[llvm-commits] [llvm] r168711 - in /llvm/trunk: lib/Analysis/ScalarEvolution.cpp test/Transforms/IndVarSimplify/eliminate-comparison.ll

[Benjamin Kramer]

On 27.11.2012, at 19:16, Benjamin Kramer <benny.kra at googlemail.com> wrote:

> Author: d0k
> Date: Tue Nov 27 12:16:32 2012
> New Revision: 168711
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=168711&view=rev
> Log:
> SCEV: Even if the latch terminator is foldable we can't deduce the result of an unrelated condition with it.
> 
> Fixes PR14432.

Chris, can you approve this for 3.2? It fixes a miscompilation and is apparently a regression from 3.1.

- Ben

> 
> Modified:
>    llvm/trunk/lib/Analysis/ScalarEvolution.cpp
>    llvm/trunk/test/Transforms/IndVarSimplify/eliminate-comparison.ll
> 
> Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=168711&r1=168710&r2=168711&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
> +++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Tue Nov 27 12:16:32 2012
> @@ -6149,9 +6149,10 @@
>   if (SimplifyICmpOperands(Pred, LHS, RHS))
>     if (LHS == RHS)
>       return CmpInst::isTrueWhenEqual(Pred);
> -  if (SimplifyICmpOperands(FoundPred, FoundLHS, FoundRHS))
> -    if (FoundLHS == FoundRHS)
> -      return CmpInst::isFalseWhenEqual(Pred);
> +
> +  // Canonicalize the found cond too.  We can't conclude a result from the
> +  // simplified values.
> +  SimplifyICmpOperands(FoundPred, FoundLHS, FoundRHS);
> 
>   // Check to see if we can make the LHS or RHS match.
>   if (LHS == FoundRHS || RHS == FoundLHS) {
> 
> Modified: llvm/trunk/test/Transforms/IndVarSimplify/eliminate-comparison.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IndVarSimplify/eliminate-comparison.ll?rev=168711&r1=168710&r2=168711&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/IndVarSimplify/eliminate-comparison.ll (original)
> +++ llvm/trunk/test/Transforms/IndVarSimplify/eliminate-comparison.ll Tue Nov 27 12:16:32 2012
> @@ -106,3 +106,57 @@
> return:
>   ret void
> }
> +
> +; PR14432
> +; Indvars should not turn the second loop into an infinite one.
> +
> +; CHECK: @func_11
> +; CHECK: %tmp5 = icmp slt i32 %__key6.0, 10
> +; CHECK-NOT: br i1 true, label %noassert68, label %unrolledend
> +
> +define i32 @func_11() nounwind uwtable {
> +entry:
> +  br label %forcond
> +
> +forcond:                                          ; preds = %noassert, %entry
> +  %__key6.0 = phi i32 [ 2, %entry ], [ %tmp37, %noassert ]
> +  %tmp5 = icmp slt i32 %__key6.0, 10
> +  br i1 %tmp5, label %noassert, label %forcond38.preheader
> +
> +forcond38.preheader:                              ; preds = %forcond
> +  br label %forcond38
> +
> +noassert:                                         ; preds = %forbody
> +  %tmp13 = sdiv i32 -32768, %__key6.0
> +  %tmp2936 = shl i32 %tmp13, 24
> +  %sext23 = shl i32 %tmp13, 24
> +  %tmp32 = icmp eq i32 %tmp2936, %sext23
> +  %tmp37 = add i32 %__key6.0, 1
> +  br i1 %tmp32, label %forcond, label %assert33
> +
> +assert33:                                         ; preds = %noassert
> +  tail call void @llvm.trap()
> +  unreachable
> +
> +forcond38:                                        ; preds = %noassert68, %forcond38.preheader
> +  %__key8.0 = phi i32 [ %tmp81, %noassert68 ], [ 2, %forcond38.preheader ]
> +  %tmp46 = icmp slt i32 %__key8.0, 10
> +  br i1 %tmp46, label %noassert68, label %unrolledend
> +
> +noassert68:                                       ; preds = %forbody39
> +  %tmp57 = sdiv i32 -32768, %__key8.0
> +  %sext34 = shl i32 %tmp57, 16
> +  %sext21 = shl i32 %tmp57, 16
> +  %tmp76 = icmp eq i32 %sext34, %sext21
> +  %tmp81 = add i32 %__key8.0, 1
> +  br i1 %tmp76, label %forcond38, label %assert77
> +
> +assert77:                                         ; preds = %noassert68
> +  tail call void @llvm.trap()
> +  unreachable
> +
> +unrolledend:                                      ; preds = %forcond38
> +  ret i32 0
> +}
> +
> +declare void @llvm.trap() noreturn nounwind
> 
> 
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