1 //===-- ARMSubtarget.cpp - ARM Subtarget Information ------------*- C++ -*-===//
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 ARM specific subclass of TargetSubtarget.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "ARMSubtarget.h"
15 #include "ARMGenSubtarget.inc"
16 #include "llvm/Module.h"
17 #include "llvm/Target/TargetMachine.h"
18 #include "llvm/Target/TargetOptions.h"
19 #include "llvm/Support/CommandLine.h"
20 using namespace llvm;
21 
22 static cl::opt<bool>
23 ReserveR9("arm-reserve-r9", cl::Hidden,
24           cl::desc("Reserve R9, making it unavailable as GPR"));
25 
26 ARMSubtarget::ARMSubtarget(const Module &M, const std::string &FS,
27                            bool isThumb)
28   : ARMArchVersion(V4T)
29   , ARMFPUType(None)
30   , IsThumb(isThumb)
31   , ThumbMode(Thumb1)
32   , IsR9Reserved(ReserveR9)
33   , stackAlignment(4)
34   , CPUString("generic")
35   , TargetType(isELF) // Default to ELF unless otherwise specified.
36   , TargetABI(ARM_ABI_APCS) {
37   // default to soft float ABI
38   if (FloatABIType == FloatABI::Default)
39     FloatABIType = FloatABI::Soft;
40 
41   // Determine default and user specified characteristics
42 
43   // Parse features string.
44   CPUString = ParseSubtargetFeatures(FS, CPUString);
45 
46   // Set the boolean corresponding to the current target triple, or the default
47   // if one cannot be determined, to true.
48   const std::string& TT = M.getTargetTriple();
49   unsigned Len = TT.length();
50   unsigned Idx = 0;
51 
52   if (Len >= 5 && TT.substr(0, 4) == "armv")
53     Idx = 4;
54   else if (Len >= 6 && TT.substr(0, 5) == "thumb") {
55     IsThumb = true;
56     if (Len >= 7 && TT[5] == 'v')
57       Idx = 6;
58   }
59   if (Idx) {
60     unsigned SubVer = TT[Idx];
61     if (SubVer > '4' && SubVer <= '9') {
62       if (SubVer >= '7') {
63         ARMArchVersion = V7A;
64       } else if (SubVer == '6') {
65         ARMArchVersion = V6;
66         if (Len >= Idx+3 && TT[Idx+1] == 't' && TT[Idx+2] == '2')
67           ARMArchVersion = V6T2;
68       } else if (SubVer == '5') {
69         ARMArchVersion = V5T;
70         if (Len >= Idx+3 && TT[Idx+1] == 't' && TT[Idx+2] == 'e')
71           ARMArchVersion = V5TE;
72       }
73       if (ARMArchVersion >= V6T2)
74         ThumbMode = Thumb2;
75     }
76   }
77 
78   if (Len >= 10) {
79     if (TT.find("-darwin") != std::string::npos)
80       // arm-darwin
81       TargetType = isDarwin;
82   } else if (TT.empty()) {
83 #if defined(__APPLE__)
84     TargetType = isDarwin;
85 #endif
86   }
87 
88   if (TT.find("eabi") != std::string::npos)
89     TargetABI = ARM_ABI_AAPCS;
90 
91   if (isAAPCS_ABI())
92     stackAlignment = 8;
93 
94   if (isTargetDarwin())
95     IsR9Reserved = ReserveR9 | (ARMArchVersion < V6);
96 }
97