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1 //===- NVVMIntrRange.cpp - Set !range metadata for NVVM intrinsics --------===//
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 pass adds appropriate !range metadata for calls to NVVM
11 // intrinsics that return a limited range of values.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "NVPTX.h"
16 #include "llvm/IR/Constants.h"
17 #include "llvm/IR/InstIterator.h"
18 #include "llvm/IR/Intrinsics.h"
19 #include "llvm/IR/Instructions.h"
20 
21 using namespace llvm;
22 
23 #define DEBUG_TYPE "nvvm-intr-range"
24 
25 namespace llvm { void initializeNVVMIntrRangePass(PassRegistry &); }
26 
27 // Add !range metadata based on limits of given SM variant.
28 static cl::opt<unsigned> NVVMIntrRangeSM("nvvm-intr-range-sm", cl::init(20),
29                                          cl::Hidden, cl::desc("SM variant"));
30 
31 namespace {
32 class NVVMIntrRange : public FunctionPass {
33  private:
34    struct {
35      unsigned x, y, z;
36    } MaxBlockSize, MaxGridSize;
37 
38  public:
39    static char ID;
NVVMIntrRange()40    NVVMIntrRange() : NVVMIntrRange(NVVMIntrRangeSM) {}
NVVMIntrRange(unsigned int SmVersion)41    NVVMIntrRange(unsigned int SmVersion) : FunctionPass(ID) {
42      MaxBlockSize.x = 1024;
43      MaxBlockSize.y = 1024;
44      MaxBlockSize.z = 64;
45 
46      MaxGridSize.x = SmVersion >= 30 ? 0x7fffffff : 0xffff;
47      MaxGridSize.y = 0xffff;
48      MaxGridSize.z = 0xffff;
49 
50      initializeNVVMIntrRangePass(*PassRegistry::getPassRegistry());
51    }
52 
53    bool runOnFunction(Function &) override;
54 };
55 }
56 
createNVVMIntrRangePass(unsigned int SmVersion)57 FunctionPass *llvm::createNVVMIntrRangePass(unsigned int SmVersion) {
58   return new NVVMIntrRange(SmVersion);
59 }
60 
61 char NVVMIntrRange::ID = 0;
62 INITIALIZE_PASS(NVVMIntrRange, "nvvm-intr-range",
63                 "Add !range metadata to NVVM intrinsics.", false, false)
64 
65 // Adds the passed-in [Low,High) range information as metadata to the
66 // passed-in call instruction.
addRangeMetadata(uint64_t Low,uint64_t High,CallInst * C)67 static bool addRangeMetadata(uint64_t Low, uint64_t High, CallInst *C) {
68   LLVMContext &Context = C->getParent()->getContext();
69   IntegerType *Int32Ty = Type::getInt32Ty(Context);
70   Metadata *LowAndHigh[] = {
71       ConstantAsMetadata::get(ConstantInt::get(Int32Ty, Low)),
72       ConstantAsMetadata::get(ConstantInt::get(Int32Ty, High))};
73   C->setMetadata(LLVMContext::MD_range, MDNode::get(Context, LowAndHigh));
74   return true;
75 }
76 
runOnFunction(Function & F)77 bool NVVMIntrRange::runOnFunction(Function &F) {
78   // Go through the calls in this function.
79   bool Changed = false;
80   for (Instruction &I : instructions(F)) {
81     CallInst *Call = dyn_cast<CallInst>(&I);
82     if (!Call)
83       continue;
84 
85     if (Function *Callee = Call->getCalledFunction()) {
86       switch (Callee->getIntrinsicID()) {
87       // Index within block
88       case Intrinsic::nvvm_read_ptx_sreg_tid_x:
89         Changed |= addRangeMetadata(0, MaxBlockSize.x, Call);
90         break;
91       case Intrinsic::nvvm_read_ptx_sreg_tid_y:
92         Changed |= addRangeMetadata(0, MaxBlockSize.y, Call);
93         break;
94       case Intrinsic::nvvm_read_ptx_sreg_tid_z:
95         Changed |= addRangeMetadata(0, MaxBlockSize.z, Call);
96         break;
97 
98       // Block size
99       case Intrinsic::nvvm_read_ptx_sreg_ntid_x:
100         Changed |= addRangeMetadata(1, MaxBlockSize.x+1, Call);
101         break;
102       case Intrinsic::nvvm_read_ptx_sreg_ntid_y:
103         Changed |= addRangeMetadata(1, MaxBlockSize.y+1, Call);
104         break;
105       case Intrinsic::nvvm_read_ptx_sreg_ntid_z:
106         Changed |= addRangeMetadata(1, MaxBlockSize.z+1, Call);
107         break;
108 
109       // Index within grid
110       case Intrinsic::nvvm_read_ptx_sreg_ctaid_x:
111         Changed |= addRangeMetadata(0, MaxGridSize.x, Call);
112         break;
113       case Intrinsic::nvvm_read_ptx_sreg_ctaid_y:
114         Changed |= addRangeMetadata(0, MaxGridSize.y, Call);
115         break;
116       case Intrinsic::nvvm_read_ptx_sreg_ctaid_z:
117         Changed |= addRangeMetadata(0, MaxGridSize.z, Call);
118         break;
119 
120       // Grid size
121       case Intrinsic::nvvm_read_ptx_sreg_nctaid_x:
122         Changed |= addRangeMetadata(1, MaxGridSize.x+1, Call);
123         break;
124       case Intrinsic::nvvm_read_ptx_sreg_nctaid_y:
125         Changed |= addRangeMetadata(1, MaxGridSize.y+1, Call);
126         break;
127       case Intrinsic::nvvm_read_ptx_sreg_nctaid_z:
128         Changed |= addRangeMetadata(1, MaxGridSize.z+1, Call);
129         break;
130 
131       // warp size is constant 32.
132       case Intrinsic::nvvm_read_ptx_sreg_warpsize:
133         Changed |= addRangeMetadata(32, 32+1, Call);
134         break;
135 
136       // Lane ID is [0..warpsize)
137       case Intrinsic::nvvm_read_ptx_sreg_laneid:
138         Changed |= addRangeMetadata(0, 32, Call);
139         break;
140 
141       default:
142         break;
143       }
144     }
145   }
146 
147   return Changed;
148 }
149