[llvm-commits] [llvm] r164561 - in /llvm/trunk: lib/Transforms/Scalar/DeadStoreElimination.cpp test/Transforms/DeadStoreElimination/libcalls.ll

[Nick Lewycky]

On 24 September 2012 16:41, Jim Grosbach <grosbach at apple.com> wrote:

>
> On Sep 24, 2012, at 3:09 PM, Nick Lewycky <nicholas at mxc.ca> wrote:
>
> > Author: nicholas
> > Date: Mon Sep 24 17:09:10 2012
> > New Revision: 164561
> >
> > URL: http://llvm.org/viewvc/llvm-project?rev=164561&view=rev
> > Log:
> > Teach DSE that strcpy, strncpy, strcat and strncat are all stores which
> may be
> > dead.
> >
> > Added:
> >    llvm/trunk/test/Transforms/DeadStoreElimination/libcalls.ll
> > Modified:
> >    llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp
> >
>


> > @@ -208,7 +229,8 @@
> > /// instruction if any.
> > static AliasAnalysis::Location
> > getLocForRead(Instruction *Inst, AliasAnalysis &AA) {
> > -  assert(hasMemoryWrite(Inst) && "Unknown instruction case");
> > +  assert(hasMemoryWrite(Inst, AA.getTargetLibraryInfo()) &&
> > +         "Unknown instruction case");
> >
> >   // The only instructions that both read and write are the mem transfer
> >   // instructions (memcpy/memmove).
> > @@ -225,23 +247,29 @@
> >   if (StoreInst *SI = dyn_cast<StoreInst>(I))
> >     return SI->isUnordered();
> >
> > -  IntrinsicInst *II = cast<IntrinsicInst>(I);
> > -  switch (II->getIntrinsicID()) {
> > -  default: llvm_unreachable("doesn't pass 'hasMemoryWrite' predicate");
> > -  case Intrinsic::lifetime_end:
> > -    // Never remove dead lifetime_end's, e.g. because it is followed by
> a
> > -    // free.
> > -    return false;
> > -  case Intrinsic::init_trampoline:
> > -    // Always safe to remove init_trampoline.
> > -    return true;
> > +  if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
> > +    switch (II->getIntrinsicID()) {
> > +    default: llvm_unreachable("doesn't pass 'hasMemoryWrite'
> predicate");
> > +    case Intrinsic::lifetime_end:
> > +      // Never remove dead lifetime_end's, e.g. because it is followed
> by a
> > +      // free.
> > +      return false;
> > +    case Intrinsic::init_trampoline:
> > +      // Always safe to remove init_trampoline.
> > +      return true;
> >
> > -  case Intrinsic::memset:
> > -  case Intrinsic::memmove:
> > -  case Intrinsic::memcpy:
> > -    // Don't remove volatile memory intrinsics.
> > -    return !cast<MemIntrinsic>(II)->isVolatile();
> > +    case Intrinsic::memset:
> > +    case Intrinsic::memmove:
> > +    case Intrinsic::memcpy:
> > +      // Don't remove volatile memory intrinsics.
> > +      return !cast<MemIntrinsic>(II)->isVolatile();
> > +    }
> >   }
> > +
> > +  if (CallSite CS = I)  // If we assume hasMemoryWrite(I) is true,
> > +    return true;        // then there's nothing left to check.
>
> warning: unused
>       variable 'CS' [-Wunused-variable]
>   if (CallSite CS = I)  // If we assume hasMemoryWrite(I) is true,
>                ^
>

Thanks! Fixed in r164576.

Nick
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