//===----------------------------------------------------------------------===//
#include "Inliner.h"
+#include "llvm/Instructions.h"
#include "llvm/Function.h"
-#include "llvm/iMemory.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Transforms/IPO.h"
-
-namespace llvm {
+using namespace llvm;
namespace {
// FunctionInfo - For each function, calculate the size of it in blocks and
// instructions.
struct FunctionInfo {
+ // NumInsts, NumBlocks - Keep track of how large each function is, which is
+ // used to estimate the code size cost of inlining it.
unsigned NumInsts, NumBlocks;
+ // ConstantArgumentWeights - Each formal argument of the function is
+ // inspected to see if it is used in any contexts where making it a constant
+ // would reduce the code size. If so, we add some value to the argument
+ // entry here.
+ std::vector<unsigned> ConstantArgumentWeights;
+
FunctionInfo() : NumInsts(0), NumBlocks(0) {}
};
RegisterOpt<SimpleInliner> X("inline", "Function Integration/Inlining");
}
-Pass *createFunctionInliningPass() { return new SimpleInliner(); }
+Pass *llvm::createFunctionInliningPass() { return new SimpleInliner(); }
+
+// CountCodeReductionForConstant - Figure out an approximation for how many
+// instructions will be constant folded if the specified value is constant.
+//
+static unsigned CountCodeReductionForConstant(Value *V) {
+ unsigned Reduction = 0;
+ for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI)
+ if (isa<BranchInst>(*UI))
+ Reduction += 40; // Eliminating a conditional branch is a big win
+ else if (SwitchInst *SI = dyn_cast<SwitchInst>(*UI))
+ // Eliminating a switch is a big win, proportional to the number of edges
+ // deleted.
+ Reduction += (SI->getNumSuccessors()-1) * 40;
+ else if (CallInst *CI = dyn_cast<CallInst>(*UI)) {
+ // Turning an indirect call into a direct call is a BIG win
+ Reduction += CI->getCalledValue() == V ? 500 : 0;
+ } else if (InvokeInst *II = dyn_cast<InvokeInst>(*UI)) {
+ // Turning an indirect call into a direct call is a BIG win
+ Reduction += CI->getCalledValue() == V ? 500 : 0;
+ } else {
+ // Figure out if this instruction will be removed due to simple constant
+ // propagation.
+ Instruction &Inst = cast<Instruction>(**UI);
+ bool AllOperandsConstant = true;
+ for (unsigned i = 0, e = Inst.getNumOperands(); i != e; ++i)
+ if (!isa<Constant>(Inst.getOperand(i)) &&
+ !isa<GlobalValue>(Inst.getOperand(i)) && Inst.getOperand(i) != V) {
+ AllOperandsConstant = false;
+ break;
+ }
+
+ if (AllOperandsConstant) {
+ // We will get to remove this instruction...
+ Reduction += 7;
+
+ // And any other instructions that use it which become constants
+ // themselves.
+ Reduction += CountCodeReductionForConstant(&Inst);
+ }
+ }
+
+ return Reduction;
+}
// getInlineCost - The heuristic used to determine if we should inline the
// function call or not.
//
int SimpleInliner::getInlineCost(CallSite CS) {
Instruction *TheCall = CS.getInstruction();
- const Function *Callee = CS.getCalledFunction();
+ Function *Callee = CS.getCalledFunction();
const Function *Caller = TheCall->getParent()->getParent();
// Don't inline a directly recursive call.
if (Callee->hasInternalLinkage() && Callee->hasOneUse())
InlineCost -= 30000;
+ // Get information about the callee...
+ FunctionInfo &CalleeFI = CachedFunctionInfo[Callee];
+
+ // If we haven't calculated this information yet...
+ if (CalleeFI.NumBlocks == 0) {
+ unsigned NumInsts = 0, NumBlocks = 0;
+
+ // 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) {
+ NumInsts += BB->size();
+ NumBlocks++;
+ }
+
+ CalleeFI.NumBlocks = NumBlocks;
+ CalleeFI.NumInsts = NumInsts;
+
+ // Check out all of the arguments to the function, figuring out how much
+ // code can be eliminated if one of the arguments is a constant.
+ std::vector<unsigned> &ArgWeights = CalleeFI.ConstantArgumentWeights;
+
+ for (Function::aiterator I = Callee->abegin(), E = Callee->aend();
+ I != E; ++I)
+ ArgWeights.push_back(CountCodeReductionForConstant(I));
+ }
+
+
// Add to the inline quality for properties that make the call valuable to
// inline. This includes factors that indicate that the result of inlining
// the function will be optimizable. Currently this just looks at arguments
// passed into the function.
//
+ unsigned ArgNo = 0;
for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
- I != E; ++I) {
+ I != E; ++I, ++ArgNo) {
// 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.
if (isa<Function>(I))
InlineCost -= 100;
- // If a constant, global variable or alloca is passed in, inlining this
- // function is likely to allow significant future optimization possibilities
- // (constant propagation, scalar promotion, and scalarization), so encourage
- // the inlining of the function.
+ // If an alloca is passed in, inlining this function is likely to allow
+ // significant future optimization possibilities (like scalar promotion, and
+ // scalarization), so encourage the inlining of the function.
//
- else if (isa<Constant>(I) || isa<GlobalVariable>(I) || isa<AllocaInst>(I))
+ else if (isa<AllocaInst>(I))
InlineCost -= 60;
+
+ // If this is a constant being passed into the function, use the argument
+ // weights calculated for the callee to determine how much will be folded
+ // away with this information.
+ else if (isa<Constant>(I) || isa<GlobalVariable>(I)) {
+ if (ArgNo < CalleeFI.ConstantArgumentWeights.size())
+ InlineCost -= CalleeFI.ConstantArgumentWeights[ArgNo];
+ }
}
// Now that we have considered all of the factors that make the call site more
// likely to be inlined, look at factors that make us not want to inline it.
- FunctionInfo &CalleeFI = CachedFunctionInfo[Callee];
-
- // If we haven't calculated this information yet...
- if (CalleeFI.NumBlocks == 0) {
- unsigned NumInsts = 0, NumBlocks = 0;
-
- // 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) {
- NumInsts += BB->size();
- NumBlocks++;
- }
- CalleeFI.NumBlocks = NumBlocks;
- CalleeFI.NumInsts = NumInsts;
- }
// Don't inline into something too big, which would make it bigger. Here, we
// count each basic block as a single unit.
// Look at the size of the callee. Each basic block counts as 20 units, and
- // each instruction counts as 10.
- InlineCost += CalleeFI.NumInsts*10 + CalleeFI.NumBlocks*20;
+ // each instruction counts as 5.
+ InlineCost += CalleeFI.NumInsts*5 + CalleeFI.NumBlocks*20;
return InlineCost;
}
-} // End llvm namespace
projects / oota-llvm.git / commitdiff