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2d64c553b4
calls that don't take a Function argument from Mips. Notable exceptions: the AsmPrinter and MipsTargetObjectFile. The latter needs to be fixed, and the former will be fixed when the general AsmPrinter changes happen. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227512 91177308-0d34-0410-b5e6-96231b3b80d8
134 lines
4.9 KiB
C++
134 lines
4.9 KiB
C++
//===-- MipsFrameLowering.cpp - Mips Frame Information --------------------===//
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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 file contains the Mips implementation of TargetFrameLowering class.
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//
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//===----------------------------------------------------------------------===//
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#include "MipsFrameLowering.h"
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#include "MCTargetDesc/MipsBaseInfo.h"
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#include "MipsAnalyzeImmediate.h"
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#include "MipsInstrInfo.h"
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#include "MipsMachineFunction.h"
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#include "MipsTargetMachine.h"
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#include "llvm/CodeGen/MachineFrameInfo.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/CodeGen/MachineModuleInfo.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/Function.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Target/TargetOptions.h"
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using namespace llvm;
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//===----------------------------------------------------------------------===//
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//
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// Stack Frame Processing methods
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// +----------------------------+
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//
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// The stack is allocated decrementing the stack pointer on
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// the first instruction of a function prologue. Once decremented,
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// all stack references are done thought a positive offset
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// from the stack/frame pointer, so the stack is considering
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// to grow up! Otherwise terrible hacks would have to be made
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// to get this stack ABI compliant :)
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//
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// The stack frame required by the ABI (after call):
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// Offset
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//
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// 0 ----------
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// 4 Args to pass
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// . saved $GP (used in PIC)
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// . Alloca allocations
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// . Local Area
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// . CPU "Callee Saved" Registers
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// . saved FP
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// . saved RA
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// . FPU "Callee Saved" Registers
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// StackSize -----------
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//
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// Offset - offset from sp after stack allocation on function prologue
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//
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// The sp is the stack pointer subtracted/added from the stack size
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// at the Prologue/Epilogue
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//
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// References to the previous stack (to obtain arguments) are done
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// with offsets that exceeds the stack size: (stacksize+(4*(num_arg-1))
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//
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// Examples:
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// - reference to the actual stack frame
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// for any local area var there is smt like : FI >= 0, StackOffset: 4
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// sw REGX, 4(SP)
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//
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// - reference to previous stack frame
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// suppose there's a load to the 5th arguments : FI < 0, StackOffset: 16.
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// The emitted instruction will be something like:
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// lw REGX, 16+StackSize(SP)
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//
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// Since the total stack size is unknown on LowerFormalArguments, all
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// stack references (ObjectOffset) created to reference the function
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// arguments, are negative numbers. This way, on eliminateFrameIndex it's
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// possible to detect those references and the offsets are adjusted to
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// their real location.
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//
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//===----------------------------------------------------------------------===//
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const MipsFrameLowering *MipsFrameLowering::create(const MipsSubtarget &ST) {
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if (ST.inMips16Mode())
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return llvm::createMips16FrameLowering(ST);
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return llvm::createMipsSEFrameLowering(ST);
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}
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// hasFP - Return true if the specified function should have a dedicated frame
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// pointer register. This is true if the function has variable sized allocas or
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// if frame pointer elimination is disabled.
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bool MipsFrameLowering::hasFP(const MachineFunction &MF) const {
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const MachineFrameInfo *MFI = MF.getFrameInfo();
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return MF.getTarget().Options.DisableFramePointerElim(MF) ||
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MFI->hasVarSizedObjects() || MFI->isFrameAddressTaken();
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}
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uint64_t MipsFrameLowering::estimateStackSize(const MachineFunction &MF) const {
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const MachineFrameInfo *MFI = MF.getFrameInfo();
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const TargetRegisterInfo &TRI = *STI.getRegisterInfo();
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int64_t Offset = 0;
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// Iterate over fixed sized objects.
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for (int I = MFI->getObjectIndexBegin(); I != 0; ++I)
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Offset = std::max(Offset, -MFI->getObjectOffset(I));
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// Conservatively assume all callee-saved registers will be saved.
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for (const MCPhysReg *R = TRI.getCalleeSavedRegs(&MF); *R; ++R) {
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unsigned Size = TRI.getMinimalPhysRegClass(*R)->getSize();
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Offset = RoundUpToAlignment(Offset + Size, Size);
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}
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unsigned MaxAlign = MFI->getMaxAlignment();
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// Check that MaxAlign is not zero if there is a stack object that is not a
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// callee-saved spill.
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assert(!MFI->getObjectIndexEnd() || MaxAlign);
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// Iterate over other objects.
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for (unsigned I = 0, E = MFI->getObjectIndexEnd(); I != E; ++I)
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Offset = RoundUpToAlignment(Offset + MFI->getObjectSize(I), MaxAlign);
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// Call frame.
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if (MFI->adjustsStack() && hasReservedCallFrame(MF))
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Offset = RoundUpToAlignment(Offset + MFI->getMaxCallFrameSize(),
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std::max(MaxAlign, getStackAlignment()));
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return RoundUpToAlignment(Offset, getStackAlignment());
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}
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