[llvm] r214423 - Fix ScalarEvolutionExpander when creating a PHI in a block with duplicate predecessors

[Bill Wendling]

Done. Thanks!

-bw

On Jul 31, 2014, at 2:24 PM, Hal Finkel <hfinkel at anl.gov> wrote:

> Bill,
> 
> I'd like this pulled into the 3.5 release branch. Andy might be the code owner here?
> 
> Thanks again,
> Hal
> 
> ----- Original Message -----
>> From: "Hal Finkel" <hfinkel at anl.gov>
>> To: llvm-commits at cs.uiuc.edu
>> Sent: Thursday, July 31, 2014 2:13:38 PM
>> Subject: [llvm] r214423 - Fix ScalarEvolutionExpander when creating a PHI in a	block with duplicate predecessors
>> 
>> Author: hfinkel
>> Date: Thu Jul 31 14:13:38 2014
>> New Revision: 214423
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=214423&view=rev
>> Log:
>> Fix ScalarEvolutionExpander when creating a PHI in a block with
>> duplicate predecessors
>> 
>> It seems that when I fixed this, almost exactly a year ago, I did not
>> quite do
>> it correctly. When we have duplicate block predecessors, we can
>> indeed not have
>> different incoming values for the same block, but we *must* have
>> duplicate
>> entries. So, instead of skipping the duplicates, we explicitly add
>> the
>> duplicate incoming values.
>> 
>> Fixes PR20442.
>> 
>> Added:
>>    llvm/trunk/test/CodeGen/PowerPC/pr20442.ll
>> Modified:
>>    llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp
>> 
>> Modified: llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp?rev=214423&r1=214422&r2=214423&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp (original)
>> +++ llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp Thu Jul 31
>> 14:13:38 2014
>> @@ -1443,8 +1443,12 @@ Value *SCEVExpander::visitAddRecExpr(con
>>     Constant *One = ConstantInt::get(Ty, 1);
>>     for (pred_iterator HPI = HPB; HPI != HPE; ++HPI) {
>>       BasicBlock *HP = *HPI;
>> -      if (!PredSeen.insert(HP))
>> +      if (!PredSeen.insert(HP)) {
>> +        // There must be an incoming value for each predecessor,
>> even the
>> +        // duplicates!
>> +
>>       CanonicalIV->addIncoming(CanonicalIV->getIncomingValueForBlock(HP),
>> HP);
>>         continue;
>> +      }
>> 
>>       if (L->contains(HP)) {
>>         // Insert a unit add instruction right before the terminator
>> 
>> Added: llvm/trunk/test/CodeGen/PowerPC/pr20442.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/PowerPC/pr20442.ll?rev=214423&view=auto
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/PowerPC/pr20442.ll (added)
>> +++ llvm/trunk/test/CodeGen/PowerPC/pr20442.ll Thu Jul 31 14:13:38
>> 2014
>> @@ -0,0 +1,79 @@
>> +; RUN: llc -mcpu=pwr7 < %s | FileCheck %s
>> +target datalayout = "E-m:e-p:32:32-i64:64-n32"
>> +target triple = "powerpc-unknown-linux-gnu"
>> +
>> +; This code would cause code generation like this after PPCCTRLoops
>> ran:
>> +;  %indvar = phi i32 [ 0, %for.body ], [ %indvar.next, %if.then6 ]
>> +;  %j.1.ph13 = phi i32 [ %j.110, %if.then6 ], [ 0, %for.body ], [ 0,
>> %for.body ]
>> +;  %c.0.ph12 = phi i32 [ %dec, %if.then6 ], [ %2, %for.body ], [ %2,
>> %for.body ]
>> +; which would fail verification because the created induction
>> variable does not
