[PATCH] D16774: AMDGPU: Stop pointlessly looking at users after a bad one is found

[Matt Arsenault via llvm-commits]

On 02/01/2016 10:12 AM, David Blaikie wrote:
>
>
> On Mon, Feb 1, 2016 at 9:51 AM, Matt Arsenault via llvm-commits 
> <llvm-commits at lists.llvm.org <mailto:llvm-commits at lists.llvm.org>> wrote:
>
>     arsenm created this revision.
>     arsenm added a reviewer: tstellarAMD.
>     arsenm added a subscriber: llvm-commits.
>     Herald added a subscriber: arsenm.
>
>     http://reviews.llvm.org/D16774
>
>     Files:
>       lib/Target/AMDGPU/AMDGPUPromoteAlloca.cpp
>
>     Index: lib/Target/AMDGPU/AMDGPUPromoteAlloca.cpp
>     ===================================================================
>     --- lib/Target/AMDGPU/AMDGPUPromoteAlloca.cpp
>     +++ lib/Target/AMDGPU/AMDGPUPromoteAlloca.cpp
>     @@ -402,7 +402,10 @@
>      static bool collectUsesWithPtrTypes(Value *Val,
>     std::vector<Value*> &WorkList) {
>        bool Success = true;
>        for (User *User : Val->users()) {
>     -    if(std::find(WorkList.begin(), WorkList.end(), User) !=
>     WorkList.end())
>     +    if (!Success)
>     +      return false;
>     +
>     +    if (std::find(WorkList.begin(), WorkList.end(), User) !=
>     WorkList.end())
>            continue;
>          if (CallInst *CI = dyn_cast<CallInst>(User)) {
>            // TODO: We might be able to handle some cases where the
>     callee is a
>     @@ -429,10 +432,10 @@
>            continue;
>
>          WorkList.push_back(User);
>     -
>     -    Success &= collectUsesWithPtrTypes(User, WorkList);
>     +    Success = collectUsesWithPtrTypes(User, WorkList);
>
>
> Why not just drop the Success variable entirely and return from here:
>
> if (!collectUsesWithPtrTypes(...))
>   return false
Return here is what I tried first, but this breaks some cases due to the 
!isPointerTy check above. Call users without pointer types would then 
fall through and incorrectly be changed. I'm planning on fixing some of 
the intrinsic handling here, so maybe after that this will be OK.

>
> Or, possibly better yet:
>
> return llvm::all_of(Val->users(), [&](User *User) {
>   ...
>   return collectUsesWithPtrTypes(User, WorkList);
> });
>


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