mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2025-11-04 05:17:07 +00:00
f5ff1d335b
and it wasn't generating calls through @PLT for these functions. hasLocalLinkage() is now false for available_externally, I attempted to fix the inliner and dce to handle available_externally properly. It passed make check. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72328 91177308-0d34-0410-b5e6-96231b3b80d8
316 lines
12 KiB
C++
316 lines
12 KiB
C++
//===- InlineCost.cpp - Cost analysis for inliner -------------------------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file implements inline cost analysis.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
|
|
#include "llvm/Transforms/Utils/InlineCost.h"
|
|
#include "llvm/Support/CallSite.h"
|
|
#include "llvm/CallingConv.h"
|
|
#include "llvm/IntrinsicInst.h"
|
|
|
|
using namespace llvm;
|
|
|
|
// CountCodeReductionForConstant - Figure out an approximation for how many
|
|
// instructions will be constant folded if the specified value is constant.
|
|
//
|
|
unsigned InlineCostAnalyzer::FunctionInfo::
|
|
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 += II->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)) && 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;
|
|
}
|
|
|
|
// CountCodeReductionForAlloca - Figure out an approximation of how much smaller
|
|
// the function will be if it is inlined into a context where an argument
|
|
// becomes an alloca.
|
|
//
|
|
unsigned InlineCostAnalyzer::FunctionInfo::
|
|
CountCodeReductionForAlloca(Value *V) {
|
|
if (!isa<PointerType>(V->getType())) return 0; // Not a pointer
|
|
unsigned Reduction = 0;
|
|
for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
|
|
Instruction *I = cast<Instruction>(*UI);
|
|
if (isa<LoadInst>(I) || isa<StoreInst>(I))
|
|
Reduction += 10;
|
|
else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(I)) {
|
|
// If the GEP has variable indices, we won't be able to do much with it.
|
|
if (!GEP->hasAllConstantIndices())
|
|
Reduction += CountCodeReductionForAlloca(GEP)+15;
|
|
} else {
|
|
// If there is some other strange instruction, we're not going to be able
|
|
// to do much if we inline this.
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
return Reduction;
|
|
}
|
|
|
|
/// analyzeFunction - Fill in the current structure with information gleaned
|
|
/// from the specified function.
|
|
void InlineCostAnalyzer::FunctionInfo::analyzeFunction(Function *F) {
|
|
unsigned NumInsts = 0, NumBlocks = 0, NumVectorInsts = 0;
|
|
|
|
// Look at the size of the callee. Each basic block counts as 20 units, and
|
|
// each instruction counts as 5.
|
|
for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
|
|
for (BasicBlock::const_iterator II = BB->begin(), E = BB->end();
|
|
II != E; ++II) {
|
|
if (isa<PHINode>(II)) continue; // PHI nodes don't count.
|
|
|
|
// Special handling for calls.
|
|
if (isa<CallInst>(II) || isa<InvokeInst>(II)) {
|
|
if (isa<DbgInfoIntrinsic>(II))
|
|
continue; // Debug intrinsics don't count as size.
|
|
|
|
CallSite CS = CallSite::get(const_cast<Instruction*>(&*II));
|
|
|
|
// If this function contains a call to setjmp or _setjmp, never inline
|
|
// it. This is a hack because we depend on the user marking their local
|
|
// variables as volatile if they are live across a setjmp call, and they
|
|
// probably won't do this in callers.
|
|
if (Function *F = CS.getCalledFunction())
|
|
if (F->isDeclaration() &&
|
|
(F->isName("setjmp") || F->isName("_setjmp"))) {
|
|
NeverInline = true;
|
|
return;
|
|
}
|
|
|
|
// Calls often compile into many machine instructions. Bump up their
|
|
// cost to reflect this.
|
|
if (!isa<IntrinsicInst>(II))
|
|
NumInsts += 5;
|
|
}
|
|
|
|
if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
|
|
if (!AI->isStaticAlloca())
|
|
this->usesDynamicAlloca = true;
|
|
}
|
|
|
|
if (isa<ExtractElementInst>(II) || isa<VectorType>(II->getType()))
|
|
++NumVectorInsts;
|
|
|
|
// Noop casts, including ptr <-> int, don't count.
|
|
if (const CastInst *CI = dyn_cast<CastInst>(II)) {
|
|
if (CI->isLosslessCast() || isa<IntToPtrInst>(CI) ||
|
|
isa<PtrToIntInst>(CI))
|
|
continue;
|
|
} else if (const GetElementPtrInst *GEPI =
|
|
dyn_cast<GetElementPtrInst>(II)) {
|
|
// If a GEP has all constant indices, it will probably be folded with
|
|
// a load/store.
|
|
if (GEPI->hasAllConstantIndices())
|
|
continue;
|
|
}
|
|
|
|
++NumInsts;
|
|
}
|
|
|
|
++NumBlocks;
|
|
}
|
|
|
|
this->NumBlocks = NumBlocks;
|
|
this->NumInsts = NumInsts;
|
|
this->NumVectorInsts = NumVectorInsts;
|
|
|
|
// 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.
|
|
for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E; ++I)
|
|
ArgumentWeights.push_back(ArgInfo(CountCodeReductionForConstant(I),
|
|
CountCodeReductionForAlloca(I)));
|
|
}
|
|
|
|
|
|
|
|
// getInlineCost - The heuristic used to determine if we should inline the
|
|
// function call or not.
