WebAssemblyOptimizeReturned.cpp [plain text]
#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> {
const char *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);
};
}
char OptimizeReturned::ID = 0;
FunctionPass *llvm::createWebAssemblyOptimizeReturned() {
return new OptimizeReturned();
}
void OptimizeReturned::visitCallSite(CallSite CS) {
for (unsigned i = 0, e = CS.getNumArgOperands(); i < e; ++i)
if (CS.paramHasAttr(1 + i, Attribute::Returned)) {
Instruction *Inst = CS.getInstruction();
Value *Arg = CS.getArgOperand(i);
if (isa<Constant>(Arg))
continue;
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;
}