llvm-6502/lib/Target/TargetInstrInfo.cpp
Evan Cheng 3ef1c8759a Teach if-converter to be more careful with predicating instructions that would
take multiple cycles to decode.
For the current if-converter clients (actually only ARM), the instructions that
are predicated on false are not nops. They would still take machine cycles to
decode. Micro-coded instructions such as LDM / STM can potentially take multiple
cycles to decode. If-converter should take treat them as non-micro-coded
simple instructions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@113570 91177308-0d34-0410-b5e6-96231b3b80d8
2010-09-10 01:29:16 +00:00

117 lines
3.9 KiB
C++

//===-- TargetInstrInfo.cpp - Target Instruction Information --------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the TargetInstrInfo class.
//
//===----------------------------------------------------------------------===//
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/Target/TargetInstrItineraries.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Support/ErrorHandling.h"
using namespace llvm;
//===----------------------------------------------------------------------===//
// TargetOperandInfo
//===----------------------------------------------------------------------===//
/// getRegClass - Get the register class for the operand, handling resolution
/// of "symbolic" pointer register classes etc. If this is not a register
/// operand, this returns null.
const TargetRegisterClass *
TargetOperandInfo::getRegClass(const TargetRegisterInfo *TRI) const {
if (isLookupPtrRegClass())
return TRI->getPointerRegClass(RegClass);
// Instructions like INSERT_SUBREG do not have fixed register classes.
if (RegClass < 0)
return 0;
// Otherwise just look it up normally.
return TRI->getRegClass(RegClass);
}
//===----------------------------------------------------------------------===//
// TargetInstrInfo
//===----------------------------------------------------------------------===//
TargetInstrInfo::TargetInstrInfo(const TargetInstrDesc* Desc,
unsigned numOpcodes)
: Descriptors(Desc), NumOpcodes(numOpcodes) {
}
TargetInstrInfo::~TargetInstrInfo() {
}
unsigned
TargetInstrInfo::getNumMicroOps(const MachineInstr *MI,
const InstrItineraryData *ItinData) const {
if (!ItinData || ItinData->isEmpty())
return 1;
unsigned Class = MI->getDesc().getSchedClass();
unsigned UOps = ItinData->Itineratries[Class].NumMicroOps;
if (UOps)
return UOps;
// The # of u-ops is dynamically determined. The specific target should
// override this function to return the right number.
return 1;
}
/// insertNoop - Insert a noop into the instruction stream at the specified
/// point.
void TargetInstrInfo::insertNoop(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI) const {
llvm_unreachable("Target didn't implement insertNoop!");
}
bool TargetInstrInfo::isUnpredicatedTerminator(const MachineInstr *MI) const {
const TargetInstrDesc &TID = MI->getDesc();
if (!TID.isTerminator()) return false;
// Conditional branch is a special case.
if (TID.isBranch() && !TID.isBarrier())
return true;
if (!TID.isPredicable())
return true;
return !isPredicated(MI);
}
/// Measure the specified inline asm to determine an approximation of its
/// length.
/// Comments (which run till the next SeparatorChar or newline) do not
/// count as an instruction.
/// Any other non-whitespace text is considered an instruction, with
/// multiple instructions separated by SeparatorChar or newlines.
/// Variable-length instructions are not handled here; this function
/// may be overloaded in the target code to do that.
unsigned TargetInstrInfo::getInlineAsmLength(const char *Str,
const MCAsmInfo &MAI) const {
// Count the number of instructions in the asm.
bool atInsnStart = true;
unsigned Length = 0;
for (; *Str; ++Str) {
if (*Str == '\n' || *Str == MAI.getSeparatorChar())
atInsnStart = true;
if (atInsnStart && !isspace(*Str)) {
Length += MAI.getMaxInstLength();
atInsnStart = false;
}
if (atInsnStart && strncmp(Str, MAI.getCommentString(),
strlen(MAI.getCommentString())) == 0)
atInsnStart = false;
}
return Length;
}