a60251d739
A linker optimization is available on PowerPC for GOT indirect PCRelative loads. The idea is that we can mark a usual GOT indirect load: pld 3, vec@got@pcrel(0), 1 lwa 3, 4(3) With a relocation to say that if we don't need to go through the GOT we can let the linker further optimize this and replace a load with a nop. pld 3, vec@got@pcrel(0), 1 .Lpcrel1: .reloc .Lpcrel1-8,R_PPC64_PCREL_OPT,.-(.Lpcrel1-8) lwa 3, 4(3) This patch adds the logic that allows the compiler to add the R_PPC64_PCREL_OPT. Reviewers: nemanjai, lei, hfinkel, sfertile, efriedma, tstellar, grosbach Reviewed By: nemanjai Differential Revision: https://reviews.llvm.org/D79864
62 lines
2.3 KiB
C++
62 lines
2.3 KiB
C++
//===- PPCELFStreamer.h - ELF Object Output --------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This is a custom MCELFStreamer for PowerPC.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_TARGET_PPC_MCELFSTREAMER_PPCELFSTREAMER_H
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#define LLVM_LIB_TARGET_PPC_MCELFSTREAMER_PPCELFSTREAMER_H
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/MC/MCELFStreamer.h"
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#include <memory>
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namespace llvm {
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class MCAsmBackend;
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class MCCodeEmitter;
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class MCContext;
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class MCSubtargetInfo;
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class PPCELFStreamer : public MCELFStreamer {
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// We need to keep track of the last label we emitted (only one) because
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// depending on whether the label is on the same line as an aligned
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// instruction or not, the label may refer to the instruction or the nop.
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MCSymbol *LastLabel;
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SMLoc LastLabelLoc;
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public:
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PPCELFStreamer(MCContext &Context, std::unique_ptr<MCAsmBackend> MAB,
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std::unique_ptr<MCObjectWriter> OW,
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std::unique_ptr<MCCodeEmitter> Emitter);
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void emitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI) override;
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// EmitLabel updates LastLabel and LastLabelLoc when a new label is emitted.
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void emitLabel(MCSymbol *Symbol, SMLoc Loc = SMLoc()) override;
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private:
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void emitPrefixedInstruction(const MCInst &Inst, const MCSubtargetInfo &STI);
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void emitGOTToPCRelReloc(const MCInst &Inst);
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void emitGOTToPCRelLabel(const MCInst &Inst);
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};
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// Check if the instruction Inst is part of a pair of instructions that make up
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// a link time GOT PC Rel optimization.
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Optional<bool> isPartOfGOTToPCRelPair(const MCInst &Inst,
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const MCSubtargetInfo &STI);
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MCELFStreamer *createPPCELFStreamer(MCContext &Context,
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std::unique_ptr<MCAsmBackend> MAB,
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std::unique_ptr<MCObjectWriter> OW,
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std::unique_ptr<MCCodeEmitter> Emitter);
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} // end namespace llvm
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#endif // LLVM_LIB_TARGET_PPC_MCELFSTREAMER_PPCELFSTREAMER_H
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