Fix a memory corruption in Dependency Analysis.

This crash occurs due to memory corruption when trying to update dependency
direction based on Constraints.

This crash was observed during lnt regression of Polybench benchmark test case dynprog.

Review: http://reviews.llvm.org/D8059
llvm-svn: 231788

diff --git a/llvm/lib/Analysis/DependenceAnalysis.cpp b/llvm/lib/Analysis/DependenceAnalysis.cpp
index 3dcfcb8..3374b48 100644 (file)
--- a/llvm/lib/Analysis/DependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/DependenceAnalysis.cpp
@@ -3651,6 +3651,8 @@ DependenceAnalysis::depends(Instruction *Src, Instruction *Dst,
       DEBUG(dbgs() << "    updating\n");
       for (int SJ = ConstrainedLevels.find_first(); SJ >= 0;
            SJ = ConstrainedLevels.find_next(SJ)) {
+        if (SJ > (int)CommonLevels)
+          break;
         updateDirection(Result.DV[SJ - 1], Constraints[SJ]);
         if (Result.DV[SJ - 1].Direction == Dependence::DVEntry::NONE)
           return nullptr;

diff --git a/llvm/test/Analysis/DependenceAnalysis/Constraints.ll b/llvm/test/Analysis/DependenceAnalysis/Constraints.ll
new file mode 100644 (file)
index 0000000..42dfac7
--- /dev/null
+++ b/llvm/test/Analysis/DependenceAnalysis/Constraints.ll
@@ -0,0 +1,103 @@
+; RUN: opt < %s -analyze -basicaa -da
+;; Check that this code doesn't abort. Test case is reduced version of lnt Polybench benchmark test case dynprog.
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@sum_c = common global [10 x [10 x [10 x i32]]] zeroinitializer
+@c = common global [10 x [10 x i32]] zeroinitializer
+@W = common global [10 x [10 x i32]] zeroinitializer
+@out_l = common global i32 0
+
+; Function Attrs: nounwind uwtable
+define void @dep_constraint_crash_test(i32 %M, i32 %N) {
+  %1 = icmp sgt i32 %N, 0
+  br i1 %1, label %.preheader.lr.ph, label %35
+
+.preheader.lr.ph:                                 ; preds = %0
+  %2 = add nsw i32 %M, -2
+  %3 = icmp slt i32 %M, 2
+  %4 = add nsw i32 %M, -1
+  %5 = sext i32 %4 to i64
+  %6 = getelementptr inbounds [10 x [10 x i32]], [10 x [10 x i32]]* @c, i64 0, i64 0, i64 %5
+  %7 = add nsw i32 %M, -1
+  %out_l.promoted = load i32, i32* @out_l
+  %8 = sext i32 %7 to i64
+  %9 = sext i32 %2 to i64
+  br label %.preheader
+
+.preheader:                                       ; preds = %._crit_edge7, %.preheader.lr.ph
+  %10 = phi i32 [ %out_l.promoted, %.preheader.lr.ph ], [ %33, %._crit_edge7 ]
+  %iter.08 = phi i32 [ 0, %.preheader.lr.ph ], [ %34, %._crit_edge7 ]
+  br i1 %3, label %._crit_edge7, label %.lr.ph6
+
+.loopexit:                                        ; preds = %._crit_edge, %.lr.ph6
+  %11 = icmp slt i64 %indvars.iv23, %9
+  %indvars.iv.next18 = add nuw nsw i64 %indvars.iv17, 1
+  %indvars.iv.next14 = add nuw i32 %indvars.iv13, 1
+  br i1 %11, label %.lr.ph6, label %._crit_edge7
+
+.lr.ph6:                                          ; preds = %.preheader, %.loopexit
+  %indvars.iv23 = phi i64 [ %indvars.iv.next24, %.loopexit ], [ 0, %.preheader ]
+  %indvars.iv17 = phi i64 [ %indvars.iv.next18, %.loopexit ], [ 1, %.preheader ]
+  %indvars.iv13 = phi i32 [ %indvars.iv.next14, %.loopexit ], [ 1, %.preheader ]
