| 1 | //===- llvm/MC/MCLinkerOptimizationHint.cpp ----- LOH handling ------------===// |
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| 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 | #include "llvm/MC/MCLinkerOptimizationHint.h" |
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| 10 | #include "llvm/MC/MCAsmLayout.h" |
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| 11 | #include "llvm/MC/MCMachObjectWriter.h" |
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| 12 | #include "llvm/Support/LEB128.h" |
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| 13 | #include "llvm/Support/raw_ostream.h" |
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| 14 | #include <cstddef> |
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| 15 | #include <cstdint> |
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| 16 | |
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| 17 | using namespace llvm; |
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| 18 | |
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| 19 | // Each LOH is composed by, in this order (each field is encoded using ULEB128): |
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| 20 | // - Its kind. |
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| 21 | // - Its number of arguments (let say N). |
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| 22 | // - Its arg1. |
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| 23 | // - ... |
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| 24 | // - Its argN. |
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| 25 | // <arg1> to <argN> are absolute addresses in the object file, i.e., |
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| 26 | // relative addresses from the beginning of the object file. |
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| 27 | void MCLOHDirective::emit_impl(raw_ostream &OutStream, |
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| 28 | const MachObjectWriter &ObjWriter, |
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| 29 | const MCAsmLayout &Layout) const { |
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| 30 | encodeULEB128(Value: Kind, OS&: OutStream); |
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| 31 | encodeULEB128(Value: Args.size(), OS&: OutStream); |
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| 32 | for (const MCSymbol *Arg : Args) |
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| 33 | encodeULEB128(Value: ObjWriter.getSymbolAddress(S: *Arg, Layout), OS&: OutStream); |
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| 34 | } |
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| 35 | |
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| 36 | void MCLOHDirective::emit(MachObjectWriter &ObjWriter, |
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| 37 | const MCAsmLayout &Layout) const { |
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| 38 | raw_ostream &OutStream = ObjWriter.W.OS; |
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| 39 | emit_impl(OutStream, ObjWriter, Layout); |
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| 40 | } |
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| 41 | |
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| 42 | uint64_t MCLOHDirective::getEmitSize(const MachObjectWriter &ObjWriter, |
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| 43 | const MCAsmLayout &Layout) const { |
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| 44 | class raw_counting_ostream : public raw_ostream { |
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| 45 | uint64_t Count = 0; |
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| 46 | |
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| 47 | void write_impl(const char *, size_t size) override { Count += size; } |
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| 48 | |
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| 49 | uint64_t current_pos() const override { return Count; } |
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| 50 | |
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| 51 | public: |
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| 52 | raw_counting_ostream() = default; |
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| 53 | ~raw_counting_ostream() override { flush(); } |
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| 54 | }; |
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| 55 | |
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| 56 | raw_counting_ostream OutStream; |
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| 57 | emit_impl(OutStream, ObjWriter, Layout); |
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| 58 | return OutStream.tell(); |
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| 59 | } |
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| 60 | |
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