|
|
//
|
|
InlineCost InlineCostAnalyzer::getInlineCost(CallSite CS,
|
|
SmallPtrSet<const Function *, 16> &NeverInline) {
|
|
Instruction *TheCall = CS.getInstruction();
|
|
Function *Callee = CS.getCalledFunction();
|
|
Function *Caller = TheCall->getParent()->getParent();
|
|
|
|
// Don't inline functions which can be redefined at link-time to mean
|
|
// something else.
|
|
if (Callee->mayBeOverridden() ||
|
|
// Don't inline functions marked noinline.
|
|
Callee->hasFnAttr(Attribute::NoInline) || NeverInline.count(Callee))
|
|
return llvm::InlineCost::getNever();
|
|
|
|
// 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 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->hasLocalLinkage() || Callee->hasAvailableExternallyLinkage()) &&
|
|
Callee->hasOneUse())
|
|
InlineCost -= 15000;
|
|
|
|
// If this function uses the coldcc calling convention, prefer not to inline
|
|
// it.
|
|
if (Callee->getCallingConv() == CallingConv::Cold)
|
|
InlineCost += 2000;
|
|
|
|
// If the instruction after the call, or if the normal destination of the
|
|
// invoke is an unreachable instruction, the function is noreturn. As such,
|
|
// there is little point in inlining this.
|
|
if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) {
|
|
if (isa<UnreachableInst>(II->getNormalDest()->begin()))
|
|
InlineCost += 10000;
|
|
} else if (isa<UnreachableInst>(++BasicBlock::iterator(TheCall)))
|
|
InlineCost += 10000;
|
|
|
|
// Get information about the callee...
|
|
FunctionInfo &CalleeFI = CachedFunctionInfo[Callee];
|
|
|
|
// If we haven't calculated this information yet, do so now.
|
|
if (CalleeFI.NumBlocks == 0)
|
|
CalleeFI.analyzeFunction(Callee);
|
|
|
|
// If we should never inline this, return a huge cost.
|
|
if (CalleeFI.NeverInline)
|
|
return InlineCost::getNever();
|
|
|
|
// FIXME: It would be nice to kill off CalleeFI.NeverInline. Then we
|
|
// could move this up and avoid computing the FunctionInfo for
|
|
// things we are going to just return always inline for. This
|
|
// requires handling setjmp somewhere else, however.
|
|
if (!Callee->isDeclaration() && Callee->hasFnAttr(Attribute::AlwaysInline))
|
|
return InlineCost::getAlways();
|
|
|
|
if (CalleeFI.usesDynamicAlloca) {
|
|
// Get infomation about the caller...
|
|
FunctionInfo &CallerFI = CachedFunctionInfo[Caller];
|
|
|
|
// If we haven't calculated this information yet, do so now.
|
|
if (CallerFI.NumBlocks == 0)
|
|
CallerFI.analyzeFunction(Caller);
|
|
|
|
// Don't inline a callee with dynamic alloca into a caller without them.
|
|
// Functions containing dynamic alloca's are inefficient in various ways;
|
|
// don't create more inefficiency.
|
|
if (!CallerFI.usesDynamicAlloca)
|
|
return InlineCost::getNever();
|
|
}
|
|
|
|
// 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, ++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.
|
|
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))
|
|
InlineCost -= 100;
|
|
|
|
// 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<AllocaInst>(I)) {
|
|
if (ArgNo < CalleeFI.ArgumentWeights.size())
|
|
InlineCost -= CalleeFI.ArgumentWeights[ArgNo].AllocaWeight;
|
|
|
|
// 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)) {
|
|
if (ArgNo < CalleeFI.ArgumentWeights.size())
|
|
InlineCost -= CalleeFI.ArgumentWeights[ArgNo].ConstantWeight;
|
|
}
|
|
}
|
|
|
|
// 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.
|
|
|
|
// Don't inline into something too big, which would make it bigger.
|
|
//
|
|
InlineCost += Caller->size()/15;
|
|
|
|
// Look at the size of the callee. Each instruction counts as 5.
|
|
InlineCost += CalleeFI.NumInsts*5;
|
|
|
|
return llvm::InlineCost::get(InlineCost);
|
|
}
|
|
|
|
// getInlineFudgeFactor - Return a > 1.0 factor if the inliner should use a
|
|
// higher threshold to determine if the function call should be inlined.
|
|
float InlineCostAnalyzer::getInlineFudgeFactor(CallSite CS) {
|
|
Function *Callee = CS.getCalledFunction();
|
|
|
|
// Get information about the callee...
|
|
FunctionInfo &CalleeFI = CachedFunctionInfo[Callee];
|
|
|
|
// If we haven't calculated this information yet, do so now.
|
|
if (CalleeFI.NumBlocks == 0)
|
|
CalleeFI.analyzeFunction(Callee);
|
|
|
|
float Factor = 1.0f;
|
|
// Single BB functions are often written to be inlined.
|
|
if (CalleeFI.NumBlocks == 1)
|
|
Factor += 0.5f;
|
|
|
|
// Be more aggressive if the function contains a good chunk (if it mades up
|
|
// at least 10% of the instructions) of vector instructions.
|
|
if (CalleeFI.NumVectorInsts > CalleeFI.NumInsts/2)
|
|
Factor += 2.0f;
|
|
else if (CalleeFI.NumVectorInsts > CalleeFI.NumInsts/10)
|
|
Factor += 1.5f;
|
|
return Factor;
|
|
}
|