1//===- HexagonRemoveExtendArgs.cpp - Remove unnecessary argument sign extends //
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// Pass that removes sign extends for function parameters. These parameters
11// are already sign extended by the caller per Hexagon's ABI
12//
13//===----------------------------------------------------------------------===//
14
15#include "Hexagon.h"
16#include "HexagonTargetMachine.h"
17#include "llvm/CodeGen/MachineFunctionAnalysis.h"
18#include "llvm/IR/Function.h"
19#include "llvm/IR/Instructions.h"
20#include "llvm/Pass.h"
21#include "llvm/Transforms/Scalar.h"
22
23using namespace llvm;
24
25namespace llvm {
26  void initializeHexagonRemoveExtendArgsPass(PassRegistry&);
27}
28
29namespace {
30  struct HexagonRemoveExtendArgs : public FunctionPass {
31  public:
32    static char ID;
33    HexagonRemoveExtendArgs() : FunctionPass(ID) {
34      initializeHexagonRemoveExtendArgsPass(*PassRegistry::getPassRegistry());
35    }
36    bool runOnFunction(Function &F) override;
37
38    const char *getPassName() const override {
39      return "Remove sign extends";
40    }
41
42    void getAnalysisUsage(AnalysisUsage &AU) const override {
43      AU.addRequired<MachineFunctionAnalysis>();
44      AU.addPreserved<MachineFunctionAnalysis>();
45      AU.addPreserved("stack-protector");
46      FunctionPass::getAnalysisUsage(AU);
47    }
48  };
49}
50
51char HexagonRemoveExtendArgs::ID = 0;
52
53INITIALIZE_PASS(HexagonRemoveExtendArgs, "reargs",
54                "Remove Sign and Zero Extends for Args", false, false)
55
56bool HexagonRemoveExtendArgs::runOnFunction(Function &F) {
57  unsigned Idx = 1;
58  for (Function::arg_iterator AI = F.arg_begin(), AE = F.arg_end(); AI != AE;
59       ++AI, ++Idx) {
60    if (F.getAttributes().hasAttribute(Idx, Attribute::SExt)) {
61      Argument* Arg = AI;
62      if (!isa<PointerType>(Arg->getType())) {
63        for (auto UI = Arg->user_begin(); UI != Arg->user_end();) {
64          if (isa<SExtInst>(*UI)) {
65            Instruction* I = cast<Instruction>(*UI);
66            SExtInst* SI = new SExtInst(Arg, I->getType());
67            assert (EVT::getEVT(SI->getType()) ==
68                    (EVT::getEVT(I->getType())));
69            ++UI;
70            I->replaceAllUsesWith(SI);
71            Instruction* First = F.getEntryBlock().begin();
72            SI->insertBefore(First);
73            I->eraseFromParent();
74          } else {
75            ++UI;
76          }
77        }
78      }
79    }
80  }
81  return true;
82}
83
84
85
86FunctionPass*
87llvm::createHexagonRemoveExtendArgs(const HexagonTargetMachine &TM) {
88  return new HexagonRemoveExtendArgs();
89}
90