contrib/llvm/lib/Target/AMDGPU/AMDGPUAnnotateUniformValues.cpp

   1 //===-- AMDGPUAnnotateUniformValues.cpp - ---------------------------------===//
   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 /// \file
  11 /// This pass adds amdgpu.uniform metadata to IR values so this information
  12 /// can be used during instruction selection.
  13 //
  14 //===----------------------------------------------------------------------===//
  15
  16 #include "AMDGPU.h"
  17 #include "AMDGPUIntrinsicInfo.h"
  18 #include "llvm/Analysis/DivergenceAnalysis.h"
  19 #include "llvm/IR/InstVisitor.h"
  20 #include "llvm/IR/IRBuilder.h"
  21 #include "llvm/Support/Debug.h"
  22 #include "llvm/Support/raw_ostream.h"
  23
  24 #define DEBUG_TYPE "amdgpu-annotate-uniform"
  25
  26 using namespace llvm;
  27
  28 namespace {
  29
  30 class AMDGPUAnnotateUniformValues : public FunctionPass,
  31                        public InstVisitor<AMDGPUAnnotateUniformValues> {
  32   DivergenceAnalysis *DA;
  33
  34 public:
  35   static char ID;
  36   AMDGPUAnnotateUniformValues() :
  37     FunctionPass(ID) { }
  38   bool doInitialization(Module &M) override;
  39   bool runOnFunction(Function &F) override;
  40   const char *getPassName() const override { return "AMDGPU Annotate Uniform Values"; }
  41   void getAnalysisUsage(AnalysisUsage &AU) const override {
  42     AU.addRequired<DivergenceAnalysis>();
  43     AU.setPreservesAll();
  44  }
  45
  46   void visitBranchInst(BranchInst &I);
  47   void visitLoadInst(LoadInst &I);
  48
  49 };
  50
  51 } // End anonymous namespace
  52
  53 INITIALIZE_PASS_BEGIN(AMDGPUAnnotateUniformValues, DEBUG_TYPE,
  54                       "Add AMDGPU uniform metadata", false, false)
  55 INITIALIZE_PASS_DEPENDENCY(DivergenceAnalysis)
  56 INITIALIZE_PASS_END(AMDGPUAnnotateUniformValues, DEBUG_TYPE,
  57                     "Add AMDGPU uniform metadata", false, false)
  58
  59 char AMDGPUAnnotateUniformValues::ID = 0;
  60
  61 static void setUniformMetadata(Instruction *I) {
  62   I->setMetadata("amdgpu.uniform", MDNode::get(I->getContext(), {}));
  63 }
  64
  65 void AMDGPUAnnotateUniformValues::visitBranchInst(BranchInst &I) {
  66   if (I.isUnconditional())
  67     return;
  68
  69   Value *Cond = I.getCondition();
  70   if (!DA->isUniform(Cond))
  71     return;
  72
  73   setUniformMetadata(I.getParent()->getTerminator());
  74 }
  75
  76 void AMDGPUAnnotateUniformValues::visitLoadInst(LoadInst &I) {
  77   Value *Ptr = I.getPointerOperand();
  78   if (!DA->isUniform(Ptr))
  79     return;
  80
  81   if (Instruction *PtrI = dyn_cast<Instruction>(Ptr))
  82     setUniformMetadata(PtrI);
  83
  84 }
  85
  86 bool AMDGPUAnnotateUniformValues::doInitialization(Module &M) {
  87   return false;
  88 }
  89
  90 bool AMDGPUAnnotateUniformValues::runOnFunction(Function &F) {
  91   if (skipFunction(F))
  92     return false;
  93
  94   DA = &getAnalysis<DivergenceAnalysis>();
  95   visit(F);
  96
  97   return true;
  98 }
  99
 100 FunctionPass *
 101 llvm::createAMDGPUAnnotateUniformValues() {
 102   return new AMDGPUAnnotateUniformValues();
 103 }