//===-- CodeGen/MachineFrameInfo.h - Abstract Stack Frame Rep. --*- C++ -*-===//
-//
-// The MachineFrameInfo class represents an abstract stack frame until
-// prolog/epilog code is inserted. This class is key to allowing stack frame
-// representation optimizations, such as frame pointer elimination. It also
-// allows more mundane (but still important) optimizations, such as reordering
-// of abstract objects on the stack frame.
//
-// To support this, the class assigns unique integer identifiers to stack
-// objects requested clients. These identifiers are negative integers for fixed
-// stack objects (such as arguments passed on the stack) or positive for objects
-// that may be reordered. Instructions which refer to stack objects use a
-// special MO_FrameIndex operand to represent these frame indexes.
+// The LLVM Compiler Infrastructure
//
-// Because this class keeps track of all references to the stack frame, it knows
-// when a variable sized object is allocated on the stack. This is the sole
-// condition which prevents frame pointer elimination, which is an important
-// optimization on register-poor architectures. Because original variable sized
-// alloca's in the source program are the only source of variable sized stack
-// objects, it is safe to decide whether there will be any variable sized
-// objects before all stack objects are known (for example, register allocator
-// spill code never needs variable sized objects).
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
-// When prolog/epilog code emission is performed, the final stack frame is built
-// and the machine instructions are modified to refer to the actual stack
-// offsets of the object, eliminating all MO_FrameIndex operands from the
-// program.
+//===----------------------------------------------------------------------===//
+//
+// The file defines the MachineFrameInfo class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CODEGEN_MACHINEFRAMEINFO_H
#define LLVM_CODEGEN_MACHINEFRAMEINFO_H
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/System/DataTypes.h"
+#include <cassert>
+#include <vector>
+
+namespace llvm {
+class raw_ostream;
class TargetData;
class TargetRegisterClass;
+class Type;
class MachineFunction;
-#include <vector>
+class MachineBasicBlock;
+class TargetFrameInfo;
+class BitVector;
+
+/// The CalleeSavedInfo class tracks the information need to locate where a
+/// callee saved register in the current frame.
+class CalleeSavedInfo {
+ unsigned Reg;
+ const TargetRegisterClass *RegClass;
+ int FrameIdx;
+
+public:
+ CalleeSavedInfo(unsigned R, const TargetRegisterClass *RC, int FI = 0)
+ : Reg(R), RegClass(RC), FrameIdx(FI) {}
+
+ // Accessors.
+ unsigned getReg() const { return Reg; }
+ const TargetRegisterClass *getRegClass() const { return RegClass; }
+ int getFrameIdx() const { return FrameIdx; }
+ void setFrameIdx(int FI) { FrameIdx = FI; }
+};
+/// The MachineFrameInfo class represents an abstract stack frame until
+/// prolog/epilog code is inserted. This class is key to allowing stack frame
+/// representation optimizations, such as frame pointer elimination. It also
+/// allows more mundane (but still important) optimizations, such as reordering
+/// of abstract objects on the stack frame.
+///
+/// To support this, the class assigns unique integer identifiers to stack
+/// objects requested clients. These identifiers are negative integers for
+/// fixed stack objects (such as arguments passed on the stack) or nonnegative
+/// for objects that may be reordered. Instructions which refer to stack
+/// objects use a special MO_FrameIndex operand to represent these frame
+/// indexes.
+///
+/// Because this class keeps track of all references to the stack frame, it
+/// knows when a variable sized object is allocated on the stack. This is the
+/// sole condition which prevents frame pointer elimination, which is an
+/// important optimization on register-poor architectures. Because original
+/// variable sized alloca's in the source program are the only source of
+/// variable sized stack objects, it is safe to decide whether there will be
+/// any variable sized objects before all stack objects are known (for
+/// example, register allocator spill code never needs variable sized
+/// objects).
+///
+/// When prolog/epilog code emission is performed, the final stack frame is
+/// built and the machine instructions are modified to refer to the actual
+/// stack offsets of the object, eliminating all MO_FrameIndex operands from
+/// the program.
+///
+/// @brief Abstract Stack Frame Information
class MachineFrameInfo {
// StackObject - Represent a single object allocated on the stack.
struct StackObject {
- // The size of this object on the stack. 0 means a variable sized object
- unsigned Size;
+ // SPOffset - The offset of this object from the stack pointer on entry to
+ // the function. This field has no meaning for a variable sized element.
