1 //===- NVVMIntrRange.cpp - Set !range metadata for NVVM intrinsics --------===//
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 pass adds appropriate !range metadata for calls to NVVM
10 // intrinsics that return a limited range of values.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "NVPTX.h"
15 #include "llvm/IR/Constants.h"
16 #include "llvm/IR/InstIterator.h"
17 #include "llvm/IR/Instructions.h"
18 #include "llvm/IR/Intrinsics.h"
19 #include "llvm/IR/IntrinsicsNVPTX.h"
20 #include "llvm/IR/PassManager.h"
21 #include "llvm/Support/CommandLine.h"
22
23 using namespace llvm;
24
25 #define DEBUG_TYPE "nvvm-intr-range"
26
27 namespace llvm { void initializeNVVMIntrRangePass(PassRegistry &); }
28
29 // Add !range metadata based on limits of given SM variant.
30 static cl::opt<unsigned> NVVMIntrRangeSM("nvvm-intr-range-sm", cl::init(20),
31 cl::Hidden, cl::desc("SM variant"));
32
33 namespace {
34 class NVVMIntrRange : public FunctionPass {
35 private:
36 unsigned SmVersion;
37
38 public:
39 static char ID;
NVVMIntrRange()40 NVVMIntrRange() : NVVMIntrRange(NVVMIntrRangeSM) {}
NVVMIntrRange(unsigned int SmVersion)41 NVVMIntrRange(unsigned int SmVersion)
42 : FunctionPass(ID), SmVersion(SmVersion) {
43
44 initializeNVVMIntrRangePass(*PassRegistry::getPassRegistry());
45 }
46
47 bool runOnFunction(Function &) override;
48 };
49 }
50
createNVVMIntrRangePass(unsigned int SmVersion)51 FunctionPass *llvm::createNVVMIntrRangePass(unsigned int SmVersion) {
52 return new NVVMIntrRange(SmVersion);
53 }
54
55 char NVVMIntrRange::ID = 0;
56 INITIALIZE_PASS(NVVMIntrRange, "nvvm-intr-range",
57 "Add !range metadata to NVVM intrinsics.", false, false)
58
59 // Adds the passed-in [Low,High) range information as metadata to the
60 // passed-in call instruction.
addRangeMetadata(uint64_t Low,uint64_t High,CallInst * C)61 static bool addRangeMetadata(uint64_t Low, uint64_t High, CallInst *C) {
62 // This call already has range metadata, nothing to do.
63 if (C->getMetadata(LLVMContext::MD_range))
64 return false;
65
66 LLVMContext &Context = C->getParent()->getContext();
67 IntegerType *Int32Ty = Type::getInt32Ty(Context);
68 Metadata *LowAndHigh[] = {
69 ConstantAsMetadata::get(ConstantInt::get(Int32Ty, Low)),
70 ConstantAsMetadata::get(ConstantInt::get(Int32Ty, High))};
71 C->setMetadata(LLVMContext::MD_range, MDNode::get(Context, LowAndHigh));
72 return true;
73 }
74
runNVVMIntrRange(Function & F,unsigned SmVersion)75 static bool runNVVMIntrRange(Function &F, unsigned SmVersion) {
76 struct {
77 unsigned x, y, z;
78 } MaxBlockSize, MaxGridSize;
79 MaxBlockSize.x = 1024;
80 MaxBlockSize.y = 1024;
81 MaxBlockSize.z = 64;
82
83 MaxGridSize.x = SmVersion >= 30 ? 0x7fffffff : 0xffff;
84 MaxGridSize.y = 0xffff;
85 MaxGridSize.z = 0xffff;
86
87 // Go through the calls in this function.
88 bool Changed = false;
89 for (Instruction &I : instructions(F)) {
90 CallInst *Call = dyn_cast<CallInst>(&I);
91 if (!Call)
92 continue;
93
94 if (Function *Callee = Call->getCalledFunction()) {
95 switch (Callee->getIntrinsicID()) {
96 // Index within block
97 case Intrinsic::nvvm_read_ptx_sreg_tid_x:
98 Changed |= addRangeMetadata(0, MaxBlockSize.x, Call);
99 break;
100 case Intrinsic::nvvm_read_ptx_sreg_tid_y:
101 Changed |= addRangeMetadata(0, MaxBlockSize.y, Call);
102 break;
103 case Intrinsic::nvvm_read_ptx_sreg_tid_z:
104 Changed |= addRangeMetadata(0, MaxBlockSize.z, Call);
105 break;
106
107 // Block size
108 case Intrinsic::nvvm_read_ptx_sreg_ntid_x:
109 Changed |= addRangeMetadata(1, MaxBlockSize.x+1, Call);
110 break;
111 case Intrinsic::nvvm_read_ptx_sreg_ntid_y:
112 Changed |= addRangeMetadata(1, MaxBlockSize.y+1, Call);
113 break;
114 case Intrinsic::nvvm_read_ptx_sreg_ntid_z:
115 Changed |= addRangeMetadata(1, MaxBlockSize.z+1, Call);
116 break;
117
118 // Index within grid
119 case Intrinsic::nvvm_read_ptx_sreg_ctaid_x:
120 Changed |= addRangeMetadata(0, MaxGridSize.x, Call);
121 break;
122 case Intrinsic::nvvm_read_ptx_sreg_ctaid_y:
123 Changed |= addRangeMetadata(0, MaxGridSize.y, Call);
124 break;
125 case Intrinsic::nvvm_read_ptx_sreg_ctaid_z:
126 Changed |= addRangeMetadata(0, MaxGridSize.z, Call);
127 break;
128
129 // Grid size
130 case Intrinsic::nvvm_read_ptx_sreg_nctaid_x:
131 Changed |= addRangeMetadata(1, MaxGridSize.x+1, Call);
132 break;
133 case Intrinsic::nvvm_read_ptx_sreg_nctaid_y:
134 Changed |= addRangeMetadata(1, MaxGridSize.y+1, Call);
135 break;
136 case Intrinsic::nvvm_read_ptx_sreg_nctaid_z:
137 Changed |= addRangeMetadata(1, MaxGridSize.z+1, Call);
138 break;
139
140 // warp size is constant 32.
141 case Intrinsic::nvvm_read_ptx_sreg_warpsize:
142 Changed |= addRangeMetadata(32, 32+1, Call);
143 break;
144
145 // Lane ID is [0..warpsize)
146 case Intrinsic::nvvm_read_ptx_sreg_laneid:
147 Changed |= addRangeMetadata(0, 32, Call);
148 break;
149
150 default:
151 break;
152 }
153 }
154 }
155
156 return Changed;
157 }
158
runOnFunction(Function & F)159 bool NVVMIntrRange::runOnFunction(Function &F) {
160 return runNVVMIntrRange(F, SmVersion);
161 }
162
NVVMIntrRangePass()163 NVVMIntrRangePass::NVVMIntrRangePass() : NVVMIntrRangePass(NVVMIntrRangeSM) {}
164
run(Function & F,FunctionAnalysisManager & AM)165 PreservedAnalyses NVVMIntrRangePass::run(Function &F,
166 FunctionAnalysisManager &AM) {
167 return runNVVMIntrRange(F, SmVersion) ? PreservedAnalyses::none()
168 : PreservedAnalyses::all();
169 }
170