mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-12-22 07:32:48 +00:00
0035f9c3b9
For the AAPCS ABI, SP must always be 4-byte aligned, and at any "public interface" it must be 8-byte aligned. For the older ARM APCS ABI, the stack alignment is just always 4 bytes. For X86, we currently align SP at entry to a function (e.g., to 16 bytes for Darwin), but no stack alignment is needed at other times, such as for a leaf function. After discussing this with Dan, I decided to go with the approach of adding a new "TransientStackAlignment" field to TargetFrameInfo. This value specifies the stack alignment that must be maintained even in between calls. It defaults to 1 except for ARM, where it is 4. (Some other targets may also want to set this if they have similar stack requirements. It's not currently required for PPC because it sets targetHandlesStackFrameRounding and handles the alignment in target-specific code.) The existing StackAlignment value specifies the alignment upon entry to a function, which is how we've been using it anyway. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82767 91177308-0d34-0410-b5e6-96231b3b80d8
92 lines
3.2 KiB
C++
92 lines
3.2 KiB
C++
//===-- llvm/Target/TargetFrameInfo.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_TARGETFRAMEINFO_H
|
|
#define LLVM_TARGET_TARGETFRAMEINFO_H
|
|
|
|
#include <utility>
|
|
|
|
namespace llvm {
|
|
|
|
/// 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 TargetFrameInfo {
|
|
public:
|
|
enum StackDirection {
|
|
StackGrowsUp, // Adding to the stack increases the stack address
|
|
StackGrowsDown // Adding to the stack decreases the stack address
|
|
};
|
|
private:
|
|
StackDirection StackDir;
|
|
unsigned StackAlignment;
|
|
unsigned TransientStackAlignment;
|
|
int LocalAreaOffset;
|
|
public:
|
|
TargetFrameInfo(StackDirection D, unsigned StackAl, int LAO,
|
|
unsigned TransAl = 1)
|
|
: StackDir(D), StackAlignment(StackAl), TransientStackAlignment(TransAl),
|
|
LocalAreaOffset(LAO) {}
|
|
|
|
virtual ~TargetFrameInfo();
|
|
|
|
// 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 std::pair<unsigned, int> *
|
|
getCalleeSavedSpillSlots(unsigned &NumEntries) const {
|
|
NumEntries = 0;
|
|
return 0;
|
|
}
|
|
};
|
|
|
|
} // End llvm namespace
|
|
|
|
#endif
|