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| 14 | pmbaty | 1 | //===- CallPromotionUtils.h - Utilities for call promotion ------*- C++ -*-===// |
| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | // |
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| 9 | // This file declares utilities useful for promoting indirect call sites to |
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| 10 | // direct call sites. |
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| 11 | // |
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| 12 | //===----------------------------------------------------------------------===// |
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| 13 | |||
| 14 | #ifndef LLVM_TRANSFORMS_UTILS_CALLPROMOTIONUTILS_H |
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| 15 | #define LLVM_TRANSFORMS_UTILS_CALLPROMOTIONUTILS_H |
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| 16 | |||
| 17 | namespace llvm { |
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| 18 | class CallBase; |
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| 19 | class CastInst; |
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| 20 | class Function; |
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| 21 | class MDNode; |
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| 22 | class Value; |
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| 23 | |||
| 24 | /// Return true if the given indirect call site can be made to call \p Callee. |
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| 25 | /// |
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| 26 | /// This function ensures that the number and type of the call site's arguments |
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| 27 | /// and return value match those of the given function. If the types do not |
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| 28 | /// match exactly, they must at least be bitcast compatible. If \p FailureReason |
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| 29 | /// is non-null and the indirect call cannot be promoted, the failure reason |
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| 30 | /// will be stored in it. |
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| 31 | bool isLegalToPromote(const CallBase &CB, Function *Callee, |
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| 32 | const char **FailureReason = nullptr); |
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| 33 | |||
| 34 | /// Promote the given indirect call site to unconditionally call \p Callee. |
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| 35 | /// |
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| 36 | /// This function promotes the given call site, returning the direct call or |
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| 37 | /// invoke instruction. If the function type of the call site doesn't match that |
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| 38 | /// of the callee, bitcast instructions are inserted where appropriate. If \p |
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| 39 | /// RetBitCast is non-null, it will be used to store the return value bitcast, |
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| 40 | /// if created. |
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| 41 | CallBase &promoteCall(CallBase &CB, Function *Callee, |
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| 42 | CastInst **RetBitCast = nullptr); |
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| 43 | |||
| 44 | /// Promote the given indirect call site to conditionally call \p Callee. |
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| 45 | /// |
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| 46 | /// This function creates an if-then-else structure at the location of the call |
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| 47 | /// site. The original call site is moved into the "else" block. A clone of the |
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| 48 | /// indirect call site is promoted, placed in the "then" block, and returned. If |
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| 49 | /// \p BranchWeights is non-null, it will be used to set !prof metadata on the |
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| 50 | /// new conditional branch. |
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| 51 | CallBase &promoteCallWithIfThenElse(CallBase &CB, Function *Callee, |
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| 52 | MDNode *BranchWeights = nullptr); |
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| 53 | |||
| 54 | /// Try to promote (devirtualize) a virtual call on an Alloca. Return true on |
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| 55 | /// success. |
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| 56 | /// |
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| 57 | /// Look for a pattern like: |
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| 58 | /// |
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| 59 | /// %o = alloca %class.Impl |
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| 60 | /// %1 = getelementptr %class.Impl, %class.Impl* %o, i64 0, i32 0, i32 0 |
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| 61 | /// store i32 (...)** bitcast (i8** getelementptr inbounds |
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| 62 | /// ({ [3 x i8*] }, { [3 x i8*] }* @_ZTV4Impl, i64 0, inrange i32 0, i64 2) |
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| 63 | /// to i32 (...)**), i32 (...)*** %1 |
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| 64 | /// %2 = getelementptr inbounds %class.Impl, %class.Impl* %o, i64 0, i32 0 |
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| 65 | /// %3 = bitcast %class.Interface* %2 to void (%class.Interface*)*** |
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| 66 | /// %vtable.i = load void (%class.Interface*)**, void (%class.Interface*)*** %3 |
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| 67 | /// %4 = load void (%class.Interface*)*, void (%class.Interface*)** %vtable.i |
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| 68 | /// call void %4(%class.Interface* nonnull %2) |
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| 69 | /// |
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| 70 | /// @_ZTV4Impl = linkonce_odr dso_local unnamed_addr constant { [3 x i8*] } |
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| 71 | /// { [3 x i8*] |
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| 72 | /// [i8* null, i8* bitcast ({ i8*, i8*, i8* }* @_ZTI4Impl to i8*), |
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| 73 | /// i8* bitcast (void (%class.Impl*)* @_ZN4Impl3RunEv to i8*)] } |
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| 74 | /// |
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| 75 | bool tryPromoteCall(CallBase &CB); |
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| 76 | |||
| 77 | /// Predicate and clone the given call site. |
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| 78 | /// |
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| 79 | /// This function creates an if-then-else structure at the location of the call |
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| 80 | /// site. The "if" condition compares the call site's called value to the given |
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| 81 | /// callee. The original call site is moved into the "else" block, and a clone |
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| 82 | /// of the call site is placed in the "then" block. The cloned instruction is |
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| 83 | /// returned. |
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| 84 | CallBase &versionCallSite(CallBase &CB, Value *Callee, MDNode *BranchWeights); |
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| 85 | |||
| 86 | } // end namespace llvm |
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| 87 | |||
| 88 | #endif // LLVM_TRANSFORMS_UTILS_CALLPROMOTIONUTILS_H |