| //===-- WebAssemblyOptimizeReturned.cpp - Optimize "returned" attributes --===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| /// |
| /// \file |
| /// Optimize calls with "returned" attributes for WebAssembly. |
| /// |
| //===----------------------------------------------------------------------===// |
| |
| #include "WebAssembly.h" |
| #include "llvm/IR/Dominators.h" |
| #include "llvm/IR/InstVisitor.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/raw_ostream.h" |
| using namespace llvm; |
| |
| #define DEBUG_TYPE "wasm-optimize-returned" |
| |
| namespace { |
| class OptimizeReturned final : public FunctionPass, |
| public InstVisitor<OptimizeReturned> { |
| StringRef getPassName() const override { |
| return "WebAssembly Optimize Returned"; |
| } |
| |
| void getAnalysisUsage(AnalysisUsage &AU) const override { |
| AU.setPreservesCFG(); |
| AU.addRequired<DominatorTreeWrapperPass>(); |
| AU.addPreserved<DominatorTreeWrapperPass>(); |
| FunctionPass::getAnalysisUsage(AU); |
| } |
| |
| bool runOnFunction(Function &F) override; |
| |
| DominatorTree *DT; |
| |
| public: |
| static char ID; |
| OptimizeReturned() : FunctionPass(ID), DT(nullptr) {} |
| |
| void visitCallSite(CallSite CS); |
| }; |
| } // End anonymous namespace |
| |
| char OptimizeReturned::ID = 0; |
| INITIALIZE_PASS(OptimizeReturned, DEBUG_TYPE, |
| "Optimize calls with \"returned\" attributes for WebAssembly", |
| false, false) |
| |
| FunctionPass *llvm::createWebAssemblyOptimizeReturned() { |
| return new OptimizeReturned(); |
| } |
| |
| void OptimizeReturned::visitCallSite(CallSite CS) { |
| for (unsigned i = 0, e = CS.getNumArgOperands(); i < e; ++i) |
| if (CS.paramHasAttr(i, Attribute::Returned)) { |
| Instruction *Inst = CS.getInstruction(); |
| Value *Arg = CS.getArgOperand(i); |
| // Ignore constants, globals, undef, etc. |
| if (isa<Constant>(Arg)) |
| continue; |
| // Like replaceDominatedUsesWith but using Instruction/Use dominance. |
| for (auto UI = Arg->use_begin(), UE = Arg->use_end(); UI != UE;) { |
| Use &U = *UI++; |
| if (DT->dominates(Inst, U)) |
| U.set(Inst); |
| } |
| } |
| } |
| |
| bool OptimizeReturned::runOnFunction(Function &F) { |
| DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree(); |
| visit(F); |
| return true; |
| } |