From 36eff0f854fa9f47394dc48dba195b93b6efac63 Mon Sep 17 00:00:00 2001 From: Hal Finkel Date: Thu, 31 Jul 2014 19:13:38 +0000 Subject: [PATCH] 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. llvm-svn: 214423 --- llvm/lib/Analysis/ScalarEvolutionExpander.cpp | 6 +- llvm/test/CodeGen/PowerPC/pr20442.ll | 79 +++++++++++++++++++++++++++ 2 files changed, 84 insertions(+), 1 deletion(-) create mode 100644 llvm/test/CodeGen/PowerPC/pr20442.ll diff --git a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp index 8c75b0d..968c619 100644 --- a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp +++ b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp @@ -1443,8 +1443,12 @@ Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) { 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 diff --git a/llvm/test/CodeGen/PowerPC/pr20442.ll b/llvm/test/CodeGen/PowerPC/pr20442.ll new file mode 100644 index 0000000..ad43a04 --- /dev/null +++ b/llvm/test/CodeGen/PowerPC/pr20442.ll @@ -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 } + +@b = common global %struct.anon* null, align 4 +@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 } + -- 2.7.4