1 //===- CodeMetrics.h - Code cost measurements -------------------*- C++ -*-===//
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 implements various weight measurements for code, helping
10 // the Inliner and other passes decide whether to duplicate its contents.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_ANALYSIS_CODEMETRICS_H
15 #define LLVM_ANALYSIS_CODEMETRICS_H
16 
17 #include "llvm/ADT/DenseMap.h"
18 
19 namespace llvm {
20 class AssumptionCache;
21 class BasicBlock;
22 class Loop;
23 class Function;
24 template <class T> class SmallPtrSetImpl;
25 class TargetTransformInfo;
26 class Value;
27 
28 /// Utility to calculate the size and a few similar metrics for a set
29 /// of basic blocks.
30 struct CodeMetrics {
31   /// True if this function contains a call to setjmp or other functions
32   /// with attribute "returns twice" without having the attribute itself.
33   bool exposesReturnsTwice = false;
34 
35   /// True if this function calls itself.
36   bool isRecursive = false;
37 
38   /// True if this function cannot be duplicated.
39   ///
40   /// True if this function contains one or more indirect branches, or it contains
41   /// one or more 'noduplicate' instructions.
42   bool notDuplicatable = false;
43 
44   /// True if this function contains a call to a convergent function.
45   bool convergent = false;
46 
47   /// True if this function calls alloca (in the C sense).
48   bool usesDynamicAlloca = false;
49 
50   /// Number of instructions in the analyzed blocks.
51   unsigned NumInsts = false;
52 
53   /// Number of analyzed blocks.
54   unsigned NumBlocks = false;
55 
56   /// Keeps track of basic block code size estimates.
57   DenseMap<const BasicBlock *, unsigned> NumBBInsts;
58 
59   /// Keep track of the number of calls to 'big' functions.
60   unsigned NumCalls = false;
61 
62   /// The number of calls to internal functions with a single caller.
63   ///
64   /// These are likely targets for future inlining, likely exposed by
65   /// interleaved devirtualization.
66   unsigned NumInlineCandidates = 0;
67 
68   /// How many instructions produce vector values.
69   ///
70   /// The inliner is more aggressive with inlining vector kernels.
71   unsigned NumVectorInsts = 0;
72 
73   /// How many 'ret' instructions the blocks contain.
74   unsigned NumRets = 0;
75 
76   /// Add information about a block to the current state.
77   void analyzeBasicBlock(const BasicBlock *BB, const TargetTransformInfo &TTI,
78                          const SmallPtrSetImpl<const Value *> &EphValues,
79                          bool PrepareForLTO = false);
80 
81   /// Collect a loop's ephemeral values (those used only by an assume
82   /// or similar intrinsics in the loop).
83   static void collectEphemeralValues(const Loop *L, AssumptionCache *AC,
84                                      SmallPtrSetImpl<const Value *> &EphValues);
85 
86   /// Collect a functions's ephemeral values (those used only by an
87   /// assume or similar intrinsics in the function).
88   static void collectEphemeralValues(const Function *L, AssumptionCache *AC,
89                                      SmallPtrSetImpl<const Value *> &EphValues);
90 };
91 
92 }
93 
94 #endif
95