[DependenceAnalysis] Check if result of getConstantPart is null

A seg-fault occurs due to a reference of a null pointer, which is
the value returned by getConstantPart. This function returns
null if the constant part is not found. The code that calls this
function needs to check for the null return value.

Differential Revision: http://reviews.llvm.org/D18718

llvm-svn: 265319

diff --git a/llvm/lib/Analysis/DependenceAnalysis.cpp b/llvm/lib/Analysis/DependenceAnalysis.cpp
index 4040ad3..9382890 100644 (file)
--- a/llvm/lib/Analysis/DependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/DependenceAnalysis.cpp
@@ -2409,6 +2409,8 @@ bool DependenceAnalysis::gcdMIVtest(const SCEV *Src,
           Constant = getConstantPart(Product);
         else
           Constant = cast<SCEVConstant>(Coeff);
+        if (!Constant)
+          return false;
         APInt ConstCoeff = Constant->getAPInt();
         RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff.abs());
       }
@@ -2427,6 +2429,8 @@ bool DependenceAnalysis::gcdMIVtest(const SCEV *Src,
           Constant = getConstantPart(Product);
         else
           Constant = cast<SCEVConstant>(Coeff);
+        if (!Constant)
+          return false;
         APInt ConstCoeff = Constant->getAPInt();
         RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff.abs());
       }
@@ -2444,6 +2448,8 @@ bool DependenceAnalysis::gcdMIVtest(const SCEV *Src,
       // or constant, in which case we give up on this direction.
       continue;
     }
+    if (!Constant)
+      continue;
     APInt ConstCoeff = Constant->getAPInt();
     RunningGCD = APIntOps::GreatestCommonDivisor(RunningGCD, ConstCoeff.abs());
     DEBUG(dbgs() << "\tRunningGCD = " << RunningGCD << "\n");

