Add a testcase demoing some of ScalarEvolution's new trip count logic.

llvm-svn: 74049

test/Analysis/ScalarEvolution/trip-count6.ll

@@ -0,0 +1,37 @@
+; RUN: llvm-as < %s | opt -analyze -disable-output -scalar-evolution \
+; RUN:  | grep {max backedge-taken count is 1\$}
+
+@mode_table = global [4 x i32] zeroinitializer          ; <[4 x i32]*> [#uses=1]
+
+define i8 @f() {
+entry:
+  tail call i32 @fegetround( )          ; <i32>:0 [#uses=1]
+  br label %bb
+
+bb:             ; preds = %bb4, %entry
+  %mode.0 = phi i8 [ 0, %entry ], [ %indvar.next, %bb4 ]                ; <i8> [#uses=4]
+  zext i8 %mode.0 to i32                ; <i32>:1 [#uses=1]
+  getelementptr [4 x i32]* @mode_table, i32 0, i32 %1           ; <i32*>:2 [#uses=1]
+  load i32* %2, align 4         ; <i32>:3 [#uses=1]
+  icmp eq i32 %3, %0            ; <i1>:4 [#uses=1]
+  br i1 %4, label %bb1, label %bb2
+
+bb1:            ; preds = %bb
+  ret i8 %mode.0
+
+bb2:            ; preds = %bb
+  icmp eq i8 %mode.0, 1         ; <i1>:5 [#uses=1]
+  br i1 %5, label %bb5, label %bb4
+
+bb4:            ; preds = %bb2
+  %indvar.next = add i8 %mode.0, 1              ; <i8> [#uses=1]
+  br label %bb
+
+bb5:            ; preds = %bb2
+  tail call void @raise_exception( ) noreturn 
+  unreachable
+}
+
+declare i32 @fegetround()
+
+declare void @raise_exception() noreturn