+ int64_t SPOffset;
+
+ // The size of this object on the stack. 0 means a variable sized object,
+ // ~0ULL means a dead object.
+ uint64_t Size;
// Alignment - The required alignment of this stack slot.
unsigned Alignment;
- // SPOffset - The offset of this object from the stack pointer on entry to
- // the function. This field has no meaning for a variable sized element.
- int SPOffset;
+ // isImmutable - If true, the value of the stack object is set before
+ // entering the function and is not modified inside the function. By
+ // default, fixed objects are immutable unless marked otherwise.
+ bool isImmutable;
- StackObject(unsigned Sz, unsigned Al, int SP)
- : Size(Sz), Alignment(Al), SPOffset(SP) {}
+ // isSpillSlot - If true, the stack object is used as spill slot. It
+ // cannot alias any other memory objects.
+ bool isSpillSlot;
+
+ StackObject(uint64_t Sz, unsigned Al, int64_t SP, bool IM,
+ bool isSS)
+ : SPOffset(SP), Size(Sz), Alignment(Al), isImmutable(IM),
+ isSpillSlot(isSS) {}
};
/// Objects - The list of stack objects allocated...
///
bool HasVarSizedObjects;
+ /// FrameAddressTaken - This boolean keeps track of whether there is a call
+ /// to builtin \@llvm.frameaddress.
+ bool FrameAddressTaken;
+
/// StackSize - The prolog/epilog code inserter calculates the final stack
/// offsets for all of the fixed size objects, updating the Objects list
/// above. It then updates StackSize to contain the number of bytes that need
/// to be allocated on entry to the function.
///
- unsigned StackSize;
+ uint64_t StackSize;
+
+ /// OffsetAdjustment - The amount that a frame offset needs to be adjusted to
+ /// have the actual offset from the stack/frame pointer. The exact usage of
+ /// this is target-dependent, but it is typically used to adjust between
+ /// SP-relative and FP-relative offsets. E.G., if objects are accessed via
+ /// SP then OffsetAdjustment is zero; if FP is used, OffsetAdjustment is set
+ /// to the distance between the initial SP and the value in FP. For many
+ /// targets, this value is only used when generating debug info (via
+ /// TargetRegisterInfo::getFrameIndexOffset); when generating code, the
+ /// corresponding adjustments are performed directly.
+ int OffsetAdjustment;
+
+ /// MaxAlignment - The prolog/epilog code inserter may process objects
+ /// that require greater alignment than the default alignment the target
+ /// provides. To handle this, MaxAlignment is set to the maximum alignment
+ /// needed by the objects on the current frame. If this is greater than the
+ /// native alignment maintained by the compiler, dynamic alignment code will
+ /// be needed.
+ ///
+ unsigned MaxAlignment;
+
+ /// AdjustsStack - Set to true if this function adjusts the stack -- e.g.,
+ /// when calling another function. This is only valid during and after
+ /// prolog/epilog code insertion.
+ bool AdjustsStack;
- /// HasCalls - Set to true if this function has any function calls. This is
- /// only valid during and after prolog/epilog code insertion.
+ /// HasCalls - Set to true if this function has any function calls.
bool HasCalls;
+ /// StackProtectorIdx - The frame index for the stack protector.
+ int StackProtectorIdx;
+
/// MaxCallFrameSize - This contains the size of the largest call frame if the
/// target uses frame setup/destroy pseudo instructions (as defined in the
/// TargetFrameInfo class). This information is important for frame pointer
/// insertion.
///
unsigned MaxCallFrameSize;
+
+ /// CSInfo - The prolog/epilog code inserter fills in this vector with each
+ /// callee saved register saved in the frame. Beyond its use by the prolog/
+ /// epilog code inserter, this data used for debug info and exception
+ /// handling.
+ std::vector<CalleeSavedInfo> CSInfo;
+
+ /// CSIValid - Has CSInfo been set yet?
+ bool CSIValid;
+
+ /// SpillObjects - A vector indicating which frame indices refer to
+ /// spill slots.
+ SmallVector<bool, 8> SpillObjects;
+
+ /// TargetFrameInfo - Target information about frame layout.
