Line data    Source code

       1             : //===-- WebAssemblyOptimizeReturned.cpp - Optimize "returned" attributes --===//
       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             : /// Optimize calls with "returned" attributes for WebAssembly.
      12             : ///
      13             : //===----------------------------------------------------------------------===//
      14             : 
      15             : #include "WebAssembly.h"
      16             : #include "llvm/IR/Dominators.h"
      17             : #include "llvm/IR/InstVisitor.h"
      18             : #include "llvm/Support/Debug.h"
      19             : #include "llvm/Support/raw_ostream.h"
      20             : using namespace llvm;
      21             : 
      22             : #define DEBUG_TYPE "wasm-optimize-returned"
      23             : 
      24             : namespace {
      25             : class OptimizeReturned final : public FunctionPass,
      26             :                                public InstVisitor<OptimizeReturned> {
      27           0 :   StringRef getPassName() const override {
      28           0 :     return "WebAssembly Optimize Returned";
      29             :   }
      30             : 
      31         298 :   void getAnalysisUsage(AnalysisUsage &AU) const override {
      32         298 :     AU.setPreservesCFG();
      33             :     AU.addRequired<DominatorTreeWrapperPass>();
      34             :     AU.addPreserved<DominatorTreeWrapperPass>();
      35         298 :     FunctionPass::getAnalysisUsage(AU);
      36         298 :   }
      37             : 
      38             :   bool runOnFunction(Function &F) override;
      39             : 
      40             :   DominatorTree *DT;
      41             : 
      42             : public:
      43             :   static char ID;
      44         596 :   OptimizeReturned() : FunctionPass(ID), DT(nullptr) {}
      45             : 
      46             :   void visitCallSite(CallSite CS);
      47             : };
      48             : } // End anonymous namespace
      49             : 
      50             : char OptimizeReturned::ID = 0;
      51      199030 : INITIALIZE_PASS(OptimizeReturned, DEBUG_TYPE,
      52             :                 "Optimize calls with \"returned\" attributes for WebAssembly",
      53             :                 false, false)
      54             : 
      55         298 : FunctionPass *llvm::createWebAssemblyOptimizeReturned() {
      56         298 :   return new OptimizeReturned();
      57             : }
      58             : 
      59           0 : void OptimizeReturned::visitCallSite(CallSite CS) {
      60           0 :   for (unsigned i = 0, e = CS.getNumArgOperands(); i < e; ++i)
      61           0 :     if (CS.paramHasAttr(i, Attribute::Returned)) {
      62             :       Instruction *Inst = CS.getInstruction();
      63           0 :       Value *Arg = CS.getArgOperand(i);
      64             :       // Ignore constants, globals, undef, etc.
      65           0 :       if (isa<Constant>(Arg))
      66             :         continue;
      67             :       // Like replaceDominatedUsesWith but using Instruction/Use dominance.
      68           0 :       for (auto UI = Arg->use_begin(), UE = Arg->use_end(); UI != UE;) {
      69             :         Use &U = *UI++;
      70           0 :         if (DT->dominates(Inst, U))
      71           0 :           U.set(Inst);
      72             :       }
      73             :     }
      74           0 : }
      75             : 
      76        3167 : bool OptimizeReturned::runOnFunction(Function &F) {
      77        3167 :   DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
      78             :   visit(F);
      79        3167 :   return true;
      80             : }