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Heavily refactor code:

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* Separate the policy decisions into a derived class [InlineSimple]
  * Move the inlining mechanics into a base class [Inliner]
  * Change the inliner to be an SCCPass, making it more structured and
    eventually pipelinable with other SCC passes


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8257 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2003-08-31 19:10:30 +00:00
parent fa7f524162
commit 237ef567f6
3 changed files with 198 additions and 127 deletions
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154
lib/Transforms/IPO/InlineSimple.cpp
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@ -1,77 +1,47 @@
//===- FunctionInlining.cpp - Code to perform function inlining -----------===//
//===- InlineSimple.cpp - Code to perform simple function inlining --------===//
//
// This file implements bottom-up inlining of functions into callees.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "inline"
#include "llvm/Transforms/IPO.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/iOther.h"
#include "Inliner.h"
#include "llvm/Function.h"
#include "llvm/iMemory.h"
#include "llvm/iTerminators.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "Support/CommandLine.h"
#include "Support/Debug.h"
#include "Support/Statistic.h"
#include <set>
#include "llvm/Transforms/IPO.h"
namespace {
Statistic<> NumInlined("inline", "Number of functions inlined");
Statistic<> NumDeleted("inline", "Number of functions deleted because all callers found");
cl::opt<unsigned> // FIXME: 200 is VERY conservative
InlineLimit("inline-threshold", cl::Hidden, cl::init(200),
cl::desc("Control the amount of inlining to perform (default = 200)"));
struct FunctionInlining : public Pass {
virtual bool run(Module &M) {
bool Changed = false;
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
Changed |= doInlining(I);
ProcessedFunctions.clear();
return Changed;
}
private:
std::set<Function*> ProcessedFunctions; // Prevent infinite recursion
bool doInlining(Function *F);
struct SimpleInliner : public Inliner {
int getInlineCost(CallSite CS);
};
RegisterOpt<FunctionInlining> X("inline", "Function Integration/Inlining");
RegisterOpt<SimpleInliner> X("inline", "Function Integration/Inlining");
}
Pass *createFunctionInliningPass() { return new FunctionInlining(); }
Pass *createFunctionInliningPass() { return new SimpleInliner(); }
// ShouldInlineFunction - The heuristic used to determine if we should inline
// the function call or not.
// getInlineCost - The heuristic used to determine if we should inline the
// function call or not.
//
static inline bool ShouldInlineFunction(CallSite CS) {
int SimpleInliner::getInlineCost(CallSite CS) {
Instruction *TheCall = CS.getInstruction();
assert(TheCall->getParent() && TheCall->getParent()->getParent() &&
"Call not embedded into a function!");
const Function *Callee = CS.getCalledFunction();
if (Callee == 0 || Callee->isExternal())
return false; // Cannot inline an indirect call... or external function.
// Don't inline a recursive call.
const Function *Caller = TheCall->getParent()->getParent();
if (Caller == Callee) return false;
// InlineQuality - This value measures how good of an inline candidate this
// call site is to inline. The initial value determines how aggressive the
// inliner is. If this value is negative after the final computation,
// inlining is not performed.
// Don't inline a directly recursive call.
if (Caller == Callee) return 2000000000;
// InlineCost - This value measures how good of an inline candidate this call
// site is to inline. A lower inline cost make is more likely for the call to
// be inlined. This value may go negative.
//
int InlineQuality = InlineLimit;
int InlineCost = 0;
// If there is only one call of the function, and it has internal linkage,
// make it almost guaranteed to be inlined.
//
if (Callee->use_size() == 1 && Callee->hasInternalLinkage())
InlineQuality += 30000;
InlineCost -= 30000;
// Add to the inline quality for properties that make the call valueable to
// inline. This includes factors that indicate that the result of inlining
@ -83,12 +53,12 @@ static inline bool ShouldInlineFunction(CallSite CS) {
// Each argument passed in has a cost at both the caller and the callee
// sides. This favors functions that take many arguments over functions
// that take few arguments.
InlineQuality += 20;
InlineCost -= 20;
// If this is a function being passed in, it is very likely that we will be
// able to turn an indirect function call into a direct function call.
if (isa<Function>(I))
InlineQuality += 100;
InlineCost -= 100;
// If a constant, global variable or alloca is passed in, inlining this
// function is likely to allow significant future optimization possibilities
@ -96,7 +66,7 @@ static inline bool ShouldInlineFunction(CallSite CS) {
// the inlining of the function.