+  %indvars.iv.next24 = add nuw nsw i64 %indvars.iv23, 1
+  %12 = icmp slt i64 %indvars.iv23, %8
+  br i1 %12, label %.lr.ph4, label %.loopexit
+
+.lr.ph4:                                          ; preds = %.lr.ph6, %._crit_edge
+  %indvars.iv19 = phi i64 [ %indvars.iv.next20, %._crit_edge ], [ %indvars.iv17, %.lr.ph6 ]
+  %indvars.iv15 = phi i32 [ %indvars.iv.next16, %._crit_edge ], [ %indvars.iv13, %.lr.ph6 ]
+  %13 = getelementptr inbounds [10 x [10 x [10 x i32]]], [10 x [10 x [10 x i32]]]* @sum_c, i64 0, i64 %indvars.iv23, i64 %indvars.iv19, i64 %indvars.iv23
+  store i32 0, i32* %13
+  %14 = add nsw i64 %indvars.iv19, -1
+  %15 = icmp slt i64 %indvars.iv23, %14
+  br i1 %15, label %.lr.ph, label %._crit_edge
+
+.lr.ph:                                           ; preds = %.lr.ph4, %.lr.ph
+  %indvars.iv11 = phi i64 [ %indvars.iv.next12, %.lr.ph ], [ %indvars.iv17, %.lr.ph4 ]
+  %16 = add nsw i64 %indvars.iv11, -1
+  %17 = getelementptr inbounds [10 x [10 x [10 x i32]]], [10 x [10 x [10 x i32]]]* @sum_c, i64 0, i64 %indvars.iv23, i64 %indvars.iv19, i64 %16
+  %18 = load i32, i32* %17
+  %19 = getelementptr inbounds [10 x [10 x i32]], [10 x [10 x i32]]* @c, i64 0, i64 %indvars.iv23, i64 %indvars.iv11
+  %20 = load i32, i32* %19
+  %21 = add nsw i32 %20, %18
+  %22 = getelementptr inbounds [10 x [10 x i32]], [10 x [10 x i32]]* @c, i64 0, i64 %indvars.iv11, i64 %indvars.iv19
+  %23 = load i32, i32* %22
+  %24 = add nsw i32 %21, %23
+  %25 = getelementptr inbounds [10 x [10 x [10 x i32]]], [10 x [10 x [10 x i32]]]* @sum_c, i64 0, i64 %indvars.iv23, i64 %indvars.iv19, i64 %indvars.iv11
+  store i32 %24, i32* %25
+  %indvars.iv.next12 = add nuw nsw i64 %indvars.iv11, 1
+  %lftr.wideiv = trunc i64 %indvars.iv.next12 to i32
+  %exitcond = icmp eq i32 %lftr.wideiv, %indvars.iv15
+  br i1 %exitcond, label %._crit_edge, label %.lr.ph
+
+._crit_edge:                                      ; preds = %.lr.ph, %.lr.ph4
+  %26 = getelementptr inbounds [10 x [10 x [10 x i32]]], [10 x [10 x [10 x i32]]]* @sum_c, i64 0, i64 %indvars.iv23, i64 %indvars.iv19, i64 %14
+  %27 = load i32, i32* %26
+  %28 = getelementptr inbounds [10 x [10 x i32]], [10 x [10 x i32]]* @W, i64 0, i64 %indvars.iv23, i64 %indvars.iv19
+  %29 = load i32, i32* %28
+  %30 = add nsw i32 %29, %27
+  %31 = getelementptr inbounds [10 x [10 x i32]], [10 x [10 x i32]]* @c, i64 0, i64 %indvars.iv23, i64 %indvars.iv19
+  store i32 %30, i32* %31
+  %indvars.iv.next16 = add nuw i32 %indvars.iv15, 1
+  %indvars.iv.next20 = add nuw nsw i64 %indvars.iv19, 1
+  %lftr.wideiv21 = trunc i64 %indvars.iv.next20 to i32
+  %exitcond22 = icmp eq i32 %lftr.wideiv21, %M
+  br i1 %exitcond22, label %.loopexit, label %.lr.ph4
+
+._crit_edge7:                                     ; preds = %.loopexit, %.preheader
+  %32 = load i32, i32* %6
+  %33 = add nsw i32 %10, %32
+  %34 = add nuw nsw i32 %iter.08, 1
+  %exitcond25 = icmp eq i32 %34, %N
+  br i1 %exitcond25, label %._crit_edge9, label %.preheader
+
+._crit_edge9:                                     ; preds = %._crit_edge7
+  store i32 %33, i32* @out_l
+  br label %35
+
+; <label>:35                                      ; preds = %._crit_edge9, %0
+  ret void
+}
+