values. This includes all of: Function arguments,
- // instruction values, constant pool entries, and basic blocks.
- //
- std::map<const Value *, Value*> ValueMap;
-
- // Add the function arguments to the mapping: (start counting at 1 to skip the
- // function reference itself)
- //
- Function::const_aiterator PTI = CalledFunc->abegin();
- for (unsigned a = 1, E = CI->getNumOperands(); a != E; ++a, ++PTI)
- ValueMap[PTI] = CI->getOperand(a);
+// doInitialization - Initializes the vector of functions that have been
+// annotated with the noinline attribute.
+bool SimpleInliner::doInitialization(CallGraph &CG) {
+
+ Module &M = CG.getModule();
+
+ // Get llvm.noinline
+ GlobalVariable *GV = M.getNamedGlobal("llvm.noinline");
- ValueMap[NewBB] = NewBB; // Returns get converted to reference NewBB
+ if (GV == 0)
+ return false;
- // Loop over all of the basic blocks in the function, inlining them as
- // appropriate. Keep track of the first basic block of the function...
- //
- for (Function::const_iterator BB = CalledFunc->begin();
- BB != CalledFunc->end(); ++BB) {
- assert(BB->getTerminator() && "BasicBlock doesn't have terminator!?!?");
+ // Don't crash on invalid code
+ if (!GV->hasInitializer())
+ return false;
+
+ const ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
+
+ if (InitList == 0)
+ return false;
+
+ // Iterate over each element and add to the NeverInline set
+ for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
+
+ // Get Source
+ const Constant *Elt = InitList->getOperand(i);
+
+ if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(Elt))
+ if (CE->getOpcode() == Instruction::BitCast)
+ Elt = CE->getOperand(0);
- // Create a new basic block to copy instructions into!
- BasicBlock *IBB = new BasicBlock("", NewBB->getParent());
- if (BB->hasName()) IBB->setName(BB->getName()+".i"); // .i = inlined once
-
- ValueMap[BB] = IBB; // Add basic block mapping.
-
- // Make sure to capture the mapping that a return will use...
- // TODO: This assumes that the RET is returning a value computed in the same
- // basic block as the return was issued from!
- //
- const TerminatorInst *TI = BB->getTerminator();
-
- // Loop over all instructions copying them over...
- Instruction *NewInst;
- for (BasicBlock::const_iterator II = BB->begin();
- II != --BB->end(); ++II) {
- IBB->getInstList().push_back((NewInst = II->clone()));
- ValueMap[II] = NewInst; // Add instruction map to value.
- if (II->hasName())
- NewInst->setName(II->getName()+".i"); // .i = inlined once
- }
-
- // Copy over the terminator now...
- switch (TI->getOpcode()) {
- case Instruction::Ret: {
- const ReturnInst *RI = cast<ReturnInst>(TI);
-
- 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((Value*)RI->getReturnValue(),
- (BasicBlock*)cast<BasicBlock>(&*BB));
- }
-
- // Add a branch to the code that was after the original Call.
- IBB->getInstList().push_back(new BranchInst(NewBB));
- break;
- }
- case Instruction::Br:
- IBB->getInstList().push_back(TI->clone());
- break;
-
- default:
- cerr << "FunctionInlining: Don't know how to handle terminator: " << TI;
- abort();
- }
- }
-
-
- // Loop over all of the instructions in the function, fixing up operand
- // references as we go. This uses ValueMap to do all the hard work.
- //
- for (Function::const_iterator BB = CalledFunc->begin();
- BB != CalledFunc->end(); ++BB) {
- BasicBlock *NBB = (BasicBlock*)ValueMap[BB];
-
- // Loop over all instructions, fixing each one as we find it...
- //
- for (BasicBlock::iterator II = NBB->begin(); II != NBB->end(); ++II)
- RemapInstruction(II, ValueMap);
- }
-
- if (PHI) {
- RemapInstruction(PHI, ValueMap); // Fix the PHI node also...
-
- // 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->getNumIncomingValues() == 1) {
- PHI->replaceAllUsesWith(PHI->getIncomingValue(0));
- PHI->getParent()->getInstList().erase(PHI);
- }
- }
-
- // 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, ValueMap[&CalledFunc->front()]);
-
- // Since we are now done with the CallInst, we can finally delete it.
- delete CI;
- return true;
-}
-
-static inline bool ShouldInlineFunction(const CallInst *CI, const Function *F) {
- assert(CI->getParent() && CI->getParent()->getParent() &&
- "Call not embedded into a function!");
-
- // Don't inline a recursive call.
- if (CI->getParent()->getParent() == F) return false;
-
- // Don't inline something too big. This is a really crappy heuristic
- if (F->size() > 3) return false;
-
- // Don't inline into something too big. This is a **really** crappy heuristic
- if (CI->getParent()->getParent()->size() > 10) return false;
-
- // Go ahead and try just about anything else.
- return true;
-}
-
-
-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);
- }
- }
+ // Insert into set of functions to never inline
+ if (const Function *F = dyn_cast<Function>(Elt))
+ NeverInline.insert(F);
}
+
return false;
}
-// 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;
-}
-
-namespace {
- struct FunctionInlining : public FunctionPass {
- virtual bool runOnFunction(Function &F) {
- return doFunctionInlining(F);
- }
- };
- RegisterOpt<FunctionInlining> X("inline", "Function Integration/Inlining");
-}
-
-Pass *createFunctionInliningPass() { return new FunctionInlining(); }
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