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

[Pawel Wodnicki]

Ben,

Have you heard from Chris about r168711 approval?

Pawel

> 
> 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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> 
> 
>