InstSimplify: The upper bound of X / C was missing a rounding step
Summary:
When calculating the upper bound of X / -8589934592, we would perform
the following calculation: Floor[INT_MAX / 8589934592]
However, flooring the result would make us wrongly come to the
conclusion that 1073741824 was not in the set of possible values.
Instead, use the ceiling of the result.
Reviewers: nicholas
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D4502
llvm-svn: 212976
diff --git a/llvm/test/Transforms/InstSimplify/compare.ll b/llvm/test/Transforms/InstSimplify/compare.ll
index 7d0cd9c..d329b7b 100644
--- a/llvm/test/Transforms/InstSimplify/compare.ll
+++ b/llvm/test/Transforms/InstSimplify/compare.ll
@@ -913,3 +913,14 @@
; CHECK-NEXT: [[CMP:%.*]] = icmp ne i32 [[DIV]], -1073741824
; CHECK-NEXT: ret i1 [[CMP]]
}
+
+define i1 @icmp_sdiv_pr20288(i64 %a) {
+ %div = sdiv i64 %a, -8589934592
+ %cmp = icmp ne i64 %div, 1073741824
+ ret i1 %cmp
+
+; CHECK-LABEL: @icmp_sdiv_pr20288
+; CHECK-NEXT: [[DIV:%.*]] = sdiv i64 %a, -8589934592
+; CHECK-NEXT: [[CMP:%.*]] = icmp ne i64 [[DIV]], 1073741824
+; CHECK-NEXT: ret i1 [[CMP]]
+}