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Diffstat (limited to 'contrib/llvm/include/llvm/MC/MCCodePadder.h')
| -rw-r--r-- | contrib/llvm/include/llvm/MC/MCCodePadder.h | 243 |
1 files changed, 243 insertions, 0 deletions
diff --git a/contrib/llvm/include/llvm/MC/MCCodePadder.h b/contrib/llvm/include/llvm/MC/MCCodePadder.h new file mode 100644 index 000000000000..1e91198597c3 --- /dev/null +++ b/contrib/llvm/include/llvm/MC/MCCodePadder.h @@ -0,0 +1,243 @@ +//===- llvm/MC/CodePadder.h - MC Code Padder --------------------*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_MC_MCCODEPADDER_H +#define LLVM_MC_MCCODEPADDER_H + +#include "MCFragment.h" +#include "llvm/ADT/DenseMap.h" +#include "llvm/ADT/SmallPtrSet.h" +#include "llvm/ADT/SmallVector.h" + +namespace llvm { + +class MCAsmLayout; +class MCCodePaddingPolicy; +class MCFragment; +class MCInst; +class MCObjectStreamer; +class MCSection; + +typedef SmallVector<const MCPaddingFragment *, 8> MCPFRange; + +struct MCCodePaddingContext { + bool IsPaddingActive; + bool IsBasicBlockInsideInnermostLoop; + bool IsBasicBlockReachableViaFallthrough; + bool IsBasicBlockReachableViaBranch; +}; + +/// Target-independent base class incharge of all code padding decisions for a +/// target. During encoding it determines if and where MCPaddingFragments will +/// be located, as later on, when layout information is available, it determines +/// their sizes. +class MCCodePadder { + MCCodePadder(const MCCodePadder &) = delete; + void operator=(const MCCodePadder &) = delete; + + /// Determines if the MCCodePaddingPolicies are active. + bool ArePoliciesActive; + + /// All the supported MCCodePaddingPolicies. + SmallPtrSet<MCCodePaddingPolicy *, 4> CodePaddingPolicies; + + /// A pointer to the fragment of the instruction whose padding is currently + /// done for. + MCPaddingFragment *CurrHandledInstFragment; + + /// A map holding the jurisdiction for each padding fragment. Key: padding + /// fragment. Value: The fragment's jurisdiction. A jurisdiction is a vector + /// of padding fragments whose conditions are being controlled by another + /// fragment, the key fragment. + DenseMap<MCPaddingFragment *, MCPFRange> FragmentToJurisdiction; + MCPFRange &getJurisdiction(MCPaddingFragment *Fragment, MCAsmLayout &Layout); + + /// A map holding the maximal instruction window size relevant for a padding + /// fragment. + DenseMap<MCPaddingFragment *, uint64_t> FragmentToMaxWindowSize; + uint64_t getMaxWindowSize(MCPaddingFragment *Fragment, MCAsmLayout &Layout); + +protected: + /// The current streamer, used to stream code padding. + MCObjectStreamer *OS; + + bool addPolicy(MCCodePaddingPolicy *Policy); + + virtual bool + basicBlockRequiresInsertionPoint(const MCCodePaddingContext &Context) { + return false; + } + + virtual bool instructionRequiresInsertionPoint(const MCInst &Inst) { + return false; + } + + virtual bool usePoliciesForBasicBlock(const MCCodePaddingContext &Context) { + return Context.IsPaddingActive; + } + +public: + MCCodePadder() + : ArePoliciesActive(false), CurrHandledInstFragment(nullptr), + OS(nullptr) {} + virtual ~MCCodePadder(); + + /// Handles all target related code padding when starting to write a new + /// basic block to an object file. + /// + /// \param OS The streamer used for writing the padding data and function. + /// \param Context the context of the padding, Embeds the basic block's + /// parameters. + void handleBasicBlockStart(MCObjectStreamer *OS, + const MCCodePaddingContext &Context); + /// Handles all target related code padding when done writing a block to an + /// object file. + /// + /// \param Context the context of the padding, Embeds the basic block's + /// parameters. + void handleBasicBlockEnd(const MCCodePaddingContext &Context); + /// Handles all target related code padding before writing a new instruction + /// to an object file. + /// + /// \param Inst the instruction. + void handleInstructionBegin(const MCInst &Inst); + /// Handles all target related code padding after writing an instruction to an + /// object file. + /// + /// \param Inst the instruction. + void handleInstructionEnd(const MCInst &Inst); + + /// Relaxes a fragment (changes the size of the padding) according to target + /// requirements. The new size computation is done w.r.t a layout. + /// + /// \param Fragment The fragment to relax. + /// \param Layout Code layout information. + /// + /// \returns true iff any relaxation occured. + bool relaxFragment(MCPaddingFragment *Fragment, MCAsmLayout &Layout); +}; + +/// The base class for all padding policies, i.e. a rule or set of rules to pad +/// the generated code. +class MCCodePaddingPolicy { + MCCodePaddingPolicy() = delete; + MCCodePaddingPolicy(const MCCodePaddingPolicy &) = delete; + void operator=(const MCCodePaddingPolicy &) = delete; + +protected: + /// A mask holding the kind of this policy, i.e. only the i'th bit will be set + /// where i is the kind number. + const uint64_t KindMask; + /// Instruction window size relevant to this policy. + const uint64_t WindowSize; + /// A boolean indicating which byte of the instruction determies its + /// instruction window. If true - the last byte of the instructions, o.w. - + /// the first byte of the instruction. + const bool InstByteIsLastByte; + + MCCodePaddingPolicy(uint64_t Kind, uint64_t WindowSize, + bool InstByteIsLastByte) + : KindMask(UINT64_C(1) << Kind), WindowSize(WindowSize), + InstByteIsLastByte(InstByteIsLastByte) {} + + /// Computes and returns the offset of the consecutive fragment of a given + /// fragment. + /// + /// \param Fragment The fragment whose consecutive offset will be computed. + /// \param Layout Code layout information. + /// + /// \returns the offset of the consecutive fragment of \p Fragment. + static uint64_t getNextFragmentOffset(const MCFragment *Fragment, + const MCAsmLayout &Layout); + /// Returns the instruction byte of an instruction pointed by a given + /// MCPaddingFragment. An instruction byte is the address of the byte of an + /// instruction which determines its instruction window. + /// + /// \param Fragment The fragment pointing to the instruction. + /// \param Layout Code layout information. + /// + /// \returns the instruction byte of an instruction pointed by \p Fragment. + uint64_t getFragmentInstByte(const MCPaddingFragment *Fragment, + MCAsmLayout &Layout) const; + uint64_t computeWindowEndAddress(const MCPaddingFragment *Fragment, + uint64_t Offset, MCAsmLayout &Layout) const; + + /// Computes and returns the penalty weight of a first instruction window in a + /// range. This requires a special function since the first window does not + /// contain all the padding fragments in that window. It only contains all the + /// padding fragments starting from the relevant insertion point. + /// + /// \param Window The first window. + /// \param Offset The offset of the parent section relative to the beginning + /// of the file, mod the window size. + /// \param Layout Code layout information. + /// + /// \returns the penalty weight of a first instruction window in a range, \p + /// Window. + double computeFirstWindowPenaltyWeight(const MCPFRange &Window, + uint64_t Offset, + MCAsmLayout &Layout) const; + /// Computes and returns the penalty caused by an instruction window. + /// + /// \param Window The instruction window. + /// \param Offset The offset of the parent section relative to the beginning + /// of the file, mod the window size. + /// \param Layout Code layout information. + /// + /// \returns the penalty caused by \p Window. + virtual double computeWindowPenaltyWeight(const MCPFRange &Window, + uint64_t Offset, + MCAsmLayout &Layout) const = 0; + +public: + virtual ~MCCodePaddingPolicy() {} + + /// Returns the kind mask of this policy - A mask holding the kind of this + /// policy, i.e. only the i'th bit will be set where i is the kind number. + uint64_t getKindMask() const { return KindMask; } + /// Returns the instruction window size relevant to this policy. + uint64_t getWindowSize() const { return WindowSize; } + /// Returns true if the last byte of an instruction determines its instruction + /// window, or false if the first of an instruction determines it. + bool isInstByteLastByte() const { return InstByteIsLastByte; } + + /// Returns true iff this policy needs padding for a given basic block. + /// + /// \param Context the context of the padding, Embeds the basic block's + /// parameters. + /// + /// \returns true iff this policy needs padding for the basic block. + virtual bool + basicBlockRequiresPaddingFragment(const MCCodePaddingContext &Context) const { + return false; + } + /// Returns true iff this policy needs padding for a given instruction. + /// + /// \param Inst The given instruction. + /// + /// \returns true iff this policy needs padding for \p Inst. + virtual bool instructionRequiresPaddingFragment(const MCInst &Inst) const { + return false; + } + /// Computes and returns the penalty caused by a range of instruction windows. + /// The weight is computed for each window separelty and then accumulated. + /// + /// \param Range The range. + /// \param Offset The offset of the parent section relative to the beginning + /// of the file, mod the window size. + /// \param Layout Code layout information. + /// + /// \returns the penalty caused by \p Range. + double computeRangePenaltyWeight(const MCPFRange &Range, uint64_t Offset, + MCAsmLayout &Layout) const; +}; + +} // namespace llvm + +#endif // LLVM_MC_MCCODEPADDER_H |