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 #include "llvm/ADT/SmallPtrSet.h"
19 
20 namespace llvm {
21 class AssumptionCache;
22 class BasicBlock;
23 class Loop;
24 class Function;
25 class Instruction;
26 class DataLayout;
27 class TargetTransformInfo;
28 class Value;
29 
30 /// Utility to calculate the size and a few similar metrics for a set
31 /// of basic blocks.
32 struct CodeMetrics {
33   /// True if this function contains a call to setjmp or other functions
34   /// with attribute "returns twice" without having the attribute itself.
35   bool exposesReturnsTwice = false;
36 
37   /// True if this function calls itself.
38   bool isRecursive = false;
39 
40   /// True if this function cannot be duplicated.
41   ///
42   /// True if this function contains one or more indirect branches, or it contains
43   /// one or more 'noduplicate' instructions.
44   bool notDuplicatable = false;
45 
46   /// True if this function contains a call to a convergent function.
47   bool convergent = false;
48 
49   /// True if this function calls alloca (in the C sense).
50   bool usesDynamicAlloca = false;
51 
52   /// Number of instructions in the analyzed blocks.
53   unsigned NumInsts = false;
54 
55   /// Number of analyzed blocks.
56   unsigned NumBlocks = false;
57 
58   /// Keeps track of basic block code size estimates.
59   DenseMap<const BasicBlock *, unsigned> NumBBInsts;
60 
61   /// Keep track of the number of calls to 'big' functions.
62   unsigned NumCalls = false;
63 
64   /// The number of calls to internal functions with a single caller.
65   ///
66   /// These are likely targets for future inlining, likely exposed by
67   /// interleaved devirtualization.
68   unsigned NumInlineCandidates = 0;
69 
70   /// How many instructions produce vector values.
71   ///
72   /// The inliner is more aggressive with inlining vector kernels.
73   unsigned NumVectorInsts = 0;
74 
75   /// How many 'ret' instructions the blocks contain.
76   unsigned NumRets = 0;
77 
78   /// Add information about a block to the current state.
79   void analyzeBasicBlock(const BasicBlock *BB, const TargetTransformInfo &TTI,
80                          const SmallPtrSetImpl<const Value*> &EphValues);
81 
82   /// Collect a loop's ephemeral values (those used only by an assume
83   /// or similar intrinsics in the loop).
84   static void collectEphemeralValues(const Loop *L, AssumptionCache *AC,
85                                      SmallPtrSetImpl<const Value *> &EphValues);
86 
87   /// Collect a functions's ephemeral values (those used only by an
88   /// assume or similar intrinsics in the function).
89   static void collectEphemeralValues(const Function *L, AssumptionCache *AC,
90                                      SmallPtrSetImpl<const Value *> &EphValues);
91 };
92 
93 }
94 
95 #endif
96