Index: llvm/lib/Analysis/ScalarEvolution.cpp
===================================================================
--- llvm/lib/Analysis/ScalarEvolution.cpp
+++ llvm/lib/Analysis/ScalarEvolution.cpp
@@ -7822,9 +7822,10 @@
   Idx = getSCEVAtScope(Idx, L);
 
   // We can only recognize very limited forms of loop index expressions, in
-  // particular, only affine AddRec's like {C1,+,C2}.
+  // particular, only affine AddRec's like {C1,+,C2}<L>.
   const SCEVAddRecExpr *IdxExpr = dyn_cast<SCEVAddRecExpr>(Idx);
-  if (!IdxExpr || !IdxExpr->isAffine() || isLoopInvariant(IdxExpr, L) ||
+  if (!IdxExpr || IdxExpr->getLoop() != L || !IdxExpr->isAffine() ||
+      isLoopInvariant(IdxExpr, L) ||
       !isa<SCEVConstant>(IdxExpr->getOperand(0)) ||
       !isa<SCEVConstant>(IdxExpr->getOperand(1)))
     return getCouldNotCompute();
Index: llvm/test/Analysis/ScalarEvolution/incorrect-exit-count.ll
===================================================================
--- /dev/null
+++ llvm/test/Analysis/ScalarEvolution/incorrect-exit-count.ll
@@ -0,0 +1,144 @@
+; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py
+; RUN: opt -analyze -scalar-evolution < %s | FileCheck %s
+
+@b = dso_local global i32 5, align 4
+@__const.f.g = private unnamed_addr constant [1 x [4 x i16]] [[4 x i16] [i16 1, i16 0, i16 0, i16 0]], align 2
+@a = common dso_local global i32 0, align 4
+@c = common dso_local global i32 0, align 4
+@d = common dso_local global i32 0, align 4
+@e = common dso_local global i32 0, align 4
+
+; When inner.loop is taken as an exiting block of outer.loop, we cannot use the
+; addrec of %storemerge1921.3, which is {3, +, -1}<inner.loop>, to calculate the
+; exit count because it doesn't belong to outer.loop.
+define dso_local i32 @f() {
+; CHECK-LABEL: 'f'
+; CHECK-NEXT:  Classifying expressions for: @f
+; CHECK-NEXT:    %storemerge23 = phi i32 [ 3, %entry ], [ %dec16, %for.inc13.3 ]
+; CHECK-NEXT:    --> {3,+,-1}<nsw><%outer.loop> U: [1,4) S: [1,4) Exits: <<Unknown>> LoopDispositions: { %outer.loop: Computable, %for.cond6: Invariant, %inner.loop: Invariant }
+; CHECK-NEXT:    %storemerge1921 = phi i32 [ 3, %outer.loop ], [ %dec, %for.end ]
+; CHECK-NEXT:    --> {3,+,-1}<nuw><nsw><%for.cond6> U: [3,4) S: [3,4) Exits: <<Unknown>> LoopDispositions: { %for.cond6: Computable, %outer.loop: Variant }
+; CHECK-NEXT:    %idxprom20 = zext i32 %storemerge1921 to i64
+; CHECK-NEXT:    --> {3,+,4294967295}<nuw><nsw><%for.cond6> U: [3,4) S: [3,4) Exits: <<Unknown>> LoopDispositions: { %for.cond6: Computable, %outer.loop: Variant }
+; CHECK-NEXT:    %arrayidx7 = getelementptr inbounds [1 x [4 x i16]], [1 x [4 x i16]]* @__const.f.g, i64 0, i64 0, i64 %idxprom20
+; CHECK-NEXT:    --> {(6 + @__const.f.g)<nuw>,+,8589934590}<nuw><%for.cond6> U: [6,-1) S: [-9223372036854775808,9223372036854775807) Exits: <<Unknown>> LoopDispositions: { %for.cond6: Computable, %outer.loop: Variant }
+; CHECK-NEXT:    %i = load i16, i16* %arrayidx7, align 2
+; CHECK-NEXT:    --> %i U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %for.cond6: Variant, %outer.loop: Variant }
+; CHECK-NEXT:    %storemerge1822.lcssa.ph = phi i32 [ 0, %for.cond6 ]
+; CHECK-NEXT:    --> 0 U: [0,1) S: [0,1)
+; CHECK-NEXT:    %storemerge1822.lcssa.ph32 = phi i32 [ 3, %inner.loop ]
+; CHECK-NEXT:    --> 3 U: [3,4) S: [3,4)
+; CHECK-NEXT:    %storemerge1822.lcssa = phi i32 [ %storemerge1822.lcssa.ph, %if.end.loopexit ], [ %storemerge1822.lcssa.ph32, %if.end.loopexit31 ]
