LLVM  6.0.0svn
StripGCRelocates.cpp
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1 //===- StripGCRelocates.cpp - Remove gc.relocates inserted by RewriteStatePoints===//
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 // This is a little utility pass that removes the gc.relocates inserted by
11 // RewriteStatepointsForGC. Note that the generated IR is incorrect,
12 // but this is useful as a single pass in itself, for analysis of IR, without
13 // the GC.relocates. The statepoint and gc.result instrinsics would still be
14 // present.
15 //===----------------------------------------------------------------------===//
16 
17 #include "llvm/IR/Function.h"
18 #include "llvm/IR/InstIterator.h"
19 #include "llvm/IR/Instructions.h"
20 #include "llvm/IR/Statepoint.h"
21 #include "llvm/IR/Type.h"
22 #include "llvm/Pass.h"
24 #include "llvm/Transforms/Scalar.h"
25 
26 using namespace llvm;
27 
28 namespace {
29 struct StripGCRelocates : public FunctionPass {
30  static char ID; // Pass identification, replacement for typeid
31  StripGCRelocates() : FunctionPass(ID) {
33  }
34 
35  void getAnalysisUsage(AnalysisUsage &Info) const override {}
36 
37  bool runOnFunction(Function &F) override;
38 
39 };
40 char StripGCRelocates::ID = 0;
41 }
42 
44  // Nothing to do for declarations.
45  if (F.isDeclaration())
46  return false;
48  // TODO: We currently do not handle gc.relocates that are in landing pads,
49  // i.e. not bound to a single statepoint token.
50  for (Instruction &I : instructions(F)) {
51  if (auto *GCR = dyn_cast<GCRelocateInst>(&I))
52  if (isStatepoint(GCR->getOperand(0)))
53  GCRelocates.push_back(GCR);
54  }
55  // All gc.relocates are bound to a single statepoint token. The order of
56  // visiting gc.relocates for deletion does not matter.
57  for (GCRelocateInst *GCRel : GCRelocates) {
58  Value *OrigPtr = GCRel->getDerivedPtr();
59  Value *ReplaceGCRel = OrigPtr;
60 
61  // All gc_relocates are i8 addrspace(1)* typed, we need a bitcast from i8
62  // addrspace(1)* to the type of the OrigPtr, if the are not the same.
63  if (GCRel->getType() != OrigPtr->getType())
64  ReplaceGCRel = new BitCastInst(OrigPtr, GCRel->getType(), "cast", GCRel);
65 
66  // Replace all uses of gc.relocate and delete the gc.relocate
67  // There maybe unncessary bitcasts back to the OrigPtr type, an instcombine
68  // pass would clear this up.
69  GCRel->replaceAllUsesWith(ReplaceGCRel);
70  GCRel->eraseFromParent();
71  }
72  return !GCRelocates.empty();
73 }
74 
75 INITIALIZE_PASS(StripGCRelocates, "strip-gc-relocates",
76  "Strip gc.relocates inserted through RewriteStatepointsForGC",
77  true, false)
79  return new StripGCRelocates();
80 }
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
F(f)
FunctionPass * createStripGCRelocatesPass()
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:245
This class represents a no-op cast from one type to another.
void replaceAllUsesWith(Value *V)
Change all uses of this to point to a new Value.
Definition: Value.cpp:430
static bool runOnFunction(Function &F, bool PostInlining)
Represent the analysis usage information of a pass.
void initializeStripGCRelocatesPass(PassRegistry &)
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:285
INITIALIZE_PASS(StripGCRelocates, "strip-gc-relocates", "Strip gc.relocates inserted through RewriteStatepointsForGC", true, false) FunctionPass *llvm
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:864
#define I(x, y, z)
Definition: MD5.cpp:58
bool isDeclaration() const
Return true if the primary definition of this global value is outside of the current translation unit...
Definition: Globals.cpp:201
bool isStatepoint(ImmutableCallSite CS)
Definition: Statepoint.cpp:27
Represents calls to the gc.relocate intrinsic.
Definition: Statepoint.h:374
LLVM Value Representation.
Definition: Value.h:73
inst_range instructions(Function *F)
Definition: InstIterator.h:134