[ValueTracking] De-pessimize isImpliedCondition around unsigned compares
Summary:
Currently `isImpliedCondition` will optimize "I +_nuw C < L ==> I < L"
only if C is positive. This is an unnecessary restriction -- the
implication holds even if `C` is negative.
Reviewers: reames, majnemer
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D14369
llvm-svn: 252332
diff --git a/llvm/test/Transforms/InstSimplify/implies.ll b/llvm/test/Transforms/InstSimplify/implies.ll
index 8e5bbf2..eb8db42 100644
--- a/llvm/test/Transforms/InstSimplify/implies.ll
+++ b/llvm/test/Transforms/InstSimplify/implies.ll
@@ -65,7 +65,7 @@
ret i1 %res
}
-; i +_{nuw} C_{>0} <u L ==> i <u L
+; i +_{nuw} C <u L ==> i <u L
define i1 @test4(i32 %length.i, i32 %i) {
; CHECK-LABEL: @test4
; CHECK: ret i1 true
@@ -116,6 +116,17 @@
ret i1 %res
}
+; i +_{nuw} C <s L ==> i < L, even if C is negative
+define i1 @test9(i32 %length.i, i32 %i) {
+; CHECK-LABEL: @test9(
+; CHECK: ret i1 true
+ %iplus1 = add nuw i32 %i, -100
+ %var29 = icmp ult i32 %i, %length.i
+ %var30 = icmp ult i32 %iplus1, %length.i
+ %res = icmp ule i1 %var30, %var29
+ ret i1 %res
+}
+
; X >=(s) Y == X ==> Y (i1 1 becomes -1 for reasoning)
define i1 @test_sge(i32 %length.i, i32 %i) {
; CHECK-LABEL: @test_sge