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llvm/lib/Target/WebAssembly/WebAssemblyOptimizeReturned.cpp
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Chandler Carruth 6b547686c5 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@351636 91177308-0d34-0410-b5e6-96231b3b80d8
2019-01-19 08:50:56 +00:00

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2.6 KiB
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//===-- WebAssemblyOptimizeReturned.cpp - Optimize "returned" attributes --===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \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) {
LLVM_DEBUG(dbgs() << "********** Optimize returned Attributes **********\n"
"********** Function: "
<< F.getName() << '\n');
DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
visit(F);
return true;
}