Commit d50861c8 authored by Andrew Trick's avatar Andrew Trick
Browse files

Fix indvars randomness by removing iteration over a map. 

I rewrote the algorithm a while back so it doesn't require map lookup,
but neglected to change the data structure. This was caught by
llvm-gcc self host, not because there's anything special about
llvm-gcc, but because it is the only test for nondeterminism we
currently have. Unit tests don't work well for everything; we should
always try to have a nondeterminism stress test running.

Fixes PR11133: llvm-gcc self host .o mismatch after enable-iv-rewrite=false

llvm-svn: 142036
parent 09c74643

llvm/lib/Transforms/Scalar/IndVarSimplify.cpp

+12 −12
Original line number Diff line number Diff line
@@ -721,10 +721,11 @@ namespace { 
  // extend operations. This information is recorded by CollectExtend and

  // provides the input to WidenIV.

  struct WideIVInfo {

    PHINode *NarrowIV;

    Type *WidestNativeType; // Widest integer type created [sz]ext

    bool IsSigned;          // Was an sext user seen before a zext?



    WideIVInfo() : WidestNativeType(0), IsSigned(false) {}

    WideIVInfo() : NarrowIV(0), WidestNativeType(0), IsSigned(false) {}

  };



  class WideIVVisitor : public IVVisitor {
@@ -734,8 +735,9 @@ namespace { 
  public:

    WideIVInfo WI;



    WideIVVisitor(ScalarEvolution *SCEV, const TargetData *TData) :

      SE(SCEV), TD(TData) {}

    WideIVVisitor(PHINode *NarrowIV, ScalarEvolution *SCEV,

                  const TargetData *TData) :

      SE(SCEV), TD(TData) { WI.NarrowIV = NarrowIV; }



    // Implement the interface used by simplifyUsersOfIV.

    virtual void visitCast(CastInst *Cast);
@@ -812,10 +814,10 @@ class WidenIV { 
  SmallVector<NarrowIVDefUse, 8> NarrowIVUsers;



public:

  WidenIV(PHINode *PN, const WideIVInfo &WI, LoopInfo *LInfo,

  WidenIV(const WideIVInfo &WI, LoopInfo *LInfo,

          ScalarEvolution *SEv, DominatorTree *DTree,

          SmallVectorImpl<WeakVH> &DI) :

    OrigPhi(PN),

    OrigPhi(WI.NarrowIV),

    WideType(WI.WidestNativeType),

    IsSigned(WI.IsSigned),

    LI(LInfo),
@@ -1181,7 +1183,7 @@ PHINode *WidenIV::CreateWideIV(SCEVExpander &Rewriter) { 
void IndVarSimplify::SimplifyAndExtend(Loop *L,

                                       SCEVExpander &Rewriter,

                                       LPPassManager &LPM) {

  std::map<PHINode *, WideIVInfo> WideIVMap;

  SmallVector<WideIVInfo, 8> WideIVs;



  SmallVector<PHINode*, 8> LoopPhis;

  for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ++I) {
@@ -1202,24 +1204,22 @@ void IndVarSimplify::SimplifyAndExtend(Loop *L, 
      PHINode *CurrIV = LoopPhis.pop_back_val();



      // Information about sign/zero extensions of CurrIV.

      WideIVVisitor WIV(SE, TD);

      WideIVVisitor WIV(CurrIV, SE, TD);



      Changed |= simplifyUsersOfIV(CurrIV, SE, &LPM, DeadInsts, &WIV);



      if (WIV.WI.WidestNativeType) {

        WideIVMap[CurrIV] = WIV.WI;

        WideIVs.push_back(WIV.WI);

      }

    } while(!LoopPhis.empty());



    for (std::map<PHINode *, WideIVInfo>::const_iterator I = WideIVMap.begin(),

           E = WideIVMap.end(); I != E; ++I) {

      WidenIV Widener(I->first, I->second, LI, SE, DT, DeadInsts);

    for (; !WideIVs.empty(); WideIVs.pop_back()) {

      WidenIV Widener(WideIVs.back(), LI, SE, DT, DeadInsts);

      if (PHINode *WidePhi = Widener.CreateWideIV(Rewriter)) {

        Changed = true;

        LoopPhis.push_back(WidePhi);

      }

    }

    WideIVMap.clear();

  }

}