+; CHECK-NEXT:    --> %storemerge1822.lcssa U: [0,4) S: [0,4)
+; CHECK-NEXT:    %i1 = load i32, i32* @e, align 4
+; CHECK-NEXT:    --> %i1 U: full-set S: full-set
+; CHECK-NEXT:    %i2 = load volatile i32, i32* @b, align 4
+; CHECK-NEXT:    --> %i2 U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %for.cond6: Variant, %outer.loop: Variant }
+; CHECK-NEXT:    %dec = add nsw i32 %storemerge1921, -1
+; CHECK-NEXT:    --> {2,+,-1}<nsw><%for.cond6> U: [2,3) S: [2,3) Exits: <<Unknown>> LoopDispositions: { %for.cond6: Computable, %outer.loop: Variant }
+; CHECK-NEXT:    %inc.lcssa.lcssa = phi i32 [ 4, %for.inc13.3 ]
+; CHECK-NEXT:    --> 4 U: [4,5) S: [4,5)
+; CHECK-NEXT:    %retval.0 = phi i32 [ %i1, %if.end ], [ 0, %cleanup.loopexit ]
+; CHECK-NEXT:    --> %retval.0 U: full-set S: full-set
+; CHECK-NEXT:    %storemerge1921.3 = phi i32 [ 3, %for.end ], [ %dec.3, %for.end.3 ]
+; CHECK-NEXT:    --> {3,+,-1}<nuw><nsw><%inner.loop> U: [3,4) S: [3,4) Exits: <<Unknown>> LoopDispositions: { %inner.loop: Computable, %outer.loop: Variant }
+; CHECK-NEXT:    %idxprom20.3 = zext i32 %storemerge1921.3 to i64
+; CHECK-NEXT:    --> {3,+,4294967295}<nuw><nsw><%inner.loop> U: [3,4) S: [3,4) Exits: <<Unknown>> LoopDispositions: { %inner.loop: Computable, %outer.loop: Variant }
+; CHECK-NEXT:    %arrayidx7.3 = getelementptr inbounds [1 x [4 x i16]], [1 x [4 x i16]]* @__const.f.g, i64 0, i64 0, i64 %idxprom20.3
+; CHECK-NEXT:    --> {(6 + @__const.f.g)<nuw>,+,8589934590}<nuw><%inner.loop> U: [6,-1) S: [-9223372036854775808,9223372036854775807) Exits: <<Unknown>> LoopDispositions: { %inner.loop: Computable, %outer.loop: Variant }
+; CHECK-NEXT:    %i7 = load i16, i16* %arrayidx7.3, align 2
+; CHECK-NEXT:    --> %i7 U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %inner.loop: Variant, %outer.loop: Variant }
+; CHECK-NEXT:    %i8 = load volatile i32, i32* @b, align 4
+; CHECK-NEXT:    --> %i8 U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %inner.loop: Variant, %outer.loop: Variant }
+; CHECK-NEXT:    %dec.3 = add nsw i32 %storemerge1921.3, -1
+; CHECK-NEXT:    --> {2,+,-1}<nsw><%inner.loop> U: [2,3) S: [2,3) Exits: <<Unknown>> LoopDispositions: { %inner.loop: Computable, %outer.loop: Variant }
+; CHECK-NEXT:    %storemerge1921.lcssa25.3 = phi i32 [ %storemerge1921.3, %for.end.3 ]
+; CHECK-NEXT:    --> %storemerge1921.lcssa25.3 U: [3,4) S: [3,4) Exits: <<Unknown>> LoopDispositions: { %outer.loop: Variant, %for.cond6: Invariant, %inner.loop: Invariant }
+; CHECK-NEXT:    %dec16 = add nsw i32 %storemerge23, -1
+; CHECK-NEXT:    --> {2,+,-1}<nsw><%outer.loop> U: [0,3) S: [0,3) Exits: <<Unknown>> LoopDispositions: { %outer.loop: Computable, %for.cond6: Invariant, %inner.loop: Invariant }
+; CHECK-NEXT:  Determining loop execution counts for: @f
+; CHECK-NEXT:  Loop %for.cond6: <multiple exits> Unpredictable backedge-taken count.
+; CHECK-NEXT:    exit count for for.cond6: 0
+; CHECK-NEXT:    exit count for for.end: ***COULDNOTCOMPUTE***
+; CHECK-NEXT:  Loop %for.cond6: max backedge-taken count is 0
+; CHECK-NEXT:  Loop %for.cond6: Unpredictable predicated backedge-taken count.
+; CHECK-NEXT:  Loop %inner.loop: <multiple exits> Unpredictable backedge-taken count.
+; CHECK-NEXT:    exit count for inner.loop: 0
+; CHECK-NEXT:    exit count for for.end.3: ***COULDNOTCOMPUTE***
+; CHECK-NEXT:  Loop %inner.loop: max backedge-taken count is 0
+; CHECK-NEXT:  Loop %inner.loop: Unpredictable predicated backedge-taken count.
