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llvm-mirror/lib/Target/Mips/MipsModuleISelDAGToDAG.h
Reed Kotler 9b753510a5 This patch enables llvm to switch between compiling for mips32/mips64
and mips16 on a per function basis.

Because this patch is somewhat involved I have provide an overview of the
key pieces of it.

The patch is written so as to not change the behavior of the non mixed
mode. We have tested this a lot but it is something new to switch subtargets
so we don't want any chance of regression in the mainline compiler until
we have more confidence in this.

Mips32/64 are very different from Mip16 as is the case of ARM vs Thumb1.
For that reason there are derived versions of the register info, frame info, 
instruction info and instruction selection classes.

Now we register three separate passes for instruction selection.
One which is used to switch subtargets (MipsModuleISelDAGToDAG.cpp) and then
one for each of the current subtargets (Mips16ISelDAGToDAG.cpp and
MipsSEISelDAGToDAG.cpp).

When the ModuleISel pass runs, it determines if there is a need to switch
subtargets and if so, the owning pointers in MipsTargetMachine are
appropriately changed.

When 16Isel or SEIsel is run, they will return immediately without doing
any work if the current subtarget mode does not apply to them.

In addition, MipsAsmPrinter needs to be reset on a function basis.

The pass BasicTargetTransformInfo is substituted with a null pass since the
pass is immutable and really needs to be a function pass for it to be
used with changing subtargets. This will be fixed in a follow on patch.

llvm-svn: 179118
2013-04-09 19:46:01 +00:00

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2.1 KiB
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//===---- MipsModuleISelDAGToDAG.h - Change Subtarget --------===//
//
// 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 pass used to change the subtarget for the
// Mips Instruction selector.
//
//===----------------------------------------------------------------------===//
#ifndef MIPSMODULEISELDAGTODAG_H
#define MIPSMODULEISELDAGTODAG_H
#include "Mips.h"
#include "MipsSubtarget.h"
#include "MipsTargetMachine.h"
#include "llvm/CodeGen/SelectionDAGISel.h"
//===----------------------------------------------------------------------===//
// Instruction Selector Implementation
//===----------------------------------------------------------------------===//
//===----------------------------------------------------------------------===//
// MipsModuleDAGToDAGISel - MIPS specific code to select MIPS machine
// instructions for SelectionDAG operations.
//===----------------------------------------------------------------------===//
namespace llvm {
class MipsModuleDAGToDAGISel : public MachineFunctionPass {
public:
static char ID;
explicit MipsModuleDAGToDAGISel(MipsTargetMachine &TM_)
: MachineFunctionPass(ID),
TM(TM_), Subtarget(TM.getSubtarget<MipsSubtarget>()) {}
// Pass Name
virtual const char *getPassName() const {
return "MIPS DAG->DAG Pattern Instruction Selection";
}
virtual bool runOnMachineFunction(MachineFunction &MF);
virtual SDNode *Select(SDNode *N) {
llvm_unreachable("unexpected");
}
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;
};
/// createMipsISelDag - This pass converts a legalized DAG into a
/// MIPS-specific DAG, ready for instruction scheduling.
FunctionPass *createMipsModuleISelDag(MipsTargetMachine &TM);
}
#endif