1 //===-- LoongArchSubtarget.cpp - LoongArch Subtarget Information -*- C++ -*--=//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements the LoongArch specific subclass of TargetSubtargetInfo.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "LoongArchSubtarget.h"
14 #include "LoongArchFrameLowering.h"
15 #include "MCTargetDesc/LoongArchBaseInfo.h"
16 
17 using namespace llvm;
18 
19 #define DEBUG_TYPE "loongarch-subtarget"
20 
21 #define GET_SUBTARGETINFO_TARGET_DESC
22 #define GET_SUBTARGETINFO_CTOR
23 #include "LoongArchGenSubtargetInfo.inc"
24 
25 void LoongArchSubtarget::anchor() {}
26 
27 LoongArchSubtarget &LoongArchSubtarget::initializeSubtargetDependencies(
28     const Triple &TT, StringRef CPU, StringRef TuneCPU, StringRef FS,
29     StringRef ABIName) {
30   bool Is64Bit = TT.isArch64Bit();
31   if (CPU.empty() || CPU == "generic")
32     CPU = Is64Bit ? "generic-la64" : "generic-la32";
33 
34   if (TuneCPU.empty())
35     TuneCPU = CPU;
36 
37   ParseSubtargetFeatures(CPU, TuneCPU, FS);
38   initializeProperties(TuneCPU);
39   if (Is64Bit) {
40     GRLenVT = MVT::i64;
41     GRLen = 64;
42   }
43 
44   if (HasLA32 == HasLA64)
45     report_fatal_error("Please use one feature of 32bit and 64bit.");
46 
47   if (Is64Bit && HasLA32)
48     report_fatal_error("Feature 32bit should be used for loongarch32 target.");
49 
50   if (!Is64Bit && HasLA64)
51     report_fatal_error("Feature 64bit should be used for loongarch64 target.");
52 
53   TargetABI = LoongArchABI::computeTargetABI(TT, ABIName);
54 
55   return *this;
56 }
57 
58 void LoongArchSubtarget::initializeProperties(StringRef TuneCPU) {
59   // Initialize CPU specific properties. We should add a tablegen feature for
60   // this in the future so we can specify it together with the subtarget
61   // features.
62 
63   // TODO: Check TuneCPU and override defaults (that are for LA464) once we
64   // support optimizing for more uarchs.
65 
66   // Default to the alignment settings empirically confirmed to perform best
67   // on LA464, with 4-wide instruction fetch and decode stages. These settings
68   // can also be overridden in initializeProperties.
69   //
70   // We default to such higher-than-minimum alignments because we assume that:
71   //
72   // * these settings should benefit most existing uarchs/users,
73   // * future general-purpose LoongArch cores are likely to have issue widths
74   //   equal to or wider than 4,
75   // * instruction sequences best for LA464 should not pessimize other future
76   //   uarchs, and
77   // * narrower cores would not suffer much (aside from slightly increased
78   //   ICache footprint maybe), compared to the gains everywhere else.
79   PrefFunctionAlignment = Align(32);
80   PrefLoopAlignment = Align(16);
81   MaxBytesForAlignment = 16;
82 }
83 
84 LoongArchSubtarget::LoongArchSubtarget(const Triple &TT, StringRef CPU,
85                                        StringRef TuneCPU, StringRef FS,
86                                        StringRef ABIName,
87                                        const TargetMachine &TM)
88     : LoongArchGenSubtargetInfo(TT, CPU, TuneCPU, FS),
89       FrameLowering(
90           initializeSubtargetDependencies(TT, CPU, TuneCPU, FS, ABIName)),
91       InstrInfo(*this), RegInfo(getHwMode()), TLInfo(TM, *this) {}
92