+; CHECK-NEXT:  Loop %outer.loop: <multiple exits> Unpredictable backedge-taken count.
+; CHECK-NEXT:    exit count for for.cond6: ***COULDNOTCOMPUTE***
+; CHECK-NEXT:    exit count for inner.loop: ***COULDNOTCOMPUTE***
+; CHECK-NEXT:    exit count for for.inc13.3: 2
+; CHECK-NEXT:  Loop %outer.loop: max backedge-taken count is 2
+; CHECK-NEXT:  Loop %outer.loop: Unpredictable predicated backedge-taken count.
+;
+entry:
+  store i32 3, i32* @a, align 4
+  br label %outer.loop
+
+outer.loop:                              ; preds = %for.inc13.3, %entry
+  %storemerge23 = phi i32 [ 3, %entry ], [ %dec16, %for.inc13.3 ]
+  br label %for.cond6
+
+for.cond6:                                        ; preds = %for.end, %outer.loop
+  %storemerge1921 = phi i32 [ 3, %outer.loop ], [ %dec, %for.end ]
+  %idxprom20 = zext i32 %storemerge1921 to i64
+  %arrayidx7 = getelementptr inbounds [1 x [4 x i16]], [1 x [4 x i16]]* @__const.f.g, i64 0, i64 0, i64 %idxprom20
+  %i = load i16, i16* %arrayidx7, align 2
+  %tobool8 = icmp eq i16 %i, 0
+  br i1 %tobool8, label %if.end.loopexit, label %for.end
+
+if.end.loopexit:                                  ; preds = %for.cond6
+  %storemerge1822.lcssa.ph = phi i32 [ 0, %for.cond6 ]
+  br label %if.end
+
+if.end.loopexit31:                                ; preds = %inner.loop
+  %storemerge1822.lcssa.ph32 = phi i32 [ 3, %inner.loop ]
+  br label %if.end
+
+if.end:                                           ; preds = %if.end.loopexit31, %if.end.loopexit
+  %storemerge1822.lcssa = phi i32 [ %storemerge1822.lcssa.ph, %if.end.loopexit ], [ %storemerge1822.lcssa.ph32, %if.end.loopexit31 ]
+  store i32 %storemerge1822.lcssa, i32* @c, align 4
+  store i32 2, i32* @d, align 4
+  %i1 = load i32, i32* @e, align 4
+  br label %cleanup
+
+for.end:                                          ; preds = %for.cond6
+  %i2 = load volatile i32, i32* @b, align 4
+  %tobool9 = icmp eq i32 %i2, 0
+  %dec = add nsw i32 %storemerge1921, -1
+  br i1 %tobool9, label %for.cond6, label %inner.loop
+
+cleanup.loopexit:                                 ; preds = %for.inc13.3
+  %inc.lcssa.lcssa = phi i32 [ 4, %for.inc13.3 ]
+  store i32 %inc.lcssa.lcssa, i32* @c, align 4
+  br label %cleanup
+
+cleanup:                                          ; preds = %cleanup.loopexit, %if.end
+  %retval.0 = phi i32 [ %i1, %if.end ], [ 0, %cleanup.loopexit ]
+  ret i32 %retval.0
+
+inner.loop:                                      ; preds = %for.end.3, %for.end
+  %storemerge1921.3 = phi i32 [ 3, %for.end ], [ %dec.3, %for.end.3 ]
+  %idxprom20.3 = zext i32 %storemerge1921.3 to i64
+  %arrayidx7.3 = getelementptr inbounds [1 x [4 x i16]], [1 x [4 x i16]]* @__const.f.g, i64 0, i64 0, i64 %idxprom20.3
+  %i7 = load i16, i16* %arrayidx7.3, align 2
+  %tobool8.3 = icmp eq i16 %i7, 0
+  br i1 %tobool8.3, label %if.end.loopexit31, label %for.end.3
+
+for.end.3:                                        ; preds = %inner.loop
+  %i8 = load volatile i32, i32* @b, align 4
+  %tobool9.3 = icmp eq i32 %i8, 0
+  %dec.3 = add nsw i32 %storemerge1921.3, -1
+  br i1 %tobool9.3, label %inner.loop, label %for.inc13.3
+
+for.inc13.3:                                      ; preds = %for.end.3
+  %storemerge1921.lcssa25.3 = phi i32 [ %storemerge1921.3, %for.end.3 ]
+  store i32 %storemerge1921.lcssa25.3, i32* @d, align 4
+  %dec16 = add nsw i32 %storemerge23, -1
+  store i32 %dec16, i32* @a, align 4
+  %tobool = icmp eq i32 %dec16, 0
+  br i1 %tobool, label %cleanup.loopexit, label %outer.loop
+}