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Diffstat (limited to 'contrib/llvm/include/llvm/Target/TargetFrameLowering.h')
| -rw-r--r-- | contrib/llvm/include/llvm/Target/TargetFrameLowering.h | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/contrib/llvm/include/llvm/Target/TargetFrameLowering.h b/contrib/llvm/include/llvm/Target/TargetFrameLowering.h new file mode 100644 index 0000000..e104b16 --- /dev/null +++ b/contrib/llvm/include/llvm/Target/TargetFrameLowering.h @@ -0,0 +1,196 @@ +//===-- llvm/Target/TargetFrameLowering.h ---------------------------*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// Interface to describe the layout of a stack frame on the target machine. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_TARGET_TARGETFRAMELOWERING_H +#define LLVM_TARGET_TARGETFRAMELOWERING_H + +#include "llvm/CodeGen/MachineBasicBlock.h" + +#include <utility> +#include <vector> + +namespace llvm { + class CalleeSavedInfo; + class MachineFunction; + class MachineBasicBlock; + class MachineMove; + class RegScavenger; + +/// Information about stack frame layout on the target. It holds the direction +/// of stack growth, the known stack alignment on entry to each function, and +/// the offset to the locals area. +/// +/// The offset to the local area is the offset from the stack pointer on +/// function entry to the first location where function data (local variables, +/// spill locations) can be stored. +class TargetFrameLowering { +public: + enum StackDirection { + StackGrowsUp, // Adding to the stack increases the stack address + StackGrowsDown // Adding to the stack decreases the stack address + }; + + // Maps a callee saved register to a stack slot with a fixed offset. + struct SpillSlot { + unsigned Reg; + int Offset; // Offset relative to stack pointer on function entry. + }; +private: + StackDirection StackDir; + unsigned StackAlignment; + unsigned TransientStackAlignment; + int LocalAreaOffset; +public: + TargetFrameLowering(StackDirection D, unsigned StackAl, int LAO, + unsigned TransAl = 1) + : StackDir(D), StackAlignment(StackAl), TransientStackAlignment(TransAl), + LocalAreaOffset(LAO) {} + + virtual ~TargetFrameLowering(); + + // These methods return information that describes the abstract stack layout + // of the target machine. + + /// getStackGrowthDirection - Return the direction the stack grows + /// + StackDirection getStackGrowthDirection() const { return StackDir; } + + /// getStackAlignment - This method returns the number of bytes to which the + /// stack pointer must be aligned on entry to a function. Typically, this + /// is the largest alignment for any data object in the target. + /// + unsigned getStackAlignment() const { return StackAlignment; } + + /// getTransientStackAlignment - This method returns the number of bytes to + /// which the stack pointer must be aligned at all times, even between + /// calls. + /// + unsigned getTransientStackAlignment() const { + return TransientStackAlignment; + } + + /// getOffsetOfLocalArea - This method returns the offset of the local area + /// from the stack pointer on entrance to a function. + /// + int getOffsetOfLocalArea() const { return LocalAreaOffset; } + + /// getCalleeSavedSpillSlots - This method returns a pointer to an array of + /// pairs, that contains an entry for each callee saved register that must be + /// spilled to a particular stack location if it is spilled. + /// + /// Each entry in this array contains a <register,offset> pair, indicating the + /// fixed offset from the incoming stack pointer that each register should be + /// spilled at. If a register is not listed here, the code generator is + /// allowed to spill it anywhere it chooses. + /// + virtual const SpillSlot * + getCalleeSavedSpillSlots(unsigned &NumEntries) const { + NumEntries = 0; + return 0; + } + + /// targetHandlesStackFrameRounding - Returns true if the target is + /// responsible for rounding up the stack frame (probably at emitPrologue + /// time). + virtual bool targetHandlesStackFrameRounding() const { + return false; + } + + /// emitProlog/emitEpilog - These methods insert prolog and epilog code into + /// the function. + virtual void emitPrologue(MachineFunction &MF) const = 0; + virtual void emitEpilogue(MachineFunction &MF, + MachineBasicBlock &MBB) const = 0; + + /// spillCalleeSavedRegisters - Issues instruction(s) to spill all callee + /// saved registers and returns true if it isn't possible / profitable to do + /// so by issuing a series of store instructions via + /// storeRegToStackSlot(). Returns false otherwise. + virtual bool spillCalleeSavedRegisters(MachineBasicBlock &MBB, + MachineBasicBlock::iterator MI, + const std::vector<CalleeSavedInfo> &CSI, + const TargetRegisterInfo *TRI) const { + return false; + } + + /// restoreCalleeSavedRegisters - Issues instruction(s) to restore all callee + /// saved registers and returns true if it isn't possible / profitable to do + /// so by issuing a series of load instructions via loadRegToStackSlot(). + /// Returns false otherwise. + virtual bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB, + MachineBasicBlock::iterator MI, + const std::vector<CalleeSavedInfo> &CSI, + const TargetRegisterInfo *TRI) const { + return false; + } + + /// hasFP - Return true if the specified function should have a dedicated + /// frame pointer register. For most targets this is true only if the function + /// has variable sized allocas or if frame pointer elimination is disabled. + virtual bool hasFP(const MachineFunction &MF) const = 0; + + /// hasReservedCallFrame - Under normal circumstances, when a frame pointer is + /// not required, we reserve argument space for call sites in the function + /// immediately on entry to the current function. This eliminates the need for + /// add/sub sp brackets around call sites. Returns true if the call frame is + /// included as part of the stack frame. + virtual bool hasReservedCallFrame(const MachineFunction &MF) const { + return !hasFP(MF); + } + + /// canSimplifyCallFramePseudos - When possible, it's best to simplify the + /// call frame pseudo ops before doing frame index elimination. This is + /// possible only when frame index references between the pseudos won't + /// need adjusting for the call frame adjustments. Normally, that's true + /// if the function has a reserved call frame or a frame pointer. Some + /// targets (Thumb2, for example) may have more complicated criteria, + /// however, and can override this behavior. + virtual bool canSimplifyCallFramePseudos(const MachineFunction &MF) const { + return hasReservedCallFrame(MF) || hasFP(MF); + } + + /// getInitialFrameState - Returns a list of machine moves that are assumed + /// on entry to all functions. Note that LabelID is ignored (assumed to be + /// the beginning of the function.) + virtual void getInitialFrameState(std::vector<MachineMove> &Moves) const; + + /// getFrameIndexOffset - Returns the displacement from the frame register to + /// the stack frame of the specified index. + virtual int getFrameIndexOffset(const MachineFunction &MF, int FI) const; + + /// getFrameIndexReference - This method should return the base register + /// and offset used to reference a frame index location. The offset is + /// returned directly, and the base register is returned via FrameReg. + virtual int getFrameIndexReference(const MachineFunction &MF, int FI, + unsigned &FrameReg) const; + + /// processFunctionBeforeCalleeSavedScan - This method is called immediately + /// before PrologEpilogInserter scans the physical registers used to determine + /// what callee saved registers should be spilled. This method is optional. + virtual void processFunctionBeforeCalleeSavedScan(MachineFunction &MF, + RegScavenger *RS = NULL) const { + + } + + /// processFunctionBeforeFrameFinalized - This method is called immediately + /// before the specified function's frame layout (MF.getFrameInfo()) is + /// finalized. Once the frame is finalized, MO_FrameIndex operands are + /// replaced with direct constants. This method is optional. + /// + virtual void processFunctionBeforeFrameFinalized(MachineFunction &MF) const { + } +}; + +} // End llvm namespace + +#endif |
