1 files changed, 82 insertions, 0 deletions
diff --git a/test/Analysis/ScalarEvolution/scev-prestart-nowrap.ll b/test/Analysis/ScalarEvolution/scev-prestart-nowrap.ll
new file mode 100644
index 0000000..3ca32bd
--- /dev/null
+++ b/test/Analysis/ScalarEvolution/scev-prestart-nowrap.ll
@@ -0,0 +1,82 @@
+; RUN: opt -analyze -scalar-evolution < %s | FileCheck %s
+
+; An example run where SCEV(%postinc)->getStart() may overflow:
+;
+; %start = INT_SMAX
+; %low.limit = INT_SMIN
+; %high.limit = < not used >
+;
+; >> entry:
+;  %postinc.start = INT_SMIN
+;
+; >> loop:
+;  %idx = %start 
+;  %postinc = INT_SMIN
+;  %postinc.inc = INT_SMIN + 1
+;  %postinc.sext = sext(INT_SMIN) = i64 INT32_SMIN
+;  %break.early = INT_SMIN `slt` INT_SMIN = false
+;  br i1 false, ___,  %early.exit
+;
+; >> early.exit:
+;  ret i64 INT32_SMIN
+
+
+define i64 @bad.0(i32 %start, i32 %low.limit, i32 %high.limit) {
+; CHECK-LABEL: Classifying expressions for: @bad.0
+ entry:
+  %postinc.start = add i32 %start, 1
+  br label %loop
+
+ loop:
+  %idx = phi i32 [ %start, %entry ], [ %idx.inc, %continue ]
+  %postinc = phi i32 [ %postinc.start, %entry ], [ %postinc.inc, %continue ]
+  %postinc.inc = add nsw i32 %postinc, 1
+  %postinc.sext = sext i32 %postinc to i64
+; CHECK:  %postinc.sext = sext i32 %postinc to i64
+; CHECK-NEXT:  -->  {(sext i32 (1 + %start) to i64),+,1}<nsw><%loop>
+  %break.early = icmp slt i32 %postinc, %low.limit
+  br i1 %break.early, label %continue, label %early.exit
+
+ continue:
+  %idx.inc = add nsw i32 %idx, 1
+  %cmp = icmp slt i32 %idx.inc, %high.limit
+  br i1 %cmp, label %loop, label %exit
+
+ exit:
+  ret i64 0
+
+ early.exit:
+  ret i64 %postinc.sext
+}
+
+define i64 @bad.1(i32 %start, i32 %low.limit, i32 %high.limit, i1* %unknown) {
+; CHECK-LABEL: Classifying expressions for: @bad.1
+ entry:
+  %postinc.start = add i32 %start, 1
+  br label %loop
+
+ loop:
+  %idx = phi i32 [ %start, %entry ], [ %idx.inc, %continue ], [ %idx.inc, %continue.1 ]
+  %postinc = phi i32 [ %postinc.start, %entry ], [ %postinc.inc, %continue ], [ %postinc.inc, %continue.1 ]
+  %postinc.inc = add nsw i32 %postinc, 1
+  %postinc.sext = sext i32 %postinc to i64
+; CHECK:  %postinc.sext = sext i32 %postinc to i64
+; CHECK-NEXT:  -->  {(sext i32 (1 + %start) to i64),+,1}<nsw><%loop>
+  %break.early = icmp slt i32 %postinc, %low.limit
+  br i1 %break.early, label %continue.1, label %early.exit
+
+ continue.1:
+  %cond = load volatile i1* %unknown
+  %idx.inc = add nsw i32 %idx, 1
+  br i1 %cond, label %loop, label %continue
+
+ continue:
+  %cmp = icmp slt i32 %idx.inc, %high.limit
+  br i1 %cmp, label %loop, label %exit
+
+ exit:
+  ret i64 0
+
+ early.exit:
+  ret i64 %postinc.sext
+}