LLVM 19.0.0git
CallPromotionUtils.h
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1//===- CallPromotionUtils.h - Utilities for call promotion ------*- 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 declares utilities useful for promoting indirect call sites to
10// direct call sites.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_TRANSFORMS_UTILS_CALLPROMOTIONUTILS_H
15#define LLVM_TRANSFORMS_UTILS_CALLPROMOTIONUTILS_H
16
17namespace llvm {
18class CallBase;
19class CastInst;
20class Function;
21class MDNode;
22class Value;
23
24/// Return true if the given indirect call site can be made to call \p Callee.
25///
26/// This function ensures that the number and type of the call site's arguments
27/// and return value match those of the given function. If the types do not
28/// match exactly, they must at least be bitcast compatible. If \p FailureReason
29/// is non-null and the indirect call cannot be promoted, the failure reason
30/// will be stored in it.
31bool isLegalToPromote(const CallBase &CB, Function *Callee,
32 const char **FailureReason = nullptr);
33
34/// Promote the given indirect call site to unconditionally call \p Callee.
35///
36/// This function promotes the given call site, returning the direct call or
37/// invoke instruction. If the function type of the call site doesn't match that
38/// of the callee, bitcast instructions are inserted where appropriate. If \p
39/// RetBitCast is non-null, it will be used to store the return value bitcast,
40/// if created.
41CallBase &promoteCall(CallBase &CB, Function *Callee,
42 CastInst **RetBitCast = nullptr);
43
44/// Promote the given indirect call site to conditionally call \p Callee.
45///
46/// This function creates an if-then-else structure at the location of the call
47/// site. The original call site is moved into the "else" block. A clone of the
48/// indirect call site is promoted, placed in the "then" block, and returned. If
49/// \p BranchWeights is non-null, it will be used to set !prof metadata on the
50/// new conditional branch.
51CallBase &promoteCallWithIfThenElse(CallBase &CB, Function *Callee,
52 MDNode *BranchWeights = nullptr);
53
54/// Try to promote (devirtualize) a virtual call on an Alloca. Return true on
55/// success.
56///
57/// Look for a pattern like:
58///
59/// %o = alloca %class.Impl
60/// %1 = getelementptr %class.Impl, %class.Impl* %o, i64 0, i32 0, i32 0
61/// store i32 (...)** bitcast (i8** getelementptr inbounds
62/// ({ [3 x i8*] }, { [3 x i8*] }* @_ZTV4Impl, i64 0, inrange i32 0, i64 2)
63/// to i32 (...)**), i32 (...)*** %1
64/// %2 = getelementptr inbounds %class.Impl, %class.Impl* %o, i64 0, i32 0
65/// %3 = bitcast %class.Interface* %2 to void (%class.Interface*)***
66/// %vtable.i = load void (%class.Interface*)**, void (%class.Interface*)*** %3
67/// %4 = load void (%class.Interface*)*, void (%class.Interface*)** %vtable.i
68/// call void %4(%class.Interface* nonnull %2)
69///
70/// @_ZTV4Impl = linkonce_odr dso_local unnamed_addr constant { [3 x i8*] }
71/// { [3 x i8*]
72/// [i8* null, i8* bitcast ({ i8*, i8*, i8* }* @_ZTI4Impl to i8*),
73/// i8* bitcast (void (%class.Impl*)* @_ZN4Impl3RunEv to i8*)] }
74///
75bool tryPromoteCall(CallBase &CB);
76
77/// Predicate and clone the given call site.
78///
79/// This function creates an if-then-else structure at the location of the call
80/// site. The "if" condition compares the call site's called value to the given
81/// callee. The original call site is moved into the "else" block, and a clone
82/// of the call site is placed in the "then" block. The cloned instruction is
83/// returned.
84CallBase &versionCallSite(CallBase &CB, Value *Callee, MDNode *BranchWeights);
85
86} // end namespace llvm
87
88#endif // LLVM_TRANSFORMS_UTILS_CALLPROMOTIONUTILS_H
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
bool isLegalToPromote(const CallBase &CB, Function *Callee, const char **FailureReason=nullptr)
Return true if the given indirect call site can be made to call Callee.
CallBase & promoteCallWithIfThenElse(CallBase &CB, Function *Callee, MDNode *BranchWeights=nullptr)
Promote the given indirect call site to conditionally call Callee.
CallBase & versionCallSite(CallBase &CB, Value *Callee, MDNode *BranchWeights)
Predicate and clone the given call site.
CallBase & promoteCall(CallBase &CB, Function *Callee, CastInst **RetBitCast=nullptr)
Promote the given indirect call site to unconditionally call Callee.
bool tryPromoteCall(CallBase &CB)
Try to promote (devirtualize) a virtual call on an Alloca.