+ ///
+ const TargetFrameInfo &TFI;
+
public:
- MachineFrameInfo() {
- NumFixedObjects = StackSize = 0;
+ explicit MachineFrameInfo(const TargetFrameInfo &tfi) : TFI(tfi) {
+ StackSize = NumFixedObjects = OffsetAdjustment = MaxAlignment = 0;
HasVarSizedObjects = false;
+ FrameAddressTaken = false;
+ AdjustsStack = false;
HasCalls = false;
+ StackProtectorIdx = -1;
MaxCallFrameSize = 0;
+ CSIValid = false;
}
/// hasStackObjects - Return true if there are any stack objects in this
///
bool hasVarSizedObjects() const { return HasVarSizedObjects; }
- /// getObjectIndexBegin - Return the minimum frame object index...
+ /// getStackProtectorIndex/setStackProtectorIndex - Return the index for the
+ /// stack protector object.
+ ///
+ int getStackProtectorIndex() const { return StackProtectorIdx; }
+ void setStackProtectorIndex(int I) { StackProtectorIdx = I; }
+
+ /// isFrameAddressTaken - This method may be called any time after instruction
+ /// selection is complete to determine if there is a call to
+ /// \@llvm.frameaddress in this function.
+ bool isFrameAddressTaken() const { return FrameAddressTaken; }
+ void setFrameAddressIsTaken(bool T) { FrameAddressTaken = T; }
+
+ /// getObjectIndexBegin - Return the minimum frame object index.
///
int getObjectIndexBegin() const { return -NumFixedObjects; }
- /// getObjectIndexEnd - Return one past the maximum frame object index...
+ /// getObjectIndexEnd - Return one past the maximum frame object index.
///
- int getObjectIndexEnd() const { return Objects.size()-NumFixedObjects; }
+ int getObjectIndexEnd() const { return (int)Objects.size()-NumFixedObjects; }
- /// getObjectSize - Return the size of the specified object
+ /// getNumFixedObjects() - Return the number of fixed objects.
+ unsigned getNumFixedObjects() const { return NumFixedObjects; }
+
+ /// getNumObjects() - Return the number of objects.
///
- int getObjectSize(int ObjectIdx) const {
- assert(ObjectIdx+NumFixedObjects < Objects.size() && "Invalid Object Idx!");
+ unsigned getNumObjects() const { return Objects.size(); }
+
+ /// getObjectSize - Return the size of the specified object.
+ ///
+ int64_t getObjectSize(int ObjectIdx) const {
+ assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
+ "Invalid Object Idx!");
return Objects[ObjectIdx+NumFixedObjects].Size;
}
- /// getObjectAlignment - Return the alignment of the specified stack object...
- int getObjectAlignment(int ObjectIdx) const {
- assert(ObjectIdx+NumFixedObjects < Objects.size() && "Invalid Object Idx!");
+ /// setObjectSize - Change the size of the specified stack object.
+ void setObjectSize(int ObjectIdx, int64_t Size) {
+ assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
+ "Invalid Object Idx!");
+ Objects[ObjectIdx+NumFixedObjects].Size = Size;
+ }
+
+ /// getObjectAlignment - Return the alignment of the specified stack object.
+ unsigned getObjectAlignment(int ObjectIdx) const {
+ assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
+ "Invalid Object Idx!");
return Objects[ObjectIdx+NumFixedObjects].Alignment;
}
+ /// setObjectAlignment - Change the alignment of the specified stack object.
+ void setObjectAlignment(int ObjectIdx, unsigned Align) {
+ assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
+ "Invalid Object Idx!");
+ Objects[ObjectIdx+NumFixedObjects].Alignment = Align;
+ MaxAlignment = std::max(MaxAlignment, Align);
+ }
+
/// getObjectOffset - Return the assigned stack offset of the specified object
/// from the incoming stack pointer.
///
- int getObjectOffset(int ObjectIdx) const {
- assert(ObjectIdx+NumFixedObjects < Objects.size() && "Invalid Object Idx!");
+ int64_t getObjectOffset(int ObjectIdx) const {
+ assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
+ "Invalid Object Idx!");
+ assert(!isDeadObjectIndex(ObjectIdx) &&
+ "Getting frame offset for a dead object?");
return Objects[ObjectIdx+NumFixedObjects].SPOffset;
}
/// setObjectOffset - Set the stack frame offset of the specified object. The
/// offset is relative to the stack pointer on entry to the function.
