/Users/buildslave/jenkins/workspace/clang-stage2-coverage-R/llvm/lib/Analysis/CostModel.cpp
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1 | | //===- CostModel.cpp ------ Cost Model Analysis ---------------------------===// |
2 | | // |
3 | | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
4 | | // See https://llvm.org/LICENSE.txt for license information. |
5 | | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
6 | | // |
7 | | //===----------------------------------------------------------------------===// |
8 | | // |
9 | | // This file defines the cost model analysis. It provides a very basic cost |
10 | | // estimation for LLVM-IR. This analysis uses the services of the codegen |
11 | | // to approximate the cost of any IR instruction when lowered to machine |
12 | | // instructions. The cost results are unit-less and the cost number represents |
13 | | // the throughput of the machine assuming that all loads hit the cache, all |
14 | | // branches are predicted, etc. The cost numbers can be added in order to |
15 | | // compare two or more transformation alternatives. |
16 | | // |
17 | | //===----------------------------------------------------------------------===// |
18 | | |
19 | | #include "llvm/ADT/STLExtras.h" |
20 | | #include "llvm/Analysis/Passes.h" |
21 | | #include "llvm/Analysis/TargetTransformInfo.h" |
22 | | #include "llvm/IR/Function.h" |
23 | | #include "llvm/Pass.h" |
24 | | #include "llvm/Support/CommandLine.h" |
25 | | #include "llvm/Support/Debug.h" |
26 | | #include "llvm/Support/raw_ostream.h" |
27 | | using namespace llvm; |
28 | | |
29 | | static cl::opt<TargetTransformInfo::TargetCostKind> CostKind( |
30 | | "cost-kind", cl::desc("Target cost kind"), |
31 | | cl::init(TargetTransformInfo::TCK_RecipThroughput), |
32 | | cl::values(clEnumValN(TargetTransformInfo::TCK_RecipThroughput, |
33 | | "throughput", "Reciprocal throughput"), |
34 | | clEnumValN(TargetTransformInfo::TCK_Latency, |
35 | | "latency", "Instruction latency"), |
36 | | clEnumValN(TargetTransformInfo::TCK_CodeSize, |
37 | | "code-size", "Code size"))); |
38 | | |
39 | | #define CM_NAME "cost-model" |
40 | | #define DEBUG_TYPE CM_NAME |
41 | | |
42 | | namespace { |
43 | | class CostModelAnalysis : public FunctionPass { |
44 | | |
45 | | public: |
46 | | static char ID; // Class identification, replacement for typeinfo |
47 | 760 | CostModelAnalysis() : FunctionPass(ID), F(nullptr), TTI(nullptr) { |
48 | 760 | initializeCostModelAnalysisPass( |
49 | 760 | *PassRegistry::getPassRegistry()); |
50 | 760 | } |
51 | | |
52 | | /// Returns the expected cost of the instruction. |
53 | | /// Returns -1 if the cost is unknown. |
54 | | /// Note, this method does not cache the cost calculation and it |
55 | | /// can be expensive in some cases. |
56 | 0 | unsigned getInstructionCost(const Instruction *I) const { |
57 | 0 | return TTI->getInstructionCost(I, TargetTransformInfo::TCK_RecipThroughput); |
58 | 0 | } |
59 | | |
60 | | private: |
61 | | void getAnalysisUsage(AnalysisUsage &AU) const override; |
62 | | bool runOnFunction(Function &F) override; |
63 | | void print(raw_ostream &OS, const Module*) const override; |
64 | | |
65 | | /// The function that we analyze. |
66 | | Function *F; |
67 | | /// Target information. |
68 | | const TargetTransformInfo *TTI; |
69 | | }; |
70 | | } // End of anonymous namespace |
71 | | |
72 | | // Register this pass. |
73 | | char CostModelAnalysis::ID = 0; |
74 | | static const char cm_name[] = "Cost Model Analysis"; |
75 | 11.0k | INITIALIZE_PASS_BEGIN(CostModelAnalysis, CM_NAME, cm_name, false, true) |
76 | 11.0k | INITIALIZE_PASS_END (CostModelAnalysis, CM_NAME, cm_name, false, true) |
77 | | |
78 | 0 | FunctionPass *llvm::createCostModelAnalysisPass() { |
79 | 0 | return new CostModelAnalysis(); |
80 | 0 | } |
81 | | |
82 | | void |
83 | 760 | CostModelAnalysis::getAnalysisUsage(AnalysisUsage &AU) const { |
84 | 760 | AU.setPreservesAll(); |
85 | 760 | } |
86 | | |
87 | | bool |
88 | 9.93k | CostModelAnalysis::runOnFunction(Function &F) { |
89 | 9.93k | this->F = &F; |
90 | 9.93k | auto *TTIWP = getAnalysisIfAvailable<TargetTransformInfoWrapperPass>(); |
91 | 9.93k | TTI = TTIWP ? &TTIWP->getTTI(F) : nullptr0 ; |
92 | 9.93k | |
93 | 9.93k | return false; |
94 | 9.93k | } |
95 | | |
96 | 9.93k | void CostModelAnalysis::print(raw_ostream &OS, const Module*) const { |
97 | 9.93k | if (!F) |
98 | 0 | return; |
99 | 9.93k | |
100 | 9.95k | for (BasicBlock &B : *F)9.93k { |
101 | 53.0k | for (Instruction &Inst : B) { |
102 | 53.0k | unsigned Cost = TTI->getInstructionCost(&Inst, CostKind); |
103 | 53.0k | if (Cost != (unsigned)-1) |
104 | 52.9k | OS << "Cost Model: Found an estimated cost of " << Cost; |
105 | 67 | else |
106 | 67 | OS << "Cost Model: Unknown cost"; |
107 | 53.0k | |
108 | 53.0k | OS << " for instruction: " << Inst << "\n"; |
109 | 53.0k | } |
110 | 9.95k | } |
111 | 9.93k | } |