1 //===- llvm/Transforms/Utils/VectorUtils.h - Vector utilities -*- C++ -*-=====//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file defines some vectorizer utilities.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_TRANSFORMS_UTILS_VECTORUTILS_H
15 #define LLVM_TRANSFORMS_UTILS_VECTORUTILS_H
16 
17 #include "llvm/ADT/ArrayRef.h"
18 #include "llvm/ADT/MapVector.h"
19 #include "llvm/Analysis/TargetLibraryInfo.h"
20 #include "llvm/IR/IntrinsicInst.h"
21 #include "llvm/IR/Intrinsics.h"
22 
23 namespace llvm {
24 
25 struct DemandedBits;
26 class GetElementPtrInst;
27 class Loop;
28 class ScalarEvolution;
29 class TargetTransformInfo;
30 class Type;
31 class Value;
32 
33 /// \brief Identify if the intrinsic is trivially vectorizable.
34 /// This method returns true if the intrinsic's argument types are all
35 /// scalars for the scalar form of the intrinsic and all vectors for
36 /// the vector form of the intrinsic.
37 bool isTriviallyVectorizable(Intrinsic::ID ID);
38 
39 /// \brief Identifies if the intrinsic has a scalar operand. It checks for
40 /// ctlz,cttz and powi special intrinsics whose argument is scalar.
41 bool hasVectorInstrinsicScalarOpd(Intrinsic::ID ID, unsigned ScalarOpdIdx);
42 
43 /// \brief Identify if call has a unary float signature
44 /// It returns input intrinsic ID if call has a single argument,
45 /// argument type and call instruction type should be floating
46 /// point type and call should only reads memory.
47 /// else return not_intrinsic.
48 Intrinsic::ID checkUnaryFloatSignature(const CallInst &I,
49                                        Intrinsic::ID ValidIntrinsicID);
50 
51 /// \brief Identify if call has a binary float signature
52 /// It returns input intrinsic ID if call has two arguments,
53 /// arguments type and call instruction type should be floating
54 /// point type and call should only reads memory.
55 /// else return not_intrinsic.
56 Intrinsic::ID checkBinaryFloatSignature(const CallInst &I,
57                                         Intrinsic::ID ValidIntrinsicID);
58 
59 /// \brief Returns intrinsic ID for call.
60 /// For the input call instruction it finds mapping intrinsic and returns
61 /// its intrinsic ID, in case it does not found it return not_intrinsic.
62 Intrinsic::ID getIntrinsicIDForCall(CallInst *CI, const TargetLibraryInfo *TLI);
63 
64 /// \brief Find the operand of the GEP that should be checked for consecutive
65 /// stores. This ignores trailing indices that have no effect on the final
66 /// pointer.
67 unsigned getGEPInductionOperand(const GetElementPtrInst *Gep);
68 
69 /// \brief If the argument is a GEP, then returns the operand identified by
70 /// getGEPInductionOperand. However, if there is some other non-loop-invariant
71 /// operand, it returns that instead.
72 Value *stripGetElementPtr(Value *Ptr, ScalarEvolution *SE, Loop *Lp);
73 
74 /// \brief If a value has only one user that is a CastInst, return it.
75 Value *getUniqueCastUse(Value *Ptr, Loop *Lp, Type *Ty);
76 
77 /// \brief Get the stride of a pointer access in a loop. Looks for symbolic
78 /// strides "a[i*stride]". Returns the symbolic stride, or null otherwise.
79 Value *getStrideFromPointer(Value *Ptr, ScalarEvolution *SE, Loop *Lp);
80 
81 /// \brief Given a vector and an element number, see if the scalar value is
82 /// already around as a register, for example if it were inserted then extracted
83 /// from the vector.
84 Value *findScalarElement(Value *V, unsigned EltNo);
85 
86 /// \brief Get splat value if the input is a splat vector or return nullptr.
87 /// The value may be extracted from a splat constants vector or from
88 /// a sequence of instructions that broadcast a single value into a vector.
89 const Value *getSplatValue(const Value *V);
90 
91 /// \brief Compute a map of integer instructions to their minimum legal type
92 /// size.
93 ///
94 /// C semantics force sub-int-sized values (e.g. i8, i16) to be promoted to int
95 /// type (e.g. i32) whenever arithmetic is performed on them.
96 ///
97 /// For targets with native i8 or i16 operations, usually InstCombine can shrink
98 /// the arithmetic type down again. However InstCombine refuses to create
99 /// illegal types, so for targets without i8 or i16 registers, the lengthening
100 /// and shrinking remains.
101 ///
102 /// Most SIMD ISAs (e.g. NEON) however support vectors of i8 or i16 even when
103 /// their scalar equivalents do not, so during vectorization it is important to
104 /// remove these lengthens and truncates when deciding the profitability of
105 /// vectorization.
106 ///
107 /// This function analyzes the given range of instructions and determines the
108 /// minimum type size each can be converted to. It attempts to remove or
109 /// minimize type size changes across each def-use chain, so for example in the
110 /// following code:
111 ///
112 ///   %1 = load i8, i8*
113 ///   %2 = add i8 %1, 2
114 ///   %3 = load i16, i16*
115 ///   %4 = zext i8 %2 to i32
116 ///   %5 = zext i16 %3 to i32
117 ///   %6 = add i32 %4, %5
118 ///   %7 = trunc i32 %6 to i16
119 ///
120 /// Instruction %6 must be done at least in i16, so computeMinimumValueSizes
121 /// will return: {%1: 16, %2: 16, %3: 16, %4: 16, %5: 16, %6: 16, %7: 16}.
122 ///
123 /// If the optional TargetTransformInfo is provided, this function tries harder
124 /// to do less work by only looking at illegal types.
125 MapVector<Instruction*, uint64_t>
126 computeMinimumValueSizes(ArrayRef<BasicBlock*> Blocks,
127                          DemandedBits &DB,
128                          const TargetTransformInfo *TTI=nullptr);
129 
130 } // llvm namespace
131 
132 #endif
133