///
- void setObjectOffset(int ObjectIdx, int SPOffset) {
- assert(ObjectIdx+NumFixedObjects < Objects.size() && "Invalid Object Idx!");
+ void setObjectOffset(int ObjectIdx, int64_t SPOffset) {
+ assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
+ "Invalid Object Idx!");
+ assert(!isDeadObjectIndex(ObjectIdx) &&
+ "Setting frame offset for a dead object?");
Objects[ObjectIdx+NumFixedObjects].SPOffset = SPOffset;
}
/// all of the fixed size frame objects. This is only valid after
/// Prolog/Epilog code insertion has finalized the stack frame layout.
///
- unsigned getStackSize() const { return StackSize; }
+ uint64_t getStackSize() const { return StackSize; }
/// setStackSize - Set the size of the stack...
///
- void setStackSize(unsigned Size) { StackSize = Size; }
+ void setStackSize(uint64_t Size) { StackSize = Size; }
+
+ /// getOffsetAdjustment - Return the correction for frame offsets.
+ ///
+ int getOffsetAdjustment() const { return OffsetAdjustment; }
+
+ /// setOffsetAdjustment - Set the correction for frame offsets.
+ ///
+ void setOffsetAdjustment(int Adj) { OffsetAdjustment = Adj; }
- /// hasCalls - Return true if the current function has no function calls.
- /// This is only valid during or after prolog/epilog code emission.
+ /// getMaxAlignment - Return the alignment in bytes that this function must be
+ /// aligned to, which is greater than the default stack alignment provided by
+ /// the target.
///
+ unsigned getMaxAlignment() const { return MaxAlignment; }
+
+ /// setMaxAlignment - Set the preferred alignment.
+ ///
+ void setMaxAlignment(unsigned Align) { MaxAlignment = Align; }
+
+ /// AdjustsStack - Return true if this function adjusts the stack -- e.g.,
+ /// when calling another function. This is only valid during and after
+ /// prolog/epilog code insertion.
+ bool adjustsStack() const { return AdjustsStack; }
+ void setAdjustsStack(bool V) { AdjustsStack = V; }
+
+ /// hasCalls - Return true if the current function has any function calls.
bool hasCalls() const { return HasCalls; }
void setHasCalls(bool V) { HasCalls = V; }
-
+
/// getMaxCallFrameSize - Return the maximum size of a call frame that must be
/// allocated for an outgoing function call. This is only available if
/// CallFrameSetup/Destroy pseudo instructions are used by the target, and
/// CreateFixedObject - Create a new object at a fixed location on the stack.
/// All fixed objects should be created before other objects are created for
- /// efficiency. This returns an index with a negative value.
+ /// efficiency. By default, fixed objects are immutable. This returns an
+ /// index with a negative value.
///
- int CreateFixedObject(unsigned Size, int SPOffset) {
- assert(Size != 0 && "Cannot allocate zero size fixed stack objects!");
- Objects.insert(Objects.begin(), StackObject(Size, 1, SPOffset));
- return -++NumFixedObjects;
- }
+ int CreateFixedObject(uint64_t Size, int64_t SPOffset,
+ bool Immutable, bool isSS);
- /// CreateStackObject - Create a new statically sized stack object, returning
- /// a postive identifier to represent it.
+
+ /// isFixedObjectIndex - Returns true if the specified index corresponds to a
+ /// fixed stack object.
+ bool isFixedObjectIndex(int ObjectIdx) const {
+ return ObjectIdx < 0 && (ObjectIdx >= -(int)NumFixedObjects);
+ }
+
+ /// isImmutableObjectIndex - Returns true if the specified index corresponds
+ /// to an immutable object.
+ bool isImmutableObjectIndex(int ObjectIdx) const {
+ assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
+ "Invalid Object Idx!");
+ return Objects[ObjectIdx+NumFixedObjects].isImmutable;
+ }
+
+ /// isSpillSlotObjectIndex - Returns true if the specified index corresponds
+ /// to a spill slot..
