llvm-mirror/lib/Target/Mips/Mips16HardFloat.h
Reed Kotler 88fbecdc6f Checkin in of first of several patches to finish implementation of
mips16/mips32 floating point interoperability. 

This patch fixes returns from mips16 functions so that if the function
was in fact called by a mips32 hard float routine, then values
that would have been returned in floating point registers are so returned.

Mips16 mode has no floating point instructions so there is no way to
load values into floating point registers.

This is needed when returning float, double, single complex, double complex
in the Mips ABI.

Helper functions in libc for mips16 are available to do this.

For efficiency purposes, these helper functions have a different calling
convention from normal Mips calls.

Registers v0,v1,a0,a1 are used to pass parameters instead of
a0,a1,a2,a3.

This is because v0,v1,a0,a1 are the natural registers used to return
floating point values in soft float. These values can then be moved
to the appropriate floating point registers with no extra cost.

The only register that is modified is ra in this call.

The helper functions make sure that the return values are in the floating
point registers that they would be in if soft float was not in effect
(which it is for mips16, though the soft float is implemented using a mips32
library that uses hard float).
 

llvm-svn: 181641
2013-05-10 22:25:39 +00:00

55 lines
1.4 KiB
C++

//===---- Mips16HardFloat.h for Mips16 Hard Float --------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines a phase which implements part of the floating point
// interoperability between Mips16 and Mips32 code.
//
//===----------------------------------------------------------------------===//
#include "MCTargetDesc/MipsMCTargetDesc.h"
#include "MipsTargetMachine.h"
#include "llvm/Pass.h"
#include "llvm/Target/TargetMachine.h"
#ifndef MIPS16HARDFLOAT_H
#define MIPS16HARDFLOAT_H
using namespace llvm;
namespace llvm {
class Mips16HardFloat : public ModulePass {
public:
static char ID;
Mips16HardFloat(MipsTargetMachine &TM_) : ModulePass(ID),
TM(TM_), Subtarget(TM.getSubtarget<MipsSubtarget>()) {
}
virtual const char *getPassName() const {
return "MIPS16 Hard Float Pass";
}
virtual bool runOnModule(Module &M);
protected:
/// Keep a pointer to the MipsSubtarget around so that we can make the right
/// decision when generating code for different targets.
const TargetMachine &TM;
const MipsSubtarget &Subtarget;
};
ModulePass *createMips16HardFloat(MipsTargetMachine &TM);
}
#endif