[llvm] r214423 - Fix ScalarEvolutionExpander when creating a PHI in a block with duplicate predecessors
Hal Finkel
hfinkel at anl.gov
Thu Jul 31 14:24:50 PDT 2014
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
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