+ bool isSpillSlotObjectIndex(int ObjectIdx) const {
+ assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
+ "Invalid Object Idx!");
+ return Objects[ObjectIdx+NumFixedObjects].isSpillSlot;;
+ }
+
+ /// isDeadObjectIndex - Returns true if the specified index corresponds to
+ /// a dead object.
+ bool isDeadObjectIndex(int ObjectIdx) const {
+ assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
+ "Invalid Object Idx!");
+ return Objects[ObjectIdx+NumFixedObjects].Size == ~0ULL;
+ }
+
+ /// CreateStackObject - Create a new statically sized stack object,
+ /// returning a nonnegative identifier to represent it.
///
- int CreateStackObject(unsigned Size, unsigned Alignment) {
+ int CreateStackObject(uint64_t Size, unsigned Alignment, bool isSS) {
assert(Size != 0 && "Cannot allocate zero size stack objects!");
- Objects.push_back(StackObject(Size, Alignment, -1));
- return Objects.size()-NumFixedObjects-1;
+ Objects.push_back(StackObject(Size, Alignment, 0, false, isSS));
+ int Index = (int)Objects.size()-NumFixedObjects-1;
+ assert(Index >= 0 && "Bad frame index!");
+ MaxAlignment = std::max(MaxAlignment, Alignment);
+ return Index;
}
- /// CreateStackObject - Create a stack object for a value of the specified
- /// LLVM type or register class.
+ /// CreateSpillStackObject - Create a new statically sized stack
+ /// object that represents a spill slot, returning a nonnegative
+ /// identifier to represent it.
///
- int CreateStackObject(const Type *Ty, const TargetData &TD);
- int CreateStackObject(const TargetRegisterClass *RC);
+ int CreateSpillStackObject(uint64_t Size, unsigned Alignment) {
+ CreateStackObject(Size, Alignment, true);
+ int Index = (int)Objects.size()-NumFixedObjects-1;
+ MaxAlignment = std::max(MaxAlignment, Alignment);
+ return Index;
+ }
+
+ /// RemoveStackObject - Remove or mark dead a statically sized stack object.
+ ///
+ void RemoveStackObject(int ObjectIdx) {
+ // Mark it dead.
+ Objects[ObjectIdx+NumFixedObjects].Size = ~0ULL;
+ }
/// CreateVariableSizedObject - Notify the MachineFrameInfo object that a
/// variable sized object has been created. This must be created whenever a
///
int CreateVariableSizedObject() {
HasVarSizedObjects = true;
- Objects.push_back(StackObject(0, 1, -1));
- return Objects.size()-NumFixedObjects-1;
+ Objects.push_back(StackObject(0, 1, 0, false, false));
+ return (int)Objects.size()-NumFixedObjects-1;
+ }
+
+ /// getCalleeSavedInfo - Returns a reference to call saved info vector for the
+ /// current function.
+ const std::vector<CalleeSavedInfo> &getCalleeSavedInfo() const {
+ return CSInfo;
}
+ /// setCalleeSavedInfo - Used by prolog/epilog inserter to set the function's
+ /// callee saved information.
+ void setCalleeSavedInfo(const std::vector<CalleeSavedInfo> &CSI) {
+ CSInfo = CSI;
+ }
+
+ /// isCalleeSavedInfoValid - Has the callee saved info been calculated yet?
+ bool isCalleeSavedInfoValid() const { return CSIValid; }
+
+ void setCalleeSavedInfoValid(bool v) { CSIValid = v; }
+
+ /// getPristineRegs - Return a set of physical registers that are pristine on
+ /// entry to the MBB.
+ ///
+ /// Pristine registers hold a value that is useless to the current function,
+ /// but that must be preserved - they are callee saved registers that have not
+ /// been saved yet.
+ ///
+ /// Before the PrologueEpilogueInserter has placed the CSR spill code, this
+ /// method always returns an empty set.
+ BitVector getPristineRegs(const MachineBasicBlock *MBB) const;
+
/// print - Used by the MachineFunction printer to print information about
/// stack objects. Implemented in MachineFunction.cpp
///
- void print(const MachineFunction &MF, std::ostream &OS) const;
+ void print(const MachineFunction &MF, raw_ostream &OS) const;
- /// dump - Call print(MF, std::cerr) to be called from the debugger.
+ /// dump - Print the function to stderr.
void dump(const MachineFunction &MF) const;
};
+} // End llvm namespace
+
#endif
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