[SCEV] Add additional tests where the max BTC is limited by wrapping.

llvm/test/Analysis/ScalarEvolution/max-backedge-taken-count-limit-by-wrapping.ll

@@ -4,8 +4,8 @@
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
-define void @max_backedge_taken_count_by_wrapping1(i8 %N, i8* %ptr) {
-; CHECK-LABEL: Determining loop execution counts for: @max_backedge_taken_count_by_wrapping1
+define void @max_backedge_taken_count_by_wrapping1_nsw_nuw(i8 %N, i8* %ptr) {
+; CHECK-LABEL: Determining loop execution counts for: @max_backedge_taken_count_by_wrapping1_nsw_nuw
 ; CHECK-NEXT:  Loop %loop: backedge-taken count is (%N /u 4)
 ; CHECK-NEXT:  Loop %loop: max backedge-taken count is 63
 ; CHECK-NEXT:  Loop %loop: Predicated backedge-taken count is (%N /u 4)
@@ -25,18 +25,38 @@ exit:
   ret void
 }
 
-; TODO: Max backedge taken count could be improved.
-define void @max_backedge_taken_count_by_wrapping2(i8 %N, i8* %ptr) {
+define void @max_backedge_taken_count_by_wrapping1_nuw(i8 %N, i8* %ptr) {
+; CHECK-LABEL: Determining loop execution counts for: @max_backedge_taken_count_by_wrapping1_nuw
+; CHECK-NEXT:  Loop %loop: backedge-taken count is (%N /u 4)
+; CHECK-NEXT:  Loop %loop: max backedge-taken count is 63
+; CHECK-NEXT:  Loop %loop: Predicated backedge-taken count is (%N /u 4)
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i8 [ 0, %entry ], [ %iv.next, %loop ]
+  %gep = getelementptr i8, i8* %ptr, i8 %iv
+  store i8 %iv, i8* %gep
+  %iv.next = add nuw i8 %iv, 4
+  %ec = icmp ne i8 %iv, %N
+  br i1 %ec, label %loop, label %exit
+
+exit:
+  ret void
+}
+
+define void @max_backedge_taken_count_by_wrapping2_nsw_nuw(i8 %N, i8* %ptr) {
 ; CHECK-LABEL: Determining loop execution counts for: @max_backedge_taken_count_by_wrapping2
-; CHECK-NEXT:  Loop %loop: backedge-taken count is ((-128 + %N) /u 4)
+; CHECK-NEXT:  Loop %loop: backedge-taken count is ((-64 + %N) /u 4)
 ; CHECK-NEXT:  Loop %loop: max backedge-taken count is 63
-; CHECK-NEXT:  Loop %loop: Predicated backedge-taken count is ((-128 + %N) /u 4)
+; CHECK-NEXT:  Loop %loop: Predicated backedge-taken count is ((-64 + %N) /u 4)
 ;
 entry:
   br label %loop
 
 loop:
-  %iv = phi i8 [ 128, %entry ], [ %iv.next, %loop ]
+  %iv = phi i8 [ 64, %entry ], [ %iv.next, %loop ]
   %gep = getelementptr i8, i8* %ptr, i8 %iv
   store i8 %iv, i8* %gep
   %iv.next = add nuw nsw i8 %iv, 4
@@ -46,3 +66,24 @@ loop:
 exit:
   ret void
 }
+
+define void @max_backedge_taken_count_by_wrapping2_nuw(i8 %N, i8* %ptr) {
+; CHECK-LABEL: Determining loop execution counts for: @max_backedge_taken_count_by_wrapping2
+; CHECK-NEXT:  Loop %loop: backedge-taken count is ((-64  + %N) /u 4)
+; CHECK-NEXT:  Loop %loop: max backedge-taken count is 63
+; CHECK-NEXT:  Loop %loop: Predicated backedge-taken count is ((-64 + %N) /u 4)
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i8 [ 64, %entry ], [ %iv.next, %loop ]
+  %gep = getelementptr i8, i8* %ptr, i8 %iv
+  store i8 %iv, i8* %gep
+  %iv.next = add nuw i8 %iv, 4
+  %ec = icmp ne i8 %iv, %N
+  br i1 %ec, label %loop, label %exit
+
+exit:
+  ret void
+}