TargetInstrInfo.cpp revision 11fad6ec660d2131e040ebdecc4433b359d05e5f 
1//===-- TargetInstrInfo.cpp - Target Instruction Information --------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements the TargetInstrInfo class.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Target/TargetInstrInfo.h"
15#include "llvm/Target/TargetRegisterInfo.h"
16#include "llvm/MC/MCAsmInfo.h"
17#include "llvm/MC/MCInstrItineraries.h"
18#include "llvm/Support/ErrorHandling.h"
19#include <cctype>
20using namespace llvm;
21
22//===----------------------------------------------------------------------===//
23//  TargetInstrInfo
24//
25// Methods that depend on CodeGen are implemented in
26// TargetInstrInfoImpl.cpp. Invoking them without linking libCodeGen raises a
27// link error.
28// ===----------------------------------------------------------------------===//
29
30TargetInstrInfo::~TargetInstrInfo() {
31}
32
33const TargetRegisterClass*
34TargetInstrInfo::getRegClass(const MCInstrDesc &MCID, unsigned OpNum,
35                             const TargetRegisterInfo *TRI,
36                             const MachineFunction &MF) const {
37  if (OpNum >= MCID.getNumOperands())
38    return 0;
39
40  short RegClass = MCID.OpInfo[OpNum].RegClass;
41  if (MCID.OpInfo[OpNum].isLookupPtrRegClass())
42    return TRI->getPointerRegClass(MF, RegClass);
43
44  // Instructions like INSERT_SUBREG do not have fixed register classes.
45  if (RegClass < 0)
46    return 0;
47
48  // Otherwise just look it up normally.
49  return TRI->getRegClass(RegClass);
50}
51
52/// insertNoop - Insert a noop into the instruction stream at the specified
53/// point.
54void TargetInstrInfo::insertNoop(MachineBasicBlock &MBB,
55                                 MachineBasicBlock::iterator MI) const {
56  llvm_unreachable("Target didn't implement insertNoop!");
57}
58
59/// Measure the specified inline asm to determine an approximation of its
60/// length.
61/// Comments (which run till the next SeparatorString or newline) do not
62/// count as an instruction.
63/// Any other non-whitespace text is considered an instruction, with
64/// multiple instructions separated by SeparatorString or newlines.
65/// Variable-length instructions are not handled here; this function
66/// may be overloaded in the target code to do that.
67unsigned TargetInstrInfo::getInlineAsmLength(const char *Str,
68                                             const MCAsmInfo &MAI) const {
69
70
71  // Count the number of instructions in the asm.
72  bool atInsnStart = true;
73  unsigned Length = 0;
74  for (; *Str; ++Str) {
75    if (*Str == '\n' || strncmp(Str, MAI.getSeparatorString(),
76                                strlen(MAI.getSeparatorString())) == 0)
77      atInsnStart = true;
78    if (atInsnStart && !std::isspace(*Str)) {
79      Length += MAI.getMaxInstLength();
80      atInsnStart = false;
81    }
82    if (atInsnStart && strncmp(Str, MAI.getCommentString(),
83                               strlen(MAI.getCommentString())) == 0)
84      atInsnStart = false;
85  }
86
87  return Length;
88}
89