diff --git a/llvm/test/Analysis/DependenceAnalysis/MIVCheckConst.ll b/llvm/test/Analysis/DependenceAnalysis/MIVCheckConst.ll
new file mode 100644 (file)
index 0000000..64e72df
--- /dev/null
+++ b/llvm/test/Analysis/DependenceAnalysis/MIVCheckConst.ll
@@ -0,0 +1,73 @@
+; RUN: opt < %s -analyze -basicaa -da
+
+; Test that the dependence analysis pass does seg-fault due to a null pointer
+; dereference. The code in gcdMIVTest requires a null check for the result of
+; getConstantPart.
+
+target datalayout = "e-m:e-p:32:32-i1:32-i64:64-a:0-v32:32-n16:32"
+
+%0 = type { i32 }
+%1 = type { [2 x [512 x %0]], [512 x %0], %2, [144 x i8], %9, %10, %11, %12, %17, [12 x i8], %18, %19, %21, [128 x i8] }
+%2 = type { [64 x i16], [64 x i16], [64 x %0], [64 x %0], [128 x %0], [128 x %0], [256 x %0], [256 x %0], [32 x %0], [32 x %0], [64 x i16], [64 x i16], [64 x i16], [64 x i16], [64 x i16], %3, %4, %5, [32 x i32], [32 x i32], [32 x i32], [32 x i32], [32 x i32], [32 x i32], %6, %7, [32 x i32], [32 x i32], [32 x i32], [64 x i16], %8, [8 x i64], [4 x i64], [2 x i64], [256 x i8], [256 x i32], [64 x i16], [64 x i16] }
+%3 = type { [64 x i32], [32 x i32], [32 x i32], [32 x i32], [32 x i32], [32 x i32], [32 x i32], [32 x i32], [32 x i32], [32 x i32], [32 x i32], [32 x i32], [32 x i32], [32 x i32], [32 x i32], [64 x i32], [64 x i32], [64 x i32], [64 x i32], [64 x i32], [64 x i32], [64 x i32], [64 x i32], [64 x i32], [64 x i16], [64 x i16], [64 x i16], [64 x i16], [64 x i16], [64 x i16], [64 x i16], [64 x i16], [64 x i16], [64 x i16], [64 x i16], [64 x i16], [32 x %0], [32 x %0], [128 x i8] }
+%4 = type { [64 x i16], [64 x i16], [64 x i16], [64 x i16], [64 x i16], [64 x i16], [64 x i16], [64 x i16] }
+%5 = type { [128 x i8], [256 x i8], [256 x i8] }
+%6 = type { [64 x i32], [128 x i16], [64 x i16], [64 x i16], [64 x i16] }
+%7 = type { [192 x %0], [192 x %0], [384 x %0], [1984 x %0] }
+%8 = type { [128 x i8], [128 x i8], [64 x i16], [64 x i16], [64 x i16], [64 x i16], [64 x i16], [64 x i16] }
+%9 = type { [32 x %0], [32 x %0], [64 x i32], [64 x i32], [64 x i32], [64 x i32] }
+%10 = type { [1536 x %0], [2048 x %0], [512 x i32], [256 x i32], [32 x %0], [64 x i32], [128 x i8], [512 x i32], [1024 x %0] }
+%11 = type { [512 x i32], [512 x i32], [1024 x %0], [512 x i32], [512 x %0] }
+%12 = type { %13, [2048 x %0], [2048 x %0], [256 x i32], [1024 x i32], %14, [512 x %0], [256 x i32], %15, [4 x [256 x %0]], [4 x [256 x %0]], [256 x i32], [8 x [32 x i32]], [8 x [32 x %0]], [384 x %0], [256 x i32], %16 }
+%13 = type { [2048 x %0] }
+%14 = type { [1024 x %0], [1024 x %0] }
+%15 = type { [256 x %0], [256 x %0] }
+%16 = type { [128 x %0], [128 x %0] }
+%17 = type { [32 x %0], [32 x i32], [32 x i32], [32 x i32], [32 x i32], [2 x [8 x [32 x %0]]], [512 x %0], [512 x %0], [58 x i16] }
+%18 = type { [512 x i8] }
+%19 = type { [2048 x %0], [2560 x i16], %20, [512 x i32], [256 x i32], [512 x i8] }
+%20 = type { [768 x i32] }
+%21 = type { [416 x i32] }
+
+define void @test(%1* %A) #0 align 2 {
+entry:
+  %v1 = load i32, i32* undef, align 4
+  br label %bb13
+
+bb13:
+  %v2 = phi i32 [ undef, %entry ], [ %v39, %bb38 ]
+  br i1 undef, label %bb15, label %bb38
+
+bb15:
+  %v3 = mul nsw i32 %v2, undef
+  br label %bb17
+
+bb17:
+  br i1 undef, label %bb21, label %bb37
+
+bb21:
+  %v22 = add nsw i32 undef, 1
+  %v23 = add i32 %v22, %v3
+  %v24 = mul nsw i32 %v23, %v1
+  %v25 = getelementptr inbounds %1, %1* %A, i32 0, i32 7, i32 1, i32 %v24
+  %v26 = bitcast %0* %v25 to <32 x i32>*
+  %v27 = load <32 x i32>, <32 x i32>* %v26, align 256
+  %v28 = add i32 undef, %v3
+  %v29 = mul nsw i32 %v28, 32
+  %v30 = getelementptr inbounds %1, %1* %A, i32 0, i32 7, i32 14, i32 %v29
+  %v31 = bitcast %0* %v30 to <32 x i32>*
+  %v32 = load <32 x i32>, <32 x i32>* %v31, align 128
+  br i1 undef, label %bb21, label %bb37
+
+bb37:
+  br i1 undef, label %bb17, label %bb38
+
+bb38:
+  %v39 = add nsw i32 %v2, 1
+  br label %bb13
+
+bb40:
+  ret void
+}
+
+attributes #0 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }