Add a cost model analysis that allows us to estimate the cost of IR-level instructions.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167324 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/CostModel.cpp b/lib/Analysis/CostModel.cpp
new file mode 100644
index 0000000..142d287
--- /dev/null
+++ b/lib/Analysis/CostModel.cpp
@@ -0,0 +1,175 @@
+//===- CostModel.cpp ------ Cost Model Analysis ---------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the cost model analysis. It provides a very basic cost
+// estimation for LLVM-IR. The cost result can be thought of as cycles, but it
+// is really unit-less. The estimated cost is ment to be used for comparing
+// alternatives.
+//
+//===----------------------------------------------------------------------===//
+
+#define CM_NAME "cost-model"
+#define DEBUG_TYPE CM_NAME
+#include "llvm/Analysis/Passes.h"
+#include "llvm/Function.h"
+#include "llvm/Instructions.h"
+#include "llvm/Pass.h"
+#include "llvm/TargetTransformInfo.h"
+#include "llvm/Value.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+
+namespace {
+ class CostModelAnalysis : public FunctionPass {
+
+ public:
+ static char ID; // Class identification, replacement for typeinfo
+ CostModelAnalysis() : FunctionPass(ID), F(0), VTTI(0) {
+ initializeCostModelAnalysisPass(
+ *PassRegistry::getPassRegistry());
+ }
+
+ /// Returns the expected cost of the instruction.
+ /// Returns -1 if the cost is unknown.
+ /// Note, this method does not cache the cost calculation and it
+ /// can be expensive in some cases.
+ unsigned getInstructionCost(Instruction *I) const;
+
+ private:
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const;
+ virtual bool runOnFunction(Function &F);
+ virtual void print(raw_ostream &OS, const Module*) const;
+
+ /// The function that we analyze.
+ Function *F;
+ /// Vector target information.
+ const VectorTargetTransformInfo *VTTI;
+ };
+} // End of anonymous namespace
+
+// Register this pass.
+char CostModelAnalysis::ID = 0;
+static const char cm_name[] = "Cost Model Analysis";
+INITIALIZE_PASS_BEGIN(CostModelAnalysis, CM_NAME, cm_name, false, true)
+INITIALIZE_PASS_END (CostModelAnalysis, CM_NAME, cm_name, false, true)
+
+FunctionPass *llvm::createCostModelAnalysisPass() {
+ return new CostModelAnalysis();
+}
+
+void
+CostModelAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesAll();
+}
+
+bool
+CostModelAnalysis::runOnFunction(Function &F) {
+ this->F = &F;
+
+ // Target information.
+ TargetTransformInfo *TTI;
+ TTI = getAnalysisIfAvailable<TargetTransformInfo>();
+ if (TTI)
+ VTTI = TTI->getVectorTargetTransformInfo();
+
+ return false;
+}
+
+unsigned CostModelAnalysis::getInstructionCost(Instruction *I) const {
+ if (!VTTI)
+ return -1;
+
+ switch (I->getOpcode()) {
+ case Instruction::Ret:
+ case Instruction::PHI:
+ case Instruction::Br: {
+ return VTTI->getCFInstrCost(I->getOpcode());
+ }
+ case Instruction::Add:
+ case Instruction::FAdd:
+ case Instruction::Sub:
+ case Instruction::FSub:
+ case Instruction::Mul:
+ case Instruction::FMul:
+ case Instruction::UDiv:
+ case Instruction::SDiv:
+ case Instruction::FDiv:
+ case Instruction::URem:
+ case Instruction::SRem:
+ case Instruction::FRem:
+ case Instruction::Shl:
+ case Instruction::LShr:
+ case Instruction::AShr:
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor: {
+ return VTTI->getArithmeticInstrCost(I->getOpcode(), I->getType());
+ }
+ case Instruction::Select: {
+ SelectInst *SI = cast<SelectInst>(I);
+ Type *CondTy = SI->getCondition()->getType();
+ return VTTI->getCmpSelInstrCost(I->getOpcode(), I->getType(), CondTy);
+ }
+ case Instruction::ICmp:
+ case Instruction::FCmp: {
+ Type *ValTy = I->getOperand(0)->getType();
+ return VTTI->getCmpSelInstrCost(I->getOpcode(), ValTy);
+ }
+ case Instruction::Store: {
+ StoreInst *SI = cast<StoreInst>(I);
+ Type *ValTy = SI->getValueOperand()->getType();
+ return VTTI->getMemoryOpCost(I->getOpcode(), ValTy,
+ SI->getAlignment(),
+ SI->getPointerAddressSpace());
+ }
+ case Instruction::Load: {
+ LoadInst *LI = cast<LoadInst>(I);
+ return VTTI->getMemoryOpCost(I->getOpcode(), I->getType(),
+ LI->getAlignment(),
+ LI->getPointerAddressSpace());
+ }
+ case Instruction::ZExt:
+ case Instruction::SExt:
+ case Instruction::FPToUI:
+ case Instruction::FPToSI:
+ case Instruction::FPExt:
+ case Instruction::PtrToInt:
+ case Instruction::IntToPtr:
+ case Instruction::SIToFP:
+ case Instruction::UIToFP:
+ case Instruction::Trunc:
+ case Instruction::FPTrunc:
+ case Instruction::BitCast: {
+ Type *SrcTy = I->getOperand(0)->getType();
+ return VTTI->getCastInstrCost(I->getOpcode(), I->getType(), SrcTy);
+ }
+ default:
+ // We don't have any information on this instruction.
+ return -1;
+ }
+}
+
+void CostModelAnalysis::print(raw_ostream &OS, const Module*) const {
+ if (!F)
+ return;
+
+ for (Function::iterator B = F->begin(), BE = F->end(); B != BE; ++B) {
+ for (BasicBlock::iterator it = B->begin(), e = B->end(); it != e; ++it) {
+ Instruction *Inst = it;
+ unsigned Cost = getInstructionCost(Inst);
+ if (Cost != (unsigned)-1)
+ OS << "Cost Model: Found an estimated cost of " << Cost;
+ else
+ OS << "Cost Model: Unknown cost";
+
+ OS << " for instruction: "<< *Inst << "\n";
+ }
+ }
+}