InstSimplify: Handle some simple tautological comparisons
This handles cases where we are comparing a masked value against itself.
The analysis could be further improved by making it recursive but such
expense is not currently justified.
llvm-svn: 222716
diff --git a/llvm/test/Transforms/InstSimplify/compare.ll b/llvm/test/Transforms/InstSimplify/compare.ll
index 38fd747..10c7ca6 100644
--- a/llvm/test/Transforms/InstSimplify/compare.ll
+++ b/llvm/test/Transforms/InstSimplify/compare.ll
@@ -1100,3 +1100,67 @@
; CHECK-LABEL: @icmp_shl_1_V_ne_31(
; CHECK-NEXT: ret i1 true
}
+
+define i1 @tautological1(i32 %A, i32 %B) {
+ %C = and i32 %A, %B
+ %D = icmp ugt i32 %C, %A
+ ret i1 %D
+; CHECK-LABEL: @tautological1(
+; CHECK: ret i1 false
+}
+
+define i1 @tautological2(i32 %A, i32 %B) {
+ %C = and i32 %A, %B
+ %D = icmp ule i32 %C, %A
+ ret i1 %D
+; CHECK-LABEL: @tautological2(
+; CHECK: ret i1 true
+}
+
+define i1 @tautological3(i32 %A, i32 %B) {
+ %C = or i32 %A, %B
+ %D = icmp ule i32 %A, %C
+ ret i1 %D
+; CHECK-LABEL: @tautological3(
+; CHECK: ret i1 true
+}
+
+define i1 @tautological4(i32 %A, i32 %B) {
+ %C = or i32 %A, %B
+ %D = icmp ugt i32 %A, %C
+ ret i1 %D
+; CHECK-LABEL: @tautological4(
+; CHECK: ret i1 false
+}
+
+define i1 @tautological5(i32 %A, i32 %B) {
+ %C = or i32 %A, %B
+ %D = icmp ult i32 %C, %A
+ ret i1 %D
+; CHECK-LABEL: @tautological5(
+; CHECK: ret i1 false
+}
+
+define i1 @tautological6(i32 %A, i32 %B) {
+ %C = or i32 %A, %B
+ %D = icmp uge i32 %C, %A
+ ret i1 %D
+; CHECK-LABEL: @tautological6(
+; CHECK: ret i1 true
+}
+
+define i1 @tautological7(i32 %A, i32 %B) {
+ %C = and i32 %A, %B
+ %D = icmp uge i32 %A, %C
+ ret i1 %D
+; CHECK-LABEL: @tautological7(
+; CHECK: ret i1 true
+}
+
+define i1 @tautological8(i32 %A, i32 %B) {
+ %C = and i32 %A, %B
+ %D = icmp ult i32 %A, %C
+ ret i1 %D
+; CHECK-LABEL: @tautological8(
+; CHECK: ret i1 false
+}