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//===- llvm/CodeGen/GlobalISel/InstructionSelect.cpp - InstructionSelect ---==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
/// \file
/// This file implements the InstructionSelect class.
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/GlobalISel/InstructionSelect.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/Twine.h"
#include "llvm/CodeGen/GlobalISel/InstructionSelector.h"
#include "llvm/CodeGen/GlobalISel/MachineLegalizer.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/IR/Function.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Target/TargetSubtargetInfo.h"
#define DEBUG_TYPE "instruction-select"
using namespace llvm;
char InstructionSelect::ID = 0;
INITIALIZE_PASS(InstructionSelect, DEBUG_TYPE,
"Select target instructions out of generic instructions",
false, false);
InstructionSelect::InstructionSelect() : MachineFunctionPass(ID) {
initializeInstructionSelectPass(*PassRegistry::getPassRegistry());
}
static void reportSelectionError(const MachineInstr &MI, const Twine &Message) {
const MachineFunction &MF = *MI.getParent()->getParent();
std::string ErrStorage;
raw_string_ostream Err(ErrStorage);
Err << Message << ":\nIn function: " << MF.getName() << '\n' << MI << '\n';
report_fatal_error(Err.str());
}
bool InstructionSelect::runOnMachineFunction(MachineFunction &MF) {
DEBUG(dbgs() << "Selecting function: " << MF.getName() << '\n');
const InstructionSelector *ISel = MF.getSubtarget().getInstructionSelector();
assert(ISel && "Cannot work without InstructionSelector");
// FIXME: freezeReservedRegs is now done in IRTranslator, but there are many
// other MF/MFI fields we need to initialize.
#ifndef NDEBUG
// Check that our input is fully legal: we require the function to have the
// Legalized property, so it should be.
// FIXME: This should be in the MachineVerifier, but it can't use the
// MachineLegalizer as it's currently in the separate GlobalISel library.
// The RegBankSelected property is already checked in the verifier. Note
// that it has the same layering problem, but we only use inline methods so
// end up not needing to link against the GlobalISel library.
if (const MachineLegalizer *MLI = MF.getSubtarget().getMachineLegalizer())
for (const MachineBasicBlock &MBB : MF)
for (const MachineInstr &MI : MBB)
if (isPreISelGenericOpcode(MI.getOpcode()) && !MLI->isLegal(MI))
reportSelectionError(MI, "Instruction is not legal");
// FIXME: We could introduce new blocks and will need to fix the outer loop.
// Until then, keep track of the number of blocks to assert that we don't.
const size_t NumBlocks = MF.size();
#endif
for (MachineBasicBlock *MBB : post_order(&MF)) {
for (MachineBasicBlock::reverse_iterator MII = MBB->rbegin(),
End = MBB->rend();
MII != End;) {
MachineInstr &MI = *MII++;
DEBUG(dbgs() << "Selecting: " << MI << '\n');
if (!ISel->select(MI))
reportSelectionError(MI, "Cannot select");
// FIXME: It would be nice to dump all inserted instructions. It's not
// obvious how, esp. considering select() can insert after MI.
}
}
assert(MF.size() == NumBlocks && "Inserting blocks is not supported yet");
// Now that selection is complete, there are no more generic vregs.
// FIXME: We're still discussing what to do with the vreg->size map:
// it's somewhat redundant (with the def MIs type size), but having to
// examine MIs is also awkward. Another alternative is to track the type on
// the vreg instead, but that's not ideal either, because it's saying that
// vregs have types, which they really don't. But then again, LLT is just
// a size and a "shape": it's probably the same information as regbank info.
MF.getRegInfo().clearVirtRegSizes();
// FIXME: Should we accurately track changes?
return true;
}
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