//
else if (isa<Constant>(I) || isa<GlobalVariable>(I) || isa<AllocaInst>(I))
InlineQuality += 60;
InlineCost -= 60;
}
// Now that we have considered all of the factors that make the call site more
@ -106,84 +76,14 @@ static inline bool ShouldInlineFunction(CallSite CS) {
// Look at the size of the callee. Each basic block counts as 20 units, and
// each instruction counts as 10.
for (Function::const_iterator BB = Callee->begin(), E = Callee->end();
BB != E; ++BB) {
InlineQuality -= BB->size()*10 + 20;
if (InlineQuality < 0) return false;
}
BB != E; ++BB)
InlineCost += BB->size()*10 + 20;
// Don't inline into something too big, which would make it bigger. Here, we
// count each basic block as a single unit.
for (Function::const_iterator BB = Caller->begin(), E = Caller->end();
BB != E; ++BB) {
--InlineQuality;
if (InlineQuality < 0) return false;
}
BB != E; ++BB)
InlineCost++;
// If we get here, this call site is high enough "quality" to inline.
DEBUG(std::cerr << "Inlining in '" << Caller->getName()
<< "', quality = " << InlineQuality << ": " << *TheCall);
return true;
return InlineCost;
}
// doInlining - Use a heuristic based approach to inline functions that seem to
// look good.
//
bool FunctionInlining::doInlining(Function *F) {
// If we have already processed this function (ie, it is recursive) don't
// revisit.
std::set<Function*>::iterator PFI = ProcessedFunctions.lower_bound(F);
if (PFI != ProcessedFunctions.end() && *PFI == F) return false;
// Insert the function in the set so it doesn't get revisited.
ProcessedFunctions.insert(PFI, F);
bool Changed = false;
for (Function::iterator BB = F->begin(); BB != F->end(); ++BB)
for (BasicBlock::iterator I = BB->begin(); I != BB->end(); ) {
bool ShouldInc = true;
// Found a call or invoke instruction?
if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
CallSite CS = CallSite::get(I);
if (Function *Callee = CS.getCalledFunction()) {
doInlining(Callee); // Inline in callees before callers!
// Decide whether we should inline this function...
if (ShouldInlineFunction(CS)) {
// Save an iterator to the instruction before the call if it exists,
// otherwise get an iterator at the end of the block... because the
// call will be destroyed.
//
BasicBlock::iterator SI;
if (I != BB->begin()) {
SI = I; --SI; // Instruction before the call...
} else {
SI = BB->end();
}
// Attempt to inline the function...
if (InlineFunction(CS)) {
++NumInlined;
Changed = true;
// Move to instruction before the call...
I = (SI == BB->end()) ? BB->begin() : SI;
ShouldInc = false; // Don't increment iterator until next time
// If we inlined the last possible call site to the function,
// delete the function body now.
if (Callee->use_empty() &&
(Callee->hasInternalLinkage()||Callee->hasLinkOnceLinkage())){
F->getParent()->getFunctionList().erase(Callee);
++NumDeleted;
if (Callee == F) return true;
}
}
}
}
}
if (ShouldInc) ++I;
}
return Changed;
}

119
lib/Transforms/IPO/Inliner.cpp Normal file
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@ -0,0 +1,119 @@
//===- InlineCommon.cpp - Code common to all inliners ---------------------===//
//
// This file implements the code shared between the LLVM inliners. This
// implements all of the boring mechanics of the bottom-up inlining.
//
//===----------------------------------------------------------------------===//
#include "Inliner.h"
#include "llvm/Module.h"
#include "llvm/iOther.h"
#include "llvm/iTerminators.h"
#include "llvm/Analysis/CallGraph.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "Support/CommandLine.h"
#include "Support/Debug.h"
#include "Support/Statistic.h"
namespace {
Statistic<> NumInlined("inline", "Number of functions inlined");
Statistic<> NumDeleted("inline", "Number of functions deleted because all callers found");
cl::opt<unsigned> // FIXME: 200 is VERY conservative
InlineLimit("inline-threshold", cl::Hidden, cl::init(200),
cl::desc("Control the amount of inlining to perform (default = 200)"));
}
Inliner::Inliner() : InlineThreshold(InlineLimit) {}
int Inliner::getRecursiveInlineCost(CallSite CS) {
return getInlineCost(CS);
}
bool Inliner::runOnSCC(const std::vector<CallGraphNode*> &SCC) {
CallGraph &CG = getAnalysis<CallGraph>();
std::set<Function*> SCCFunctions;
DEBUG(std::cerr << "Inliner visiting SCC:");
for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
SCCFunctions.insert(SCC[i]->getFunction());
DEBUG(std::cerr << " " << (SCC[i]->getFunction() ?
SCC[i]->getFunction()->getName() : "INDIRECTNODE"));
}
DEBUG(std::cerr << "\n");
bool Changed = false;
for (std::set<Function*>::iterator SCCI = SCCFunctions.begin(),
E = SCCFunctions.end(); SCCI != E; ++SCCI) {
Function *F = *SCCI;
if (F == 0 || F->isExternal()) continue;
DEBUG(std::cerr << " Inspecting function: " << F->getName() << "\n");
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
for (BasicBlock::iterator I = BB->begin(); I != BB->end(); ) {
bool ShouldInc = true;
// Found a call or invoke instruction?
if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
CallSite CS = CallSite::get(I);
if (Function *Callee = CS.getCalledFunction())
if (!Callee->isExternal()) {
// Determine whether this is a function IN the SCC...
bool inSCC = SCCFunctions.count(Callee);
// If the policy determines that we should inline this function,
// try to do so...
int InlineCost = inSCC ? getRecursiveInlineCost(CS) :
getInlineCost(CS);
if (InlineCost < (int)InlineThreshold) {
DEBUG(std::cerr << " Inlining: cost=" << InlineCost
<< ", Call: " << *CS.getInstruction());
// Save an iterator to the instruction before the call if it
// exists, otherwise get an iterator at the end of the
// block... because the call will be destroyed.
//
BasicBlock::iterator SI;
if (I != BB->begin()) {
SI = I; --SI; // Instruction before the call...
} else {
SI = BB->end();
}
if (performInlining(CS, SCCFunctions)) {
// Move to instruction before the call...
I = (SI == BB->end()) ? BB->begin() : SI;
ShouldInc = false; // Don't increment iterator until next time
Changed = true;
}
}
}
}
if (ShouldInc) ++I;
}
}
return Changed;
}
bool Inliner::performInlining(CallSite CS, std::set<Function*> &SCC) {
Function *Callee = CS.getCalledFunction();
Function *Caller = CS.getInstruction()->getParent()->getParent();
// Attempt to inline the function...
if (!InlineFunction(CS)) return false;
++NumInlined;
// If we inlined the last possible call site to the function,
// delete the function body now.
if (Callee->use_empty() && Callee != Caller &&
(Callee->hasInternalLinkage() || Callee->hasLinkOnceLinkage())) {
DEBUG(std::cerr << " -> Deleting dead function: "
<< Callee->getName() << "\n");
std::set<Function*>::iterator I = SCC.find(Callee);
if (I != SCC.end()) // Remove function from this SCC...
SCC.erase(I);
Callee->getParent()->getFunctionList().erase(Callee);
++NumDeleted;
}
return true;
}

52
lib/Transforms/IPO/Inliner.h Normal file
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@ -0,0 +1,52 @@
//===- InlineCommon.h - Code common to all inliners -------------*- C++ -*-===//
//
// This file defines a simple policy-based bottom-up inliner. This file
// implements all of the boring mechanics of the bottom-up inlining, while the
// subclass determines WHAT to inline, which is the much more interesting
// component.
//
//===----------------------------------------------------------------------===//
#ifndef INLINER_H
#define INLINER_H
#define DEBUG_TYPE "inline"
#include "llvm/CallGraphSCCPass.h"
#include <set>
class CallSite;
/// Inliner - This class contains all of the helper code which is used to
/// perform the inlining operations that does not depend on the policy.
///
struct Inliner : public CallGraphSCCPass {
Inliner();
// Main run interface method, this implements the interface required by the
// Pass class.
virtual bool runOnSCC(const std::vector<CallGraphNode *> &SCC);
/// This method returns the value specified by the -inline-threshold value,
/// specified on the command line. This is typically not directly needed.
///
unsigned getInlineThreshold() const { return InlineThreshold; }
/// getInlineCost - This method must be implemented by the subclass to
/// determine the cost of inlining the specified call site. If the cost
/// returned is greater than the current inline threshold, the call site is
/// not inlined.
///
virtual int getInlineCost(CallSite CS) = 0;
/// getRecursiveInlineCost - This method can be implemented by subclasses if
/// it wants to treat calls to functions within the current SCC specially. If
/// this method is not overloaded, it just chains to getInlineCost().
///
virtual int getRecursiveInlineCost(CallSite CS);
private:
unsigned InlineThreshold;
bool performInlining(CallSite CS, std::set<Function*> &SCC);
};
#endif