1 files changed, 164 insertions, 0 deletions
diff --git a/llvm/test/Analysis/ScalarEvolution/shift-op.ll b/llvm/test/Analysis/ScalarEvolution/shift-op.ll
new file mode 100644
index 00000000000..fe832d56768
--- /dev/null
+++ b/llvm/test/Analysis/ScalarEvolution/shift-op.ll
@@ -0,0 +1,164 @@
+; RUN: opt -analyze -scalar-evolution < %s | FileCheck %s
+
+define void @test0(i32 %init) {
+; CHECK-LABEL: Classifying expressions for: @test0
+; CHECK: Loop %loop: max backedge-taken count is 32
+ entry:
+  br label %loop
+
+ loop:
+  %iv = phi i32 [ %init, %entry ], [ %iv.shift, %loop ]
+  %iv.shift = lshr i32 %iv, 1
+  %exit.cond = icmp eq i32 %iv, 0
+  br i1 %exit.cond, label %leave, label %loop
+
+ leave:
+  ret void
+}
+
+define void @test1(i32 %init) {
+; CHECK-LABEL: Classifying expressions for: @test1
+; CHECK: Loop %loop: max backedge-taken count is 32
+ entry:
+  br label %loop
+
+ loop:
+  %iv = phi i32 [ %init, %entry ], [ %iv.shift, %loop ]
+  %iv.shift = shl i32 %iv, 1
+  %exit.cond = icmp eq i32 %iv, 0
+  br i1 %exit.cond, label %leave, label %loop
+
+ leave:
+  ret void
+}
+
+define void @test2(i32 %init) {
+; CHECK-LABEL: Determining loop execution counts for: @test2
+; CHECK: Loop %loop: Unpredictable max backedge-taken count.
+
+; Unpredictable because %iv could "stabilize" to either -1 or 0,
+; depending on %init.
+ entry:
+  br label %loop
+
+ loop:
+  %iv = phi i32 [ %init, %entry ], [ %iv.shift, %loop ]
+  %iv.shift = ashr i32 %iv, 1
+  %exit.cond = icmp eq i32 %iv, 0
+  br i1 %exit.cond, label %leave, label %loop
+
+ leave:
+  ret void
+}
+
+define void @test3(i32* %init.ptr) {
+; CHECK-LABEL: Determining loop execution counts for: @test3
+; CHECK: Loop %loop: max backedge-taken count is 32
+ entry:
+  %init = load i32, i32* %init.ptr, !range !0
+  br label %loop
+
+ loop:
+  %iv = phi i32 [ %init, %entry ], [ %iv.shift, %loop ]
+  %iv.shift = ashr i32 %iv, 1
+  %exit.cond = icmp eq i32 %iv, 0
+  br i1 %exit.cond, label %leave, label %loop
+
+ leave:
+  ret void
+}
+
+define void @test4(i32* %init.ptr) {
+; CHECK-LABEL: Classifying expressions for: @test4
+; CHECK-LABEL: Loop %loop: max backedge-taken count is 32
+ entry:
+  %init = load i32, i32* %init.ptr, !range !1
+  br label %loop
+
+ loop:
+  %iv = phi i32 [ %init, %entry ], [ %iv.shift, %loop ]
+  %iv.shift = ashr i32 %iv, 1
+  %exit.cond = icmp eq i32 %iv, -1
+  br i1 %exit.cond, label %leave, label %loop
+
+ leave:
+  ret void
+}
+
+define void @test5(i32* %init.ptr) {
+; CHECK-LABEL: Determining loop execution counts for: @test5
+; CHECK: Loop %loop: Unpredictable max backedge-taken count.
+
+; %iv will "stabilize" to -1, so this is an infinite loop
+ entry:
+  %init = load i32, i32* %init.ptr, !range !1
+  br label %loop
+
+ loop:
+  %iv = phi i32 [ %init, %entry ], [ %iv.shift, %loop ]
+  %iv.shift = ashr i32 %iv, 1
+  %exit.cond = icmp eq i32 %iv, 0
+  br i1 %exit.cond, label %leave, label %loop
+
+ leave:
+  ret void
+}
+
+define void @test6(i32 %init, i32 %shift.amt) {
+; CHECK-LABEL: Determining loop execution counts for: @test6
+; CHECK: Loop %loop: Unpredictable max backedge-taken count.
+
+; Potentially infinite loop, since %shift.amt could be 0
+ entry:
+  br label %loop
+
+ loop:
+  %iv = phi i32 [ %init, %entry ], [ %iv.shift, %loop ]
+  %iv.shift = lshr i32 %iv, %shift.amt
+  %exit.cond = icmp eq i32 %iv, 0
+  br i1 %exit.cond, label %leave, label %loop
+
+ leave:
+  ret void
+}
+
+define void @test7(i32 %init) {
+; CHECK-LABEL: Classifying expressions for: @test7
+; CHECK: Loop %loop: max backedge-taken count is 32
+
+ entry:
+  br label %loop
+
+ loop:
+  %iv = phi i32 [ %init, %entry ], [ %iv.shift, %loop ]
+  %iv.shift = lshr i32 %iv, 1
+  %exit.cond = icmp eq i32 %iv.shift, 0
+  br i1 %exit.cond, label %leave, label %loop
+
+ leave:
+  ret void
+}
+
+define void @test8(i32 %init) {
+; CHECK-LABEL: Classifying expressions for: @test8
+; CHECK: Loop %loop: Unpredictable max backedge-taken count.
+
+; In this test case, %iv.test stabilizes to 127, not -1, so the loop
+; is infinite.
+
+ entry:
+  br label %loop
+
+ loop:
+  %iv = phi i32 [ %init, %entry ], [ %iv.shift, %loop ]
+  %iv.shift = ashr i32 %iv, 1
+  %iv.test = lshr i32 %iv, 1
+  %exit.cond = icmp eq i32 %iv.test, -1
+  br i1 %exit.cond, label %leave, label %loop
+
+ leave:
+  ret void
+}
+
+!0 = !{i32 0, i32 50000}
+!1 = !{i32 -5000, i32 -1}