[llvm] r323515 - [CallSiteSplitting] Fix infinite loop when recording conditions.

[Hans Wennborg via llvm-commits]

Merged to 6.0 in r323771.

On Fri, Jan 26, 2018 at 11:36 AM, Florian Hahn via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: fhahn
> Date: Fri Jan 26 02:36:50 2018
> New Revision: 323515
>
> URL: http://llvm.org/viewvc/llvm-project?rev=323515&view=rev
> Log:
> [CallSiteSplitting] Fix infinite loop when recording conditions.
>
> Fix infinite loop when recording conditions by correctly marking basic
> blocks as visited.
>
> Fixes https://bugs.llvm.org/show_bug.cgi?id=36105
>
> Modified:
>     llvm/trunk/lib/Transforms/Scalar/CallSiteSplitting.cpp
>     llvm/trunk/test/Transforms/CallSiteSplitting/callsite-no-splitting.ll
>
> Modified: llvm/trunk/lib/Transforms/Scalar/CallSiteSplitting.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/
> CallSiteSplitting.cpp?rev=323515&r1=323514&r2=323515&view=diff
> ============================================================
> ==================
> --- llvm/trunk/lib/Transforms/Scalar/CallSiteSplitting.cpp (original)
> +++ llvm/trunk/lib/Transforms/Scalar/CallSiteSplitting.cpp Fri Jan 26
> 02:36:50 2018
> @@ -140,10 +140,11 @@ static void recordConditions(CallSite CS
>    recordCondition(CS, Pred, CS.getInstruction()->getParent(),
> Conditions);
>    BasicBlock *From = Pred;
>    BasicBlock *To = Pred;
> -  SmallPtrSet<BasicBlock *, 4> Visited = {From};
> +  SmallPtrSet<BasicBlock *, 4> Visited;
>    while (!Visited.count(From->getSinglePredecessor()) &&
>           (From = From->getSinglePredecessor())) {
>      recordCondition(CS, From, To, Conditions);
> +    Visited.insert(From);
>      To = From;
>    }
>  }
>
> Modified: llvm/trunk/test/Transforms/CallSiteSplitting/callsite-no-
> splitting.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/
> Transforms/CallSiteSplitting/callsite-no-splitting.ll?rev=
> 323515&r1=323514&r2=323515&view=diff
> ============================================================
> ==================
> --- llvm/trunk/test/Transforms/CallSiteSplitting/callsite-no-splitting.ll
> (original)
> +++ llvm/trunk/test/Transforms/CallSiteSplitting/callsite-no-splitting.ll
> Fri Jan 26 02:36:50 2018
> @@ -16,3 +16,27 @@ Tail:
>    %r = call i32 @callee(i32* %a, i32 %v, i32 %p)
>    ret i32 %r
>  }
> +
> +define void @fn1(i16 %p1) {
> +entry:
> +  ret void
> +}
> +
> +define void @fn2() {
> +  ret void
> +
> +; Unreachable code below
> +
> +for.inc:                                          ; preds = %for.inc
> +  br i1 undef, label %for.end6, label %for.inc
> +
> +for.end6:                                         ; preds = %for.inc
> +  br i1 undef, label %lor.rhs, label %lor.end
> +
> +lor.rhs:                                          ; preds = %for.end6
> +  br label %lor.end
> +
> +lor.end:                                          ; preds = %for.end6,
> %lor.rhs
> +  call void @fn1(i16 0)
> +  ret void
> +}
>
>
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