diff options
| -rw-r--r-- | lib/Analysis/ScalarEvolution.cpp | 6 | ||||
| -rw-r--r-- | test/Analysis/ScalarEvolution/SolveQuadraticEquation.ll | 21 |
2 files changed, 27 insertions, 0 deletions
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index f0f3b1cb66..a654648578 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -5370,6 +5370,12 @@ SolveQuadraticEquation(const SCEVAddRecExpr *AddRec, ScalarEvolution &SE) { SqrtTerm *= B; SqrtTerm -= Four * (A * C); + if (SqrtTerm.isNegative()) { + // The loop is provably infinite. + const SCEV *CNC = SE.getCouldNotCompute(); + return std::make_pair(CNC, CNC); + } + // Compute sqrt(B^2-4ac). This is guaranteed to be the nearest // integer value or else APInt::sqrt() will assert. APInt SqrtVal(SqrtTerm.sqrt()); diff --git a/test/Analysis/ScalarEvolution/SolveQuadraticEquation.ll b/test/Analysis/ScalarEvolution/SolveQuadraticEquation.ll index 06f1b6fe33..e946d7a64b 100644 --- a/test/Analysis/ScalarEvolution/SolveQuadraticEquation.ll +++ b/test/Analysis/ScalarEvolution/SolveQuadraticEquation.ll @@ -80,3 +80,24 @@ for.cond539.preheader: unreachable } ; CHECK: Determining loop execution counts for: @test3 + +; PR13489 +; We used to crash on this too. + +define void @test4() { +entry: + br label %for.body + +for.body: ; preds = %for.body, %entry + %v2.02 = phi i64 [ 2, %entry ], [ %phitmp, %for.body ] + %v1.01 = phi i64 [ -2, %entry ], [ %sub1, %for.body ] + %sub1 = sub i64 %v1.01, %v2.02 + %phitmp = add i64 %v2.02, 2 + %tobool = icmp eq i64 %sub1, %phitmp + br i1 %tobool, label %for.end, label %for.body + +for.end: ; preds = %for.body + ret void +} + +; CHECK: Determining loop execution counts for: @test4 |