8bb059ab63
Summary: Before this patch, `relaxInstruction` takes three arguments, the first argument refers to the instruction before relaxation and the third argument is the output instruction after relaxation. There are two quite strange things: 1) The first argument's type is `const MCInst &`, the third argument's type is `MCInst &`, but they may be aliased to the same variable 2) The backends of ARM, AMDGPU, RISC-V, Hexagon assume that the third argument is a fresh uninitialized `MCInst` even if `relaxInstruction` may be called like `relaxInstruction(Relaxed, STI, Relaxed)` in a loop. In this patch, we drop the thrid argument, and let `relaxInstruction` directly modify the given instruction. Also, this patch fixes the bug https://bugs.llvm.org/show_bug.cgi?id=45580, which is introduced by D77851, and breaks the assumption of ARM, AMDGPU, RISC-V, Hexagon. Reviewers: Razer6, MaskRay, jyknight, asb, luismarques, enderby, rtaylor, colinl, bcain Reviewed By: Razer6, MaskRay, bcain Subscribers: bcain, nickdesaulniers, nathanchance, wuzish, annita.zhang, arsenm, dschuff, jyknight, dylanmckay, sdardis, nemanjai, jvesely, nhaehnle, tpr, sbc100, jgravelle-google, kristof.beyls, hiraditya, aheejin, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, PkmX, jocewei, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, kerbowa, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D78364
83 lines
3.1 KiB
C++
83 lines
3.1 KiB
C++
//===-- ARMAsmBackend.h - ARM Assembler Backend -----------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_TARGET_ARM_ARMASMBACKEND_H
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#define LLVM_LIB_TARGET_ARM_ARMASMBACKEND_H
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#include "MCTargetDesc/ARMFixupKinds.h"
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#include "MCTargetDesc/ARMMCTargetDesc.h"
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#include "llvm/MC/MCAsmBackend.h"
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#include "llvm/MC/MCSubtargetInfo.h"
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#include "llvm/Support/TargetRegistry.h"
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namespace llvm {
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class ARMAsmBackend : public MCAsmBackend {
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// The STI from the target triple the MCAsmBackend was instantiated with
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// note that MCFragments may have a different local STI that should be
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// used in preference.
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const MCSubtargetInfo &STI;
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bool isThumbMode; // Currently emitting Thumb code.
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public:
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ARMAsmBackend(const Target &T, const MCSubtargetInfo &STI,
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support::endianness Endian)
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: MCAsmBackend(Endian), STI(STI),
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isThumbMode(STI.getTargetTriple().isThumb()) {}
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unsigned getNumFixupKinds() const override {
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return ARM::NumTargetFixupKinds;
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}
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// FIXME: this should be calculated per fragment as the STI may be
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// different.
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bool hasNOP() const { return STI.getFeatureBits()[ARM::HasV6T2Ops]; }
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Optional<MCFixupKind> getFixupKind(StringRef Name) const override;
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const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override;
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bool shouldForceRelocation(const MCAssembler &Asm, const MCFixup &Fixup,
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const MCValue &Target) override;
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unsigned adjustFixupValue(const MCAssembler &Asm, const MCFixup &Fixup,
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const MCValue &Target, uint64_t Value,
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bool IsResolved, MCContext &Ctx,
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const MCSubtargetInfo *STI) const;
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void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
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const MCValue &Target, MutableArrayRef<char> Data,
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uint64_t Value, bool IsResolved,
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const MCSubtargetInfo *STI) const override;
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unsigned getRelaxedOpcode(unsigned Op, const MCSubtargetInfo &STI) const;
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bool mayNeedRelaxation(const MCInst &Inst,
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const MCSubtargetInfo &STI) const override;
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const char *reasonForFixupRelaxation(const MCFixup &Fixup,
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uint64_t Value) const;
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bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value,
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const MCRelaxableFragment *DF,
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const MCAsmLayout &Layout) const override;
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void relaxInstruction(MCInst &Inst,
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const MCSubtargetInfo &STI) const override;
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bool writeNopData(raw_ostream &OS, uint64_t Count) const override;
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void handleAssemblerFlag(MCAssemblerFlag Flag) override;
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unsigned getPointerSize() const { return 4; }
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bool isThumb() const { return isThumbMode; }
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void setIsThumb(bool it) { isThumbMode = it; }
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};
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} // end namespace llvm
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#endif
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