>> +; have as many predecessor entries as the other PHIs.
>> +; CHECK-LABEL: @fn1
>> +; CHECK: mtctr
>> +
>> +%struct.anon = type { i32 }
>> +%struct.anon.0 = type { i32 }
>> +
>> + at b = common global %struct.anon* null, align 4
>> + at a = common global %struct.anon.0* null, align 4
>> +
>> +; Function Attrs: nounwind readonly uwtable
>> +define i32 @fn1() #0 {
>> +entry:
>> +  %0 = load %struct.anon** @b, align 4
>> +  %1 = ptrtoint %struct.anon* %0 to i32
>> +  %cmp = icmp sgt %struct.anon* %0, null
>> +  %2 = load %struct.anon.0** @a, align 4
>> +  br i1 %cmp, label %for.bodythread-pre-split, label %if.end8
>> +
>> +for.bodythread-pre-split:                         ; preds = %entry
>> +  %aclass = getelementptr inbounds %struct.anon.0* %2, i32 0, i32 0
>> +  %.pr = load i32* %aclass, align 4
>> +  br label %for.body
>> +
>> +for.body:                                         ; preds =
>> %for.bodythread-pre-split, %for.body
>> +  switch i32 %.pr, label %for.body [
>> +    i32 0, label %while.body.lr.ph.preheader
>> +    i32 2, label %while.body.lr.ph.preheader
>> +  ]
>> +
>> +while.body.lr.ph.preheader:                       ; preds =
>> %for.body, %for.body
>> +  br label %while.body.lr.ph
>> +
>> +while.body.lr.ph:                                 ; preds =
>> %while.body.lr.ph.preheader, %if.then6
>> +  %j.1.ph13 = phi i32 [ %j.110.lcssa, %if.then6 ], [ 0,
>> %while.body.lr.ph.preheader ]
>> +  %c.0.ph12 = phi i32 [ %dec, %if.then6 ], [ %1,
>> %while.body.lr.ph.preheader ]
>> +  br label %while.body
>> +
>> +while.cond:                                       ; preds =
>> %while.body
>> +  %cmp2 = icmp slt i32 %inc7, %c.0.ph12
>> +  br i1 %cmp2, label %while.body, label %if.end8.loopexit
>> +
>> +while.body:                                       ; preds =
>> %while.body.lr.ph, %while.cond
>> +  %j.110 = phi i32 [ %j.1.ph13, %while.body.lr.ph ], [ %inc7,
>> %while.cond ]
>> +  %aclass_index = getelementptr inbounds %struct.anon* %0, i32
>> %j.110, i32 0
>> +  %3 = load i32* %aclass_index, align 4
>> +  %aclass5 = getelementptr inbounds %struct.anon.0* %2, i32 %3, i32
>> 0
>> +  %4 = load i32* %aclass5, align 4
>> +  %tobool = icmp eq i32 %4, 0
>> +  %inc7 = add nsw i32 %j.110, 1
>> +  br i1 %tobool, label %while.cond, label %if.then6
>> +
>> +if.then6:                                         ; preds =
>> %while.body
>> +  %j.110.lcssa = phi i32 [ %j.110, %while.body ]
>> +  %dec = add nsw i32 %c.0.ph12, -1
>> +  %cmp29 = icmp slt i32 %j.110.lcssa, %dec
>> +  br i1 %cmp29, label %while.body.lr.ph, label %if.end8.loopexit17
>> +
>> +if.end8.loopexit:                                 ; preds =
>> %while.cond
>> +  br label %if.end8
>> +
>> +if.end8.loopexit17:                               ; preds =
>> %if.then6
>> +  br label %if.end8
>> +
>> +if.end8:                                          ; preds =
>> %if.end8.loopexit17, %if.end8.loopexit, %entry
>> +  ret i32 undef
>> +}
>> +
>> +attributes #0 = { nounwind readonly uwtable }
>> +
>> 
>> 
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>> 
> 
> -- 
> Hal Finkel
> Assistant Computational Scientist
> Leadership Computing Facility
> Argonne National Laboratory